Author name code: christensen-dalsgaard ADS astronomy entries on 2022-09-14 author:"Christensen-Dalsgaard, Jorgen" ------------------------------------------------------------------------ Title: Evolution of dipolar mixed-mode coupling factor in red giant stars: impact of buoyancy spike Authors: Jiang, C.; Cunha, M.; Christensen-Dalsgaard, J.; Zhang, Q. S.; Gizon, L. Bibcode: 2022MNRAS.515.3853J Altcode: 2022arXiv220709878J; 2022MNRAS.tmp.1954J Mixed modes observed in red giants allow for investigation of the stellar interior structures. One important feature in these structures is the buoyancy spike caused by the discontinuity of the chemical gradient left behind during the first dredge-up. The buoyancy spike emerges at the base of the convective zone in low-luminosity red giants and later becomes a glitch when the g-mode cavity expands to encompass the spike. Here, we study the impact of the buoyancy spike on the dipolar mixed modes using stellar models with different properties. We find that the applicability of the asymptotic formalisms for the coupling factor, q, varies depending on the location of the evanescent zone, relative to the position of the spike. Significant deviations between the value of q inferred from fitting the oscillation frequencies and either of the formalisms proposed in the literature are found in models with a large frequency separation in the interval 5-15 μHz, with evanescent zones located in a transition region that may be thin or thick. However, it is still possible to reconcile q with the predictions from the asymptotic formalisms, by choosing which formalism to use according to the value of q. For stars approaching the luminosity bump, the buoyancy spike becomes a glitch and strongly affects the mode frequencies. Fitting the frequencies without accounting for the glitch leads to unphysical variations in the inferred q, but we show that this is corrected when properly accounting for the glitch in the fitting. Title: Towards solar measurements of nuclear reaction rates Authors: Bellinger, Earl Patrick; Christensen-Dalsgaard, Jørgen Bibcode: 2022arXiv220613570B Altcode: Nuclear reaction rates are a fundamental yet uncertain ingredient in stellar evolution models. The astrophysical S-factor pertaining to the initial reaction in the proton-proton chain is uncertain at the 1% level, which contributes a systematic but generally unpropagated error of similar order in the theoretical ages of stars. In this work, we study the prospect of improving the measurement of this and other reaction rates in the pp chain and CNO cycle using helioseismology and solar neutrinos. We show that when other aspects of the solar model are improved, then it shall be possible using current solar data to improve the precision of this measurement by nearly an order of magnitude, and hence the corresponding uncertainty on the ages of low-mass stars by a similar amount. Title: Core overshoot constrained by the absence of a solar convective core and some solar-like stars Authors: Zhang, Qian-Sheng; Christensen-Dalsgaard, Jørgen; Li, Yan Bibcode: 2022MNRAS.512.4852Z Altcode: 2022arXiv220308686Z; 2022MNRAS.tmp..742Z Convective-core overshoot mixing is a significant uncertainty in stellar evolution. Because numerical simulations and turbulent convection models predict exponentially decreasing radial rms turbulent velocity, a popular treatment for overshoot mixing is to apply a diffusion process with an exponentially decreasing diffusion coefficient. It is important to investigate the parameters of the diffusion coefficient because they determine the efficiency of the mixing in the overshoot region. In this paper, we have investigated the effects of the core overshoot mixing on the properties of the core in solar models. We have constrained the parameters of the overshoot model by using helioseismic inferences and the observation of the solar 8B neutrino flux. For solar-mass stars, the core overshoot mixing helps to prolong the lifetime of the convective core developed at the zero-age main sequence. If the strength of the mixing is sufficiently high, then the convective core in a solar model could survive until the present solar age, leading to large deviations of the sound speed and density profiles compared with the helioseismic inferences. The 8B neutrino flux also favours a radiative solar core. These observations provide a constraint on the parameters of the exponential diffusion model of the convective overshoot mixing. A limited asteroseismic investigation of 13 Kepler low-mass stars with 1.0 < M/M⊙ < 1.5 shows a mass-dependent range of the overshoot parameter. The overshoot mixing processes for different elements are analysed in detail. It is found that the exponential diffusion overshoot model leads to different effective overshoot mixing lengths for elements with different nuclear equilibrium time-scales. Title: ET White Paper: To Find the First Earth 2.0 Authors: Ge, Jian; Zhang, Hui; Zang, Weicheng; Deng, Hongping; Mao, Shude; Xie, Ji-Wei; Liu, Hui-Gen; Zhou, Ji-Lin; Willis, Kevin; Huang, Chelsea; Howell, Steve B.; Feng, Fabo; Zhu, Jiapeng; Yao, Xinyu; Liu, Beibei; Aizawa, Masataka; Zhu, Wei; Li, Ya-Ping; Ma, Bo; Ye, Quanzhi; Yu, Jie; Xiang, Maosheng; Yu, Cong; Liu, Shangfei; Yang, Ming; Wang, Mu-Tian; Shi, Xian; Fang, Tong; Zong, Weikai; Liu, Jinzhong; Zhang, Yu; Zhang, Liyun; El-Badry, Kareem; Shen, Rongfeng; Tam, Pak-Hin Thomas; Hu, Zhecheng; Yang, Yanlv; Zou, Yuan-Chuan; Wu, Jia-Li; Lei, Wei-Hua; Wei, Jun-Jie; Wu, Xue-Feng; Sun, Tian-Rui; Wang, Fa-Yin; Zhang, Bin-Bin; Xu, Dong; Yang, Yuan-Pei; Li, Wen-Xiong; Xiang, Dan-Feng; Wang, Xiaofeng; Wang, Tinggui; Zhang, Bing; Jia, Peng; Yuan, Haibo; Zhang, Jinghua; Xuesong Wang, Sharon; Gan, Tianjun; Wang, Wei; Zhao, Yinan; Liu, Yujuan; Wei, Chuanxin; Kang, Yanwu; Yang, Baoyu; Qi, Chao; Liu, Xiaohua; Zhang, Quan; Zhu, Yuji; Zhou, Dan; Zhang, Congcong; Yu, Yong; Zhang, Yongshuai; Li, Yan; Tang, Zhenghong; Wang, Chaoyan; Wang, Fengtao; Li, Wei; Cheng, Pengfei; Shen, Chao; Li, Baopeng; Pan, Yue; Yang, Sen; Gao, Wei; Song, Zongxi; Wang, Jian; Zhang, Hongfei; Chen, Cheng; Wang, Hui; Zhang, Jun; Wang, Zhiyue; Zeng, Feng; Zheng, Zhenhao; Zhu, Jie; Guo, Yingfan; Zhang, Yihao; Li, Yudong; Wen, Lin; Feng, Jie; Chen, Wen; Chen, Kun; Han, Xingbo; Yang, Yingquan; Wang, Haoyu; Duan, Xuliang; Huang, Jiangjiang; Liang, Hong; Bi, Shaolan; Gai, Ning; Ge, Zhishuai; Guo, Zhao; Huang, Yang; Li, Gang; Li, Haining; Li, Tanda; Yuxi; Lu; Rix, Hans-Walter; Shi, Jianrong; Song, Fen; Tang, Yanke; Ting, Yuan-Sen; Wu, Tao; Wu, Yaqian; Yang, Taozhi; Yin, Qing-Zhu; Gould, Andrew; Lee, Chung-Uk; Dong, Subo; Yee, Jennifer C.; Shvartzvald, Yossi; Yang, Hongjing; Kuang, Renkun; Zhang, Jiyuan; Liao, Shilong; Qi, Zhaoxiang; Yang, Jun; Zhang, Ruisheng; Jiang, Chen; Ou, Jian-Wen; Li, Yaguang; Beck, Paul; Bedding, Timothy R.; Campante, Tiago L.; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; García, Rafael A.; Gaulme, Patrick; Gizon, Laurent; Hekker, Saskia; Huber, Daniel; Khanna, Shourya; Li, Yan; Mathur, Savita; Miglio, Andrea; Mosser, Benoît; Ong, J. M. Joel; Santos, Ângela R. G.; Stello, Dennis; Bowman, Dominic M.; Lares-Martiz, Mariel; Murphy, Simon; Niu, Jia-Shu; Ma, Xiao-Yu; Molnár, László; Fu, Jian-Ning; De Cat, Peter; Su, Jie; consortium, the ET Bibcode: 2022arXiv220606693G Altcode: We propose to develop a wide-field and ultra-high-precision photometric survey mission, temporarily named "Earth 2.0 (ET)". This mission is designed to measure, for the first time, the occurrence rate and the orbital distributions of Earth-sized planets. ET consists of seven 30cm telescopes, to be launched to the Earth-Sun's L2 point. Six of these are transit telescopes with a field of view of 500 square degrees. Staring in the direction that encompasses the original Kepler field for four continuous years, this monitoring will return tens of thousands of transiting planets, including the elusive Earth twins orbiting solar-type stars. The seventh telescope is a 30cm microlensing telescope that will monitor an area of 4 square degrees toward the galactic bulge. This, combined with simultaneous ground-based KMTNet observations, will measure masses for hundreds of long-period and free-floating planets. Together, the transit and the microlensing telescopes will revolutionize our understandings of terrestrial planets across a large swath of orbital distances and free space. In addition, the survey data will also facilitate studies in the fields of asteroseismology, Galactic archeology, time-domain sciences, and black holes in binaries. Title: Searching for dark energy with the Sun Authors: Saltas, Ippocratis D.; Christensen-Dalsgaard, Jørgen Bibcode: 2022arXiv220514134S Altcode: General extensions of General Relativity (GR) based on bona fide degrees of freedom predict a fifth force which operates within massive objects, opening up an exciting opportunity to perform precision tests of gravity at stellar scales. Here, focusing on general scalar-tensor theories for dark energy, we utilize the Sun as our laboratory and search for imprints of the fifth-force effect on the solar equilibrium structure. With analytic results and numerical simulations, we explain how the different solar regions offer powerful ways to test gravity. Accounting for the delicate interplay between fifth force and solar microphysics such as opacity, diffusion, equation of state and metallicity, we demonstrate that the fifth force still leaves a sharp signature on the solar sound speed, in a region where simple estimates of input physics uncertainties become negligible. For general scalar-field extensions of GR, known as (U-)DHOST, based solely on the observational helioseismic errors, our analysis at the equilibrium level allows to place an approximate constraint on the fifth-force coupling strength of $-10^{-3} \lesssim \mathcal{Y} \lesssim 5\cdot 10^{-4}$ at $2\sigma$. This result improves previous stellar constraints by $\sim 3$ orders of magnitude, and should be confirmed and improved by future helioseismic inversions in modified gravity combined with an elaborate accounting of theoretical uncertainties. Our analysis can be applied to a wide set of theories beyond GR, and also paves the way for helioseismic analyses in this context. In this regard, we discuss how the solar radiative and convective zone can be employed as promising laboratories to test generic theories of gravity. Title: VizieR Online Data Catalog: LCs of RR Lyrae stars from TESS (Molnar+, 2022) Authors: Molnar, L.; Bodi, A.; Pal, A.; Bhardwaj, A.; Hambsch, F. -J.; Benko, J. M.; Derekas, A.; Ebadi, M.; Joyce, M.; Hasanzadeh, A.; Kolenberg, K.; Lund, M. B.; Nemec, J. M.; Netzel, H.; Ngeow, C. -C.; Pepper, J.; Plachy, E.; Prudil, Z.; Siverd, R. J.; Skarka, M.; Smolec, R.; Sodor, A.; Sylla, S.; Szabo, P.; Szabo, R.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Ricker, G. R. Bibcode: 2022yCat..22580008M Altcode: In this paper we studied an initial selection of 126 known or candidate bright RR Lyrae stars within Sectors 1 and 2 of the Transiting Exoplanet Survey Satellite (TESS) mission, 118 of which turned out to be real pulsators.

Sectors 1 and 2 lasted for 27.9 and 27.4 days, with 1.13 and 1.44day long mid-sector gaps, respectively. During each sector, the entire field of view is recorded as full-frame images (FFI) at a 30 minute cadence, while selected targets are measured with 2 minute cadence.

In Sectors 1 and 2, three targets were observed as 2 minute cadence targets, part of the TESS Asteroseismic Science Consortium (TASC) target list (ST Pic in both sectors, BV Aqr in S1, and RU Scl in S2). The rest of the RR Lyrae stars were FFI targets. See Section 2.

(11 data files). Title: No swan song for Sun-as-a-star helioseismology: Performances of the Solar-SONG prototype for individual mode characterisation Authors: Breton, S. N.; Pallé, P. L.; García, R. A.; Fredslund Andersen, M.; Grundahl, F.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Mathur, S. Bibcode: 2022A&A...658A..27B Altcode: 2021arXiv211012698B The GOLF instrument on board SoHO has been in operation for almost 25 years, but the ageing of the instrument has now strongly affected its performance, especially in the low-frequency pressure-mode (p-mode) region. At the end of the SoHO mission, the ground-based network BiSON will remain the only facility able to perform Sun-integrated helioseismic observations. Therefore, we want to assess the helioseismic performances of an échelle spectrograph such as SONG. The high precision of such an instrument and the quality of the data acquired for asteroseismic purposes call for an evaluation of the instrument's ability to perform global radial-velocity measurements of the solar disk. Data acquired during the Solar-SONG 2018 observation campaign at the Teide Observatory are used to study mid- and low-frequency p modes. A Solar-SONG time series of 30 days in duration is reduced with a combination of the traditional IDL iSONG pipeline and a new Python pipeline described in this paper. A mode fitting method built around a Bayesian approach is then performed on the Solar-SONG and contemporaneous GOLF, BiSON, and HMI data. For this contemporaneous time series, Solar-SONG is able to characterise p modes at a lower frequency than BiSON or GOLF (1750 μHz versus 1946 and 2157 μHz, respectively), while for HMI it is possible to characterise a mode at 1686 μHz. The decrease in GOLF sensitivity is then evaluated through the evolution of its low-frequency p-mode characterisation abilities over the years: a set of 30-day-long GOLF time series, considered at the same period of the year from 1996 to 2017, is analysed. We show that it is more difficult to accurately characterise p modes in the range 1680 to 2160 μHz when considering the most recent time series. By comparing the global power level of different frequency regions, we also observe that the Solar-SONG noise level in the 1000 to 1500 μHz region is lower than for any GOLF subseries considered in this work. While the global p-mode power-level ratio is larger for GOLF during the first years of the mission, this ratio decreases over the years and is bested by Solar-SONG for every time series after 2000. All these observations strongly suggest that efforts should be made towards deploying more Solar-SONG nodes in order to acquire longer time series with better duty cycles. Title: A 20 Second Cadence View of Solar-type Stars and Their Planets with TESS: Asteroseismology of Solar Analogs and a Recharacterization of π Men c Authors: Huber, Daniel; White, Timothy R.; Metcalfe, Travis S.; Chontos, Ashley; Fausnaugh, Michael M.; Ho, Cynthia S. K.; Van Eylen, Vincent; Ball, Warrick H.; Basu, Sarbani; Bedding, Timothy R.; Benomar, Othman; Bossini, Diego; Breton, Sylvain; Buzasi, Derek L.; Campante, Tiago L.; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Cunha, Margarida S.; Deal, Morgan; García, Rafael A.; García Muñoz, Antonio; Gehan, Charlotte; González-Cuesta, Lucía; Jiang, Chen; Kayhan, Cenk; Kjeldsen, Hans; Lundkvist, Mia S.; Mathis, Stéphane; Mathur, Savita; Monteiro, Mário J. P. F. G.; Nsamba, Benard; Ong, Jia Mian Joel; Pakštienė, Erika; Serenelli, Aldo M.; Silva Aguirre, Victor; Stassun, Keivan G.; Stello, Dennis; Norgaard Stilling, Sissel; Lykke Winther, Mark; Wu, Tao; Barclay, Thomas; Daylan, Tansu; Günther, Maximilian N.; Hermes, J. J.; Jenkins, Jon M.; Latham, David W.; Levine, Alan M.; Ricker, George R.; Seager, Sara; Shporer, Avi; Twicken, Joseph D.; Vanderspek, Roland K.; Winn, Joshua N. Bibcode: 2022AJ....163...79H Altcode: 2021arXiv210809109H We present an analysis of the first 20 second cadence light curves obtained by the TESS space telescope during its extended mission. We find improved precision of 20 second data compared to 2 minute data for bright stars when binned to the same cadence (≍10%-25% better for T ≲ 8 mag, reaching equal precision at T ≍ 13 mag), consistent with pre-flight expectations based on differences in cosmic-ray mitigation algorithms. We present two results enabled by this improvement. First, we use 20 second data to detect oscillations in three solar analogs (γ Pav, ζ Tuc, and π Men) and use asteroseismology to measure their radii, masses, densities, and ages to ≍1%, ≍3%, ≍1%, and ≍20% respectively, including systematic errors. Combining our asteroseismic ages with chromospheric activity measurements, we find evidence that the spread in the activity-age relation is linked to stellar mass and thus the depth of the convection zone. Second, we combine 20 second data and published radial velocities to recharacterize π Men c, which is now the closest transiting exoplanet for which detailed asteroseismology of the host star is possible. We show that π Men c is located at the upper edge of the planet radius valley for its orbital period, confirming that it has likely retained a volatile atmosphere and that the "asteroseismic radius valley" remains devoid of planets. Our analysis favors a low eccentricity for π Men c (<0.1 at 68% confidence), suggesting efficient tidal dissipation (Q/k 2,1 ≲ 2400) if it formed via high-eccentricity migration. Combined, these early results demonstrate the strong potential of TESS 20 second cadence data for stellar astrophysics and exoplanet science. Title: First Results on RR Lyrae Stars with the TESS Space Telescope: Untangling the Connections between Mode Content, Colors, and Distances Authors: Molnár, L.; Bódi, A.; Pál, A.; Bhardwaj, A.; Hambsch, F. -J.; Benkő, J. M.; Derekas, A.; Ebadi, M.; Joyce, M.; Hasanzadeh, A.; Kolenberg, K.; Lund, M. B.; Nemec, J. M.; Netzel, H.; Ngeow, C. -C.; Pepper, J.; Plachy, E.; Prudil, Z.; Siverd, R. J.; Skarka, M.; Smolec, R.; Sódor, Á.; Sylla, S.; Szabó, P.; Szabó, R.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Ricker, G. R. Bibcode: 2022ApJS..258....8M Altcode: 2021arXiv210907329M The Transiting Exoplanet Survey Satellite (TESS) space telescope is collecting continuous, high-precision optical photometry of stars throughout the sky, including thousands of RR Lyrae stars. In this paper, we present results for an initial sample of 118 nearby RR Lyrae stars observed in TESS Sectors 1 and 2. We use differential image photometry to generate light curves and analyze their mode content and modulation properties. We combine accurate light-curve parameters from TESS with parallax and color information from the Gaia mission to create a comprehensive classification scheme. We build a clean sample, preserving RR Lyrae stars with unusual light-curve shapes, while separating other types of pulsating stars. We find that a large fraction of RR Lyrae stars exhibit various low-amplitude modes, but the distribution of those modes is markedly different from those of the bulge stars. This suggests that differences in physical parameters have an observable effect on the excitation of extra modes, potentially offering a way to uncover the origins of these signals. However, mode identification is hindered by uncertainties when identifying the true pulsation frequencies of the extra modes. We compare mode amplitude ratios in classical double-mode stars to stars with extra modes at low amplitudes and find that they separate into two distinct groups. Finally, we find a high percentage of modulated stars among the fundamental mode pulsators, but also find that at least 28% of them do not exhibit modulation, confirming that a significant fraction of stars lack the Blazhko effect. Title: The BAyesian STellar algorithm (BASTA): a fitting tool for stellar studies, asteroseismology, exoplanets, and Galactic archaeology Authors: Aguirre Børsen-Koch, V.; Rørsted, J. L.; Justesen, A. B.; Stokholm, A.; Verma, K.; Winther, M. L.; Knudstrup, E.; Nielsen, K. B.; Sahlholdt, C.; Larsen, J. R.; Cassisi, S.; Serenelli, A. M.; Casagrande, L.; Christensen-Dalsgaard, J.; Davies, G. R.; Ferguson, J. W.; Lund, M. N.; Weiss, A.; White, T. R. Bibcode: 2022MNRAS.509.4344A Altcode: 2021arXiv210914622A; 2021MNRAS.tmp.2660B We introduce the public version of the BAyesian STellar Algorithm (BASTA), an open-source code written in PYTHON to determine stellar properties based on a set of astrophysical observables. BASTA has been specifically designed to robustly combine large data sets that include asteroseismology, spectroscopy, photometry, and astrometry. We describe the large number of asteroseismic observations that can be fit by the code and how these can be combined with atmospheric properties (as well as parallaxes and apparent magnitudes), making it the most complete analysis pipeline available for oscillating main-sequence, subgiant, and red giant stars. BASTA relies on a set of pre-built stellar isochrones or a custom-designed library of stellar tracks, which can be further refined using our interpolation method (both along and across stellar tracks or isochrones). We perform recovery tests with simulated data that reveal levels of accuracy at the few percent level for radii, masses, and ages when individual oscillation frequencies are considered, and show that asteroseismic ages with statistical uncertainties below 10 per cent are within reach if our stellar models are reliable representations of stars. BASTAis extensively documented and includes a suite of examples to support easy adoption and further development by new users. Title: Solar structure and evolution Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2021LRSP...18....2C Altcode: 2020arXiv200706488C The Sun provides a critical benchmark for the general study of stellar structure and evolution. Also, knowledge about the internal properties of the Sun is important for the understanding of solar atmospheric phenomena, including the solar magnetic cycle. Here I provide a brief overview of the theory of stellar structure and evolution, including the physical processes and parameters that are involved. This is followed by a discussion of solar evolution, extending from the birth to the latest stages. As a background for the interpretation of observations related to the solar interior I provide a rather extensive analysis of the sensitivity of solar models to the assumptions underlying their calculation. I then discuss the detailed information about the solar interior that has become available through helioseismic investigations and the detection of solar neutrinos, with further constraints provided by the observed abundances of the lightest elements. Revisions in the determination of the solar surface abundances have led to increased discrepancies, discussed in some detail, between the observational inferences and solar models. I finally briefly address the relation of the Sun to other similar stars and the prospects for asteroseismic investigations of stellar structure and evolution. Title: PLATO hare-and-hounds exercise: asteroseismic model fitting of main-sequence solar-like pulsators Authors: Cunha, M. S.; Roxburgh, I. W.; Aguirre Børsen-Koch, V.; Ball, W. H.; Basu, S.; Chaplin, W. J.; Goupil, M. -J.; Nsamba, B.; Ong, J.; Reese, D. R.; Verma, K.; Belkacem, K.; Campante, T.; Christensen-Dalsgaard, J.; Clara, M. T.; Deheuvels, S.; Monteiro, M. J. P. F. G.; Noll, A.; Ouazzani, R. M.; Rørsted, J. L.; Stokholm, A.; Winther, M. L. Bibcode: 2021MNRAS.508.5864C Altcode: 2021MNRAS.tmp.2643C; 2021arXiv211003332C Asteroseismology is a powerful tool to infer fundamental stellar properties. The use of these asteroseismic-inferred properties in a growing number of astrophysical contexts makes it vital to understand their accuracy. Consequently, we performed a hare-and-hounds exercise where the hares simulated data for six artificial main-sequence stars and the hounds inferred their properties based on different inference procedures. To mimic a pipeline such as that planned for the PLATO mission, all hounds used the same model grid. Some stars were simulated using the physics adopted in the grid, others a different one. The maximum relative differences found (in absolute value) between the inferred and true values of the mass, radius, and age were 4.32, 1.33, and 11.25 per cent, respectively. The largest systematic differences in radius and age were found for a star simulated assuming gravitational settling, not accounted for in the model grid, with biases of -0.88 per cent (radius) and 8.66 per cent (age). For the mass, the most significant bias (-3.16 per cent) was found for a star with a helium enrichment ratio outside the grid range. Moreover, an ~7 per cent dispersion in age was found when adopting different prescriptions for the surface corrections or shifting the classical observations by ±1σ. The choice of the relative weight given to the classical and seismic constraints also impacted significantly the accuracy and precision of the results. Interestingly, only a few frequencies were required to achieve accurate results on the mass and radius. For the age the same was true when at least one l = 2 mode was considered. Title: The TESS Mission Target Selection Procedure Authors: Fausnaugh, Michael; Morgan, Ed; Vanderspek, Roland; Pepper, Joshua; Burke, Christopher J.; Levine, Alan M.; Rudat, Alexander; Villaseñor, Jesus Noel S.; Vezie, Michael; Goeke, Robert F.; Ricker, George R.; Latham, David W.; Seager, S.; Winn, Joshua N.; Jenkins, Jon M.; Bakos, G. Á.; Barclay, Thomas; Berta-Thompson, Zachory K.; Bouma, Luke G.; Boyd, Patricia T.; Brasseur, C. E.; Burt, Jennifer; Caldwell, Douglas A.; Charbonneau, David; Christensen-Dalsgaard, J.; Clampin, Mark; Collins, Karen A.; Colón, Knicole D.; De Lee, Nathan; Dunham, Edward; Fleming, Scott W.; Fong, William; Garcia Soto, Aylin; Scott Gaudi, B.; Guerrero, Natalia M.; Hesse, Katharine; Holman, Matthew J.; Huang, Chelsea X.; Kaltenegger, Lisa; Lissauer, Jack J.; McDermott, Scott; McLean, Brian; Mireles, Ismael; Mullally, Susan E.; Oelkers, Ryan J.; Paegert, Martin; Pál, András; Quintana, Elisa V.; Rinehart, S. A.; Rodriguez, David R.; Rose, Mark; Sasselov, Dimitar D.; Schlieder, Joshua E.; Sha, Lizhou; Shporer, Avi; Smith, Jeffrey C.; Stassun, Keivan G.; Tenenbaum, Peter; Ting, Eric B.; Torres, Guillermo; Twicken, Joseph D.; Vanderburg, Andrew; Wohler, Bill; Yu, Liang Bibcode: 2021PASP..133i5002F Altcode: 2021arXiv210902665F We describe the target selection procedure by which stars are selected for 2 minute and 20 s observations by TESS. We first list the technical requirements of the TESS instrument and ground systems processing that limit the total number of target slots. We then describe algorithms used by the TESS Payload Operation Center (POC) to merge candidate targets requested by the various TESS mission elements (the Target Selection Working Group, TESS Asteroseismic Science Consortium, and Guest Investigator office). Lastly, we summarize the properties of the observed TESS targets over the two-year primary TESS mission. We find that the POC target selection algorithm results in 2.1-3.4 times as many observed targets as target slots allocated for each mission element. We also find that the sky distribution of observed targets is different from the sky distributions of candidate targets due to technical constraints that require a relatively even distribution of targets across the TESS fields of view. We caution researchers exploring statistical analyses of TESS planet-host stars that the population of observed targets cannot be characterized by any simple set of criteria applied to the properties of the input Candidate Target Lists. Title: Asteroseismic Inference of the Central Structure in a Subgiant Star Authors: Bellinger, Earl P.; Basu, Sarbani; Hekker, Saskia; Christensen-Dalsgaard, Jørgen; Ball, Warrick H. Bibcode: 2021ApJ...915..100B Altcode: 2021arXiv210504564B Asteroseismic measurements enable inferences of the underlying stellar structure, such as the density and the speed of sound at various points within the interior of the star. This provides an opportunity to test stellar evolution theory by assessing whether the predicted structure of a star agrees with the measured structure. Thus far, this kind of inverse analysis has only been applied to the Sun and three solar-like main-sequence stars. Here we extend the technique to stars on the subgiant branch, and apply it to one of the best-characterized subgiants of the Kepler mission, HR 7322. The observation of mixed oscillation modes in this star facilitates inferences of the conditions of its inert helium core, nuclear-burning hydrogen shell, and the deeper parts of its radiative envelope. We find that despite significant differences in the mode frequencies, the structure near to the center of this star does not differ significantly from the predicted structure. Title: VizieR Online Data Catalog: Oscillations in red giants from TESS data (Silva+, 2020) Authors: Silva Aguirre, V.; Stello, D.; Stokholm, A.; Mosumgaard, J. R.; Ball, W. H.; Basu, S.; Bossini, D.; Bugnet, L.; Buzasi, D.; Campante, T. L.; Carboneau, L.; Chaplin, W. J.; Corsaro, E.; Davies, G. R.; Elsworth, Y.; Garcia, R. A.; Gaulme, P.; Hall, O. J.; Handberg, R.; Hon, M.; Kallinger, T.; Kang, L.; Lund, M. N.; Mathur, S.; Mints, A.; Mosser, B.; Celik Orhan, Z.; Rodrigues, T. S.; Vrard, M.; Yildiz, M.; Zinn, J. C.; Ortel, S.; Beck, P. G.; Bell, K. J.; Guo, Z.; Jiang, C.; Kuszlewicz, J. S.; Kuehn, C. A.; Li, T.; Lundkvist, M. S.; Pinsonneault, M.; Tayar, J.; Cunha, M. S.; Hekker, S.; Huber, D.; Miglio, A.; Monteiro, M. J. P. F. G.; Slumstrup, D.; Winther, M. L.; Angelou, G.; Benomar, O.; Bodi, A.; de Moura, B. L.; Deheuvels, S.; Derekas, A.; di Mauro, M. P.; Dupret, M. -A.; Jimenez, A.; Lebreton, Y.; Matthews, J.; Nardetto, N.; Do Nascimento, J. D.; Pereira, F.; Rodriguez Diaz, L. F.; Serenelli, A. M.; Spitoni, E.; Stonkute, E.; Suarez, J. C.; Szabo, R.; van Eylen, V.; Ventura, R.; Verma, K.; Weiss, A.; Wu, T.; Barclay, T.; Christensen-Dalsgaard, J.; Jenkins, J. M.; Kjeldsen, H.; Ricker, G. R.; Seager, S.; Vanderspek, R. Bibcode: 2021yCat..18899034S Altcode: Since the onset of the "space revolution" of high-precision high-cadence photometry, asteroseismology has been demonstrated as a powerful tool for informing Galactic archeology investigations. The launch of the NASA Transiting Exoplanet Survey Satellite (TESS) mission has enabled seismic-based inferences to go full sky-providing a clear advantage for large ensemble studies of the different Milky Way components. Here we demonstrate its potential for investigating the Galaxy by carrying out the first asteroseismic ensemble study of red giant stars observed by TESS. We use a sample of 25 stars for which we measure their global asteroseimic observables and estimate their fundamental stellar properties, such as radius, mass, and age. Significant improvements are seen in the uncertainties of our estimates when combining seismic observables from TESS with astrometric measurements from the Gaia mission compared to when the seismology and astrometry are applied separately. Specifically, when combined we show that stellar radii can be determined to a precision of a few percent, masses to 5%-10%, and ages to the 20% level. This is comparable to the precision typically obtained using end-of-mission Kepler data.

(1 data file). Title: A comprehensive look at RR Lyrae stars through high-precision photometry and astrometry Authors: Molnár, László; Bódi, Attila; Pál, András; Bhardwaj, Anupam; Hambsch, Franz-Josef; Benkő, József; Derekas, Aliz; Ebadi, Mohammad; Joyce, Meridith; Hasanzadeh, Amir; Kolenberg, Katrien; Lund, Michael B.; Nemec, James N.; Netzel, Henryka; Ngeow, Chow-Choong; Pepper, Joshua; Plachy, Emese; Prudil, Zdenek; Siverd, Robert J.; Skarka, Marek; Smolec, Radek; Sódor, Ádám; Sylla, Salma; Szabó, Pál; Szabó, Róbert; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen; Ricker, George R. Bibcode: 2021tsc2.confE..41M Altcode: The TESS and Gaia missions are both collecting data of exquisite quality for RR Lyrae-type pulsating stars. We combine light curve shape information from TESS with distances and brightnesses from Gaia to build a detailed classification scheme that is able to filter out intrinsically fainter binaries and rotational variables as well as short-period Cepheids that otherwise have light curves very similar to that of RR Lyrae stars, while preserving targets with unusual light curve shapes. We build a clean sample from the RR Lyrae stars in the vicinity of the Sun, out to 5-10 kpc distances. Based on the TESS light curves we find that a large fraction of RR Lyrae stars exhibit various additional low-amplitude modes. The distribution of extra modes in period is markedly different from that of stars within the bulge and globular clusters, signaling a metallicity dependence in the mode periods and excitation mechanisms. We also detect a possible dependence of extra modes from color and hence effective temperatures in overtone RRc stars. While these new results have brought us closer to true asteroseismic analysis of RR Lyrae stars, we show through new échelle-type diagrams that mode identification is still hindered by the strong influence of the radial mode(s) dominating the pulsation. Title: VizieR Online Data Catalog: TESS observations of Cepheid stars (Plachy+, 2021) Authors: Plachy, E.; Pal, A.; Bodi, A.; Szabo, P.; Molnar, L.; Szabados, L.; Benko, J. M.; Anderson, R. I.; Bellinger, E. P.; Bhardwaj, A.; Ebadi, M.; Gazeas, K.; Hambsch, F. -J.; Hasanzadeh, A.; Jurkovic, M. I.; Kalaee, M. J.; Kervella, P.; Kolenberg, K.; Mikolajczyk, P.; Nardetto, N.; Nemec, J. M.; Netzel, H.; Ngeow, C. -C.; Ozuyar, D.; Pascual-Granado, J.; Pilecki, B.; Ripepi, V.; Skarka, M.; Smolec, R.; Sodor, A.; Szabo, R.; Christensen-Dalsgaard, J.; Jenkins, J. M.; Kjeldsen, H.; Ricker, G. R.; Vanderspek, R. Bibcode: 2021yCat..22530011P Altcode: The NASA Transiting Exoplanet Survey Satellite (TESS) observations consist of ~27 day long measurements with constant pointing to a 24°x96° field of view, called a "sector". In this paper, we present the first results on Cepheid stars observed with TESS, covering the first five out of 26 sectors of its primary 2yr near all-sky mission (2018-2019).

(3 data files). Title: VizieR Online Data Catalog: 117 exoplanets in habitable zone with Kepler DR25 (Bryson+, 2021) Authors: Bryson, S.; Kunimoto, M.; Kopparapu, R. K.; Coughlin, J. L.; Borucki, W. J.; Koch, D.; Aguirre, V. S.; Allen, C.; Barentsen, G.; Batalha, N. M.; Berger, T.; Boss, A.; Buchhave, L. A.; Burke, C. J.; Caldwell, D. A.; Campbell, J. R.; Catanzarite, J.; Chandrasekaran, H.; Chaplin, W. J.; Christiansen, J. L.; Christensen-Dalsgaard, J.; Ciardi, D. R.; Clarke, B. D.; Cochran, W. D.; Dotson, J. L.; Doyle, L. R.; Duarte, E. S.; Dunham, E. W.; Dupree, A. K.; Endl, M.; Fanson, J. L.; Ford, E. B.; Fujieh, M.; Gautier, T. N., III; Geary, J. C.; Gilliland, R. L.; Girouard, F. R.; Gould, A.; Haas, M. R.; Henze, C. E.; Holman, M. J.; Howard, A. W.; Howell, S. B.; Huber, D.; Hunter, R. C.; Jenkins, J. M.; Kjeldsen, H.; Kolodziejczak, J.; Larson, K.; Latham, D. W.; Li, J.; Mathur, S.; Meibom, S.; Middour, C.; Morris, R. L.; Morton, T. D.; Mullally, F.; Mullally, S. E.; Pletcher, D.; Prsa, A.; Quinn, S. N.; Quintana, E. V.; Ragozzine, D.; Ramirez, S. V.; Sanderfer, D. T.; Sasselov, D.; Seader, S. E.; Shabram, M.; Shporer, A.; Smith, J. C.; Steffen, J. H.; Still, M.; Torres, G.; Troeltzsch, J.; Twicken, J. D.; Uddin, A. K.; van Cleve, J. E.; Voss, J.; Weiss, L. M.; Welsh, W. F.; Wohler, B.; Zamudio, K. A. Bibcode: 2021yCat..51610036B Altcode: We present the occurrence rates for rocky planets in the habitable zones (HZs) of main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and Gaia-based stellar properties. We provide the first analysis in terms of star-dependent instellation flux, which allows us to track HZ planets. We define {eta}{Earth} as the HZ occurrence of planets with radii between 0.5 and 1.5 R{Earth} orbiting stars with effective temperatures between 4800 and 6300K. We find that {eta}{Earth} for the conservative HZ is between 0.37-0.21+0.48 (errors reflect 68% credible intervals) and 0.60-0.36+0.90 planets per star, while the optimistic HZ occurrence is between 0.58-0.33+0.73 and 0.88-0.51+1.28 planets per star. These bounds reflect two extreme assumptions about the extrapolation of completeness beyond orbital periods where DR25 completeness data are available. The large uncertainties are due to the small number of detected small HZ planets. We find similar occurrence rates between using Poisson likelihood Bayesian analysis and using Approximate Bayesian Computation. Our results are corrected for catalog completeness and reliability. Both completeness and the planet occurrence rate are dependent on stellar effective temperature. We also present occurrence rates for various stellar populations and planet size ranges. We estimate with 95% confidence that, on average, the nearest HZ planet around G and K dwarfs is ~6pc away and there are ~4 HZ rocky planets around G and K dwarfs within 10pc of the Sun.

(1 data file). Title: TESS Observations of Cepheid Stars: First Light Results Authors: Plachy, E.; Pál, A.; Bódi, A.; Szabó, P.; Molnár, L.; Szabados, L.; Benkő, J. M.; Anderson, R. I.; Bellinger, E. P.; Bhardwaj, A.; Ebadi, M.; Gazeas, K.; Hambsch, F. -J.; Hasanzadeh, A.; Jurkovic, M. I.; Kalaee, M. J.; Kervella, P.; Kolenberg, K.; Mikołajczyk, P.; Nardetto, N.; Nemec, J. M.; Netzel, H.; Ngeow, C. -C.; Ozuyar, D.; Pascual-Granado, J.; Pilecki, B.; Ripepi, V.; Skarka, M.; Smolec, R.; Sódor, Á.; Szabó, R.; Christensen-Dalsgaard, J.; Jenkins, J. M.; Kjeldsen, H.; Ricker, G. R.; Vanderspek, R. Bibcode: 2021ApJS..253...11P Altcode: 2020arXiv201209709P We present the first analysis of Cepheid stars observed by the TESS space mission in Sectors 1-5. Our sample consists of 25 pulsators: ten fundamental mode, three overtone and two double-mode classical Cepheids, plus three type II and seven anomalous Cepheids. The targets were chosen from fields with different stellar densities, both from the Galactic field and from the Magellanic System. Three targets have 2 minutes cadence light curves available by the TESS Science Processing Operations Center: for the rest, we prepared custom light curves from the full-frame images with our own differential photometric FITSH pipeline. Our main goal was to explore the potential and the limitations of TESS concerning the various subtypes of Cepheids. We detected many low-amplitude features: weak modulation, period jitter, and timing variations due to light-time effect. We also report signs of nonradial modes and the first discovery of such a mode in an anomalous Cepheid, the overtone star XZ Cet, which we then confirmed with ground-based multicolor photometric measurements. We prepared a custom photometric solution to minimize saturation effects in the bright fundamental-mode classical Cepheid, β Dor with the lightkurve software, and we revealed strong evidence of cycle-to-cycle variations in the star. In several cases, however, fluctuations in the pulsation could not be distinguished from instrumental effects, such as contamination from nearby sources, which also varies between sectors. Finally, we discuss how precise light-curve shapes will be crucial not only for classification purposes but also to determine physical properties of these stars. Title: The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Data Authors: Bryson, Steve; Kunimoto, Michelle; Kopparapu, Ravi K.; Coughlin, Jeffrey L.; Borucki, William J.; Koch, David; Aguirre, Victor Silva; Allen, Christopher; Barentsen, Geert; Batalha, Natalie M.; Berger, Travis; Boss, Alan; Buchhave, Lars A.; Burke, Christopher J.; Caldwell, Douglas A.; Campbell, Jennifer R.; Catanzarite, Joseph; Chandrasekaran, Hema; Chaplin, William J.; Christiansen, Jessie L.; Christensen-Dalsgaard, Jørgen; Ciardi, David R.; Clarke, Bruce D.; Cochran, William D.; Dotson, Jessie L.; Doyle, Laurance R.; Duarte, Eduardo Seperuelo; Dunham, Edward W.; Dupree, Andrea K.; Endl, Michael; Fanson, James L.; Ford, Eric B.; Fujieh, Maura; Gautier, Thomas N., III; Geary, John C.; Gilliland, Ronald L.; Girouard, Forrest R.; Gould, Alan; Haas, Michael R.; Henze, Christopher E.; Holman, Matthew J.; Howard, Andrew W.; Howell, Steve B.; Huber, Daniel; Hunter, Roger C.; Jenkins, Jon M.; Kjeldsen, Hans; Kolodziejczak, Jeffery; Larson, Kipp; Latham, David W.; Li, Jie; Mathur, Savita; Meibom, Søren; Middour, Chris; Morris, Robert L.; Morton, Timothy D.; Mullally, Fergal; Mullally, Susan E.; Pletcher, David; Prsa, Andrej; Quinn, Samuel N.; Quintana, Elisa V.; Ragozzine, Darin; Ramirez, Solange V.; Sanderfer, Dwight T.; Sasselov, Dimitar; Seader, Shawn E.; Shabram, Megan; Shporer, Avi; Smith, Jeffrey C.; Steffen, Jason H.; Still, Martin; Torres, Guillermo; Troeltzsch, John; Twicken, Joseph D.; Uddin, Akm Kamal; Van Cleve, Jeffrey E.; Voss, Janice; Weiss, Lauren M.; Welsh, William F.; Wohler, Bill; Zamudio, Khadeejah A. Bibcode: 2021AJ....161...36B Altcode: 2020arXiv201014812B We present the occurrence rates for rocky planets in the habitable zones (HZs) of main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and Gaia-based stellar properties. We provide the first analysis in terms of star-dependent instellation flux, which allows us to track HZ planets. We define η⊕ as the HZ occurrence of planets with radii between 0.5 and 1.5 R⊕ orbiting stars with effective temperatures between 4800 and 6300 K. We find that η⊕ for the conservative HZ is between ${0.37}_{-0.21}^{+0.48}$ (errors reflect 68% credible intervals) and ${0.60}_{-0.36}^{+0.90}$ planets per star, while the optimistic HZ occurrence is between ${0.58}_{-0.33}^{+0.73}$ and ${0.88}_{-0.51}^{+1.28}$ planets per star. These bounds reflect two extreme assumptions about the extrapolation of completeness beyond orbital periods where DR25 completeness data are available. The large uncertainties are due to the small number of detected small HZ planets. We find similar occurrence rates between using Poisson likelihood Bayesian analysis and using Approximate Bayesian Computation. Our results are corrected for catalog completeness and reliability. Both completeness and the planet occurrence rate are dependent on stellar effective temperature. We also present occurrence rates for various stellar populations and planet size ranges. We estimate with 95% confidence that, on average, the nearest HZ planet around G and K dwarfs is ∼6 pc away and there are ∼4 HZ rocky planets around G and K dwarfs within 10 pc of the Sun. Title: Seismic solar models from Ledoux discriminant inversions Authors: Buldgen, G.; Eggenberger, P.; Baturin, V. A.; Corbard, T.; Christensen-Dalsgaard, J.; Salmon, S. J. A. J.; Noels, A.; Oreshina, A. V.; Scuflaire, R. Bibcode: 2020A&A...642A..36B Altcode: 2020arXiv200710222B Context. The Sun constitutes an excellent laboratory of fundamental physics. With the advent of helioseismology, we were able to probe its internal layers with unprecendented precision and thoroughness. However, the current state of solar modelling is still stained by tedious issues. One of these central problems is related to the disagreement between models computed with recent photospheric abundances and helioseismic constraints. The observed discrepancies raise questions on some fundamental ingredients entering the computation of solar and stellar evolution models.
Aims: We used solar evolutionary models as initial conditions for reintegrating their structure using Ledoux discriminant inversions. The resulting models are defined as seismic solar models, satisfying the equations of hydrostatic equilibrium. These seismic models will allow us to better constrain the internal structure of the Sun and provide complementary information to that of calibrated standard and non-standard models.
Methods: We used inversions of the Ledoux discriminant to reintegrate seismic solar models satisfying the equations of hydrostatic equilibrium. These seismic models were computed using various reference models with different equations of state, abundances, and opacity tables. We checked the robustness of our approach by confirming the good agreement of our seismic models in terms of sound speed, density, and entropy proxy inversions, as well as frequency-separation ratios of low-degree pressure modes.
Results: Our method allows us to determine the Ledoux discriminant profile of the Sun with an excellent accuracy and compute full profiles of this quantity. Our seismic models show an agreement with seismic data of ≈0.1% in sound speed, density, and entropy proxy after seven iterations in addition to an excellent agreement with the observed frequency-separation ratios. They surpass all standard and non-standard evolutionary models including ad hoc modifications of their physical ingredients that aim to reproduce helioseismic constraints.
Conclusions: The obtained seismic Ledoux discriminant profile, as well as the full consistent structure obtained from our reconstruction procedure paves the way for renewed attempts at constraining the solar modelling problem and the missing physical processes acting in the solar interior by breaking free from the hypotheses of evolutionary models. Title: Erratum: Variations of the mixing character of dipolar mixed modes in red giant stars Authors: Jiang, C.; Cunha, M.; Christensen-Dalsgaard, J.; Zhang, Q. S. Bibcode: 2020MNRAS.497..167J Altcode: No abstract at ADS Title: High-precision abundances of elements in solar-type stars. Evidence of two distinct sequences in abundance-age relations Authors: Nissen, P. E.; Christensen-Dalsgaard, J.; Mosumgaard, J. R.; Silva Aguirre, V.; Spitoni, E.; Verma, K. Bibcode: 2020A&A...640A..81N Altcode: 2020arXiv200606013N
Aims: Previous high-precision studies of abundances of elements in solar twin stars are extended to a wider metallicity range to see how the trends of element ratios with stellar age depend on [Fe/H].
Methods: HARPS spectra with signal-to-noise ratios S/N ≳ 600 at λ ∼ 6000 Å were analysed with MARCS model atmospheres to obtain 1D LTE abundances of C, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Sr, and Y for 72 nearby solar-type stars with metallicities in the range of -0.3 ≲ [Fe/H] ≲ +0.3 and ASTEC stellar models were used to determine stellar ages from effective temperatures, luminosities obtained via Gaia DR2 parallaxes, and heavy element abundances.
Results: The age-metallicity distribution appears to consist of the following two distinct populations: a sequence of old stars with a steep rise of [Fe/H] to ∼ + 0.3 dex at an age of ∼7 Gyr and a younger sequence with [Fe/H] increasing from about -0.3 dex to ∼ + 0.2 dex over the last 6 Gyr. Furthermore, the trends of several abundance ratios, [O/Fe], [Na/Fe], [Ca/Fe], and [Ni/Fe], as a function of stellar age, split into two corresponding sequences. The [Y/Mg]-age relation, on the other hand, shows no offset between the two age sequences and has no significant dependence on [Fe/H], but the components of a visual binary star, ζ Reticuli, have a large and puzzling deviation.
Conclusions: The split of the age-metallicity distribution into two sequences may be interpreted as evidence of two episodes of accretion of gas onto the Galactic disk with a quenching of star formation in between. Some of the [X/Fe]-age relations support this scenario but other relations are not so easy to explain, which calls for a deeper study of systematic errors in the derived abundances as a function of [Fe/H], in particular 3D non-LTE effects.

Full Tables 1 and 2 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/640/A81 Title: Asteroseismology of 36 Kepler subgiants - II. Determining ages from detailed modelling Authors: Li, Tanda; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen; Stello, Dennis; Li, Yaguang; Keen, Matthew A. Bibcode: 2020MNRAS.495.3431L Altcode: 2020arXiv200600901L; 2020MNRAS.tmp.1467L Detailed modelling of stellar oscillations is able to give precise estimates for stellar ages, but the inferred results typically depend on the adopted model parameters used for the age inference. High-quality asteroseismic data with precise measurements of mixed modes are available for 36 Kepler subgiants. To obtain a handle on the robustness of the ages for these stars, we first study the dependencies of seismic ages on three model input parameters. We find that inferred ages do not change systematically with the helium fraction (Y) or the mixing-length parameter (αMLT) but depend strongly on the metallicity ([M/H]) of the model. The results indicate that age estimates of subgiants have less model dependence and hence are more reliable than those of main-sequence stars or red giants. We then model individual oscillation frequencies of the same 36 Kepler subgiants, using observed metallicities, and obtain their ages with an average precision of ∼15 per cent. The comparison with previous age estimates with different stellar codes or input physics shows good agreement (mostly within 2σ). We hence suggest that seismology-determined ages of subgiants are not greatly model dependent. Title: Variations of the mixing character of dipolar mixed modes in red giant stars Authors: Jiang, C.; Cunha, M.; Christensen-Dalsgaard, J.; Zhang, QS Bibcode: 2020MNRAS.495..621J Altcode: 2020MNRAS.tmp.1405J; 2020arXiv200501464J Because of the high-quality data of space missions, the detection of mixed modes has become possible in numerous stars. In this work, we investigate how the mixing character of dipolar mixed modes changes with stellar evolution, as well as with frequency within each stellar model. This is achieved by monitoring the variations in the coupling strength and the period spacing of dipolar mixed modes in red-giant models. These parameters are measured by fitting the asymptotic expansion of mixed modes to the model frequencies of a grid of red-giant models with masses between 1.0 and 2.0 M⊙ and three different chemical abundances. The coupling strength and the period spacing decrease with stellar evolution. We find that the slopes of their decreasing trends depend on the radial order of the pressure mode component. A non-negligible increase of the coupling strength with frequency by up to around 40 per cent is found in the observable frequency range for a set of red-giant models. On the contrary, no significant changes of the period spacing with frequency are found. The changes in the mixing character of the modes are in most cases affected by the model mass and metallicity. Buoyancy glitches also have an impact on the mixing character. Significant fluctuations in the estimated coupling strength and period spacing are found for models approaching the luminosity bump, if the glitch impact of the frequencies is not considered in the applied asymptotic expansion. Title: TESS Asteroseismic Analysis of the Known Exoplanet Host Star HD 222076 Authors: Jiang, Chen; Bedding, Timothy R.; Stassun, Keivan G.; Veras, Dimitri; Corsaro, Enrico; Buzasi, Derek L.; Mikołajczyk, Przemysław; Zhang, Qian-sheng; Ou, Jian-wen; Campante, Tiago L.; Rodrigues, Thaíise S.; Nsamba, Benard; Bossini, Diego; Kane, Stephen R.; Ong, Jia Mian Joel; Yıldız, Mutlu; Çelik Orhan, Zeynep; Örtel, Sibel; Wu, Tao; Zhang, Xinyi; Li, Tanda; Basu, Sarbani; Cunha, Margarida S.; Christensen-Dalsgaard, Jørgen; Chaplin, William J. Bibcode: 2020ApJ...896...65J Altcode: 2020arXiv200500272J The Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey mission aiming to search for exoplanets that transit bright stars. The high-quality photometric data of TESS are excellent for the asteroseismic study of solar-like stars. In this work, we present an asteroseismic analysis of the red-giant star HD 222076 hosting a long-period (2.4 yr) giant planet discovered through radial velocities. Solar-like oscillations of HD 222076 are detected around 203 μHz by TESS for the first time. Asteroseismic modeling, using global asteroseismic parameters as inputs, yields a determination of the stellar mass ( ${M}_{\star }=1.12\pm 0.12\,{M}_{\odot }$ ), radius ( ${R}_{\star }=4.34\pm 0.21\,{R}_{\odot }$ ), and age (7.4 ± 2.7 Gyr), with precisions greatly improved from previous studies. The period spacing of the dipolar mixed modes extracted from the observed power spectrum reveals that the star is on the red-giant branch burning hydrogen in a shell surrounding the core. We find that the planet will not escape the tidal pull of the star and will be engulfed into it within about 800 Myr, before the tip of the red-giant branch is reached. Title: VizieR Online Data Catalog: Abundances of 72 solar-type stars (Nissen+, 2020) Authors: Nissen, P. E.; Christensen-Dalsgaard, J.; Mosumgaard, J. R.; Silva Aguirre, V.; Spitoni, E.; Verma, K. Bibcode: 2020yCat..36400081N Altcode: Stellar parameters are given in Table 1 and abundance ratios with respect to Fe in Table 2.

(2 data files). Title: Doppler Imaging and Differential Rotation of σ2 Coronae Borealis Using SONG Authors: Xiang, Yue; Gu, Shenghong; Cameron, A. Collier; Barnes, J. R.; Christensen-Dalsgaard, J.; Grundahl, F.; Antoci, V.; Andersen, M. F.; Pallé, P. L. Bibcode: 2020ApJ...893..164X Altcode: 2020arXiv200502592X We present new Doppler images of both components of the double-lined binary σ2 CrB, based on the high-resolution spectroscopic data collected during 11 nights in 2015 March-April. The observed spectra form two independent data sets with sufficient phase coverage. We apply the least-squares deconvolution to all observed spectra to obtain high signal-to-noise mean profiles, from which we derive the Doppler images of both components of σ2 CrB simultaneously. The surfaces of both F9 and G0 components are dominated by pronounced polar spots. The F9 component exhibits a weak spot at latitude 30° and its mid-to-low latitudes are relatively featureless. The G0 star shows an extended spot structure at latitude 30°, and its surface spot coverage is larger than that of the F9 star, which suggests a higher level of magnetic activity. With the cross-correlation method, we derive a solar-like surface differential rotation on the G0 star of σ2 CrB for the first time, and the surface shear rate is ΔΩ = 0.180 ± 0.004 rad days-1 and α = ΔΩ/Ωeq = 0.032 ± 0.001. We do not obtain a clear surface shear law for the F9 star due to the lack of mid-to-low latitude features, but detect a systematic longitude shift of high-latitude spots, which indicates a slower rotation with respect to the corotating frame. Title: The Aarhus red giants challenge. I. Stellar structures in the red giant branch phase Authors: Silva Aguirre, V.; Christensen-Dalsgaard, J.; Cassisi, S.; Miller Bertolami, M.; Serenelli, A.; Stello, D.; Weiss, A.; Angelou, G.; Jiang, C.; Lebreton, Y.; Spada, F.; Bellinger, E. P.; Deheuvels, S.; Ouazzani, R. M.; Pietrinferni, A.; Mosumgaard, J. R.; Townsend, R. H. D.; Battich, T.; Bossini, D.; Constantino, T.; Eggenberger, P.; Hekker, S.; Mazumdar, A.; Miglio, A.; Nielsen, K. B.; Salaris, M. Bibcode: 2020A&A...635A.164S Altcode: 2019arXiv191204909S Context. With the advent of space-based asteroseismology, determining accurate properties of red-giant stars using their observed oscillations has become the focus of many investigations due to their implications in a variety of fields in astrophysics. Stellar models are fundamental in predicting quantities such as stellar age, and their reliability critically depends on the numerical implementation of the physics at play in this evolutionary phase.
Aims: We introduce the Aarhus red giants challenge, a series of detailed comparisons between widely used stellar evolution and oscillation codes that aim to establish the minimum level of uncertainties in properties of red giants arising solely from numerical implementations. We present the first set of results focusing on stellar evolution tracks and structures in the red-giant-branch (RGB) phase.
Methods: Using nine state-of-the-art stellar evolution codes, we defined a set of input physics and physical constants for our calculations and calibrated the convective efficiency to a specific point on the main sequence. We produced evolutionary tracks and stellar structure models at a fixed radius along the red-giant branch for masses of 1.0 M⊙, 1.5 M⊙, 2.0 M⊙, and 2.5 M⊙, and compared the predicted stellar properties.
Results: Once models have been calibrated on the main sequence, we find a residual spread in the predicted effective temperatures across all codes of ∼20 K at solar radius and ∼30-40 K in the RGB regardless of the considered stellar mass. The predicted ages show variations of 2-5% (increasing with stellar mass), which we attribute to differences in the numerical implementation of energy generation. The luminosity of the RGB-bump shows a spread of about 10% for the considered codes, which translates into magnitude differences of ∼0.1 mag in the optical V-band. We also compare the predicted [C/N] abundance ratio and find a spread of 0.1 dex or more for all considered masses.
Conclusions: Our comparisons show that differences at the level of a few percent still remain in evolutionary calculations of red giants branch stars despite the use of the same input physics. These are mostly due to differences in the energy generation routines and interpolation across opacities, and they call for further investigation on these matters in the context of using properties of red giants as benchmarks for astrophysical studies.

All our evolutionary calculations and models are available at https://github.com/vsilvagui/aarhus_RG_challenge Title: The Aarhus red giants challenge. II. Stellar oscillations in the red giant branch phase Authors: Christensen-Dalsgaard, J.; Silva Aguirre, V.; Cassisi, S.; Miller Bertolami, M.; Serenelli, A.; Stello, D.; Weiss, A.; Angelou, G.; Jiang, C.; Lebreton, Y.; Spada, F.; Bellinger, E. P.; Deheuvels, S.; Ouazzani, R. M.; Pietrinferni, A.; Mosumgaard, J. R.; Townsend, R. H. D.; Battich, T.; Bossini, D.; Constantino, T.; Eggenberger, P.; Hekker, S.; Mazumdar, A.; Miglio, A.; Nielsen, K. B.; Salaris, M. Bibcode: 2020A&A...635A.165C Altcode: 2020arXiv200202816C Contact. The large quantity of high-quality asteroseismic data that have been obtained from space-based photometric missions and the accuracy of the resulting frequencies motivate a careful consideration of the accuracy of computed oscillation frequencies of stellar models, when applied as diagnostics of the model properties.
Aims: Based on models of red-giant stars that have been independently calculated using different stellar evolution codes, we investigate the extent to which the differences in the model calculation affect the model oscillation frequencies and other asteroseismic diagnostics.
Methods: For each of the models, which cover four different masses and different evolution stages on the red-giant branch, we computed full sets of low-degree oscillation frequencies using a single pulsation code and, from these frequencies, typical asteroseismic diagnostics. In addition, we carried out preliminary analyses to relate differences in the oscillation properties to the corresponding model differences.
Results: In general, the differences in asteroseismic properties between the different models greatly exceed the observational precision of these properties. This is particularly true for the nonradial modes whose mixed acoustic and gravity-wave character makes them sensitive to the structure of the deep stellar interior and, hence, to details of their evolution. In some cases, identifying these differences led to improvements in the final models presented here and in Paper I; here we illustrate particular examples of this.
Conclusions: Further improvements in stellar modelling are required in order fully to utilise the observational accuracy to probe intrinsic limitations in the modelling and improve our understanding of stellar internal physics. However, our analysis of the frequency differences and their relation to stellar internal properties provides a striking illustration of the potential, in particular, of the mixed modes of red-giant stars for the diagnostics of stellar interiors. Title: Detection and Characterization of Oscillating Red Giants: First Results from the TESS Satellite Authors: Silva Aguirre, Víctor; Stello, Dennis; Stokholm, Amalie; Mosumgaard, Jakob R.; Ball, Warrick H.; Basu, Sarbani; Bossini, Diego; Bugnet, Lisa; Buzasi, Derek; Campante, Tiago L.; Carboneau, Lindsey; Chaplin, William J.; Corsaro, Enrico; Davies, Guy R.; Elsworth, Yvonne; García, Rafael A.; Gaulme, Patrick; Hall, Oliver J.; Handberg, Rasmus; Hon, Marc; Kallinger, Thomas; Kang, Liu; Lund, Mikkel N.; Mathur, Savita; Mints, Alexey; Mosser, Benoit; Çelik Orhan, Zeynep; Rodrigues, Thaíse S.; Vrard, Mathieu; Yıldız, Mutlu; Zinn, Joel C.; Örtel, Sibel; Beck, Paul G.; Bell, Keaton J.; Guo, Zhao; Jiang, Chen; Kuszlewicz, James S.; Kuehn, Charles A.; Li, Tanda; Lundkvist, Mia S.; Pinsonneault, Marc; Tayar, Jamie; Cunha, Margarida S.; Hekker, Saskia; Huber, Daniel; Miglio, Andrea; F. G. Monteiro, Mario J. P.; Slumstrup, Ditte; Winther, Mark L.; Angelou, George; Benomar, Othman; Bódi, Attila; De Moura, Bruno L.; Deheuvels, Sébastien; Derekas, Aliz; Di Mauro, Maria Pia; Dupret, Marc-Antoine; Jiménez, Antonio; Lebreton, Yveline; Matthews, Jaymie; Nardetto, Nicolas; do Nascimento, Jose D., Jr.; Pereira, Filipe; Rodríguez Díaz, Luisa F.; Serenelli, Aldo M.; Spitoni, Emanuele; Stonkutė, Edita; Suárez, Juan Carlos; Szabó, Robert; Van Eylen, Vincent; Ventura, Rita; Verma, Kuldeep; Weiss, Achim; Wu, Tao; Barclay, Thomas; Christensen-Dalsgaard, Jørgen; Jenkins, Jon M.; Kjeldsen, Hans; Ricker, George R.; Seager, Sara; Vanderspek, Roland Bibcode: 2020ApJ...889L..34S Altcode: 2019arXiv191207604S; 2020ApJ...889L..34A Since the onset of the "space revolution" of high-precision high-cadence photometry, asteroseismology has been demonstrated as a powerful tool for informing Galactic archeology investigations. The launch of the NASA Transiting Exoplanet Survey Satellite (TESS) mission has enabled seismic-based inferences to go full sky—providing a clear advantage for large ensemble studies of the different Milky Way components. Here we demonstrate its potential for investigating the Galaxy by carrying out the first asteroseismic ensemble study of red giant stars observed by TESS. We use a sample of 25 stars for which we measure their global asteroseimic observables and estimate their fundamental stellar properties, such as radius, mass, and age. Significant improvements are seen in the uncertainties of our estimates when combining seismic observables from TESS with astrometric measurements from the Gaia mission compared to when the seismology and astrometry are applied separately. Specifically, when combined we show that stellar radii can be determined to a precision of a few percent, masses to 5%-10%, and ages to the 20% level. This is comparable to the precision typically obtained using end-of-mission Kepler data. Title: Dynamics of the Sun and Stars; Honoring the Life and Work of Michael J. Thompson Authors: Monteiro, Mário J. P. F. G.; García, Rafael A.; Christensen-Dalsgaard, Jørgen; McIntosh, Scott W. Bibcode: 2020ASSP...57.....M Altcode: No abstract at ADS Title: Open Discussion Authors: García, R. A.; Mathur, S.; Monteiro, M. J. P. F. G.; Christensen-Dalsgaard, J.; McIntosh, S. W. Bibcode: 2020ASSP...57..329G Altcode: During the last morning of the conference, a one-hour open discussion allowed the participants to debate some of the "hot" topics presented all along the meeting as well as on some of the key issues in the field mostly related with the work Prof. Michael J. Thompson studied during his carrier. The discussion covered theory and methods, current and future modeling efforts, observations, and future instrumentation. At the end, Dr. Robin Thompson discussed about the use of inversion methods in his current research, of particular interest these days, about the control of infectious disease outbreaks. Title: Coupling 1D stellar evolution with 3D-hydrodynamical simulations on-the-fly II: stellar evolution and asteroseismic applications Authors: Mosumgaard, Jakob Rørsted; Jørgensen, Andreas Christ Sølvsten; Weiss, Achim; Silva Aguirre, Víctor; Christensen-Dalsgaard, Jørgen Bibcode: 2020MNRAS.491.1160M Altcode: 2019arXiv191010163M; 2019arXiv191010163R; 2019MNRAS.tmp.2585M Models of stellar structure and evolution are an indispensable tool in astrophysics, yet they are known to incorrectly reproduce the outer convective layers of stars. In the first paper of this series, we presented a novel procedure to include the mean structure of 3D hydrodynamical simulations on-the-fly in stellar models, and found it to significantly improve the outer stratification and oscillation frequencies of a standard solar model. In this work, we extend the analysis of the method; specifically how the transition point between envelope and interior affects the models. We confirm the versatility of our method by successfully repeating the entire procedure for a different grid of 3D hydrosimulations. Furthermore, the applicability of the procedure was investigated across the HR diagram and an accuracy comparable to the solar case was found. Moreover, we explored the implications on stellar evolution and find that the red-giant branch is shifted about 40 K to higher effective temperatures. Finally, we present for the first time an asteroseismic analysis based on stellar models fully utilizing the stratification of 3D simulations on-the-fly. These new models significantly reduce the asteroseismic surface term for the two selected stars in the Kepler field. We extend the analysis to red giants and characterize the shape of the surface effect in this regime. Lastly, we stress that the interpolation required by our method would benefit from new 3D simulations, resulting in a finer sampling of the grid. Title: Contemplating the Future Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2020ASSP...57..335C Altcode: The prospects for the further development of stellar astrophysics remain golden. Much can still be done based on the Kepler data, the TESS mission is providing data over most of the sky, at a 10 min cadence in the extended phase, PLATO will provide data comparable with those of Kepler for relatively near-by stars, ground-based observations yield data of even higher quality for selected stars, and Gaia is revolutionizing the determination of global stellar properties. On the modelling side ever more realistic simulations are becoming possible of dynamic phenomena in stellar interiors, and new techniques, known as artificial intelligence or deep learning, are helping the analysis of the huge amounts of data that are becoming available. Much of this effort is aimed at applications of stellar physics in other areas of astrophysics, such as exoplanets or Galactic archaeology. In the excitement of these developments, in the spirit of Michael we should not forget the basic goal of improving our physical understanding of stars, combining human intelligence and intuition with mathematical analysis and modelling, observations, and data interpretation. This should be kept in mind in our work and, even more importantly, in the education of coming generations of stellar astrophysicists. Title: A solution to the ``solar abundance'' problem Authors: Zhang, Q. -S.; Li, Y.; Christensen-Dalsgaard, J. Bibcode: 2020svos.conf..303Z Altcode: We report a solution to the long-standing ``solar abundance'' problem. Solar models that include three extra physical processes (convective overshoot, solar wind and PMS accretion) which are missing from standard solar models are shown to be consistent simultaneously with helioseismic inferences (the depth and helium abundance of the convection zone and profiles of sound speed and density), the observed solar Li abundance, and solar neutrino fluxes. Title: Asteroseismic signatures of the helium core flash Authors: Miller Bertolami, M. M.; Battich, T.; Córsico, A. H.; Christensen-Dalsgaard, J.; Althaus, L. G. Bibcode: 2020NatAs...4...67M Altcode: 2019NatAs.tmp..452M; 2020arXiv200502070M All evolved stars of up to 2 solar masses undergo a helium core flash at the end of their first stage as a giant star. Although theoretically predicted more than 50 years ago1,2, this core flash phase has yet to be observationally probed. We show here that gravity modes stochastically excited by helium-flash-driven convection are able to reach the stellar surface and induce periodic photometric variabilities in hot subdwarf stars with amplitudes of the order of a few thousandths of a magnitude. As such, they can now be detected by space-based photometry with the Transiting Exoplanet Survey Satellite in relatively bright stars (for example, Johnson-Cousins magnitudes of IC ≲ 13 mag)3. The range of predicted periods spans from a few thousand seconds to tens of thousands of seconds, depending on the details of the excitation region. In addition, we find that stochastically excited pulsations reproduce the pulsations observed in a few helium-rich hot subdwarf stars. These stars, particularly the future Transiting Exoplanet Survey Satellite target Feige 46, are the most promising candidates to probe the helium core flash for the first time. Title: Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi Authors: Chaplin, William J.; Serenelli, Aldo M.; Miglio, Andrea; Morel, Thierry; Mackereth, J. Ted; Vincenzo, Fiorenzo; Kjeldsen, Hans; Basu, Sarbani; Ball, Warrick H.; Stokholm, Amalie; Verma, Kuldeep; Mosumgaard, Jakob Rørsted; Silva Aguirre, Victor; Mazumdar, Anwesh; Ranadive, Pritesh; Antia, H. M.; Lebreton, Yveline; Ong, Joel; Appourchaux, Thierry; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen; Creevey, Orlagh; García, Rafael A.; Handberg, Rasmus; Huber, Daniel; Kawaler, Steven D.; Lund, Mikkel N.; Metcalfe, Travis S.; Stassun, Keivan G.; Bazot, Michäel; Beck, Paul G.; Bell, Keaton J.; Bergemann, Maria; Buzasi, Derek L.; Benomar, Othman; Bossini, Diego; Bugnet, Lisa; Campante, Tiago L.; Orhan, Zeynep çelik; Corsaro, Enrico; González-Cuesta, Lucía; Davies, Guy R.; Di Mauro, Maria Pia; Egeland, Ricky; Elsworth, Yvonne P.; Gaulme, Patrick; Ghasemi, Hamed; Guo, Zhao; Hall, Oliver J.; Hasanzadeh, Amir; Hekker, Saskia; Howe, Rachel; Jenkins, Jon M.; Jiménez, Antonio; Kiefer, René; Kuszlewicz, James S.; Kallinger, Thomas; Latham, David W.; Lundkvist, Mia S.; Mathur, Savita; Montalbán, Josefina; Mosser, Benoit; Bedón, Andres Moya; Nielsen, Martin Bo; Örtel, Sibel; Rendle, Ben M.; Ricker, George R.; Rodrigues, Thaíse S.; Roxburgh, Ian W.; Safari, Hossein; Schofield, Mathew; Seager, Sara; Smalley, Barry; Stello, Dennis; Szabó, Róbert; Tayar, Jamie; Themeßl, Nathalie; Thomas, Alexandra E. L.; Vanderspek, Roland K.; van Rossem, Walter E.; Vrard, Mathieu; Weiss, Achim; White, Timothy R.; Winn, Joshua N.; Yıldız, Mutlu Bibcode: 2020NatAs...4..382C Altcode: 2020NatAs.tmp....7C; 2020arXiv200104653C Over the course of its history, the Milky Way has ingested multiple smaller satellite galaxies1. Although these accreted stellar populations can be forensically identified as kinematically distinct structures within the Galaxy, it is difficult in general to date precisely the age at which any one merger occurred. Recent results have revealed a population of stars that were accreted via the collision of a dwarf galaxy, called Gaia-Enceladus1, leading to substantial pollution of the chemical and dynamical properties of the Milky Way. Here we identify the very bright, naked-eye star ν Indi as an indicator of the age of the early in situ population of the Galaxy. We combine asteroseismic, spectroscopic, astrometric and kinematic observations to show that this metal-poor, alpha-element-rich star was an indigenous member of the halo, and we measure its age to be 11.0 ±0.7 ? (stat) ±0.8 ? (sys) billion years. The star bears hallmarks consistent with having been kinematically heated by the Gaia-Enceladus collision. Its age implies that the earliest the merger could have begun was 11.6 and 13.2 billion years ago, at 68% and 95% confidence, respectively. Computations based on hierarchical cosmological models slightly reduce the above limits. Title: Asteroseismic Constraints on the Cosmic-time Variation of the Gravitational Constant from an Ancient Main-sequence Star Authors: Bellinger, Earl Patrick; Christensen-Dalsgaard, Jørgen Bibcode: 2019ApJ...887L...1B Altcode: 2019arXiv190906378B We investigate the variation of the gravitational constant G over the history of the universe by modeling the effects on the evolution and asteroseismology of the low-mass star KIC 7970740, which is one of the oldest (∼11 Gyr) and best-observed solar-like oscillators in the Galaxy. From these data we find \dot{G}/G=(2.1+/- 2.9)× 10-12 yr-1, that is, no evidence for any variation in G. We also find a Bayesian asteroseismic estimate of the age of the universe as well as astrophysical S-factors for five nuclear reactions obtained through a 12-dimensional stellar evolution Markov Chain Monte Carlo simulation. Title: Testing Stellar Evolution with Asteroseismic Inversions of a Main-sequence Star Harboring a Small Convective Core Authors: Bellinger, Earl P.; Basu, Sarbani; Hekker, Saskia; Christensen-Dalsgaard, Jørgen Bibcode: 2019ApJ...885..143B Altcode: 2019arXiv191000603B The goal of stellar evolution theory is to predict the structure of stars throughout their lifetimes. Usually, these predictions can be assessed only indirectly, for example by comparing predicted and observed effective temperatures and luminosities. Thanks now to asteroseismology, which can reveal the internal structure of stars, it becomes possible to compare the predictions from stellar evolution theory to actual stellar structures. In this work, we present an inverse analysis of the oscillation data from the solar-type star KIC 6225718, which was observed by the Kepler space observatory during its nominal mission. As its mass is about 20% greater than solar, this star is predicted to transport energy by convection in its nuclear-burning core. We find significant differences between the predicted and actual structure of the star in the radiative interior near to the convective core. In particular, the predicted sound speed is higher than observed in the deep interior of the star, and too low at a fractional radius of 0.25 and beyond. The cause of these discrepancies is unknown, and is not remedied by known physics in the form of convective overshooting or elemental diffusion. Title: Analytical modelling of period spacings across the HR diagram Authors: Cunha, M. S.; Avelino, P. P.; Christensen-Dalsgaard, J.; Stello, D.; Vrard, M.; Jiang, C.; Mosser, B. Bibcode: 2019MNRAS.490..909C Altcode: 2019MNRAS.tmp.2220C; 2019arXiv190904966C The characterization of stellar cores may be accomplished through the modelling of asteroseismic data from stars exhibiting either gravity-mode or mixed-mode pulsations, potentially shedding light on the physical processes responsible for the production, mixing, and segregation of chemical elements. In this work, we validate against model data an analytical expression for the period spacing that will facilitate the inference of the properties of stellar cores, including the detection and characterization of buoyancy glitches (strong chemical gradients). This asymptotically based analytical expression is tested both in models with and without buoyancy glitches. It does not assume that glitches are small and, consequently, predicts non-sinusoidal glitch-induced period-spacing variations, as often seen in model and real data. We show that the glitch position and width inferred from the fitting of the analytical expression to model data consisting of pure gravity modes are in close agreement (typically better than 7 per cent relative difference) with the properties measured directly from the stellar models. In the case of fitting mixed-mode model data, the same expression is shown to reproduce well the numerical results, when the glitch properties are known a priori. In addition, the fits performed to mixed-mode model data reveal a frequency dependence of the coupling coefficient, q, for a moderate-luminosity red-giant-branch model star. Finally, we find that fitting the analytical expression to the mixed-mode period spacings may provide a way to infer the frequencies of the pure acoustic dipole modes that would exist if no coupling took place between acoustic and gravity waves. Title: TESS Asteroseismology of the Known Red-giant Host Stars HD 212771 and HD 203949 Authors: Campante, Tiago L.; Corsaro, Enrico; Lund, Mikkel N.; Mosser, Benoît; Serenelli, Aldo; Veras, Dimitri; Adibekyan, Vardan; Antia, H. M.; Ball, Warrick; Basu, Sarbani; Bedding, Timothy R.; Bossini, Diego; Davies, Guy R.; Delgado Mena, Elisa; García, Rafael A.; Handberg, Rasmus; Hon, Marc; Kane, Stephen R.; Kawaler, Steven D.; Kuszlewicz, James S.; Lucas, Miles; Mathur, Savita; Nardetto, Nicolas; Nielsen, Martin B.; Pinsonneault, Marc H.; Reffert, Sabine; Silva Aguirre, Víctor; Stassun, Keivan G.; Stello, Dennis; Stock, Stephan; Vrard, Mathieu; Yıldız, Mutlu; Chaplin, William J.; Huber, Daniel; Bean, Jacob L.; Çelik Orhan, Zeynep; Cunha, Margarida S.; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans; Metcalfe, Travis S.; Miglio, Andrea; Monteiro, Mário J. P. F. G.; Nsamba, Benard; Örtel, Sibel; Pereira, Filipe; Sousa, Sérgio G.; Tsantaki, Maria; Turnbull, Margaret C. Bibcode: 2019ApJ...885...31C Altcode: 2019arXiv190905961C The Transiting Exoplanet Survey Satellite (TESS) is performing a near all-sky survey for planets that transit bright stars. In addition, its excellent photometric precision enables asteroseismology of solar-type and red-giant stars, which exhibit convection-driven, solar-like oscillations. Simulations predict that TESS will detect solar-like oscillations in nearly 100 stars already known to host planets. In this paper, we present an asteroseismic analysis of the known red-giant host stars HD 212771 and HD 203949, both systems having a long-period planet detected through radial velocities. These are the first detections of oscillations in previously known exoplanet-host stars by TESS, further showcasing the mission’s potential to conduct asteroseismology of red-giant stars. We estimate the fundamental properties of both stars through a grid-based modeling approach that uses global asteroseismic parameters as input. We discuss the evolutionary state of HD 203949 in depth and note the large discrepancy between its asteroseismic mass (M * = 1.23 ± 0.15 M ⊙ if on the red-giant branch or M * = 1.00 ± 0.16 M ⊙ if in the clump) and the mass quoted in the discovery paper (M * = 2.1 ± 0.1 M ⊙), implying a change >30% in the planet’s mass. Assuming HD 203949 to be in the clump, we investigate the planet’s past orbital evolution and discuss how it could have avoided engulfment at the tip of the red-giant branch. Finally, HD 212771 was observed by K2 during its Campaign 3, thus allowing for a preliminary comparison of the asteroseismic performances of TESS and K2. We estimate the ratio of the observed oscillation amplitudes for this star to be {A}\max {TESS}/{A}\max K2=0.75+/- 0.14, consistent with the expected ratio of ∼0.85 due to the redder bandpass of TESS. Title: VizieR Online Data Catalog: High-precision radial velocities for HD 221416 (Huber+, 2019) Authors: Huber, D.; Chaplin, W. J.; Chontos, A.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Bedding, T. R.; Ball, W.; Brahm, R.; Espinoza, N.; Henning, T.; Jordan, A.; Sarkis, P.; Knudstrup, E.; Albrecht, S.; Grundahl, F.; Andersen, M. F.; Palle, P. L.; Crossfield, I.; Fulton, B.; Howard, A. W.; Isaacson, H. T.; Weiss, L. M.; Handberg, R.; Lund, M. N.; Serenelli, A. M.; Rorsted Mosumgaard, J.; Stokholm, A.; Bieryla, A.; Buchhave, L. A.; Latham, D. W.; Quinn, S. N.; Gaidos, E.; Hirano, T.; Ricker, G. R.; Vanderspek, R. K.; Seager, S.; Jenkins, J. M.; Winn, J. N.; Antia, H. M.; Appourchaux, T.; Basu, S.; Bell, K. J.; Benomar, O.; Bonanno, A.; Buzasi, D. L.; Campante, T. L.; Celik Orhan, Z.; Corsaro, E.; Cunha, M. S.; Davies, G. R.; Deheuvels, S.; Grunblatt, S. K.; Hasanzadeh, A.; di Mauro, M. P.; Garcia, R. A.; Gaulme, P.; Girardi, L.; Guzik, J. A.; Hon, M.; Jiang, C.; Kallinger, T.; Kawaler, S. D.; Kuszlewicz, J. S.; Lebreton, Y.; Li, T.; Lucas, M.; Lundkvist, M. S.; Mann, A. W.; Mathis, S.; Mathur, S.; Mazumdar, A.; Metcalfe, T. S.; Miglio, A.; Monteiro, M. J. P. F. G.; Mosser, B.; Noll, A.; Nsamba, B.; Ong, J. M. J.; Ortel, S.; Pereira, F.; Ranadive, P.; Regulo, C.; Rodrigues, T. S.; Roxburgh, I. W.; Aguirre, V. S.; Smalley, B.; Schofield, M.; Sousa, S. G.; Stassun, K. G.; Stello, D.; Tayar, J.; White, T. R.; Verma, K.; Vrard, M.; Yildiz, M.; Baker, D.; Bazot, M.; Beichmann, C.; Bergmann, C.; Bugnet, L.; Cale, B.; Carlino, R.; Cartwright, S. M.; Christiansen, J. L.; Ciardi, D. R.; Creevey, O.; Dittmann, J. A.; Do Nascimento, J. -D., Jr.; van Eylen, V.; Furesz, G.; Gagne, J.; Gao, P.; Gazeas, K.; Giddens, F.; Hall, O. J.; Hekker, S.; Ireland, M. J.; Latouf, N.; Lebrun, D.; Levine, A. M.; Matzko, W.; Natinsky, E.; Page, E.; Plavchan, P.; Mansouri-Samani, M.; McCauliff, S.; Mullally, S. E.; Orenstein, B.; Soto, A. G.; Paegert, M.; van Saders, J. L.; Schnaible, C.; Soderblom, D. R.; Szabo, R.; Tanner, A.; Tinney, C. G.; Teske, J.; Thomas, A.; Trampedach, R.; Wright, D.; Yuan, T. T.; Zohrabi, F. Bibcode: 2019yCat..51570245H Altcode: We obtained high-resolution spectra of HD 221416 using several facilities within the TESS Follow-up Observation Program (TFOP), including HIRES (Vogt et al. 1994SPIE.2198..362V) on the 10 m telescope at Keck Observatory (Maunakea, Hawai'i); the Hertzsprung SONG Telescope at Teide Observatory (Tenerife; Grundahl et al. 2017ApJ...836..142G); HARPS (Mayor et al. 2003Msngr.114...20M), FEROS (Kaufer et al. 1999Msngr..95....8K), Coralie (Queloz et al. 2001Msngr.105....1Q), and FIDEOS (Vanzi et al. 2018MNRAS.477.5041V) on the MPG/ESO 3.6 m, 2.2 m, 1.2 m, and 1 m telescopes at La Silla Observatory (Chile); Veloce (Gilbert et al. 2018SPIE10702E..0YG) on the 3.9 m Anglo-Australian Telescope at Siding Spring Observatory (Australia); TRES (Furesz 2008, PhD thesis Univ. Szeged) on the 1.5 m Tillinghast reflector at the F. L. Whipple Observatory (Mt. Hopkins, Arizona); and iSHELL (Rayner et al. 2012SPIE.8446E..2CR) on the NASA IRTF Telescope (Maunakea, Hawai'i). All spectra used in this paper were obtained between 2018 November 11 and December 30 and have a minimum spectral resolution of R~44000.

(1 data file). Title: Solar Models with Convective Overshoot, Solar-wind Mass Loss, and PMS Disk Accretion: Helioseismic Quantities, Li Depletion, and Neutrino Fluxes Authors: Zhang, Qian-Sheng; Li, Yan; Christensen-Dalsgaard, Jørgen Bibcode: 2019ApJ...881..103Z Altcode: 2019arXiv190702166Z Helioseismic observations have revealed many properties of the Sun: the depth and helium abundance of the convection zone, the sound speed, and the density profiles in the solar interior. Those constraints have been used to judge the stellar evolution theory. With the old solar composition (e.g., GS98), the solar standard model is in reasonable agreement with the helioseismic constraints. However, a solar model with a revised composition (e.g., AGSS09) with a low abundance Z of heavy elements cannot be consistent with those constraints. This is the so-called “solar abundance problem,” standing for more than 10 yr even with the recent upward revised Ne abundance. Many mechanisms have been proposed to mitigate the problem. However, there is still no low-Z solar model satisfying all helioseismic constraints. In this paper, we report a possible solution to the solar abundance problem. With some extra physical processes that are not included in the standard model, solar models can be significantly improved. Our new solar models with convective overshoot, the solar wind, and early mass accretion show consistency with helioseismic constraints, the solar Li abundance, and observations of solar neutrino fluxes. Title: Damping rates and frequency corrections of Kepler LEGACY stars Authors: Houdek, G.; Lund, M. N.; Trampedach, R.; Christensen-Dalsgaard, J.; Handberg, R.; Appourchaux, T. Bibcode: 2019MNRAS.487..595H Altcode: 2019MNRAS.tmp.1157H; 2019arXiv190413170H Linear damping rates and modal frequency corrections of radial oscillation modes in selected LEGACY main-sequence stars are estimated by means of a non-adiabatic stability analysis. The selected stellar sample covers stars observed by Kepler with a large range of surface temperatures and surface gravities. A non-local, time-dependent convection model is perturbed to assess stability against pulsation modes. The mixing-length parameter is calibrated to the surface-convection-zone depth of a stellar model obtained from fitting adiabatic frequencies to the LEGACY observations, and two of the non-local convection parameters are calibrated to the corresponding LEGACY linewidth measurements. The remaining non-local convection parameters in the 1D calculations are calibrated so as to reproduce profiles of turbulent pressure and of the anisotropy of the turbulent velocity field of corresponding 3D hydrodynamical simulations. The atmospheric structure in the 1D stability analysis adopts a temperature-optical-depth relation derived from 3D hydrodynamical simulations. Despite the small number of parameters to adjust, we find good agreement with detailed shapes of both turbulent pressure profiles and anisotropy profiles with depth, and with damping rates as a function of frequency. Furthermore, we find the absolute modal frequency corrections, relative to a standard adiabatic pulsation calculation, to increase with surface temperature and surface gravity. Title: A Hot Saturn Orbiting an Oscillating Late Subgiant Discovered by TESS Authors: Huber, Daniel; Chaplin, William J.; Chontos, Ashley; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen; Bedding, Timothy R.; Ball, Warrick; Brahm, Rafael; Espinoza, Nestor; Henning, Thomas; Jordán, Andrés; Sarkis, Paula; Knudstrup, Emil; Albrecht, Simon; Grundahl, Frank; Fredslund Andersen, Mads; Pallé, Pere L.; Crossfield, Ian; Fulton, Benjamin; Howard, Andrew W.; Isaacson, Howard T.; Weiss, Lauren M.; Handberg, Rasmus; Lund, Mikkel N.; Serenelli, Aldo M.; Rørsted Mosumgaard, Jakob; Stokholm, Amalie; Bieryla, Allyson; Buchhave, Lars A.; Latham, David W.; Quinn, Samuel N.; Gaidos, Eric; Hirano, Teruyuki; Ricker, George R.; Vanderspek, Roland K.; Seager, Sara; Jenkins, Jon M.; Winn, Joshua N.; Antia, H. M.; Appourchaux, Thierry; Basu, Sarbani; Bell, Keaton J.; Benomar, Othman; Bonanno, Alfio; Buzasi, Derek L.; Campante, Tiago L.; Çelik Orhan, Z.; Corsaro, Enrico; Cunha, Margarida S.; Davies, Guy R.; Deheuvels, Sebastien; Grunblatt, Samuel K.; Hasanzadeh, Amir; Di Mauro, Maria Pia; García, Rafael A.; Gaulme, Patrick; Girardi, Léo; Guzik, Joyce A.; Hon, Marc; Jiang, Chen; Kallinger, Thomas; Kawaler, Steven D.; Kuszlewicz, James S.; Lebreton, Yveline; Li, Tanda; Lucas, Miles; Lundkvist, Mia S.; Mann, Andrew W.; Mathis, Stéphane; Mathur, Savita; Mazumdar, Anwesh; Metcalfe, Travis S.; Miglio, Andrea; Monteiro, Mário J. P. F. G.; Mosser, Benoit; Noll, Anthony; Nsamba, Benard; Ong, Jia Mian Joel; Örtel, S.; Pereira, Filipe; Ranadive, Pritesh; Régulo, Clara; Rodrigues, Thaíse S.; Roxburgh, Ian W.; Silva Aguirre, Victor; Smalley, Barry; Schofield, Mathew; Sousa, Sérgio G.; Stassun, Keivan G.; Stello, Dennis; Tayar, Jamie; White, Timothy R.; Verma, Kuldeep; Vrard, Mathieu; Yıldız, M.; Baker, David; Bazot, Michaël; Beichmann, Charles; Bergmann, Christoph; Bugnet, Lisa; Cale, Bryson; Carlino, Roberto; Cartwright, Scott M.; Christiansen, Jessie L.; Ciardi, David R.; Creevey, Orlagh; Dittmann, Jason A.; Do Nascimento, Jose-Dias, Jr.; Van Eylen, Vincent; Fürész, Gabor; Gagné, Jonathan; Gao, Peter; Gazeas, Kosmas; Giddens, Frank; Hall, Oliver J.; Hekker, Saskia; Ireland, Michael J.; Latouf, Natasha; LeBrun, Danny; Levine, Alan M.; Matzko, William; Natinsky, Eva; Page, Emma; Plavchan, Peter; Mansouri-Samani, Masoud; McCauliff, Sean; Mullally, Susan E.; Orenstein, Brendan; Garcia Soto, Aylin; Paegert, Martin; van Saders, Jennifer L.; Schnaible, Chloe; Soderblom, David R.; Szabó, Róbert; Tanner, Angelle; Tinney, C. G.; Teske, Johanna; Thomas, Alexandra; Trampedach, Regner; Wright, Duncan; Yuan, Thomas T.; Zohrabi, Farzaneh Bibcode: 2019AJ....157..245H Altcode: 2019arXiv190101643H We present the discovery of HD 221416 b, the first transiting planet identified by the Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology of the host star is possible. HD 221416 b (HIP 116158, TOI-197) is a bright (V = 8.2 mag), spectroscopically classified subgiant that oscillates with an average frequency of about 430 μHz and displays a clear signature of mixed modes. The oscillation amplitude confirms that the redder TESS bandpass compared to Kepler has a small effect on the oscillations, supporting the expected yield of thousands of solar-like oscillators with TESS 2 minute cadence observations. Asteroseismic modeling yields a robust determination of the host star radius (R ⋆ = 2.943 ± 0.064 R ⊙), mass (M ⋆ = 1.212 ± 0.074 M ⊙), and age (4.9 ± 1.1 Gyr), and demonstrates that it has just started ascending the red-giant branch. Combining asteroseismology with transit modeling and radial-velocity observations, we show that the planet is a “hot Saturn” (R p = 9.17 ± 0.33 R ⊕) with an orbital period of ∼14.3 days, irradiance of F = 343 ± 24 F ⊕, and moderate mass (M p = 60.5 ± 5.7 M ⊕) and density (ρ p = 0.431 ± 0.062 g cm-3). The properties of HD 221416 b show that the host-star metallicity-planet mass correlation found in sub-Saturns (4-8 R ⊕) does not extend to larger radii, indicating that planets in the transition between sub-Saturns and Jupiters follow a relatively narrow range of densities. With a density measured to ∼15%, HD 221416 b is one of the best characterized Saturn-size planets to date, augmenting the small number of known transiting planets around evolved stars and demonstrating the power of TESS to characterize exoplanets and their host stars using asteroseismology. Title: Helioseismology and solar neutrinos Authors: Christensen-Dalsgaard, JøRgen Bibcode: 2019sone.conf...81C Altcode: 2018arXiv180903000C The studies of solar neutrinos and helioseismology have been closely intertwined since the first neutrino experiment and the first observations of solar oscillations in the sixties. Early detailed helioseismic analyses provided strong support for the standard solar model and hence a clear indication that the solution to the discrepancy between the predicted and observed neutrino fluxes had to be found in terms of neutrino physics, as now fully confirmed by direct observations. With the full characterization of neutrino properties we are now in a position to combine neutrino observations and helioseismology to obtain a more complete understanding of conditions in the solar core. Here I provide a personal and largely historical overview of these developments. Title: Stellar modeling and asteroseismology Authors: Christensen-Dalsgaard, Jorgen Bibcode: 2019psce.confE...3C Altcode: No abstract at ADS Title: Oscillations in the Sun with SONG: Setting the scale for asteroseismic investigations Authors: Fredslund Andersen, M.; Pallé, P.; Jessen-Hansen, J.; Wang, K.; Grundahl, F.; Bedding, T. R.; Roca Cortes, T.; Yu, J.; Mathur, S.; Gacia, R. A.; Arentoft, T.; Régulo, C.; Tronsgaard, R.; Kjeldsen, H.; Christensen-Dalsgaard, J. Bibcode: 2019A&A...623L...9F Altcode: 2019arXiv190210717F Context. We present the first high-cadence multiwavelength radial-velocity observations of the Sun-as-a-star, carried out during 57 consecutive days using the stellar échelle spectrograph at the Hertzsprung SONG Telescope operating at the Teide Observatory.
Aims: Our aim was to produce a high-quality data set and reference values for the global helioseismic parameters νmax, ⊙ and Δν⊙ of the solar p-modes using the SONG instrument. The obtained data set or the inferred values should then be used when the scaling relations are applied to other stars showing solar-like oscillations observed with SONG or similar instruments.
Methods: We used different approaches to analyse the power spectrum of the time series to determine νmax, ⊙: simple Gaussian fitting and heavy smoothing of the power spectrum. We determined Δν⊙ using the method of autocorrelation of the power spectrum. The amplitude per radial mode was determined using the method described in Kjeldsen et al. (2008, ApJ, 682, 1370).
Results: We found the following values for the solar oscillations using the SONG spectrograph: νmax, ⊙ = 3141 ± 12 μHz, Δν⊙ = 134.98 ± 0.04 μHz, and an average amplitude of the strongest radial modes of 16.6 ± 0.4 cm s-1. These values are consistent with previous measurements with other techniques.

Based on observations made at the Hertzsprung SONG telescope operated at the Spanish Observatorio del Teide on the island of Tenerife by the Aarhus and Copenhagen Universities and by the Instituto de Astrofísica de Canarias. Title: Latitudinal differential rotation in the solar analogues 16 Cygni A and B Authors: Bazot, M.; Benomar, O.; Christensen-Dalsgaard, J.; Gizon, L.; Hanasoge, S.; Nielsen, M.; Petit, P.; Sreenivasan, K. R. Bibcode: 2019A&A...623A.125B Altcode: 2019arXiv190201676B Context. Asteroseismology has undergone a profound transformation as a scientific field following the CoRoT and Kepler space missions. The latter is now yielding the first measurements of latitudinal differential rotation obtained directly from oscillation frequencies. Differential rotation is a fundamental mechanism of the stellar dynamo effect.
Aims: Our goal is to measure the amount of differential rotation in the solar analogues 16 Cyg A and B, which are the components of a binary system. These stars are the brightest observed by Kepler and have therefore been extensively observed, with exquisite precision on their oscillation frequencies.
Methods: We modelled the acoustic power spectrum of 16 Cyg A and B using a model that takes into account the contribution of differential rotation to the rotational frequency splitting. The estimation was carried out in a Bayesian setting. We then inverted these results to obtain the rotation profile of both stars under the assumption of a solar-like functional form.
Results: We observe that the magnitude of latitudinal differential rotation has a strong chance of being solar-like for both stars, their rotation rates being higher at the equator than at the pole. The measured latitudinal differential rotation, defined as the difference of rotation rate between the equator and the pole, is 320 ± 269 nHz and 440-383+363 nHz for 16 Cyg A and B, respectively, confirming that the rotation rates of these stars are almost solar-like. Their equatorial rotation rates are 535 ± 75 nHz and 565-129+150 nHz. Our results are in good agreement with measurements obtained from spectropolarimetry, spectroscopy, and photometry.
Conclusions: We present the first conclusive measurement of latitudinal differential rotation for solar analogues. Their rotational profiles are very close to those of the Sun. These results depend weakly on the uncertainties of the stellar parameters. Title: The Asteroseismic Target List for Solar-like Oscillators Observed in 2 minute Cadence with the Transiting Exoplanet Survey Satellite Authors: Schofield, Mathew; Chaplin, William J.; Huber, Daniel; Campante, Tiago L.; Davies, Guy R.; Miglio, Andrea; Ball, Warrick H.; Appourchaux, Thierry; Basu, Sarbani; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen; Creevey, Orlagh; García, Rafael A.; Handberg, Rasmus; Kawaler, Steven D.; Kjeldsen, Hans; Latham, David W.; Lund, Mikkel N.; Metcalfe, Travis S.; Ricker, George R.; Serenelli, Aldo; Silva Aguirre, Victor; Stello, Dennis; Vanderspek, Roland Bibcode: 2019ApJS..241...12S Altcode: 2019arXiv190110148S We present the target list of solar-type stars to be observed in short-cadence (2 minute) for asteroseismology by the NASA Transiting Exoplanet Survey Satellite (TESS) during its 2 year nominal survey mission. The solar-like Asteroseismic Target List (ATL) is comprised of bright, cool main-sequence and subgiant stars and forms part of the larger target list of the TESS Asteroseismic Science Consortium. The ATL uses the Gaia Data Release 2 and the Extended Hipparcos Compilation (XHIP) to derive fundamental stellar properties, to calculate detection probabilities, and to produce a rank-ordered target list. We provide a detailed description of how the ATL was produced and calculate expected yields for solar-like oscillators based on the nominal photometric performance by TESS. We also provide a publicly available source code that can be used to reproduce the ATL, thereby enabling comparisons of asteroseismic results from TESS with predictions from synthetic stellar populations. Title: Asteroseismic modelling of the subgiant μ Herculis using SONG data: lifting the degeneracy between age and model input parameters Authors: Li, Tanda; Bedding, Timothy R.; Kjeldsen, Hans; Stello, Dennis; Christensen-Dalsgaard, Jørgen; Deng, Licai Bibcode: 2019MNRAS.483..780L Altcode: 2018arXiv181013015L; 2018MNRAS.tmp.2856L We model the oscillations of the SONG target μ Herculis to estimate the parameters of the star. The ℓ = 1 mixed modes of μ Her provide strong constraints on stellar properties. The mass and age given by our asteroseismic modelling are 1.10^{+0.11}_{-0.06} M⊙ and 7.55^{+0.96}_{-0.79} Gyr, respectively. The initial helium abundance is also constrained at around Yinit = 0.28, suggesting a ratio in the elements enrichment law (ΔY/ΔZ) around 1.3, which is closed to the solar value. The mixing-length parameter converges to about 1.7, which is ∼10 per cent lower than the solar value and consistent with the results from hydrodynamic simulations. Our estimates of stellar mass and age agree very well with the previous modelling results with different input physics. Adding asteroseismic information makes these determinations less model dependent than is typically the case when only surface information is available. Our studies of the model dependence (mass, initial helium and metallicity fractions, and the mixing-length parameter) of the age determination indicate that accurate stellar ages (≲10 per cent) can be expected from asteroseismic modelling for stars similar to μ Her. The ℓ = 1 bumped modes, which are sensitive to the mean density of the helium core, provide a useful `clock' that provides additional constraints on its age. Title: A giant impact as the likely origin of different twins in the Kepler-107 exoplanet system Authors: Bonomo, Aldo S.; Zeng, Li; Damasso, Mario; Leinhardt, Zoë M.; Justesen, Anders B.; Lopez, Eric; Lund, Mikkel N.; Malavolta, Luca; Silva Aguirre, Victor; Buchhave, Lars A.; Corsaro, Enrico; Denman, Thomas; Lopez-Morales, Mercedes; Mills, Sean M.; Mortier, Annelies; Rice, Ken; Sozzetti, Alessandro; Vanderburg, Andrew; Affer, Laura; Arentoft, Torben; Benbakoura, Mansour; Bouchy, François; Christensen-Dalsgaard, Jørgen; Collier Cameron, Andrew; Cosentino, Rosario; Dressing, Courtney D.; Dumusque, Xavier; Figueira, Pedro; Fiorenzano, Aldo F. M.; García, Rafael A.; Handberg, Rasmus; Harutyunyan, Avet; Johnson, John A.; Kjeldsen, Hans; Latham, David W.; Lovis, Christophe; Lundkvist, Mia S.; Mathur, Savita; Mayor, Michel; Micela, Giusi; Molinari, Emilio; Motalebi, Fatemeh; Nascimbeni, Valerio; Nava, Chantanelle; Pepe, Francesco; Phillips, David F.; Piotto, Giampaolo; Poretti, Ennio; Sasselov, Dimitar; Ségransan, Damien; Udry, Stéphane; Watson, Chris Bibcode: 2019NatAs...3..416B Altcode: 2019NatAs.tmp..201B; 2019arXiv190201316B Measures of exoplanet bulk densities indicate that small exoplanets with radius less than 3 Earth radii (R⊕) range from low-density sub-Neptunes containing volatile elements1 to higher-density rocky planets with Earth-like2 or iron-rich3 (Mercury-like) compositions. Such astonishing diversity in observed small exoplanet compositions may be the product of different initial conditions of the planet-formation process or different evolutionary paths that altered the planetary properties after formation4. Planet evolution may be especially affected by either photoevaporative mass loss induced by high stellar X-ray and extreme ultraviolet (XUV) flux5 or giant impacts6. Although there is some evidence for the former7,8, there are no unambiguous findings so far about the occurrence of giant impacts in an exoplanet system. Here, we characterize the two innermost planets of the compact and near-resonant system Kepler-107 (ref. 9). We show that they have nearly identical radii (about 1.5-1.6R⊕), but the outer planet Kepler-107 c is more than twice as dense (about 12.6 g cm-3) as the innermost Kepler-107 b (about 5.3 g cm-3). In consequence, Kepler-107 c must have a larger iron core fraction than Kepler-107 b. This imbalance cannot be explained by the stellar XUV irradiation, which would conversely make the more-irradiated and less-massive planet Kepler-107 b denser than Kepler-107 c. Instead, the dissimilar densities are consistent with a giant impact event on Kepler-107 c that would have stripped off part of its silicate mantle. This hypothesis is supported by theoretical predictions from collisional mantle stripping10, which match the mass and radius of Kepler-107 c. Title: TESS Discovery of an Ultra-short-period Planet around the Nearby M Dwarf LHS 3844 Authors: Vanderspek, Roland; Huang, Chelsea X.; Vanderburg, Andrew; Ricker, George R.; Latham, David W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Burt, Jennifer; Dittmann, Jason; Newton, Elisabeth; Quinn, Samuel N.; Shporer, Avi; Charbonneau, David; Irwin, Jonathan; Ment, Kristo; Winters, Jennifer G.; Collins, Karen A.; Evans, Phil; Gan, Tianjun; Hart, Rhodes; Jensen, Eric L. N.; Kielkopf, John; Mao, Shude; Waalkes, William; Bouchy, François; Marmier, Maxime; Nielsen, Louise D.; Ottoni, Gaël; Pepe, Francesco; Ségransan, Damien; Udry, Stéphane; Henry, Todd; Paredes, Leonardo A.; James, Hodari-Sadiki; Hinojosa, Rodrigo H.; Silverstein, Michele L.; Palle, Enric; Berta-Thompson, Zachory; Crossfield, Ian; Davies, Misty D.; Dragomir, Diana; Fausnaugh, Michael; Glidden, Ana; Pepper, Joshua; Morgan, Edward H.; Rose, Mark; Twicken, Joseph D.; Villaseñor, Jesus Noel S.; Yu, Liang; Bakos, Gaspar; Bean, Jacob; Buchhave, Lars A.; Christensen-Dalsgaard, Jørgen; Christiansen, Jessie L.; Ciardi, David R.; Clampin, Mark; De Lee, Nathan; Deming, Drake; Doty, John; Jernigan, J. Garrett; Kaltenegger, Lisa; Lissauer, Jack J.; McCullough, P. R.; Narita, Norio; Paegert, Martin; Pal, Andras; Rinehart, Stephen; Sasselov, Dimitar; Sato, Bun'ei; Sozzetti, Alessandro; Stassun, Keivan G.; Torres, Guillermo Bibcode: 2019ApJ...871L..24V Altcode: 2018arXiv180907242V Data from the newly commissioned Transiting Exoplanet Survey Satellite has revealed a “hot Earth” around LHS 3844, an M dwarf located 15 pc away. The planet has a radius of 1.303+/- 0.022 R ⊕ and orbits the star every 11 hr. Although the existence of an atmosphere around such a strongly irradiated planet is questionable, the star is bright enough (I = 11.9, K = 9.1) for this possibility to be investigated with transit and occultation spectroscopy. The star’s brightness and the planet’s short period will also facilitate the measurement of the planet’s mass through Doppler spectroscopy. Title: Asteroseismology of the Hyades red giant and planet host ɛ Tauri Authors: Arentoft, T.; Grundahl, F.; White, T. R.; Slumstrup, D.; Handberg, R.; Lund, M. N.; Brogaard, K.; Andersen, M. F.; Silva Aguirre, V.; Zhang, C.; Chen, X.; Yan, Z.; Pope, B. J. S.; Huber, D.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Jessen-Hansen, J.; Antoci, V.; Frandsen, S.; Bedding, T. R.; Pallé, P. L.; Garcia, R. A.; Deng, L.; Hon, M.; Stello, D.; Jørgensen, U. G. Bibcode: 2019A&A...622A.190A Altcode: 2019arXiv190106187A Context. Asteroseismic analysis of solar-like stars allows us to determine physical parameters such as stellar mass, with a higher precision compared to most other methods. Even in a well-studied cluster such as the Hyades, the masses of the red giant stars are not well known, and previous mass estimates are based on model calculations (isochrones). The four known red giants in the Hyades are assumed to be clump (core-helium-burning) stars based on their positions in colour-magnitude diagrams, however asteroseismology offers an opportunity to test this assumption.
Aims: Using asteroseismic techniques combined with other methods, we aim to derive physical parameters and the evolutionary stage for the planet hosting star ɛ Tau, which is one of the four red giants located in the Hyades.
Methods: We analysed time-series data from both ground and space to perform the asteroseismic analysis. By combining high signal-to-noise radial-velocity data from the ground-based SONG network with continuous space-based data from the revised Kepler mission K2, we derive and characterize 27 individual oscillation modes for ɛ Tau, along with global oscillation parameters such as the large frequency separation Δν and the ratio between the amplitude of the oscillations measured in radial velocity and intensity as a function of frequency. The latter has been measured previously for only two stars, the Sun and Procyon. Combining the seismic analysis with interferometric and spectroscopic measurements, we derive physical parameters for ɛ Tau, and discuss its evolutionary status.
Results: Along with other physical parameters, we derive an asteroseismic mass for ɛ Tau of M = 2.458 ± 0.073 M⊙, which is slightly lower than previous estimates, and which leads to a revised minimum mass of the planetary companion. Noting that the SONG and K2 data are non-simultaneous, we estimate the amplitude ratio between intensity and radial velocity to be 42.2 ± 2.3 ppm m-1 s, which is higher than expected from scaling relations.

Time-series data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/622/A190Based on observations made with the SONG telescopes operated on the Spanish Observatorio del Teide (Tenerife) and at the Chinese Delingha Observatory (Qinghai) by the Aarhus and Copenhagen Universities, by the Instituto de Astrofísica de Canarias and by the National Astronomical Observatories of China, and with NASA's K2 mission. Title: VizieR Online Data Catalog: eps Tau intensity and RV time-series data (Arentoft+, 2019) Authors: Arentoft, T.; Grundahl, F.; White, T. R.; Slumstrup, D.; Handberg, R.; Lund, M. N.; Brogaard, K.; Andersen, M. F.; Silva Aguirre, V.; Zhang, C.; Chen, X.; Yan, Z.; Pope, B. J. S.; Huber, D.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Jessen-Hansen, J.; Antoci, V.; Frandsen, S.; Bedding, T. R.; Palle, P. L.; Garcia, R. A.; Deng, L.; Hon, M.; Stello, D.; Jorgensen, U. G. Bibcode: 2019yCat..36220190A Altcode: Time-series data for epsilon Tau; photometric time-series data from the revised Kepler mission K2 and radial-velocity measurements from SONG (Stellar Observations Network Group). The time series have been filtered in order to remove variations and instrumental effects at low frequencies.

(2 data files). Title: TESS Discovery of a Transiting Super-Earth in the pi Mensae System Authors: Huang, Chelsea X.; Burt, Jennifer; Vanderburg, Andrew; Günther, Maximilian N.; Shporer, Avi; Dittmann, Jason A.; Winn, Joshua N.; Wittenmyer, Rob; Sha, Lizhou; Kane, Stephen R.; Ricker, George R.; Vanderspek, Roland K.; Latham, David W.; Seager, Sara; Jenkins, Jon M.; Caldwell, Douglas A.; Collins, Karen A.; Guerrero, Natalia; Smith, Jeffrey C.; Quinn, Samuel N.; Udry, Stéphane; Pepe, Francesco; Bouchy, François; Ségransan, Damien; Lovis, Christophe; Ehrenreich, David; Marmier, Maxime; Mayor, Michel; Wohler, Bill; Haworth, Kari; Morgan, Edward H.; Fausnaugh, Michael; Ciardi, David R.; Christiansen, Jessie; Charbonneau, David; Dragomir, Diana; Deming, Drake; Glidden, Ana; Levine, Alan M.; McCullough, P. R.; Yu, Liang; Narita, Norio; Nguyen, Tam; Morton, Tim; Pepper, Joshua; Pál, András; Rodriguez, Joseph E.; Stassun, Keivan G.; Torres, Guillermo; Sozzetti, Alessandro; Doty, John P.; Christensen-Dalsgaard, Jørgen; Laughlin, Gregory; Clampin, Mark; Bean, Jacob L.; Buchhave, Lars A.; Bakos, G. Á.; Sato, Bun'ei; Ida, Shigeru; Kaltenegger, Lisa; Palle, Enric; Sasselov, Dimitar; Butler, R. P.; Lissauer, Jack; Ge, Jian; Rinehart, S. A. Bibcode: 2018ApJ...868L..39H Altcode: 2018arXiv180905967H We report the detection of a transiting planet around π Men (HD 39091), using data from the Transiting Exoplanet Survey Satellite (TESS). The solar-type host star is unusually bright (V = 5.7) and was already known to host a Jovian planet on a highly eccentric, 5.7 yr orbit. The newly discovered planet has a size of 2.04 ± 0.05 R ⊕ and an orbital period of 6.27 days. Radial-velocity data from the High-Accuracy Radial-velocity Planet Searcher and Anglo-Australian Telescope/University College London Echelle Spectrograph archives also displays a 6.27 day periodicity, confirming the existence of the planet and leading to a mass determination of 4.82 ± 0.85 M ⊕. The star’s proximity and brightness will facilitate further investigations, such as atmospheric spectroscopy, asteroseismology, the Rossiter-McLaughlin effect, astrometry, and direct imaging. Title: Coupling 1D stellar evolution with 3D-hydrodynamical simulations on the fly - I. A new standard solar model Authors: Jørgensen, Andreas Christ Sølvsten; Mosumgaard, Jakob Rørsted; Weiss, Achim; Silva Aguirre, Víctor; Christensen-Dalsgaard, Jørgen Bibcode: 2018MNRAS.481L..35J Altcode: 2018arXiv180808886C; 2018MNRAS.tmpL.155J Standard 1D stellar evolution models do not correctly reproduce the structure of the outermost layers of stars with convective envelopes. This has been a long-standing problem in stellar modelling affecting both the predicted evolutionary paths and the attributed oscillation frequencies, and indirectly biasing numerous quantities derived from stellar evolution calculations. We present a novel method that mostly eliminates these structural defects by appending mean 3D simulations of stellar envelopes. In contrast to previous attempts, we impose the complete structure derived from 3D simulations at each time-step during the entire evolution. For this purpose, we interpolate in grids of pre-computed 3D simulations and use the resulting structure as boundary conditions, in order to solve the stellar structure equations for the 1D interior at each time-step. Our method provides a continuous transition in many quantities from the interior to the imposed interpolated 3D surface layers. We present a solar calibration model and show that the obtained structure of the surface layers reliably mimics that of the underlying 3D simulations for the present Sun. Moreover, we perform a helioseismic analysis, showing that our method mostly eliminates the structural contribution to the discrepancy between model frequencies and observed p-mode frequencies. Title: Modelling the solar twin 18 Scorpii Authors: Bazot, M.; Creevey, O.; Christensen-Dalsgaard, J.; Meléndez, J. Bibcode: 2018A&A...619A.172B Altcode: 2018arXiv181001387B Context. Solar twins are objects of great interest in that they allow us to understand better how stellar evolution and structure are affected by variations of the stellar mass, age and chemical composition in the vicinity of the commonly accepted solar values.
Aims: We aim to use the existing spectrophotometric, interferometric and asteroseismic data for the solar twin 18 Sco to constrain stellar evolution models. 18 Sco is the brightest solar twin and is a good benchmark for the study of solar twins. The goal is to obtain realistic estimates of its physical characteristics (mass, age, initial chemical composition, mixing-length parameter) and realistic associated uncertainties using stellar models.
Methods: We set up a Bayesian model that relates the statistical properties of the data to the probability density of the stellar parameters. Special care is given to the modelling of the likelihood for the seismic data, using Gaussian mixture models. The probability densities of the stellar parameters are approximated numerically using an adaptive MCMC algorithm. From these approximate distributions we proceeded to a statistical analysis. We also performed the same exercise using local optimisation.
Results: The precision on the mass is approximately 6%. The precision reached on X0 and Z0 and the mixing-length parameter are respectively 6%, 9%, and 35%. The posterior density for the age is bimodal, with modes at 4.67 Gyr and 6.95 Gyr, the first one being slightly more likely. We show that this bimodality is directly related to the structure of the seismic data. When asteroseismic data or interferometric data are excluded, we find significant losses of precision for the mass and the initial hydrogen-mass fraction. Our final estimates of the uncertainties from the Bayesian analysis are significantly larger than values inferred from local optimization. This also holds true for several estimates of the age encountered in the literature.

Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (run ID: 183.D-0729(A)). Title: Butterfly diagram of a Sun-like star observed using asteroseismology Authors: Bazot, M.; Nielsen, M. B.; Mary, D.; Christensen-Dalsgaard, J.; Benomar, O.; Petit, P.; Gizon, L.; Sreenivasan, K. R.; White, T. R. Bibcode: 2018A&A...619L...9B Altcode: 2018arXiv181008630B Stellar magnetic fields are poorly understood, but are known to be important for stellar evolution and exoplanet habitability. They drive stellar activity, which is the main observational constraint on theoretical models for magnetic field generation and evolution. Starspots are the main manifestation of the magnetic fields at the stellar surface. In this study we measured the variation in their latitude with time, called a butterfly diagram in the solar case, for the solar analogue HD 173701 (KIC 8006161). To this end, we used Kepler data to combine starspot rotation rates at different epochs and the asteroseismically determined latitudinal variation in the stellar rotation rates. We observe a clear variation in the latitude of the starspots. It is the first time such a diagram has been constructed using asteroseismic data. Title: Asteroseismic detection of latitudinal differential rotation in 13 Sun-like stars Authors: Benomar, O.; Bazot, M.; Nielsen, M. B.; Gizon, L.; Sekii, T.; Takata, M.; Hotta, H.; Hanasoge, S.; Sreenivasan, K. R.; Christensen-Dalsgaard, J. Bibcode: 2018Sci...361.1231B Altcode: 2018arXiv180907938B The differentially rotating outer layers of stars are thought to play a role in driving their magnetic activity, but the underlying mechanisms that generate and sustain differential rotation are poorly understood. We report the measurement using asteroseismology of latitudinal differential rotation in the convection zones of 40 Sun-like stars. For the most significant detections, the stars’ equators rotate approximately twice as fast as their midlatitudes. The latitudinal shear inferred from asteroseismology is much larger than predictions from numerical simulations. Title: High-precision abundances of elements in stars with asteroseismic ages Authors: Nissen, P. E.; Aguirre, V. Silva; Christensen-Dalsgaard, J.; Collet, R.; Grundahl, F.; Slumstrup, D. Bibcode: 2018IAUS..334..166N Altcode: High-precision abundances of elements have been derived from HARPS-N spectra of F and G main-sequence stars having ages determined from oscillation frequencies delivered by the Kepler mission. The tight relations between abundance ratios of refractory elements, e.g., [Mg/Fe] and [Y/Mg], and stellar age previously found for solar twin stars are confirmed. These relations provide new information on nucleosynthesis and Galactic evolution. Abundance ratios between volatile and refractory elements, e.g., [C/Fe] and [O/Fe], show on the other hand a significant scatter at a given age, which may be related to planet-star interactions. This is a potential problem for chemical tagging studies. Title: Using low-mass stars as a tool: efforts towards precise models Authors: Weiss, Achim; Aguirre, Victor Silva; Christensen-Dalsgaard, Jørgen Bibcode: 2018IAUS..334..178W Altcode: We present results of an on-going effort to identify the minimum level of systematic, purely numerical differences in low-mass stellar models on the Red Giant Branch, by comparing models in selected phases for pre-defined physical input assumptions. Title: Stellar models with calibrated convection and temperature stratification from 3D hydrodynamics simulations Authors: Mosumgaard, Jakob Rørsted; Ball, Warrick H.; Silva Aguirre, Víctor; Weiss, Achim; Christensen-Dalsgaard, Jørgen Bibcode: 2018MNRAS.478.5650M Altcode: 2018arXiv180600020R; 2018MNRAS.tmp.1388M; 2018MNRAS.478.5663M Stellar evolution codes play a major role in present-day astrophysics, yet they share common simplifications related to the outer layers of stars. We seek to improve on this by the use of results from realistic and highly detailed 3D hydrodynamics simulations of stellar convection. We implement a temperature stratification extracted directly from the 3D simulations into two stellar evolution codes to replace the simplified atmosphere normally used. Our implementation also contains a non-constant mixing-length parameter, which varies as a function of the stellar surface gravity and temperature - also derived from the 3D simulations. We give a detailed account of our fully consistent implementation and compare to earlier works, and also provide a freely available MESA-module. The evolution of low-mass stars with different masses is investigated, and we present for the first time an asteroseismic analysis of a standard solar model utilizing calibrated convection and temperature stratification from 3D simulations. We show that the inclusion of 3D results has an almost insignificant impact on the evolution and structure of stellar models - the largest effect are changes in effective temperature of order 30 K seen in the pre-main sequence and in the red-giant branch. However, this work provides the first step for producing self-consistent evolutionary calculations using fully incorporated 3D atmospheres from on-the-fly interpolation in grids of simulations. Title: VizieR Online Data Catalog: Kepler planetary cand. VIII. DR25 reliability (Thompson+, 2018) Authors: Thompson, S. E.; Coughlin, J. L.; Hoffman, K.; Mullally, F.; Christiansen, J. L.; Burke, C. J.; Bryson, S.; Batalha, N.; Haas, M. R.; Catanzarite, J.; Rowe, J. F.; Barentsen, G.; Caldwell, D. A.; Clarke, B. D.; Jenkins, J. M.; Li, J.; Latham, D. W.; Lissauer, J. J.; Mathur, S.; Morris, R. L.; Seader, S. E.; Smith, J. C.; Klaus, T. C.; Twicken, J. D.; van Cleve, J. E.; Wohler, B.; Akeson, R.; Ciardi, D. R.; Cochran, W. D.; Henze, C. E.; Howell, S. B.; Huber, D.; Prsa, A.; Ramirez, S. V.; Morton, T. D.; Barclay, T.; Campbell, J. R.; Chaplin, W. J.; Charbonneau, D.; Christensen-Dalsgaard, J.; Dotson, J. L.; Doyle, L.; Dunham, E. W.; Dupree, A. K.; Ford, E. B.; Geary, J. C.; Girouard, F. R.; Isaacson, H.; Kjeldsen, H.; Quintana, E. V.; Ragozzine, D.; Shabram, M.; Shporer, A.; Aguirre, V. S.; Steffen, J. H.; Still, M.; Tenenbaum, P.; Welsh, W. F.; Wolfgang, A.; Zamudio, K. A.; Koch, D. G.; Borucki, W. J. Bibcode: 2018yCat..22350038T Altcode: We present the Kepler Object of Interest (KOI) catalog of transiting exoplanets based on searching 4yr of Kepler time series photometry (Data Release 25, Q1-Q17: Twicken+, 2016, J/AJ/152/158). The catalog contains 8054 KOIs, of which 4034 are planet candidates with periods between 0.25 and 632 days. Of these candidates, 219 are new, including two in multiplanet systems (KOI-82.06 and KOI-2926.05) and 10 high-reliability, terrestrial-size, habitable zone candidates. This catalog was created using a tool called the Robovetter, which automatically vets the DR25 threshold crossing events (TCEs). The Robovetter also vetted simulated data sets and measured how well it was able to separate TCEs caused by noise from those caused by low signal-to-noise transits. We discuss the Robovetter and the metrics it uses to sort TCEs. For orbital periods less than 100 days the Robovetter completeness (the fraction of simulated transits that are determined to be planet candidates) across all observed stars is greater than 85%. For the same period range, the catalog reliability (the fraction of candidates that are not due to instrumental or stellar noise) is greater than 98%. However, for low signal-to-noise candidates between 200 and 500 days around FGK-dwarf stars, the Robovetter is 76.7% complete and the catalog is 50.5% reliable.

(6 data files). Title: On the hydrostatic stratification of the solar tachocline Authors: Christensen-Dalsgaard, J.; Gough, D. O.; Knudstrup, E. Bibcode: 2018MNRAS.477.3845C Altcode: 2018MNRAS.tmp..730C; 2018arXiv180308675C We present an attempt to reconcile the solar tachocline glitch, a thin layer immediately beneath the convection zone in which the seismically inferred sound speed in the Sun exceeds corresponding values in standard solar models, with a degree of partial material mixing which we presume to have resulted from a combination of convective overshoot, wave transport, and tachocline circulation. We first summarize the effects either of modifying in the models the opacity in the radiative interior or of incorporating either slow or fast tachocline circulation. Neither alone is successful. We then consider, without physical justification, incomplete material redistribution immediately beneath the convection zone which is slow enough not to disturb radiative equilibrium. It is modelled simply as a diffusion process. We find that, in combination with an appropriate opacity modification, it is possible to find a density-dependent diffusion coefficient that removes the glitch almost entirely, with a radiative envelope that is consistent with seismology. Title: Modelling linewidths of Kepler red giants in NGC 6819 Authors: Aarslev, Magnus J.; Houdek, Günter; Handberg, Rasmus; Christensen-Dalsgaard, Jørgen Bibcode: 2018MNRAS.478...69A Altcode: 2018MNRAS.tmp..945A; 2018arXiv180406255A We present a comparison between theoretical, frequency-dependent, damping rates and linewidths of radial-mode oscillations in red giant stars located in the open cluster NGC 6819. The calculations adopt a time-dependent non-local convection model, with the turbulent pressure profile being calibrated to results of 3D hydrodynamical simulations of stellar atmospheres. The linewidths are obtained from extensive peakbagging of Kepler light curves. These observational results are of unprecedented quality owing to the long continuous observations by Kepler. The uniqueness of the Kepler mission also means that, for asteroseismic properties, this is the best data that will be available for a long time to come. We therefore take great care in modelling nine RGB stars in NGC 6819 using information from 3D simulations to obtain realistic temperature stratifications and calibrated turbulent pressure profiles. Our modelled damping rates reproduce well the Kepler observations, including the characteristic depression in the linewidths around the frequency of maximum oscillation power. Furthermore, we thoroughly test the sensitivity of the calculated damping rates to changes in the parameters of the non-local convection model. Title: The mass and age of the first SONG target: the red giant 46 LMi Authors: Frandsen, S.; Fredslund Andersen, M.; Brogaard, K.; Jiang, C.; Arentoft, T.; Grundahl, F.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Weiss, E.; Pallé, P.; Antoci, V.; Kjærgaard, P.; Sørensen, A. N.; Skottfelt, J.; Jørgensen, U. G. Bibcode: 2018A&A...613A..53F Altcode: 2018arXiv180602095F Context. The Stellar Observation Network Group (SONG) is an initiative to build a worldwide network of 1m telescopes with high-precision radial-velocity spectrographs. Here we analyse the first radial-velocity time series of a red-giant star measured by the SONG telescope at Tenerife. The asteroseismic results demonstrate a major increase in the achievable precision of the parameters for red-giant stars obtainable from ground-based observations. Reliable tests of the validity of these results are needed, however, before the accuracy of the parameters can be trusted.
Aims: We analyse the first SONG time series for the star 46 LMi, which has a precise parallax and an angular diameter measured from interferometry, and therefore a good determination of the stellar radius. We use asteroseismic scaling relations to obtain an accurate mass, and modelling to determine the age.
Methods: A 55-day time series of high-resolution, high S/N spectra were obtained with the first SONG telescope. We derive the asteroseismic parameters by analysing the power spectrum. To give a best guess on the large separation of modes in the power spectrum, we have applied a new method which uses the scaling of Kepler red-giant stars to 46 LMi.
Results: Several methods have been applied: classical estimates, seismic methods using the observed time series, and model calculations to derive the fundamental parameters of 46 LMi. Parameters determined using the different methods are consistent within the uncertainties. We find the following values for the mass M (scaling), radius R (classical), age (modelling), and surface gravity (combining mass and radius): M = 1.09 ± 0.04M⊙, R = 7.95 ± 0.11R⊙ age t = 8.2 ± 1.9 Gy, and logg = 2.674 ± 0.013.
Conclusions: The exciting possibilities for ground-based asteroseismology of solar-like oscillations with a fully robotic network have been illustrated with the results obtained from just a single site of the SONG network. The window function is still a severe problem which will be solved when there are more nodes in the network.

Based on observations made with the Hertzsprung SONG telescope operated at the Spanish Observatorio del Teide on the island of Tenerife by the Aarhus and Copenhagen Universities and by the Instituto de Astrofísica de Canarias. Title: Asteroseismology with solar-like oscillations Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2018vsss.book..125C Altcode: No abstract at ADS Title: Planetary Candidates Observed by Kepler. VIII. A Fully Automated Catalog with Measured Completeness and Reliability Based on Data Release 25 Authors: Thompson, Susan E.; Coughlin, Jeffrey L.; Hoffman, Kelsey; Mullally, Fergal; Christiansen, Jessie L.; Burke, Christopher J.; Bryson, Steve; Batalha, Natalie; Haas, Michael R.; Catanzarite, Joseph; Rowe, Jason F.; Barentsen, Geert; Caldwell, Douglas A.; Clarke, Bruce D.; Jenkins, Jon M.; Li, Jie; Latham, David W.; Lissauer, Jack J.; Mathur, Savita; Morris, Robert L.; Seader, Shawn E.; Smith, Jeffrey C.; Klaus, Todd C.; Twicken, Joseph D.; Van Cleve, Jeffrey E.; Wohler, Bill; Akeson, Rachel; Ciardi, David R.; Cochran, William D.; Henze, Christopher E.; Howell, Steve B.; Huber, Daniel; Prša, Andrej; Ramírez, Solange V.; Morton, Timothy D.; Barclay, Thomas; Campbell, Jennifer R.; Chaplin, William J.; Charbonneau, David; Christensen-Dalsgaard, Jørgen; Dotson, Jessie L.; Doyle, Laurance; Dunham, Edward W.; Dupree, Andrea K.; Ford, Eric B.; Geary, John C.; Girouard, Forrest R.; Isaacson, Howard; Kjeldsen, Hans; Quintana, Elisa V.; Ragozzine, Darin; Shabram, Megan; Shporer, Avi; Silva Aguirre, Victor; Steffen, Jason H.; Still, Martin; Tenenbaum, Peter; Welsh, William F.; Wolfgang, Angie; Zamudio, Khadeejah A.; Koch, David G.; Borucki, William J. Bibcode: 2018ApJS..235...38T Altcode: 2017arXiv171006758T We present the Kepler Object of Interest (KOI) catalog of transiting exoplanets based on searching 4 yr of Kepler time series photometry (Data Release 25, Q1-Q17). The catalog contains 8054 KOIs, of which 4034 are planet candidates with periods between 0.25 and 632 days. Of these candidates, 219 are new, including two in multiplanet systems (KOI-82.06 and KOI-2926.05) and 10 high-reliability, terrestrial-size, habitable zone candidates. This catalog was created using a tool called the Robovetter, which automatically vets the DR25 threshold crossing events (TCEs). The Robovetter also vetted simulated data sets and measured how well it was able to separate TCEs caused by noise from those caused by low signal-to-noise transits. We discuss the Robovetter and the metrics it uses to sort TCEs. For orbital periods less than 100 days the Robovetter completeness (the fraction of simulated transits that are determined to be planet candidates) across all observed stars is greater than 85%. For the same period range, the catalog reliability (the fraction of candidates that are not due to instrumental or stellar noise) is greater than 98%. However, for low signal-to-noise candidates between 200 and 500 days around FGK-dwarf stars, the Robovetter is 76.7% complete and the catalog is 50.5% reliable. The KOI catalog, the transit fits, and all of the simulated data used to characterize this catalog are available at the NASA Exoplanet Archive. Title: Using the phase shift to asymptotically characterize the dipolar mixed modes in post-main-sequence stars Authors: Jiang, C.; Christensen-Dalsgaard, J.; Cunha, M. Bibcode: 2018MNRAS.474.5413J Altcode: 2017arXiv171202966J Mixed modes have been extensively observed in post-main-sequence stars by the Kepler and CoRoT space missions. The mixture of the p and g modes can be measured by the dimensionless coefficient q, the so-called coupling strength factor. In this paper, we discuss the utility of the phase shifts θ from the eigenvalue condition for mixed modes as a tool to characterize dipolar mixed modes from the theoretical as well as the practical point of view. Unlike the coupling strength, whose variation in a given star is very small over the relevant frequency range, the phase shifts vary significantly for different modes. The analysis in terms of θ can also provide a better understanding of the pressure and gravity radial order for a given mixed mode. Observed frequencies of the Kepler red-giant star KIC 3744043 are used to test the method. The results are very promising. Title: Helioseismology: Observations and Space Missions Authors: Palle, P. L.; Appourchaux, T.; Christensen-Dalsgaard, J.; Garcia, R. A. Bibcode: 2018arXiv180200674P Altcode: The great success of Helioseismology resides in the remarkable progress achieved in the understanding of the structure and dynamics of the solar interior. This success mainly relies on the ability to conceive, implement, and operate specific instrumentation with enough sensitivity to detect and measure small fluctuations (in velocity and/or intensity) on the solar surface that are well below one meter per second or a few parts per million. Furthermore the limitation of the ground observations imposing the day-night cycle (thus a periodic discontinuity in the observations) was overcome with the deployment of ground-based networks --properly placed at different longitudes all over the Earth-- allowing longer and continuous observations of the Sun and consequently increasing their duty cycles. In this chapter, we start by a short historical overview of helioseismology. Then we describe the different techniques used to do helioseismic analyses along with a description of the main instrumental concepts. We in particular focus on the instruments that have been operating long enough to study the solar magnetic activity. Finally, we give a highlight of the main results obtained with such high-duty cycle observations (>80%) lasting over the last few decades. Title: Ages for Exoplanet Host Stars Authors: Christensen-Dalsgaard, Jørgen; Aguirre, Víctor Silva Bibcode: 2018haex.bookE.184C Altcode: 2018arXiv180303125C Age is an important characteristic of a planetary system but also one that is difficult to determine. Assuming that the host star and the planets are formed at the same time, the challenge is to determine the stellar age. Asteroseismology provides precise age determination, but in many cases the required detailed pulsation observations are not available. Here we concentrate on other techniques, which may have broader applicability but also serious limitations. Further development of this area requires improvements in our understanding of the evolution of stars and their age-dependent characteristics, combined with observations that allow reliable calibration of the various techniques. Title: High-precision abundances of elements in Kepler LEGACY stars. Verification of trends with stellar age Authors: Nissen, P. E.; Silva Aguirre, V.; Christensen-Dalsgaard, J.; Collet, R.; Grundahl, F.; Slumstrup, D. Bibcode: 2017A&A...608A.112N Altcode: 2017arXiv171003544N Context. A previous study of solar twin stars has revealed the existence of correlations between some abundance ratios and stellar age providing new knowledge about nucleosynthesis and Galactic chemical evolution.
Aims: High-precision abundances of elements are determined for stars with asteroseismic ages in order to test the solar twin relations.
Methods: HARPS-N spectra with signal-to-noise ratios S/N ≳ 250 and MARCS model atmospheres were used to derive abundances of C, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, and Y in ten stars from the Kepler LEGACY sample (including the binary pair 16 Cyg A and B) selected to have metallicities in the range - 0.15 < [ Fe / H ] < + 0.15 and ages between 1 and 7 Gyr. Stellar gravities were obtained from seismic data and effective temperatures were determined by comparing non-LTE iron abundances derived from Fe I and Fe II lines. Available non-LTE corrections were also applied when deriving abundances of the other elements.
Results: The abundances of the Kepler stars support the [X/Fe]-age relations previously found for solar twins. [Mg/Fe], [Al/Fe], and [Zn/Fe] decrease by 0.1 dex over the lifetime of the Galactic thin disk due to delayed contribution of iron from Type Ia supernovae relative to prompt production of Mg, Al, and Zn in Type II supernovae. [Y/Mg] and [Y/Al], on the other hand, increase by 0.3 dex, which can be explained by an increasing contribution of s-process elements from low-mass AGB stars as time goes on. The trends of [C/Fe] and [O/Fe] are more complicated due to variations of the ratio between refractory and volatile elements among stars of similar age. Two stars with about the same age as the Sun show very different trends of [X/H] as a function of elemental condensation temperature Tc and for 16 Cyg, the two components have an abundance difference, which increases with Tc. These anomalies may be connected to planet-star interactions.

Based on spectra obtained with HARPS-N@TNG under programme A33TAC_1.Tables 1 and 2 are also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A112 Title: Asteroseismic masses of retired planet-hosting A-stars using SONG Authors: Stello, Dennis; Huber, Daniel; Grundahl, Frank; Lloyd, James; Ireland, Mike; Casagrande, Luca; Fredslund, Mads; Bedding, Timothy R.; Palle, Pere L.; Antoci, Victoria; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen Bibcode: 2017MNRAS.472.4110S Altcode: 2017arXiv170809613S To better understand how planets form, it is important to study planet occurrence rates as a function of stellar mass. However, estimating masses of field stars is often difficult. Over the past decade, a controversy has arisen about the inferred occurrence rate of gas-giant planets around evolved intermediate-mass stars - the so-called 'retired A-stars'. The high masses of these red-giant planet hosts, derived using spectroscopic information and stellar evolution models, have been called into question. Here, we address the controversy by determining the masses of eight evolved planet-hosting stars using asteroseismology. We compare the masses with spectroscopic-based masses from the Exoplanet Orbit Database,which were previously adopted to infer properties of the exoplanets and their hosts. We find a significant one-sided offset between the two sets of masses for stars with spectroscopic masses above roughly 1.6 M⊙, suggestive of an average 15-20 per cent overestimate of the adopted spectroscopic-based masses. The only star in our sample well below this mass limit is also the only one not showing this offset. Finally, we note that the scatter across literature values of spectroscopic-based masses often exceeds their formal uncertainties, making it comparable to the offset we report here. Title: VizieR Online Data Catalog: 61 main-sequence and subgiant oscillations (Appourchaux+, 2012) Authors: Appourchaux, T.; Chaplin, W. J.; Garcia, R. A.; Gruberbauer, M.; Verner, G. A.; Antia, H. M.; Benomar, O.; Campante, T. L.; Davies, G. R.; Deheuvels, S.; Handberg, R.; Hekker, S.; Howe, R.; Regulo, C.; Salabert, D.; Bedding, T. R.; White, T. R.; Ballot, J.; Mathur, S.; Silva Aguirre, V.; Elsworth, Y. P.; Basu, S.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Uddin, K.; Stumpe, M. C.; Barclay, T. Bibcode: 2017yCat..35430054A Altcode: Kepler observations are obtained in two different operating modes: long cadence (LC) and short cadence (SC) (Gilliland et al., 2010ApJ...713L.160G; Jenkins et al., 2010ApJ...713L..87J). This work is based on SC data. For the brightest stars (down to Kepler magnitude, Kp~=12), SC observations can be obtained for a limited number of stars (up to 512 at any given time) with a faster sampling cadence of 58.84876s (Nyquist frequency of ~8.5mHz), which permits a more precise transit timing and the performance of asteroseismology. Kepler observations are divided into three-month-long quarters (Q). A subset of 61 solar-type stars observed during quarters Q5-Q7 (March 22, 2010 to December 22, 2010) were chosen because they have oscillation modes with high signal-to-noise ratios. This length of data gives a frequency resolution of about 0.04uHz.

(2 data files). Title: Erratum: “Standing on the Shoulders of Dwarfs: The Kepler Asteroseismic LEGACY Sample. I. Oscillation Mode Parameters” (2017, ApJ, 835, 172) Authors: Lund, Mikkel N.; Silva Aguirre, Víctor; Davies, Guy R.; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Houdek, Günter; White, Timothy R.; Bedding, Timothy R.; Ball, Warrick H.; Huber, Daniel; Antia, H. M.; Lebreton, Yveline; Latham, David W.; Handberg, Rasmus; Verma, Kuldeep; Basu, Sarbani; Casagrande, Luca; Justesen, Anders B.; Kjeldsen, Hans; Mosumgaard, Jakob R. Bibcode: 2017ApJ...850..110L Altcode: No abstract at ADS Title: A semi-analytical computation of the theoretical uncertainties of the solar neutrino flux Authors: Jørgensen, Andreas C. S.; Christensen-Dalsgaard, Jørgen Bibcode: 2017MNRAS.471.4802J Altcode: 2018arXiv180809153C We present a comparison between Monte Carlo simulations and a semi-analytical approach that reproduces the theoretical probability distribution functions of the solar neutrino fluxes, stemming from the pp, pep, hep, 7Be, 8B, 13N, 15O and 17F source reactions. We obtain good agreement between the two approaches. Thus, the semi-analytical method yields confidence intervals that closely match those found, based on Monte Carlo simulations, and points towards the same general symmetries of the investigated probability distribution functions. Furthermore, the negligible computational cost of this method is a clear advantage over Monte Carlo simulations, making it trivial to take new observational constraints on the input parameters into account. Title: Improving 1D Stellar Models with 3D Atmospheres Authors: Mosumgaard, Jakob Rørsted; Silva Aguirre, Víctor; Weiss, Achim; Christensen-Dalsgaard, Jørgen; Trampedach, Regner Bibcode: 2017EPJWC.16003009M Altcode: 2016arXiv161007323R; 2017EPJWC.16003009R; 2016arXiv161007323M Stellar evolution codes play a major role in present-day astrophysics, yet they share common issues. In this work we seek to remedy some of those by the use of results from realistic and highly detailed 3D hydrodynamical simulations of stellar atmospheres. We have implemented a new temperature stratification extracted directly from the 3D simulations into the Garching Stellar Evolution Code to replace the simplified atmosphere normally used. Secondly, we have implemented the use of a variable mixing-length parameter, which changes as a function of the stellar surface gravity and temperature - also derived from the 3D simulations. Furthermore, to make our models consistent, we have calculated new opacity tables to match the atmospheric simulations. Here, we present the modified code and initial results on stellar evolution using it. Title: Foreword Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2017EPJWC.16000002C Altcode: No abstract at ADS Title: A fitting LEGACY - modelling Kepler's best stars Authors: Aarslev, Magnus J.; Christensen-Dalsgaard, Jørgen; Lund, Mikkel N.; Silva Aguirre, Victor; Gough, Douglas Bibcode: 2017EPJWC.16003010A Altcode: The LEGACY sample represents the best solar-like stars observed in the Kepler mission[5, 8]. The 66 stars in the sample are all on the main sequence or only slightly more evolved. They each have more than one year's observation data in short cadence, allowing for precise extraction of individual frequencies. Here we present model fits using a modified ASTFIT procedure employing two different near-surface-effect corrections, one by Christensen-Dalsgaard[4] and a newer correction proposed by Ball & Gizon[1]. We then compare the results obtained using the different corrections. We find that using the latter correction yields lower masses and significantly lower χ2 values for a large part of the sample. Title: Promoting access to and use of seismic data in a large scientific community. SpaceInn data handling and archiving Authors: Michel, Eric; Belkacem, Kevin; Samadi, Reza; Assis Peralta, Raphael de; Renié, Christian; Abed, Mahfoudh; Lin, Guangyuan; Christensen-Dalsgaard, Jørgen; Houdek, Günter; Handberg, Rasmus; Gizon, Laurent; Burston, Raymond; Nagashima, Kaori; Pallé, Pere; Poretti, Ennio; Rainer, Monica; Mistò, Angelo; Panzera, Maria Rosa; Roth, Markus Bibcode: 2017EPJWC.16001011M Altcode: The growing amount of seismic data available from space missions (SOHO, CoRoT, Kepler, SDO,…) but also from ground-based facilities (GONG, BiSON, ground-based large programmes…), stellar modelling and numerical simulations, creates new scientific perspectives such as characterizing stellar populations in our Galaxy or planetary systems by providing model-independent global properties of stars such as mass, radius, and surface gravity within several percent accuracy, as well as constraints on the age. These applications address a broad scientific community beyond the solar and stellar one and require combining indices elaborated with data from different databases (e.g. seismic archives and ground-based spectroscopic surveys). It is thus a basic requirement to develop a simple and effcient access to these various data resources and dedicated tools. In the framework of the European project SpaceInn (FP7), several data sources have been developed or upgraded. The Seismic Plus Portal has been developed, where synthetic descriptions of the most relevant existing data sources can be found, as well as tools allowing to localize existing data for given objects or period and helping the data query. This project has been developed within the Virtual Observatory (VO) framework. In this paper, we give a review of the various facilities and tools developed within this programme. The SpaceInn project (Exploitation of Space Data for Innovative Helio- and Asteroseismology) has been initiated by the European Helio- and Asteroseismology Network (HELAS). Title: A view into the core of α Cen A Authors: Bazot, Michaël; Christensen-Dalsgaard, Jørgen; Benomar, Othman; Gizon, Laurent Bibcode: 2017EPJWC.16003006B Altcode: We present results of modelling of α Cen A. In order to estimate the physical parameters of this star, we modelled spectroscopic, interferometric, astrometric and asteroseismic data. To that effect we chose to use a Bayesian approach to parameter estimation, which allowed us, in particular, to define our prior knowledge on the parameters. An important question we wanted to address was to assess whether or not α Cen A has a convective core. We found that the data we used give indecisive results on this issue. If the star has a convective core, and provided that overshooting is taken into account, there is a possibility for the star to be in the peculiar state in which the ppII chain is the main driver of nuclear energy generation. We also found a non-negligible probability for α Cen A to be a very early subgiant. Title: Data preparation for asteroseismology with TESS Authors: Lund, Mikkel N.; Handberg, Rasmus; Kjeldsen, Hans; Chaplin, William J.; Christensen-Dalsgaard, Jørgen Bibcode: 2017EPJWC.16001005L Altcode: 2016arXiv161002702L The Transiting Exoplanet Survey Satellite (TESS) is a NASA Astrophysics Explorer mission. Following its scheduled launch in 2017, TESS will focus on detecting exoplanets around the nearest and brightest stars in the sky, for which detailed follow-up observations are possible. TESS will, as the NASA Kepler mission, include a asteroseismic program that will be organized within the TESS Asteroseismic Science Consortium (TASC), building on the success of the Kepler Asteroseismic Science Consortium (KASC). Within TASC data for asteroseismic analysis will be prepared by the TASC Working Group 0 (WG-0), who will facilitate data to the community via the TESS Asteroseismic Science Operations Center (TASOC), again building on the success of the corresponding KASOC platform for Kepler. Here, we give an overview of the steps being taken within WG-0 to prepare for the upcoming TESS mission. Title: VizieR Online Data Catalog: Kepler LEGACY stars high-precision abundances (Nissen+, 2017) Authors: Nissen, P. E.; Silva Aguirre, V.; Christensen-Dalsgaard, J.; Collet, R.; Grundahl, F.; Slumstrup, D. Bibcode: 2017yCat..36080112N Altcode: Stellar parameters are given in Table 1 and abundance ratios relative to Fe in Table 2.

(2 data files). Title: VizieR Online Data Catalog: Kepler asteroseismic LEGACY sample. I. Oscillations (Lund+, 2017) Authors: Lund, M. N.; Silva Aguirre, V.; Davies, G. R.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Houdek, G.; White, T. R.; Bedding, T. R.; Ball, W. H.; Huber, D.; Antia, H. M.; Lebreton, Y.; Latham, D. W.; Handberg, R.; Verma, K.; Basu, S.; Casagrande, L.; Justesen, A. B.; Kjeldsen, H.; Mosumgaard, J. R. Bibcode: 2017yCat..18350172L Altcode: The advent of space-based missions like Kepler has revolutionized the study of solar-type stars, particularly through the measurement and modeling of their resonant modes of oscillation. Here we analyze a sample of 66 Kepler main-sequence stars showing solar-like oscillations as part of the Kepler seismic LEGACY project. We use Kepler short-cadence data, of which each star has at least 12 months, to create frequency-power spectra optimized for asteroseismology. For each star, we identify its modes of oscillation and extract parameters such as frequency, amplitude, and line width using a Bayesian Markov chain Monte Carlo "peak-bagging" approach. We report the extracted mode parameters for all 66 stars, as well as derived quantities such as frequency difference ratios, the large and small separations Δν and δν02; the behavior of line widths with frequency and line widths at νmax with Teff, for which we derive parametrizations; and behavior of mode visibilities. These average properties can be applied in future peak-bagging exercises to better constrain the parameters of the stellar oscillation spectra. The frequencies and frequency ratios can tightly constrain the fundamental parameters of these solar-type stars, and mode line widths and amplitudes can test models of mode damping and excitation.

(4 data files). Title: VizieR Online Data Catalog: Kepler asteroseismic LEGACY sample. II. (Silva Aguirre+, 2017) Authors: Silva Aguirre, V.; Lund, M. N.; Antia, H. M.; Ball, W. H.; Basu, S.; Christensen-Dalsgaard, J.; Lebreton, Y.; Reese, D. R.; Verma, K.; Casagrande, L.; Justesen, A. B.; Mosumgaard, J. R.; Chaplin, W. J.; Bedding, T. R.; Davies, G. R.; Handberg, R.; Houdek, G.; Huber, D.; Kjeldsen, H.; Latham, D. W.; White, T. R.; Coelho, H. R.; Miglio, A.; Rendle, B. Bibcode: 2017yCat..18350173S Altcode: The 66 stars comprising the LEGACY sample were chosen from more than 500 main-sequence and subgiant targets in which Kepler detected oscillations (Chaplin+ 2014, J/ApJS/210/1). We selected all targets that had more than one year of short-cadence observations, and where inspection of the power spectrum did not reveal any clear signature of bumped l=1 modes.

(3 data files). Title: PLATO as it is : A legacy mission for Galactic archaeology Authors: Miglio, A.; Chiappini, C.; Mosser, B.; Davies, G. R.; Freeman, K.; Girardi, L.; Jofré, P.; Kawata, D.; Rendle, B. M.; Valentini, M.; Casagrande, L.; Chaplin, W. J.; Gilmore, G.; Hawkins, K.; Holl, B.; Appourchaux, T.; Belkacem, K.; Bossini, D.; Brogaard, K.; Goupil, M. -J.; Montalbán, J.; Noels, A.; Anders, F.; Rodrigues, T.; Piotto, G.; Pollacco, D.; Rauer, H.; Prieto, C. Allende; Avelino, P. P.; Babusiaux, C.; Barban, C.; Barbuy, B.; Basu, S.; Baudin, F.; Benomar, O.; Bienaymé, O.; Binney, J.; Bland-Hawthorn, J.; Bressan, A.; Cacciari, C.; Campante, T. L.; Cassisi, S.; Christensen-Dalsgaard, J.; Combes, F.; Creevey, O.; Cunha, M. S.; Jong, R. S.; Laverny, P.; Degl'Innocenti, S.; Deheuvels, S.; Depagne, É.; Ridder, J.; Matteo, P. Di; Mauro, M. P. Di; Dupret, M. -A.; Eggenberger, P.; Elsworth, Y.; Famaey, B.; Feltzing, S.; García, R. A.; Gerhard, O.; Gibson, B. K.; Gizon, L.; Haywood, M.; Handberg, R.; Heiter, U.; Hekker, S.; Huber, D.; Ibata, R.; Katz, D.; Kawaler, S. D.; Kjeldsen, H.; Kurtz, D. W.; Lagarde, N.; Lebreton, Y.; Lund, M. N.; Majewski, S. R.; Marigo, P.; Martig, M.; Mathur, S.; Minchev, I.; Morel, T.; Ortolani, S.; Pinsonneault, M. H.; Plez, B.; Moroni, P. G. Prada; Pricopi, D.; Recio-Blanco, A.; Reylé, C.; Robin, A.; Roxburgh, I. W.; Salaris, M.; Santiago, B. X.; Schiavon, R.; Serenelli, A.; Sharma, S.; Aguirre, V. Silva; Soubiran, C.; Steinmetz, M.; Stello, D.; Strassmeier, K. G.; Ventura, P.; Ventura, R.; Walton, N. A.; Worley, C. C. Bibcode: 2017AN....338..644M Altcode: 2017arXiv170603778M Deciphering the assembly history of the Milky Way is a formidable task, which becomes possible only if one can produce high-resolution chrono-chemo-kinematical maps of the Galaxy. Data from large-scale astrometric and spectroscopic surveys will soon provide us with a well-defined view of the current chemo-kinematical structure of the Milky Way, but will only enable a blurred view on the temporal sequence that led to the present-day Galaxy. As demonstrated by the (ongoing) exploitation of data from the pioneering photometric missions CoRoT, Kepler, and K2, asteroseismology provides the way forward: solar-like oscillating giants are excellent evolutionary clocks thanks to the availability of seismic constraints on their mass and to the tight age-initial-mass relation they adhere to. In this paper we identify five key outstanding questions relating to the formation and evolution of the Milky Way that will need precise and accurate ages for large samples of stars to be addressed, and we identify the requirements in terms of number of targets and the precision on the stellar properties that are needed to tackle such questions. By quantifying the asteroseismic yields expected from PLATO for red-giant stars, we demonstrate that these requirements are within the capabilities of the current instrument design, provided that observations are sufficiently long to identify the evolutionary state and allow robust and precise determination of acoustic-mode frequencies. This will allow us to harvest data of sufficient quality to reach a 10% precision in age. This is a fundamental pre-requisite to then reach the more ambitious goal of a similar level of accuracy, which will only be possible if we have to hand a careful appraisal of systematic uncertainties on age deriving from our limited understanding of stellar physics, a goal which conveniently falls within the main aims of PLATO's core science. Title: Kepler sheds new and unprecedented light on the variability of a blue supergiant: Gravity waves in the O9.5Iab star HD 188209 Authors: Aerts, C.; Símon-Díaz, S.; Bloemen, S.; Debosscher, J.; Pápics, P. I.; Bryson, S.; Still, M.; Moravveji, E.; Williamson, M. H.; Grundahl, F.; Fredslund Andersen, M.; Antoci, V.; Pallé, P. L.; Christensen-Dalsgaard, J.; Rogers, T. M. Bibcode: 2017A&A...602A..32A Altcode: 2017arXiv170301514A Stellar evolution models are most uncertain for evolved massive stars. Asteroseismology based on high-precision uninterrupted space photometry has become a new way to test the outcome of stellar evolution theory and was recently applied to a multitude of stars, but not yet to massive evolved supergiants.Our aim is to detect, analyse and interpret the photospheric and wind variability of the O9.5 Iab star HD 188209 from Kepler space photometry and long-term high-resolution spectroscopy. We used Kepler scattered-light photometry obtained by the nominal mission during 1460 d to deduce the photometric variability of this O-type supergiant. In addition, we assembled and analysed high-resolution high signal-to-noise spectroscopy taken with four spectrographs during some 1800 d to interpret the temporal spectroscopic variability of the star. The variability of this blue supergiant derived from the scattered-light space photometry is in full in agreement with the one found in the ground-based spectroscopy. We find significant low-frequency variability that is consistently detected in all spectral lines of HD 188209. The photospheric variability propagates into the wind, where it has similar frequencies but slightly higher amplitudes. The morphology of the frequency spectra derived from the long-term photometry and spectroscopy points towards a spectrum of travelling waves with frequency values in the range expected for an evolved O-type star. Convectively-driven internal gravity waves excited in the stellar interior offer the most plausible explanation of the detected variability.

Based on photometric observations made with the NASA Kepler satellite and on spectroscopic observations made with four telescopes: the Nordic Optical Telescope operated by NOTSA and the Mercator Telescope operated by the Flemish Community, both at the Observatorio del Roque de los Muchachos (La Palma, Spain) of the Instituto de Astrofísica de Canarias, the T13 2.0 m Automatic Spectroscopic Telescope (AST) operated by Tennessee State University at the Fairborn Observatory, and the Hertzsprung SONG telescope operated on the Spanish Observatorio del Teide on the island of Tenerife by the Aarhus and Copenhagen Universities and by the Instituto de Astrofísica de Canarias, Spain. Title: Giant star seismology Authors: Hekker, S.; Christensen-Dalsgaard, J. Bibcode: 2017A&ARv..25....1H Altcode: 2016arXiv160907487H The internal properties of stars in the red-giant phase undergo significant changes on relatively short timescales. Long near-uninterrupted high-precision photometric timeseries observations from dedicated space missions such as CoRoT and Kepler have provided seismic inferences of the global and internal properties of a large number of evolved stars, including red giants. These inferences are confronted with predictions from theoretical models to improve our understanding of stellar structure and evolution. Our knowledge and understanding of red giants have indeed increased tremendously using these seismic inferences, and we anticipate that more information is still hidden in the data. Unraveling this will further improve our understanding of stellar evolution. This will also have significant impact on our knowledge of the Milky Way Galaxy as well as on exo-planet host stars. The latter is important for our understanding of the formation and structure of planetary systems. Title: Kepler observations of the asteroseismic binary HD 176465 Authors: White, T. R.; Benomar, O.; Silva Aguirre, V.; Ball, W. H.; Bedding, T. R.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Garcia, R. A.; Gizon, L.; Stello, D.; Aigrain, S.; Antia, H. M.; Appourchaux, T.; Bazot, M.; Campante, T. L.; Creevey, O. L.; Davies, G. R.; Elsworth, Y. P.; Gaulme, P.; Handberg, R.; Hekker, S.; Houdek, G.; Howe, R.; Huber, D.; Karoff, C.; Marques, J. P.; Mathur, S.; McQuillan, A.; Metcalfe, T. S.; Mosser, B.; Nielsen, M. B.; Régulo, C.; Salabert, D.; Stahn, T. Bibcode: 2017A&A...601A..82W Altcode: 2016arXiv160909581W; 2016A&A...601A..82W Binary star systems are important for understanding stellar structure and evolution, and are especially useful when oscillations can be detected and analysed with asteroseismology. However, only four systems are known in which solar-like oscillations are detected in both components. Here, we analyse the fifth such system, HD 176465, which was observed by Kepler. We carefully analysed the system's power spectrum to measure individual mode frequencies, adapting our methods where necessary to accommodate the fact that both stars oscillate in a similar frequency range. We also modelled the two stars independently by fitting stellar models to the frequencies and complementaryparameters. We are able to cleanly separate the oscillation modes in both systems. The stellar models produce compatible ages and initial compositions for the stars, as is expected from their common and contemporaneous origin. Combining the individual ages, the system is about 3.0 ± 0.5 Gyr old. The two components of HD 176465 are young physically-similar oscillating solar analogues, the first such system to be found, and provide important constraints for stellar evolution and asteroseismology. Title: The asteroseismic surface effect from a grid of 3D convection simulations - I. Frequency shifts from convective expansion of stellar atmospheres Authors: Trampedach, Regner; Aarslev, Magnus J.; Houdek, Günter; Collet, Remo; Christensen-Dalsgaard, Jørgen; Stein, Robert F.; Asplund, Martin Bibcode: 2017MNRAS.466L..43T Altcode: 2016arXiv161102638T We analyse the effect on adiabatic stellar oscillation frequencies of replacing the near-surface layers in 1D stellar structure models with averaged 3D stellar surface convection simulations. The main difference is an expansion of the atmosphere by 3D convection, expected to explain a major part of the asteroseismic surface effect, a systematic overestimation of p-mode frequencies due to inadequate surface physics. We employ pairs of 1D stellar envelope models and 3D simulations from a previous calibration of the mixing-length parameter, α. That calibration constitutes the hitherto most consistent matching of 1D models to 3D simulations, ensuring that their differences are not spurious, but entirely due to the 3D nature of convection. The resulting frequency shift is identified as the structural part of the surface effect. The important, typically non-adiabatic, modal components of the surface effect are not included in this analysis, but relegated to future papers. Evaluating the structural surface effect at the frequency of maximum mode amplitude, νmax , we find shifts from δν = -0.8 μHz for giants at log g = 2.2 to - 35 μHz for a (Teff = 6901 K, log g = 4.29) dwarf. The fractional effect δν(νmax )/νmax , ranges from -0.1 per cent for a cool dwarf (4185 K, 4.74) to -6 per cent for a warm giant (4962 K, 2.20). Title: Standing on the Shoulders of Dwarfs: the Kepler Asteroseismic LEGACY Sample. I. Oscillation Mode Parameters Authors: Lund, Mikkel N.; Silva Aguirre, Víctor; Davies, Guy R.; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Houdek, Günter; White, Timothy R.; Bedding, Timothy R.; Ball, Warrick H.; Huber, Daniel; Antia, H. M.; Lebreton, Yveline; Latham, David W.; Handberg, Rasmus; Verma, Kuldeep; Basu, Sarbani; Casagrande, Luca; Justesen, Anders B.; Kjeldsen, Hans; Mosumgaard, Jakob R. Bibcode: 2017ApJ...835..172L Altcode: 2016arXiv161200436L The advent of space-based missions like Kepler has revolutionized the study of solar-type stars, particularly through the measurement and modeling of their resonant modes of oscillation. Here we analyze a sample of 66 Kepler main-sequence stars showing solar-like oscillations as part of the Kepler seismic LEGACY project. We use Kepler short-cadence data, of which each star has at least 12 months, to create frequency-power spectra optimized for asteroseismology. For each star, we identify its modes of oscillation and extract parameters such as frequency, amplitude, and line width using a Bayesian Markov chain Monte Carlo “peak-bagging” approach. We report the extracted mode parameters for all 66 stars, as well as derived quantities such as frequency difference ratios, the large and small separations {{Δ }}ν and δ {ν }02; the behavior of line widths with frequency and line widths at {ν }\max with {T}{eff}, for which we derive parametrizations; and behavior of mode visibilities. These average properties can be applied in future peak-bagging exercises to better constrain the parameters of the stellar oscillation spectra. The frequencies and frequency ratios can tightly constrain the fundamental parameters of these solar-type stars, and mode line widths and amplitudes can test models of mode damping and excitation. Title: Standing on the Shoulders of Dwarfs: the Kepler Asteroseismic LEGACY Sample. II.Radii, Masses, and Ages Authors: Silva Aguirre, Víctor; Lund, Mikkel N.; Antia, H. M.; Ball, Warrick H.; Basu, Sarbani; Christensen-Dalsgaard, Jørgen; Lebreton, Yveline; Reese, Daniel R.; Verma, Kuldeep; Casagrande, Luca; Justesen, Anders B.; Mosumgaard, Jakob R.; Chaplin, William J.; Bedding, Timothy R.; Davies, Guy R.; Handberg, Rasmus; Houdek, Günter; Huber, Daniel; Kjeldsen, Hans; Latham, David W.; White, Timothy R.; Coelho, Hugo R.; Miglio, Andrea; Rendle, Ben Bibcode: 2017ApJ...835..173S Altcode: 2016arXiv161108776S We use asteroseismic data from the Kepler satellite to determine fundamental stellar properties of the 66 main-sequence targets observed for at least one full year by the mission. We distributed tens of individual oscillation frequencies extracted from the time series of each star among seven modeling teams who applied different methods to determine radii, masses, and ages for all stars in the sample. Comparisons among the different results reveal a good level of agreement in all stellar properties, which is remarkable considering the variety of codes, input physics, and analysis methods employed by the different teams. Average uncertainties are of the order of ∼2% in radius, ∼4% in mass, and ∼10% in age, making this the best-characterized sample of main-sequence stars available to date. Our predicted initial abundances and mixing-length parameters are checked against inferences from chemical enrichment laws ΔY/ΔZ and predictions from 3D atmospheric simulations. We test the accuracy of the determined stellar properties by comparing them to the Sun, angular diameter measurements, Gaia parallaxes, and binary evolution, finding excellent agreement in all cases and further confirming the robustness of asteroseismically determined physical parameters of stars when individual frequencies of oscillation are available. Baptised as the Kepler dwarfs LEGACY sample, these stars are the solar-like oscillators with the best asteroseismic properties available for at least another decade. All data used in this analysis and the resulting stellar parameters are made publicly available for the community. Title: First Results from the Hertzsprung SONG Telescope: Asteroseismology of the G5 Subgiant Star μ Herculis Authors: Grundahl, F.; Fredslund Andersen, M.; Christensen-Dalsgaard, J.; Antoci, V.; Kjeldsen, H.; Handberg, R.; Houdek, G.; Bedding, T. R.; Pallé, P. L.; Jessen-Hansen, J.; Silva Aguirre, V.; White, T. R.; Frandsen, S.; Albrecht, S.; Andersen, M. I.; Arentoft, T.; Brogaard, K.; Chaplin, W. J.; Harpsøe, K.; Jørgensen, U. G.; Karovicova, I.; Karoff, C.; Kjærgaard Rasmussen, P.; Lund, M. N.; Sloth Lundkvist, M.; Skottfelt, J.; Norup Sørensen, A.; Tronsgaard, R.; Weiss, E. Bibcode: 2017ApJ...836..142G Altcode: 2017arXiv170103365G We report the first asteroseismic results obtained with the Hertzsprung Stellar Observations Network Group Telescope from an extensive high-precision radial-velocity observing campaign of the subgiant μ Herculis. The data set was collected during 215 nights in 2014 and 2015. We detected a total of 49 oscillation modes with l values from zero to three, including some l = 1 mixed modes. Based on the rotational splitting observed in l = 1 modes, we determine a rotational period of 52 days and a stellar inclination angle of 63°. The parameters obtained through modeling of the observed oscillation frequencies agree very well with independent observations and imply a stellar mass between 1.11 and 1.15 M ⊙ and an age of {7.8}-0.4+0.3 Gyr. Furthermore, the high-quality data allowed us to determine the acoustic depths of the He II ionization layer and the base of the convection zone.

Based on observations made with the Hertzsprung SONG telescope operated on the Spanish Observatorio del Teide on the island of Tenerife by the Aarhus and Copenhagen Universities and by the Instituto de Astrofísica de Canarias. Title: Testing stellar evolution models with the retired A star HD 185351 Authors: Hjørringgaard, J. G.; Silva Aguirre, V.; White, T. R.; Huber, D.; Pope, B. J. S.; Casagrande, L.; Justesen, A. B.; Christensen-Dalsgaard, J. Bibcode: 2017MNRAS.464.3713H Altcode: 2016MNRAS.tmp.1542H; 2016arXiv161005990H The physical parameters of the retired A star HD 185351 were analysed in great detail by Johnson et al. using interferometry, spectroscopy, and asteroseismology. Results from all independent methods are consistent with HD 185351 having a mass in excess of 1.5 M⊙. However, the study also showed that not all observational constraints could be reconciled in stellar evolutionary models, leading to mass estimates ranging from ∼1.6 to 1.9 M⊙ and casting doubts on the accuracy of stellar properties determined from asteroseismology. Here, we solve this discrepancy and construct a theoretical model in agreement with all observational constraints on the physical parameters of HD 185351. The effects of varying input physics are examined as well as the additional constraint of the observed g-mode period spacing is considered. This quantity is found to be sensitive to the inclusion of additional mixing from the convective core during the main sequence, and can be used to calibrate the overshooting efficiency using low-luminosity red giant stars. A theoretical model with metallicity [Fe/H] = 0.16 dex, mixing-length parameter αMLT = 2.00, and convective overshooting efficiency parameter f = 0.030 is found to be in complete agreement with all observational constraints for a stellar mass of M ≃ 1.60 M⊙. Title: On the surface physics affecting solar oscillation frequencies Authors: Houdek, G.; Trampedach, R.; Aarslev, M. J.; Christensen-Dalsgaard, J. Bibcode: 2017MNRAS.464L.124H Altcode: 2016arXiv160906129H Adiabatic oscillation frequencies of stellar models, computed with the standard mixing-length formulation for convection, increasingly deviate with radial order from observations in solar-like stars. Standard solar models overestimate adiabatic frequencies by as much as ∼ 20 μHz. In this Letter, we address the physical processes of turbulent convection that are predominantly responsible for the frequency differences between standard models and observations, also called `surface effects'. We compare measured solar frequencies from the Michelson Doppler Imager instrument on the SOlar and Heliospheric Observatory spacecraft with frequency calculations that include 3D hydrodynamical simulation results in the equilibrium model, non-adiabatic effects, and a consistent treatment of the turbulent pressure in both the equilibrium and stability computations. With the consistent inclusion of the above physics in our model computation, we are able to reproduce the observed solar frequencies to ≲3 μHz without the need of any additional ad hoc functional corrections. Title: Asteroseismic Properties of Solar-type Stars Observed with the NASA K2 Mission: Results from Campaigns 1-3 and Prospects for Future Observations Authors: Lund, Mikkel N.; Chaplin, William J.; Casagrande, Luca; Silva Aguirre, Víctor; Basu, Sarbani; Bieryla, Allyson; Christensen-Dalsgaard, Jørgen; Latham, David W.; White, Timothy R.; Davies, Guy R.; Huber, Daniel; Buchhave, Lars A.; Handberg, Rasmus Bibcode: 2016PASP..128l4204L Altcode: 2016arXiv160807292L We present an asteroseismic analysis of 33 solar-type stars observed in short cadence (SC) during Campaigns (C) 1-3 of the NASA K2 mission. We were able to extract both average seismic parameters and individual mode frequencies for stars with dominant frequencies up to ∼3300 μHz, and we find that data for some targets are good enough to allow for a measurement of the rotational splitting. Modeling of the extracted parameters is performed by using grid-based methods using average parameters and individual frequencies together with spectroscopic parameters. For the target selection in C3, stars were chosen as in C1 and C2 to cover a wide range in parameter space to better understand the performance and noise characteristics. For C3 we still detected oscillations in 73% of the observed stars that we proposed. Future K2 campaigns hold great promise for the study of nearby clusters and the chemical evolution and age-metallicity relation of nearby field stars in the solar neighborhood. We expect oscillations to be detected in ∼388 SC targets if the K2 mission continues until C18, which will greatly complement the ∼500 detections of solar-like oscillations made for SC targets during the nominal Kepler mission. For ∼30-40 of these, including several members of the Hyades open cluster, we furthermore expect that inference from interferometry should be possible. Title: Detection of Solar-like Oscillations, Observational Constraints, and Stellar Models for θ Cyg, the Brightest Star Observed By the Kepler Mission Authors: Guzik, J. A.; Houdek, G.; Chaplin, W. J.; Smalley, B.; Kurtz, D. W.; Gilliland, R. L.; Mullally, F.; Rowe, J. F.; Bryson, S. T.; Still, M. D.; Antoci, V.; Appourchaux, T.; Basu, S.; Bedding, T. R.; Benomar, O.; Garcia, R. A.; Huber, D.; Kjeldsen, H.; Latham, D. W.; Metcalfe, T. S.; Pápics, P. I.; White, T. R.; Aerts, C.; Ballot, J.; Boyajian, T. S.; Briquet, M.; Bruntt, H.; Buchhave, L. A.; Campante, T. L.; Catanzaro, G.; Christensen-Dalsgaard, J.; Davies, G. R.; Doğan, G.; Dragomir, D.; Doyle, A. P.; Elsworth, Y.; Frasca, A.; Gaulme, P.; Gruberbauer, M.; Handberg, R.; Hekker, S.; Karoff, C.; Lehmann, H.; Mathias, P.; Mathur, S.; Miglio, A.; Molenda-Żakowicz, J.; Mosser, B.; Murphy, S. J.; Régulo, C.; Ripepi, V.; Salabert, D.; Sousa, S. G.; Stello, D.; Uytterhoeven, K. Bibcode: 2016ApJ...831...17G Altcode: 2016arXiv160701035G θ Cygni is an F3 spectral type magnitude V = 4.48 main-sequence star that was the brightest star observed by the original Kepler spacecraft mission. Short-cadence (58.8 s) photometric data using a custom aperture were first obtained during Quarter 6 (2010 June-September) and subsequently in Quarters 8 and 12-17. We present analyses of solar-like oscillations based on Q6 and Q8 data, identifying angular degree l = 0, 1, and 2 modes with frequencies of 1000-2700 μHz, a large frequency separation of 83.9 ± 0.4 μHz, and maximum oscillation amplitude at frequency ν max = 1829 ± 54 μHz. We also present analyses of new ground-based spectroscopic observations, which, combined with interferometric angular diameter measurements, give T eff = 6697 ± 78 K, radius 1.49 ± 0.03 R ⊙, [Fe/H] = -0.02 ± 0.06 dex, and log g = 4.23 ± 0.03. We calculate stellar models matching these constraints using the Yale Rotating Evolution Code and the Asteroseismic Modeling Portal. The best-fit models have masses of 1.35-1.39 M ⊙ and ages of 1.0-1.6 Gyr. θ Cyg’s T eff and log g place it cooler than the red edge of the γ Doradus instability region established from pre-Kepler ground-based observations, but just at the red edge derived from pulsation modeling. The pulsation models show γ Dor gravity modes driven by the convective blocking mechanism, with frequencies of 1-3 cycles per day (11 to 33 μHz). However, gravity modes were not seen in Kepler data; one signal at 1.776 cycles per day (20.56 μHz) may be attributable to a faint, possibly background, binary. Title: The Asteroseismic Potential of TESS: Exoplanet-host Stars Authors: Campante, T. L.; Schofield, M.; Kuszlewicz, J. S.; Bouma, L.; Chaplin, W. J.; Huber, D.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Bossini, D.; North, T. S. H.; Appourchaux, T.; Latham, D. W.; Pepper, J.; Ricker, G. R.; Stassun, K. G.; Vanderspek, R.; Winn, J. N. Bibcode: 2016ApJ...830..138C Altcode: 2016arXiv160801138C New insights on stellar evolution and stellar interior physics are being made possible by asteroseismology. Throughout the course of the Kepler mission, asteroseismology has also played an important role in the characterization of exoplanet-host stars and their planetary systems. The upcoming NASA Transiting Exoplanet Survey Satellite (TESS) will be performing a near all-sky survey for planets that transit bright nearby stars. In addition, its excellent photometric precision, combined with its fine time sampling and long intervals of uninterrupted observations, will enable asteroseismology of solar-type and red-giant stars. Here we develop a simple test to estimate the detectability of solar-like oscillations in TESS photometry of any given star. Based on an all-sky stellar and planetary synthetic population, we go on to predict the asteroseismic yield of the TESS mission, placing emphasis on the yield of exoplanet-host stars for which we expect to detect solar-like oscillations. This is done for both the target stars (observed at a 2-minute cadence) and the full-frame-image stars (observed at a 30-minute cadence). A similar exercise is also conducted based on a compilation of known host stars. We predict that TESS will detect solar-like oscillations in a few dozen target hosts (mainly subgiant stars but also in a smaller number of F dwarfs), in up to 200 low-luminosity red-giant hosts, and in over 100 solar-type and red-giant known hosts, thereby leading to a threefold improvement in the asteroseismic yield of exoplanet-host stars when compared to Kepler's. Title: Towards 21st century stellar models: Star clusters, supercomputing and asteroseismology Authors: Campbell, S. W.; Constantino, T. N.; D'Orazi, V.; Meakin, C.; Stello, D.; Christensen-Dalsgaard, J.; Kuehn, C.; De Silva, G. M.; Arnett, W. D.; Lattanzio, J. C.; MacLean, B. T. Bibcode: 2016AN....337..788C Altcode: 2015arXiv151204774C Stellar models provide a vital basis for many aspects of astronomy and astrophysics. Recent advances in observational astronomy - through asteroseismology, precision photometry, high-resolution spectroscopy, and large-scale surveys - are placing stellar models under greater quantitative scrutiny than ever. The model limitations are being exposed and the next generation of stellar models is needed as soon as possible. The current uncertainties in the models propagate to the later phases of stellar evolution, hindering our understanding of stellar populations and chemical evolution. Here we give a brief overview of the evolution, importance, and substantial uncertainties of core helium burning stars in particular and then briefly discuss a range of methods, both theoretical and observational, that we are using to advance the modelling.

This study uses observational data from from HST, VLT, AAT, Kepler, and supercomputing resources in Australia provided by the National Computational Infrastructure (NCI) and Pawsey Supercomputing Centre. Title: Nominal Values for Selected Solar and Planetary Quantities: IAU 2015 Resolution B3 Authors: Prša, Andrej; Harmanec, Petr; Torres, Guillermo; Mamajek, Eric; Asplund, Martin; Capitaine, Nicole; Christensen-Dalsgaard, Jørgen; Depagne, Éric; Haberreiter, Margit; Hekker, Saskia; Hilton, James; Kopp, Greg; Kostov, Veselin; Kurtz, Donald W.; Laskar, Jacques; Mason, Brian D.; Milone, Eugene F.; Montgomery, Michele; Richards, Mercedes; Schmutz, Werner; Schou, Jesper; Stewart, Susan G. Bibcode: 2016AJ....152...41P Altcode: 2016arXiv160509788P In this brief communication we provide the rationale for and the outcome of the International Astronomical Union (IAU) resolution vote at the XXIXth General Assembly in Honolulu, Hawaii, in 2015, on recommended nominal conversion constants for selected solar and planetary properties. The problem addressed by the resolution is a lack of established conversion constants between solar and planetary values and SI units: a missing standard has caused a proliferation of solar values (e.g., solar radius, solar irradiance, solar luminosity, solar effective temperature, and solar mass parameter) in the literature, with cited solar values typically based on best estimates at the time of paper writing. As precision of observations increases, a set of consistent values becomes increasingly important. To address this, an IAU Working Group on Nominal Units for Stellar and Planetary Astronomy formed in 2011, uniting experts from the solar, stellar, planetary, exoplanetary, and fundamental astronomy, as well as from general standards fields to converge on optimal values for nominal conversion constants. The effort resulted in the IAU 2015 Resolution B3, passed at the IAU General Assembly by a large majority. The resolution recommends the use of nominal solar and planetary values, which are by definition exact and are expressed in SI units. These nominal values should be understood as conversion factors only, not as the true solar/planetary properties or current best estimates. Authors and journal editors are urged to join in using the standard values set forth by this resolution in future work and publications to help minimize further confusion. Title: On the uncertain nature of the core of α Cen A Authors: Bazot, M.; Christensen-Dalsgaard, J.; Gizon, L.; Benomar, O. Bibcode: 2016MNRAS.460.1254B Altcode: 2016MNRAS.tmp..725B; 2016arXiv160307583B High-quality astrometric, spectroscopic, interferometric and, importantly, asteroseismic observations are available for α Cen A, which is the closest binary star system to earth. Taking all these constraints into account, we study the internal structure of the star by means of theoretical modelling. Using the Aarhus STellar Evolution Code (ASTEC) and the tools of Computational Bayesian Statistics, in particular a Markov chain Monte Carlo algorithm, we perform statistical inferences for the physical characteristics of the star. We find that α Cen A has a probability of approximately 40 per cent of having a convective core. This probability drops to few per cent if one considers reduced rates for the 14N(p,γ)15O reaction. These convective cores have fractional radii less than 8 per cent when overshoot is neglected. Including overshooting also leads to the possibility of a convective core mostly sustained by the ppII chain energy output. We finally show that roughly 30 per cent of the stellar models describing α Cen A are in the subgiant regime. Title: SpaceInn hare-and-hounds exercise: Estimation of stellar properties using space-based asteroseismic data Authors: Reese, D. R.; Chaplin, W. J.; Davies, G. R.; Miglio, A.; Antia, H. M.; Ball, W. H.; Basu, S.; Buldgen, G.; Christensen-Dalsgaard, J.; Coelho, H. R.; Hekker, S.; Houdek, G.; Lebreton, Y.; Mazumdar, A.; Metcalfe, T. S.; Silva Aguirre, V.; Stello, D.; Verma, K. Bibcode: 2016A&A...592A..14R Altcode: 2016arXiv160408404R Context. Detailed oscillation spectra comprising individual frequencies for numerous solar-type stars and red giants are either currently available, e.g. courtesy of the CoRoT, Kepler, and K2 missions, or will become available with the upcoming NASA TESS and ESA PLATO 2.0 missions. The data can lead to a precise characterisation of these stars thereby improving our understanding of stellar evolution, exoplanetary systems, and the history of our galaxy.
Aims: Our goal is to test and compare different methods for obtaining stellar properties from oscillation frequencies and spectroscopic constraints. Specifically, we would like to evaluate the accuracy of the results and reliability of the associated error bars, and to see where there is room for improvement.
Methods: In the context of the SpaceInn network, we carried out a hare-and-hounds exercise in which one group, the hares, simulated observations of oscillation spectra for a set of ten artificial solar-type stars, and a number of hounds applied various methods for characterising these stars based on the data produced by the hares. Most of the hounds fell into two main groups. The first group used forward modelling (I.e. applied various search/optimisation algorithms in a stellar parameter space) whereas the second group relied on acoustic glitch signatures.
Results: Results based on the forward modelling approach were accurate to 1.5% (radius), 3.9% (mass), 23% (age), 1.5% (surface gravity), and 1.8% (mean density), as based on the root mean square difference. Individual hounds reached different degrees of accuracy, some of which were substantially better than the above average values. For the two 1M⊙ stellar targets, the accuracy on the age is better than 10% thereby satisfying the requirements for the PLATO 2.0 mission. High stellar masses and atomic diffusion (which in our models does not include the effects of radiative accelerations) proved to be sources of difficulty. The average accuracies for the acoustic radii of the base of the convection zone, the He II ionisation, and the Γ1 peak located between the two He ionisation zones were 17%, 2.4%, and 1.9%, respectively. The results from the forward modelling were on average more accurate than those from the glitch fitting analysis as the latter seemed to be affected by aliasing problems for some of the targets.
Conclusions: Our study indicates that forward modelling is the most accurate way of interpreting the pulsation spectra of solar-type stars. However, given its model-dependent nature, this method needs to be complemented by model-independent results from, e.g. glitch analysis. Furthermore, our results indicate that global rather than local optimisation algorithms should be used in order to obtain robust error bars. Title: The Transiting Exoplanet Survey Satellite Authors: Ricker, G. R.; Vanderspek, R.; Winn, J.; Seager, S.; Berta-Thompson, Z.; Levine, A.; Villasenor, J.; Latham, D.; Charbonneau, D.; Holman, M.; Johnson, J.; Sasselov, D.; Szentgyorgyi, A.; Torres, G.; Bakos, G.; Brown, T.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Clampin, M.; Rinehart, S.; Deming, D.; Doty, J.; Dunham, E.; Ida, S.; Kawai, N.; Sato, B.; Jenkins, J.; Lissauer, J.; Jernigan, G.; Kaltenegger, L.; Laughlin, G.; Lin, D.; McCullough, P.; Narita, N.; Pepper, J.; Stassun, K.; Udry, S. Bibcode: 2016SPIE.9904E..2BR Altcode: No abstract at ADS Title: VizieR Online Data Catalog: Surface gravity for 220 Kepler stars (Campante+, 2014) Authors: Campante, T. L.; Chaplin, W. J.; Lund, M. N.; Huber, D.; Hekker, S.; Garcia, R. A.; Corsaro, E.; Handberg, R.; Miglio, A.; Arentoft, T.; Basu, S.; Bedding, T. R.; Christensen-Dalsgaard, J.; Davies, G. R.; Elsworth, Y. P.; Gilliland, R. L.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Lundkvist, M.; Metcalfe, T. S.; Silva Aguirre, V.; Stello, D. Bibcode: 2016yCat..17830123C Altcode: We propose lower-limit surface gravity estimates for Kepler solar-type planet-candidate host stars with no detected oscillations, as given in Table4.

(1 data file). Title: Testing the asymptotic relation for period spacings from mixed modes of red giants observed with the Kepler mission Authors: Buysschaert, B.; Beck, P. G.; Corsaro, E.; Christensen-Dalsgaard, J.; Aerts, C.; Arentoft, T.; Kjeldsen, H.; García, R. A.; Silva Aguirre, V.; Degroote, P. Bibcode: 2016A&A...588A..82B Altcode: 2016arXiv160202716B Context. Dipole mixed pulsation modes of consecutive radial order have been detected for thousands of low-mass red-giant stars with the NASA space telescope Kepler. These modes have the potential to reveal information on the physics of the deep stellar interior.
Aims: Different methods have been proposed to derive an observed value for the gravity-mode period spacing, the most prominent one relying on a relation derived from asymptotic pulsation theory applied to the gravity-mode character of the mixed modes. Our aim is to compare results based on this asymptotic relation with those derived from an empirical approach for three pulsating red-giant stars.
Methods: We developed a data-driven method to perform frequency extraction and mode identification. Next, we used the identified dipole mixed modes to determine the gravity-mode period spacing by means of an empirical method and by means of the asymptotic relation. In our methodology we consider the phase offset, ɛg, of the asymptotic relation as a free parameter.
Results: Using the frequencies of the identified dipole mixed modes for each star in the sample, we derived a value for the gravity-mode period spacing using the two different methods. These values differ by less than 5%. The average precision we achieved for the period spacing derived from the asymptotic relation is better than 1%, while that of our data-driven approach is 3%.
Conclusions: Good agreement is found between values for the period spacing derived from the asymptotic relation and from the empirical method. The achieved uncertainties are small, but do not support the ultra-high precision claimed in the literature. The precision from our data-driven method is mostly affected by the differing number of observed dipole mixed modes. For the asymptotic relation, the phase offset, ɛg, remains ill defined, but enables a more robust analysis of both the asymptotic period spacing and the dimensionless coupling factor. However, its estimation might still offer a valuable observational diagnostic for future theoretical modeling. Title: Hot super-Earths stripped by their host stars Authors: Lundkvist, M. S.; Kjeldsen, H.; Albrecht, S.; Davies, G. R.; Basu, S.; Huber, D.; Justesen, A. B.; Karoff, C.; Silva Aguirre, V.; van Eylen, V.; Vang, C.; Arentoft, T.; Barclay, T.; Bedding, T. R.; Campante, T. L.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Elsworth, Y. P.; Gilliland, R. L.; Handberg, R.; Hekker, S.; Kawaler, S. D.; Lund, M. N.; Metcalfe, T. S.; Miglio, A.; Rowe, J. F.; Stello, D.; Tingley, B.; White, T. R. Bibcode: 2016NatCo...711201L Altcode: 2016arXiv160405220L Simulations predict that hot super-Earth sized exoplanets can have their envelopes stripped by photoevaporation, which would present itself as a lack of these exoplanets. However, this absence in the exoplanet population has escaped a firm detection. Here we demonstrate, using asteroseismology on a sample of exoplanets and exoplanet candidates observed during the Kepler mission that, while there is an abundance of super-Earth sized exoplanets with low incident fluxes, none are found with high incident fluxes. We do not find any exoplanets with radii between 2.2 and 3.8 Earth radii with incident flux above 650 times the incident flux on Earth. This gap in the population of exoplanets is explained by evaporation of volatile elements and thus supports the predictions. The confirmation of a hot-super-Earth desert caused by evaporation will add an important constraint on simulations of planetary systems, since they must be able to reproduce the dearth of close-in super-Earths. Title: Spin-Orbit Alignment of Exoplanet Systems: Ensemble Analysis Using Asteroseismology Authors: Campante, T. L.; Lund, M. N.; Kuszlewicz, J. S.; Davies, G. R.; Chaplin, W. J.; Albrecht, S.; Winn, J. N.; Bedding, T. R.; Benomar, O.; Bossini, D.; Handberg, R.; Santos, A. R. G.; Van Eylen, V.; Basu, S.; Christensen-Dalsgaard, J.; Elsworth, Y. P.; Hekker, S.; Hirano, T.; Huber, D.; Karoff, C.; Kjeldsen, H.; Lundkvist, M. S.; North, T. S. H.; Silva Aguirre, V.; Stello, D.; White, T. R. Bibcode: 2016ApJ...819...85C Altcode: 2016arXiv160106052C The angle ψ between a planet’s orbital axis and the spin axis of its parent star is an important diagnostic of planet formation, migration, and tidal evolution. We seek empirical constraints on ψ by measuring the stellar inclination Is via asteroseismology for an ensemble of 25 solar-type hosts observed with NASA’s Kepler satellite. Our results for Is are consistent with alignment at the 2σ level for all stars in the sample, meaning that the system surrounding the red-giant star Kepler-56 remains as the only unambiguous misaligned multiple-planet system detected to date. The availability of a measurement of the projected spin-orbit angle λ for two of the systems allows us to estimate ψ. We find that the orbit of the hot Jupiter HAT-P-7b is likely to be retrograde (\psi =116\buildrel{\circ}\over{.} {4}-14.7+30.2), whereas that of Kepler-25c seems to be well aligned with the stellar spin axis (\psi =12\buildrel{\circ}\over{.} {6}-11.0+6.7). While the latter result is in apparent contradiction with a statement made previously in the literature that the multi-transiting system Kepler-25 is misaligned, we show that the results are consistent, given the large associated uncertainties. Finally, we perform a hierarchical Bayesian analysis based on the asteroseismic sample in order to recover the underlying distribution of ψ. The ensemble analysis suggests that the directions of the stellar spin and planetary orbital axes are correlated, as conveyed by a tendency of the host stars to display large values of inclination. Title: VizieR Online Data Catalog: Fundamental parameters of Kepler stars (Silva Aguirre+, 2015) Authors: Silva Aguirre, V.; Davies, G. R.; Basu, S.; Christensen-Dalsgaard, J.; Creevey, O.; Metcalfe, T. S.; Bedding, T. R.; Casagrande, L.; Handberg, R.; Lund, M. N.; Nissen, P. E.; Chaplin, W. J.; Huber, D.; Serenelli, A. M.; Stello, D.; van Eylen, V.; Campante, T. L.; Elsworth, Y.; Gilliland, R. L.; Hekker, S.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Lundkvist, M. S. Bibcode: 2016yCat..74522127S Altcode: Our sample has been extracted from the 77 exoplanet host stars presented in Huber et al. (2013, Cat. J/ApJ/767/127).

We have made use of the full time-base of observations from the Kepler satellite to uniformly determine precise fundamental stellar parameters, including ages, for a sample of exoplanet host stars where high-quality asteroseismic data were available. We devised a Bayesian procedure flexible in its input and applied it to different grids of models to study systematics from input physics and extract statistically robust properties for all stars.

(4 data files). Title: Oscillation frequencies for 35 Kepler solar-type planet-hosting stars using Bayesian techniques and machine learning Authors: Davies, G. R.; Silva Aguirre, V.; Bedding, T. R.; Handberg, R.; Lund, M. N.; Chaplin, W. J.; Huber, D.; White, T. R.; Benomar, O.; Hekker, S.; Basu, S.; Campante, T. L.; Christensen-Dalsgaard, J.; Elsworth, Y.; Karoff, C.; Kjeldsen, H.; Lundkvist, M. S.; Metcalfe, T. S.; Stello, D. Bibcode: 2016MNRAS.456.2183D Altcode: 2015arXiv151102105D Kepler has revolutionized our understanding of both exoplanets and their host stars. Asteroseismology is a valuable tool in the characterization of stars and Kepler is an excellent observing facility to perform asteroseismology. Here we select a sample of 35 Kepler solar-type stars which host transiting exoplanets (or planet candidates) with detected solar-like oscillations. Using available Kepler short cadence data up to Quarter 16 we create power spectra optimized for asteroseismology of solar-type stars. We identify modes of oscillation and estimate mode frequencies by `peak bagging' using a Bayesian Markov Chain Monte Carlo framework. In addition, we expand the methodology of quality assurance using a Bayesian unsupervised machine learning approach. We report the measured frequencies of the modes of oscillation for all 35 stars and frequency ratios commonly used in detailed asteroseismic modelling. Due to the high correlations associated with frequency ratios we report the covariance matrix of all frequencies measured and frequency ratios calculated. These frequencies, frequency ratios, and covariance matrices can be used to obtain tight constraint on the fundamental parameters of these planet-hosting stars. Title: Asteroseismology with solar-like oscillations Authors: Christensen-Dalsgaard, J. Bibcode: 2016arXiv160206838C Altcode: Almost 100 years ago Sir Arthur Eddington noted that the interiors of stars were inaccessible to observations. The advent of helio- and asteroseismology has completely changed this assessment. Helioseismology has provided very detailed information about the interior structure and dynamics of the Sun, highlighting remaining issues in our understanding of the solar interior. In the last decade extensive observations of stellar oscillations, in particular from space photometry, have provided very detailed information about the global and internal properties of stars. Here I provide an overview of these developments, including the remarkable insight that has been obtained on the properties of evolved stars. Title: The Kepler-454 System: A Small, Not-rocky Inner Planet, a Jovian World, and a Distant Companion Authors: Gettel, Sara; Charbonneau, David; Dressing, Courtney D.; Buchhave, Lars A.; Dumusque, Xavier; Vanderburg, Andrew; Bonomo, Aldo S.; Malavolta, Luca; Pepe, Francesco; Collier Cameron, Andrew; Latham, David W.; Udry, Stéphane; Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W.; Davies, Guy R.; Silva Aguirre, Victor; Kjeldsen, Hans; Bedding, Timothy R.; Lopez, Eric; Affer, Laura; Cosentino, Rosario; Figueira, Pedro; Fiorenzano, Aldo F. M.; Harutyunyan, Avet; Johnson, John Asher; Lopez-Morales, Mercedes; Lovis, Christophe; Mayor, Michel; Micela, Giusi; Molinari, Emilio; Motalebi, Fatemeh; Phillips, David F.; Piotto, Giampaolo; Queloz, Didier; Rice, Ken; Sasselov, Dimitar; Ségransan, Damien; Sozzetti, Alessandro; Watson, Chris; Basu, Sarbani; Campante, Tiago L.; Christensen-Dalsgaard, Jørgen; Kawaler, Steven D.; Metcalfe, Travis S.; Handberg, Rasmus; Lund, Mikkel N.; Lundkvist, Mia S.; Huber, Daniel; Chaplin, William J. Bibcode: 2016ApJ...816...95G Altcode: 2015arXiv151109097G Kepler-454 (KOI-273) is a relatively bright (V = 11.69 mag), Sun-like star that hosts a transiting planet candidate in a 10.6 day orbit. From spectroscopy, we estimate the stellar temperature to be 5687 ± 50 K, its metallicity to be [m/H] = 0.32 ± 0.08, and the projected rotational velocity to be v sin I < 2.4 km s-1. We combine these values with a study of the asteroseismic frequencies from short cadence Kepler data to estimate the stellar mass to be {1.028}-0.03+0.04{M}⊙ , the radius to be 1.066 ± 0.012 R⊙, and the age to be {5.25}-1.39+1.41 Gyr. We estimate the radius of the 10.6 day planet as 2.37 ± 0.13 R⊕. Using 63 radial velocity observations obtained with the HARPS-N spectrograph on the Telescopio Nazionale Galileo and 36 observations made with the HIRES spectrograph at the Keck Observatory, we measure the mass of this planet to be 6.8 ± 1.4 M⊕. We also detect two additional non-transiting companions, a planet with a minimum mass of 4.46 ± 0.12 MJ in a nearly circular 524 day orbit and a massive companion with a period >10 years and mass >12.1 MJ. The 12 exoplanets with radii <2.7 R⊕ and precise mass measurements appear to fall into two populations, with those <1.6 R⊕ following an Earth-like composition curve and larger planets requiring a significant fraction of volatiles. With a density of 2.76 ± 0.73 g cm-3, Kepler-454b lies near the mass transition between these two populations and requires the presence of volatiles and/or H/He gas. Title: Internal Rotation of the Red-giant Star KIC 4448777 by Means of Asteroseismic Inversion Authors: Di Mauro, M. P.; Ventura, R.; Cardini, D.; Stello, D.; Christensen-Dalsgaard, J.; Dziembowski, W. A.; Paternò, L.; Beck, P. G.; Bloemen, S.; Davies, G. R.; De Smedt, K.; Elsworth, Y.; García, R. A.; Hekker, S.; Mosser, B.; Tkachenko, A. Bibcode: 2016ApJ...817...65D Altcode: 2015arXiv151106160D We study the dynamics of the stellar interior of the early red-giant star KIC 4448777 by asteroseismic inversion of 14 splittings of the dipole mixed modes obtained from Kepler observations. In order to overcome the complexity of the oscillation pattern typical of red-giant stars, we present a procedure to extract the rotational splittings from the power spectrum. We find not only that the core rotates from a minimum of 8 to a maximum of 17 times faster than the surface, confirming previous inversion results generated for other red giants (Deheuvels et al.), but we also estimate the variation of the angular velocity within the helium core with a spatial resolution of 0.001R and verify the hypothesis of a sharp discontinuity in the inner stellar rotation. The results show that the entire core rotates rigidly and provide evidence for an angular velocity gradient around the base of the hydrogen-burning shell; however, we do not succeed in characterizing the rotational slope, due to the intrinsic limits of the applied techniques. The angular velocity, from the edge of the core, appears to decrease with increasing distance from the center, reaching an average value in the convective envelope of 68 ± 22 nHz. We conclude that a set of data that includes only dipolar modes is sufficient to infer quite accurately the rotation of a red giant not only in the dense core but also, with a lower level of confidence, in part of the radiative region and in the convective envelope. Title: Asteroseismology of Exoplanet-Host Stars in the TESS Era Authors: Campante, Tiago L.; Schofield, Mathew; Chaplin, William J.; Huber, Daniel; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans; Latham, David W.; Ricker, George R.; Winn, Joshua Bibcode: 2015ESS.....350303C Altcode: New insights on stellar evolution and stellar interiors physics are being made possible by asteroseismology, the study of stars by the observation of their natural, resonant oscillations. Throughout the duration of the Kepler mission, asteroseismology has also played an important role in the characterization of host stars and their planetary systems. Examples include the precise estimation of the fundamental properties of stellar hosts, the obliquity determination of planetary systems, or the orbital eccentricity determination via asterodensity profiling. The Transiting Exoplanet Survey Satellite (TESS) will perform a wide-field survey for planets that transit bright host stars. Its excellent photometric precision and long intervals of uninterrupted observations will enable asteroseismology of solar-type stars and their evolved counterparts. Based on existing all-sky simulations of the stellar and planetary populations, we investigate the asteroseismic yield of the mission, placing particular emphasis on the yield of exoplanet-host stars for which we expect to detect solar-like oscillations. This is done both for the cohort of target stars (observed at a 2-min cadence), which will mainly involve low-mass main-sequence hosts, as well as for the cohort of “full-frame image” stars (observed at a 30-min cadence). The latter cohort offers the exciting prospect of conducting asteroseismology on a significant number of evolved hosts. Also, the brightest solar-type hosts with asteroseismology will become some of the best characterized planetary systems known to date. Finally, we discuss the impact of the detected oscillations on the accuracy/precision of the derived properties of the host stars and their planetary systems. Title: IAU 2015 Resolution B2 on Recommended Zero Points for the Absolute and Apparent Bolometric Magnitude Scales Authors: Mamajek, E. E.; Torres, G.; Prsa, A.; Harmanec, P.; Asplund, M.; Bennett, P. D.; Capitaine, N.; Christensen-Dalsgaard, J.; Depagne, E.; Folkner, W. M.; Haberreiter, M.; Hekker, S.; Hilton, J. L.; Kostov, V.; Kurtz, D. W.; Laskar, J.; Mason, B. D.; Milone, E. F.; Montgomery, M. M.; Richards, M. T.; Schou, J.; Stewart, S. G. Bibcode: 2015arXiv151006262M Altcode: The XXIXth IAU General Assembly in Honolulu adopted IAU 2015 Resolution B2 on recommended zero points for the absolute and apparent bolometric magnitude scales. The resolution was proposed by the IAU Inter-Division A-G Working Group on Nominal Units for Stellar and Planetary Astronomy after consulting with a broad spectrum of researchers from the astronomical community. Resolution B2 resolves the long-standing absence of an internationally-adopted zero point for the absolute and apparent bolometric magnitude scales. Resolution B2 defines the zero point of the absolute bolometric magnitude scale such that a radiation source with $M_{\rm Bol}$ = 0 has luminosity L$_{\circ}$ = 3.0128e28 W. The zero point of the apparent bolometric magnitude scale ($m_{\rm Bol}$ = 0) corresponds to irradiance $f_{\circ}$ = 2.518021002e-8 W/m$^2$. The zero points were chosen so that the nominal solar luminosity (3.828e26 W) adopted by IAU 2015 Resolution B3 corresponds approximately to $M_{\rm Bol}$(Sun) = 4.74, the value most commonly adopted in recent literature. The nominal total solar irradiance (1361 W/m$^2$) adopted in IAU 2015 Resolution B3 corresponds approximately to apparent bolometric magnitude $m_{\rm bol}$(Sun) = -26.832. Implicit in the IAU 2015 Resolution B2 definition of the apparent bolometric magnitude scale is an exact definition for the parsec (648000/$\pi$ au) based on the IAU 2012 Resolution B2 definition of the astronomical unit. Title: Asteroseismology of Solar-Type Stars with K2: Detection of Oscillations in C1 Data Authors: Chaplin, W. J.; Lund, M. N.; Handberg, R.; Basu, S.; Buchhave, L. A.; Campante, T. L.; Davies, G. R.; Huber, D.; Latham, D. W.; Latham, C. A.; Serenelli, A.; Antia, H. M.; Appourchaux, T.; Ball, W. H.; Benomar, O.; Casagrande, L.; Christensen-Dalsgaard, J.; Coelho, H. R.; Creevey, O. L.; Elsworth, Y.; García, R. A.; Gaulme, P.; Hekker, S.; Kallinger, T.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Lundkvist, M. S.; Marcadon, F.; Mathur, S.; Miglio, A.; Mosser, B.; Régulo, C.; Roxburgh, I. W.; Silva Aguirre, V.; Stello, D.; Verma, K.; White, T. R.; Bedding, T. R.; Barclay, T.; Buzasi, D. L.; Dehuevels, S.; Gizon, L.; Houdek, G.; Howell, S. B.; Salabert, D.; Soderblom, D. R. Bibcode: 2015PASP..127.1038C Altcode: 2015arXiv150701827C We present the first detections by the NASA K2 Mission of oscillations in solar-type stars, using short-cadence data collected during K2 Campaign\,1 (C1). We understand the asteroseismic detection thresholds for C1-like levels of photometric performance, and we can detect oscillations in subgiants having dominant oscillation frequencies around $1000\,\rm \mu Hz$. Changes to the operation of the fine-guidance sensors are expected to give significant improvements in the high-frequency performance from C3 onwards. A reduction in the excess high-frequency noise by a factor of two-and-a-half in amplitude would bring main-sequence stars with dominant oscillation frequencies as high as ${\simeq 2500}\,\rm \mu Hz$ into play as potential asteroseismic targets for K2. Title: IAU 2015 Resolution B3 on Recommended Nominal Conversion Constants for Selected Solar and Planetary Properties Authors: Mamajek, E. E.; Prsa, A.; Torres, G.; Harmanec, P.; Asplund, M.; Bennett, P. D.; Capitaine, N.; Christensen-Dalsgaard, J.; Depagne, E.; Folkner, W. M.; Haberreiter, M.; Hekker, S.; Hilton, J. L.; Kostov, V.; Kurtz, D. W.; Laskar, J.; Mason, B. D.; Milone, E. F.; Montgomery, M. M.; Richards, M. T.; Schou, J.; Stewart, S. G. Bibcode: 2015arXiv151007674M Altcode: Astronomers commonly quote the properties of celestial objects in units of parameters for the Sun, Jupiter, or the Earth. The resolution presented here was proposed by the IAU Inter-Division Working Group on Nominal Units for Stellar and Planetary Astronomy and passed by the XXIXth IAU General Assembly in Honolulu. IAU 2015 Resolution B3 adopts a set of nominal solar, terrestrial, and jovian conversion constants for stellar and (exo)planetary astronomy which are defined to be exact SI values. While the nominal constants are based on current best estimates (CBEs; which have uncertainties, are not secularly constant, and are updated regularly using new observations), they should be interpreted as standard values and not as CBEs. IAU 2015 Resolution B3 adopts five solar conversion constants (nominal solar radius, nominal total solar irradiance, nominal solar luminosity, nominal solar effective temperature, and nominal solar mass parameter) and six planetary conversion constants (nominal terrestrial equatorial radius, nominal terrestrial polar radius, nominal jovian equatorial radius, nominal jovian polar radius, nominal terrestrial mass parameter, and nominal jovian mass parameter). Title: On the red-giant luminosity bump Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2015MNRAS.453..666C Altcode: 2015arXiv150705531C The increase in luminosity as a star evolves on the red-giant branch is interrupted briefly when the hydrogen-burning shell reaches the vicinity of the composition discontinuity left behind from the first convective dredge-up. The non-monotonic variation of luminosity causes an accumulation of stars, known as the `bump', in the distribution of stars in the colour-magnitude diagrams of stellar clusters, which has substantial diagnostic potential. Here, I present numerical results on this behaviour and discuss the physical reason for the luminosity variation, with the goal of strengthening the understanding of origin of the phenomenon and hence of its diagnostic potential. Title: Oscillations in g-mode period spacings in red giants as a way to determine their state of evolution Authors: Cunha, M. S.; Stello, D.; Avelino, P. P.; Christensen-Dalsgaard, J. Bibcode: 2015EPJWC.10101014C Altcode: In this work we consider the sensitivity of gravity-mode period spacings to sharp changes in the inner structure of red giant stars, more specifically in the buoyancy frequency inside the g-mode propagation cavity. Based on a comparison between the solutions to the linear pulsation equations in the Cowling approximation for pure g-modes with results obtained with a full oscillation code we identify and correctly interpret the signature of the above-mentioned sharp variations in the period spacings. Two examples, of red giant models in different evolutionary phases, are discussed. Detection of these signatures in CoRoT, Kepler or future PLATO red-giant stars would pin down their evolutionary state in an unprecedented way. Title: The treatment of mixing in core helium burning models - I. Implications for asteroseismology Authors: Constantino, Thomas; Campbell, Simon W.; Christensen-Dalsgaard, Jørgen; Lattanzio, John C.; Stello, Dennis Bibcode: 2015MNRAS.452..123C Altcode: 2015arXiv150601209C The detection of mixed oscillation modes offers a unique insight into the internal structure of core helium burning (CHeB) stars. The stellar structure during CHeB is very uncertain because the growth of the convective core, and/or the development of a semiconvection zone, is critically dependent on the treatment of convective boundaries. In this study we calculate a suite of stellar structure models and their non-radial pulsations to investigate why the predicted asymptotic g-mode ℓ = 1 period spacing ΔΠ1 is systematically lower than is inferred from Kepler field stars. We find that only models with large convective cores, such as those calculated with our newly proposed `maximal-overshoot' scheme, can match the average ΔΠ1 reported. However, we also find another possible solution that is related to the method used to determine ΔΠ1: mode trapping can raise the observationally inferred ΔΠ1 well above its true value. Even after accounting for these two proposed resolutions to the discrepancy in average ΔΠ1, models still predict more CHeB stars with low ΔΠ1 ( ≲ 270 s) than are observed. We establish two possible remedies for this: (i) there may be a difficulty in determining ΔΠ1 for early CHeB stars (when ΔΠ1 is lowest) because of the effect that the sharp composition profile at the hydrogen burning shell has on the pulsations, or (ii) the mass of the helium core at the flash is higher than predicted. Our conclusions highlight the need for the reporting of selection effects in asteroseismic population studies in order to safely use this information to constrain stellar evolution theory. Title: KOI-3158: The oldest known system of terrestrial-size planets Authors: Campante, T. L.; Barclay, T.; Swift, J. J.; Huber, D.; Adibekyan, V. Zh.; Cochran, W.; Burke, C. J.; Isaacson, H.; Quintana, E. V.; Davies, G. R.; Silva Aguirre, V.; Ragozzine, D.; Riddle, R.; Baranec, C.; Basu, S.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Metcalfe, T. S.; Bedding, T. R.; Handberg, R.; Stello, D.; Brewer, J. M.; Hekker, S.; Karoff, C.; Kolbl, R.; Law, N. M.; Lundkvist, M.; Miglio, A.; Rowe, J. F.; Santos, N. C.; Van Laerhoven, C.; Arentoft, T.; Elsworth, Y. P.; Fischer, D. A.; Kawaler, S. D.; Kjeldsen, H.; Lund, M. N.; Marcy, G. W.; Sousa, S. G.; Sozzetti, A.; White, T. R. Bibcode: 2015EPJWC.10102004C Altcode: 2015arXiv150107869C The first discoveries of exoplanets around Sun-like stars have fueled efforts to find ever smaller worlds evocative of Earth and other terrestrial planets in the Solar System. While gas-giant planets appear to form preferentially around metal-rich stars, small planets (with radii less than four Earth radii) can form under a wide range of metallicities. This implies that small, including Earth-size, planets may have readily formed at earlier epochs in the Universe's history when metals were far less abundant. We report Kepler spacecraft observations of KOI-3158, a metal-poor Sun-like star from the old population of the Galactic thick disk, which hosts five planets with sizes between Mercury and Venus. We used asteroseismology to directly measure a precise age of 11.2 ± 1.0 Gyr for the host star, indicating that KOI-3158 formed when the Universe was less than 20 % of its current age and making it the oldest known system of terrestrial-size planets. We thus show that Earth-size planets have formed throughout most of the Universe's 13.8-billion-year history, providing scope for the existence of ancient life in the Galaxy. Title: What asteroseismology can do for exoplanets Authors: Van Eylen, Vincent; Lund, Mikkel N.; Silva Aguirre, Victor; Arentoft, Torben; Kjeldsen, Hans; Albrecht, Simon; Chaplin, William J.; Isaacson, Howard; Pedersen, May G.; Jessen-Hansen, Jens; Tingley, Brandon; Christensen-Dalsgaard, Jørgen; Aerts, Conny; Campante, Tiago L.; Bryson, Steve T. Bibcode: 2015EPJWC.10102005V Altcode: 2014arXiv1412.4848V We describe three useful applications of asteroseismology in the context of exoplanet science: (1) the detailed characterisation of exoplanet host stars; (2) the measurement of stellar inclinations; and (3) the determination of orbital eccentricity from transit duration making use of asteroseismic stellar densities. We do so using the example system Kepler-410 [1]. This is one of the brightest (V = 9.4) Kepler exoplanet host stars, containing a small (2.8 R⊕) transiting planet in a long orbit (17.8 days), and one or more additional non-transiting planets as indicated by transit timing variations. The validation of Kepler-410 (KOI-42) was complicated due to the presence of a companion star, and the planetary nature of the system was confirmed after analyzing a Spitzer transit observation as well as ground-based follow-up observations. Title: The Internal Rotation Profile of the B-type Star KIC 10526294 from Frequency Inversion of its Dipole Gravity Modes Authors: Triana, S. A.; Moravveji, E.; Pápics, P. I.; Aerts, C.; Kawaler, S. D.; Christensen-Dalsgaard, J. Bibcode: 2015ApJ...810...16T Altcode: 2015arXiv150704574T; 2015arXiv150704574A The internal angular momentum distribution of a star is the key to determining its evolution. Fortunately, stellar internal rotation can be probed through studies of rotationally split nonradial oscillation modes. In particular, the detection of nonradial gravity modes (g modes) in massive young stars has recently become feasible thanks to the Kepler space mission. Our goal is to derive the internal rotation profile of the Kepler B8V star KIC 10526294 through asteroseismology. We interpret the observed rotational splittings of its dipole g modes using four different approaches based on the best seismic models of the star and their rotational kernels. We show that these kernels can resolve differential rotation within the radiative envelope if a smooth rotational profile is assumed and if the observational errors are small. Based on Kepler data, we find that the rotation rate near the core-envelope boundary is well constrained to 163 ± 89 nHz. The seismic data are consistent with rigid rotation but a profile with counter-rotation within the envelope has a statistical advantage over constant rotation. Our study should be repeated for other massive stars with a variety of stellar parameters in order to determine the physical conditions that control the internal rotation profile of young massive stars, with the aim of improving the input physics of their models. Title: The Surface of Stellar Models - Now with more 3D simulations! Authors: Trampedach, Regner; Christensen-Dalsgaard, Jørgen; Asplund, Martin; Stein, Robert F.; Nordlund, Åke Bibcode: 2015EPJWC.10106064T Altcode: We have constructed a grid of 3D hydrodynamic simulations of deep convective and line-blanketed atmospheres. We have developed a new consistent method for computing and employing T(τ) relations from these simulations, as surface boundary conditions for 1D stellar structure models. These 1D models have, in turn, had their mixing-length, α, calibrated against the averaged structure of each of the simulations. Both α and T(τ) vary significantly with Teff and log g. Title: Ages and fundamental properties of Kepler exoplanet host stars from asteroseismology Authors: Silva Aguirre, V.; Davies, G. R.; Basu, S.; Christensen-Dalsgaard, J.; Creevey, O.; Metcalfe, T. S.; Bedding, T. R.; Casagrande, L.; Handberg, R.; Lund, M. N.; Nissen, P. E.; Chaplin, W. J.; Huber, D.; Serenelli, A. M.; Stello, D.; Van Eylen, V.; Campante, T. L.; Elsworth, Y.; Gilliland, R. L.; Hekker, S.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Lundkvist, M. S. Bibcode: 2015MNRAS.452.2127S Altcode: 2015arXiv150407992S We present a study of 33 Kepler planet-candidate host stars for which asteroseismic observations have sufficiently high signal-to-noise ratio to allow extraction of individual pulsation frequencies. We implement a new Bayesian scheme that is flexible in its input to process individual oscillation frequencies, combinations of them, and average asteroseismic parameters, and derive robust fundamental properties for these targets. Applying this scheme to grids of evolutionary models yields stellar properties with median statistical uncertainties of 1.2 per cent (radius), 1.7 per cent (density), 3.3 per cent (mass), 4.4 per cent (distance), and 14 per cent (age), making this the exoplanet host-star sample with the most precise and uniformly determined fundamental parameters to date. We assess the systematics from changes in the solar abundances and mixing-length parameter, showing that they are smaller than the statistical errors. We also determine the stellar properties with three other fitting algorithms and explore the systematics arising from using different evolution and pulsation codes, resulting in 1 per cent in density and radius, and 2 per cent and 7 per cent in mass and age, respectively. We confirm previous findings of the initial helium abundance being a source of systematics comparable to our statistical uncertainties, and discuss future prospects for constraining this parameter by combining asteroseismology and data from space missions. Finally, we compare our derived properties with those obtained using the global average asteroseismic observables along with effective temperature and metallicity, finding excellent level of agreement. Owing to selection effects, our results show that the majority of the high signal-to-noise ratio asteroseismic Kepler host stars are older than the Sun. Title: Division II: Commission 12: Solar Radiation and Structure Authors: Kosovichev, Alexander; Cauzzi, Gianna; Martinez Pillet, Valentin; Asplund, Martin; Brandenburg, Axel; Chou, Dean-Yi; Christensen-Dalsgaard, Jorgen; Gan, Weiqun; Kuznetsov, Vladimir D.; Rovira, Marta G.; Shchukina, Nataliya; Venkatakrishnan, P. Bibcode: 2015IAUTB..28..109K Altcode: The President of C12, Alexander Kosovichev, presented the status of the Commission and its working Group(s). Primary activities included organization of international meetings (IAU Symposia, Special Sessions and Joint Discussion); review and support of proposals for IAU sponsored meetings; organization of working groups on the Commission topics to promote the international cooperation; preparation of triennial report on the organizational and science activities of Commission members. Commission 12 broadly encompasses topics of solar research which include studies of the Sun's internal structure, composition, dynamics and magnetism (through helioseismology and other techniques), studies of the quiet photosphere, chromosphere and corona, and also research of the mechanisms of solar radiation, and its variability on various time scales. Some overlap with topics covered by Commission 10 Solar Activity is unavoidable, and many activities are sponsored jointly by these two commissions. The Commission website can be found at http://sun.stanford.edu/IAU-Com12/, with information about related IAU Symposiums and activities, and links to appropriate web sites. Title: The Stellar Observations Network Group - first results Authors: Antoci, Victoria; Grundahl, Frank; Christensen-Dalsgaard, Joergen; Kjeldsen, Hans Bibcode: 2015IAUGA..2258061A Altcode: SONG - the Stellar Observations Network Group is a Danish-led project set to design and build a global network of 1-m telescopes to carry out detailed studies of solar-like stars using asteroseismology and to discover and characterise exo-planets and their star system. Here we present more than 100 nights of high-precision radial velocity measurements from 2014 of the subgiant mu Herculis. Preliminary analyses of the largest ground-based data set ever obtained for such as star clearly show the detection of stochastically excited pressure modes. The high quality of our data allows unique extraction of individual modes over many orders in the frequency spectrum, leading to studies of rotation, convection, near-surface effects, core structure using mixed modes and stellar activity. Title: From the Sun to the distant stars, and back: Future research directions Authors: Christensen-Dalsgaard, J. Bibcode: 2015exse.book..276C Altcode: No abstract at ADS Title: Helioseismology: Observations and space missions Authors: Pallé, P. L.; Appourchaux, T.; Christensen-Dalsgaard, J.; Garcxía, I. A. Bibcode: 2015exse.book...25P Altcode: No abstract at ADS Title: A bright outlook for helio- and asteroseismology Authors: Christensen-Dalsgaard, J. Bibcode: 2015exse.book....5C Altcode: No abstract at ADS Title: Structural Glitches near the Cores of Red Giants Revealed by Oscillations in g-mode Period Spacings from Stellar Models Authors: Cunha, M. S.; Stello, D.; Avelino, P. P.; Christensen-Dalsgaard, J.; Townsend, R. H. D. Bibcode: 2015ApJ...805..127C Altcode: 2015arXiv150309085C With recent advances in asteroseismology it is now possible to peer into the cores of red giants, potentially providing a way to study processes such as nuclear burning and mixing through their imprint as sharp structural variations—glitches—in the stellar cores. Here we show how such core glitches can affect the oscillations we observe in red giants. We derive an analytical expression describing the expected frequency pattern in the presence of a glitch. This formulation also accounts for the coupling between acoustic and gravity waves. From an extensive set of canonical stellar models we find glitch-induced variation in the period spacing and inertia of non-radial modes during several phases of red giant evolution. Significant changes are seen in the appearance of mode amplitude and frequency patterns in asteroseismic diagrams such as the power spectrum and the échelle diagram. Interestingly, along the red giant branch glitch-induced variation occurs only at the luminosity bump, potentially providing a direct seismic indicator of stars in that particular evolution stage. Similarly, we find the variation at only certain post-helium-ignition evolution stages, namely, in the early phases of helium core burning and at the beginning of helium shell burning, signifying the asymptotic giant branch bump. Based on our results, we note that assuming stars to be glitch-free, while they are not, can result in an incorrect estimate of the period spacing. We further note that including diffusion and mixing beyond classical Schwarzschild could affect the characteristics of the glitches, potentially providing a way to study these physical processes. Title: Kepler-432: A Red Giant Interacting with One of its Two Long-period Giant Planets Authors: Quinn, Samuel N.; White, Timothy. R.; Latham, David W.; Chaplin, William J.; Handberg, Rasmus; Huber, Daniel; Kipping, David M.; Payne, Matthew J.; Jiang, Chen; Silva Aguirre, Victor; Stello, Dennis; Sliski, David H.; Ciardi, David R.; Buchhave, Lars A.; Bedding, Timothy R.; Davies, Guy R.; Hekker, Saskia; Kjeldsen, Hans; Kuszlewicz, James S.; Everett, Mark E.; Howell, Steve B.; Basu, Sarbani; Campante, Tiago L.; Christensen-Dalsgaard, Jørgen; Elsworth, Yvonne P.; Karoff, Christoffer; Kawaler, Steven D.; Lund, Mikkel N.; Lundkvist, Mia; Esquerdo, Gilbert A.; Calkins, Michael L.; Berlind, Perry Bibcode: 2015ApJ...803...49Q Altcode: 2014arXiv1411.4666Q We report the discovery of Kepler-432b, a giant planet ({{M}b}=5.41-0.18+0.32 {{M}Jup}, {{R}b}=1.145-0.039+0.036 {{R}Jup}) transiting an evolved star ({{M}\star }=1.32-0.07+0.10 {{M}⊙ },{{R}\star }=4.06-0.08+0.12 {{R}⊙ }) with an orbital period of {{P}b}=52.501129-0.000053+0.000067 days. Radial velocities (RVs) reveal that Kepler-432b orbits its parent star with an eccentricity of e=0.5134-0.0089+0.0098, which we also measure independently with asterodensity profiling (AP; e=0.507-0.114+0.039), thereby confirming the validity of AP on this particular evolved star. The well-determined planetary properties and unusually large mass also make this planet an important benchmark for theoretical models of super-Jupiter formation. Long-term RV monitoring detected the presence of a non-transiting outer planet (Kepler-432c; {{M}c}sin {{i}c}=2.43-0.24+0.22 {{M}Jup}, {{P}c}=406.2-2.5+3.9 days), and adaptive optics imaging revealed a nearby (0\buildrel{\prime\prime}\over{.} 87), faint companion (Kepler-432B) that is a physically bound M dwarf. The host star exhibits high signal-to-noise ratio asteroseismic oscillations, which enable precise measurements of the stellar mass, radius, and age. Analysis of the rotational splitting of the oscillation modes additionally reveals the stellar spin axis to be nearly edge-on, which suggests that the stellar spin is likely well aligned with the orbit of the transiting planet. Despite its long period, the obliquity of the 52.5 day orbit may have been shaped by star-planet interaction in a manner similar to hot Jupiter systems, and we present observational and theoretical evidence to support this scenario. Finally, as a short-period outlier among giant planets orbiting giant stars, study of Kepler-432b may help explain the distribution of massive planets orbiting giant stars interior to 1 AU. Title: Song Authors: Christensen-Dalsgaard, Jorgen Bibcode: 2015mwss.confE..44C Altcode: No abstract at ADS Title: An Ancient Extrasolar System with Five Sub-Earth-size Planets Authors: Campante, T. L.; Barclay, T.; Swift, J. J.; Huber, D.; Adibekyan, V. Zh.; Cochran, W.; Burke, C. J.; Isaacson, H.; Quintana, E. V.; Davies, G. R.; Silva Aguirre, V.; Ragozzine, D.; Riddle, R.; Baranec, C.; Basu, S.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Metcalfe, T. S.; Bedding, T. R.; Handberg, R.; Stello, D.; Brewer, J. M.; Hekker, S.; Karoff, C.; Kolbl, R.; Law, N. M.; Lundkvist, M.; Miglio, A.; Rowe, J. F.; Santos, N. C.; Van Laerhoven, C.; Arentoft, T.; Elsworth, Y. P.; Fischer, D. A.; Kawaler, S. D.; Kjeldsen, H.; Lund, M. N.; Marcy, G. W.; Sousa, S. G.; Sozzetti, A.; White, T. R. Bibcode: 2015ApJ...799..170C Altcode: 2015arXiv150106227C The chemical composition of stars hosting small exoplanets (with radii less than four Earth radii) appears to be more diverse than that of gas-giant hosts, which tend to be metal-rich. This implies that small, including Earth-size, planets may have readily formed at earlier epochs in the universe's history when metals were more scarce. We report Kepler spacecraft observations of Kepler-444, a metal-poor Sun-like star from the old population of the Galactic thick disk and the host to a compact system of five transiting planets with sizes between those of Mercury and Venus. We validate this system as a true five-planet system orbiting the target star and provide a detailed characterization of its planetary and orbital parameters based on an analysis of the transit photometry. Kepler-444 is the densest star with detected solar-like oscillations. We use asteroseismology to directly measure a precise age of 11.2 ± 1.0 Gyr for the host star, indicating that Kepler-444 formed when the universe was less than 20% of its current age and making it the oldest known system of terrestrial-size planets. We thus show that Earth-size planets have formed throughout most of the universe's 13.8 billion year history, leaving open the possibility for the existence of ancient life in the Galaxy. The age of Kepler-444 not only suggests that thick-disk stars were among the hosts to the first Galactic planets, but may also help to pinpoint the beginning of the era of planet formation. Title: The two-colour EMCCD instrument for the Danish 1.54 m telescope and SONG Authors: Skottfelt, J.; Bramich, D. M.; Hundertmark, M.; Jørgensen, U. G.; Michaelsen, N.; Kjærgaard, P.; Southworth, J.; Sørensen, A. N.; Andersen, M. F.; Andersen, M. I.; Christensen-Dalsgaard, J.; Frandsen, S.; Grundahl, F.; Harpsøe, K. B. W.; Kjeldsen, H.; Pallé, P. L. Bibcode: 2015A&A...574A..54S Altcode: 2014arXiv1411.7401S We report on the implemented design of a two-colour instrument based on electron-multiplying CCD (EMCCD) detectors. This instrument is currently installed at the Danish 1.54 m telescope at ESO's La Silla Observatory in Chile, and will be available at the SONG (Stellar Observations Network Group) 1m telescope node at Tenerife and at other SONG nodes as well. We present the software system for controlling the two-colour instrument and calibrating the high frame-rate imaging data delivered by the EMCCD cameras. An analysis of the performance of the Two-Colour Instrument at the Danish telescope shows an improvement in spatial resolution of up to a factor of two when doing shift-and-add compared with conventional imaging, and the possibility of doing high-precision photometry of EMCCD data in crowded fields. The Danish telescope, which was commissioned in 1979, is limited by a triangular coma at spatial resolutions below 0.5 arcsec, and better results will thus be achieved at the near diffraction-limited optical system on the SONG telescopes, where spatial resolutions close to 0.2 arcsec have been achieved. Regular EMCCD operations have been running at the Danish telescope for several years and produced a number of scientific discoveries, including microlensing detected exoplanets, detecting previously unknown variable stars in dense globular clusters, and discovering two rings around the small asteroid-like object (10199) Chariklo.

Based on data collected with the Danish 1.54m telescope at ESO's La Silla Observatory. Title: Erratum: Sounding stellar cycles with Kepler - II. Ground-based observations Authors: Karoff, C.; Metcalfe, T. S.; Chaplin, W. J.; Frandsen, S.; Grundahl, F.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Nielsen, M. B.; Frimann, S.; Thygesen, A. O.; Arentoft, T.; Amby, T. M.; Sousa, S. G.; Buzasi, D. L. Bibcode: 2015MNRAS.446.1139K Altcode: No abstract at ADS Title: Transiting Exoplanet Survey Satellite (TESS) Authors: Ricker, George R.; Winn, Joshua N.; Vanderspek, Roland; Latham, David W.; Bakos, Gáspár Á.; Bean, Jacob L.; Berta-Thompson, Zachory K.; Brown, Timothy M.; Buchhave, Lars; Butler, Nathaniel R.; Butler, R. Paul; Chaplin, William J.; Charbonneau, David; Christensen-Dalsgaard, Jørgen; Clampin, Mark; Deming, Drake; Doty, John; De Lee, Nathan; Dressing, Courtney; Dunham, Edward W.; Endl, Michael; Fressin, Francois; Ge, Jian; Henning, Thomas; Holman, Matthew J.; Howard, Andrew W.; Ida, Shigeru; Jenkins, Jon M.; Jernigan, Garrett; Johnson, John Asher; Kaltenegger, Lisa; Kawai, Nobuyuki; Kjeldsen, Hans; Laughlin, Gregory; Levine, Alan M.; Lin, Douglas; Lissauer, Jack J.; MacQueen, Phillip; Marcy, Geoffrey; McCullough, Peter R.; Morton, Timothy D.; Narita, Norio; Paegert, Martin; Palle, Enric; Pepe, Francesco; Pepper, Joshua; Quirrenbach, Andreas; Rinehart, Stephen A.; Sasselov, Dimitar; Sato, Bun'ei; Seager, Sara; Sozzetti, Alessandro; Stassun, Keivan G.; Sullivan, Peter; Szentgyorgyi, Andrew; Torres, Guillermo; Udry, Stephane; Villasenor, Joel Bibcode: 2015JATIS...1a4003R Altcode: The Transiting Exoplanet Survey Satellite (TESS) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its 2-year mission, TESS will employ four wide-field optical charge-coupled device cameras to monitor at least 200,000 main-sequence dwarf stars with IC≈4-13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from 1 month to 1 year, depending mainly on the star's ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10 to 100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every 4 months, inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the nearest and brightest stars hosting transiting planets, which will endure as highly favorable targets for detailed investigations. Title: Hardware and software for a robotic network of telescopes - SONG Authors: Andersen, M. F.; Grundahl, F.; Christensen-Dalsgaard, J.; Frandsen, S.; Jørgensen, U. G.; Kjeldsen, H.; Pallé, P.; Skottfelt, J.; Sørensen, A. N.; Weiss, E. Bibcode: 2014RMxAC..45...83A Altcode: 2019arXiv190108300A SONG aims at setting up a network of small 1m telescopes around the globe to observe stars uninterrupted throughout days, weeks and even months. This paper describes the fundamental aspects for putting up such a network and how we will operate each site as part of the full network. The SONG observatories will be working autonomously and automatic and can be fully controlled remotely. Title: Improvements to stellar structure models, based on a grid of 3D convection simulations - II. Calibrating the mixing-length formulation Authors: Trampedach, Regner; Stein, Robert F.; Christensen-Dalsgaard, Jørgen; Nordlund, Åke; Asplund, Martin Bibcode: 2014MNRAS.445.4366T Altcode: 2014arXiv1410.1559T We perform a calibration of the mixing length of convection in stellar structure models against realistic 3D radiation-coupled hydrodynamics simulations of convection in stellar surface layers, determining the adiabat deep in convective stellar envelopes. The mixing-length parameter α is calibrated by matching averages of the 3D simulations to 1D stellar envelope models, ensuring identical atomic physics in the two cases. This is done for a previously published grid of solar-metallicity convection simulations, covering from 4200 to 6900 K on the main sequence, and from 4300 to 5000 K for giants with log g = 2.2. Our calibration results in an α varying from 1.6 for the warmest dwarf, which is just cool enough to admit a convective envelope, and up to 2.05 for the coolest dwarfs in our grid. In between these is a triangular plateau of α ∼ 1.76. The Sun is located on this plateau and has seen little change during its evolution so far. When stars ascend the giant branch, they largely do so along tracks of constant α, with α decreasing with increasing mass. Title: On the asymptotic acoustic-mode phase in red giant stars and its dependence on evolutionary state Authors: Christensen-Dalsgaard, Jørgen; Silva Aguirre, Victor; Elsworth, Yvonne; Hekker, Saskia Bibcode: 2014MNRAS.445.3685C Altcode: 2014arXiv1409.7949C Asteroseismic investigations based on the wealth of data now available, in particular from the CoRoT and Kepler missions, require a good understanding of the relation between the observed quantities and the properties of the underlying stellar structure. Kallinger et al. found a relation between their determination of the asymptotic phase of radial oscillations in evolved stars and the evolutionary state, separating ascending-branch red giants from helium-burning stars in the `red clump'. Here, we provide a detailed analysis of this relation, which is found to derive from differences between these two classes of stars in the thermodynamic state of the convective envelope. There is potential for distinguishing red giants and clump stars based on the phase determined from observations that are too short to allow distinction based on determination of the period spacing for mixed modes. The analysis of the phase may also point to a better understanding of the potential for using the helium-ionization-induced acoustic glitch to determine the helium abundance in the envelopes of these stars. Title: Verification of asymptotic relation for mixed modes in red giant stars Authors: Jiang, C.; Christensen-Dalsgaard, J. Bibcode: 2014MNRAS.444.3622J Altcode: 2014arXiv1406.1825J High-precision space observations, such as made by the Kepler and CoRoT missions, allow us to detect mixed modes for l = 1 modes in their high signal-to-noise photometry data. By means of asteroseismology, the inner structure of red giant (RG) stars is revealed for the first time with the help of mixed modes. We analyse these mixed modes of a 1.3 M⊙ RG model theoretically from the approximate asymptotic descriptions of oscillations. While fitting observed frequencies with the eigenvalue condition for mixed modes, a good estimate of period spacing and coupling strength is also acquired for more evolved models. We show that the behaviour of the mode inertia in a given mode varies dramatically when the coupling is strong. An approximation of period spacings is also obtained from the asymptotic dispersion relation, which provides a good estimate of the coupling strength as well as period spacing when g-mode-like mixed modes are sufficiently dense. By comparing the theoretical coupling strength from the integral expression with the ones from fitting methods, we confirmed that the theoretical asymptotic equation is problematic in the evanescent region due to the potential singularities as well as the use of the Cowling approximation. Title: The PLATO 2.0 mission Authors: Rauer, H.; Catala, C.; Aerts, C.; Appourchaux, T.; Benz, W.; Brandeker, A.; Christensen-Dalsgaard, J.; Deleuil, M.; Gizon, L.; Goupil, M. -J.; Güdel, M.; Janot-Pacheco, E.; Mas-Hesse, M.; Pagano, I.; Piotto, G.; Pollacco, D.; Santos, Ċ.; Smith, A.; Suárez, J. -C.; Szabó, R.; Udry, S.; Adibekyan, V.; Alibert, Y.; Almenara, J. -M.; Amaro-Seoane, P.; Eiff, M. Ammler-von; Asplund, M.; Antonello, E.; Barnes, S.; Baudin, F.; Belkacem, K.; Bergemann, M.; Bihain, G.; Birch, A. C.; Bonfils, X.; Boisse, I.; Bonomo, A. S.; Borsa, F.; Brandão, I. M.; Brocato, E.; Brun, S.; Burleigh, M.; Burston, R.; Cabrera, J.; Cassisi, S.; Chaplin, W.; Charpinet, S.; Chiappini, C.; Church, R. P.; Csizmadia, Sz.; Cunha, M.; Damasso, M.; Davies, M. B.; Deeg, H. J.; Díaz, R. F.; Dreizler, S.; Dreyer, C.; Eggenberger, P.; Ehrenreich, D.; Eigmüller, P.; Erikson, A.; Farmer, R.; Feltzing, S.; de Oliveira Fialho, F.; Figueira, P.; Forveille, T.; Fridlund, M.; García, R. A.; Giommi, P.; Giuffrida, G.; Godolt, M.; Gomes da Silva, J.; Granzer, T.; Grenfell, J. L.; Grotsch-Noels, A.; Günther, E.; Haswell, C. A.; Hatzes, A. P.; Hébrard, G.; Hekker, S.; Helled, R.; Heng, K.; Jenkins, J. M.; Johansen, A.; Khodachenko, M. L.; Kislyakova, K. G.; Kley, W.; Kolb, U.; Krivova, N.; Kupka, F.; Lammer, H.; Lanza, A. F.; Lebreton, Y.; Magrin, D.; Marcos-Arenal, P.; Marrese, P. M.; Marques, J. P.; Martins, J.; Mathis, S.; Mathur, S.; Messina, S.; Miglio, A.; Montalban, J.; Montalto, M.; Monteiro, M. J. P. F. G.; Moradi, H.; Moravveji, E.; Mordasini, C.; Morel, T.; Mortier, A.; Nascimbeni, V.; Nelson, R. P.; Nielsen, M. B.; Noack, L.; Norton, A. J.; Ofir, A.; Oshagh, M.; Ouazzani, R. -M.; Pápics, P.; Parro, V. C.; Petit, P.; Plez, B.; Poretti, E.; Quirrenbach, A.; Ragazzoni, R.; Raimondo, G.; Rainer, M.; Reese, D. R.; Redmer, R.; Reffert, S.; Rojas-Ayala, B.; Roxburgh, I. W.; Salmon, S.; Santerne, A.; Schneider, J.; Schou, J.; Schuh, S.; Schunker, H.; Silva-Valio, A.; Silvotti, R.; Skillen, I.; Snellen, I.; Sohl, F.; Sousa, S. G.; Sozzetti, A.; Stello, D.; Strassmeier, K. G.; Švanda, M.; Szabó, Gy. M.; Tkachenko, A.; Valencia, D.; Van Grootel, V.; Vauclair, S. D.; Ventura, P.; Wagner, F. W.; Walton, N. A.; Weingrill, J.; Werner, S. C.; Wheatley, P. J.; Zwintz, K. Bibcode: 2014ExA....38..249R Altcode: 2014ExA...tmp...41R; 2013arXiv1310.0696R PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 s readout cadence and 2 with 2.5 s candence) providing a wide field-of-view (2232 deg 2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2 %, 4-10 % and 10 % for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50 % of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0. The PLATO 2.0 catalogue allows us to e.g.: - complete our knowledge of planet diversity for low-mass objects, - correlate the planet mean density-orbital distance distribution with predictions from planet formation theories,- constrain the influence of planet migration and scattering on the architecture of multiple systems, and - specify how planet and system parameters change with host star characteristics, such as type, metallicity and age. The catalogue will allow us to study planets and planetary systems at different evolutionary phases. It will further provide a census for small, low-mass planets. This will serve to identify objects which retained their primordial hydrogen atmosphere and in general the typical characteristics of planets in such low-mass, low-density range. Planets detected by PLATO 2.0 will orbit bright stars and many of them will be targets for future atmosphere spectroscopy exploring their atmosphere. Furthermore, the mission has the potential to detect exomoons, planetary rings, binary and Trojan planets. The planetary science possible with PLATO 2.0 is complemented by its impact on stellar and galactic science via asteroseismology as well as light curves of all kinds of variable stars, together with observations of stellar clusters of different ages. This will allow us to improve stellar models and study stellar activity. A large number of well-known ages from red giant stars will probe the structure and evolution of our Galaxy. Asteroseismic ages of bright stars for different phases of stellar evolution allow calibrating stellar age-rotation relationships. Together with the results of ESA's Gaia mission, the results of PLATO 2.0 will provide a huge legacy to planetary, stellar and galactic science. Title: Erratum: "Differential Rotation in Main-sequence Solar-like Stars: Qualitative Inference from Asteroseismic Data" (2014, Apj, 790, 121) Authors: Nørup Lund, Mikkel; Miesch, Mark S.; Christensen-Dalsgaard, Jørgen Bibcode: 2014ApJ...794...96N Altcode: No abstract at ADS Title: Properties of 42 Solar-type Kepler Targets from the Asteroseismic Modeling Portal Authors: Metcalfe, T. S.; Creevey, O. L.; Doğan, G.; Mathur, S.; Xu, H.; Bedding, T. R.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Karoff, C.; Trampedach, R.; Benomar, O.; Brown, B. P.; Buzasi, D. L.; Campante, T. L.; Çelik, Z.; Cunha, M. S.; Davies, G. R.; Deheuvels, S.; Derekas, A.; Di Mauro, M. P.; García, R. A.; Guzik, J. A.; Howe, R.; MacGregor, K. B.; Mazumdar, A.; Montalbán, J.; Monteiro, M. J. P. F. G.; Salabert, D.; Serenelli, A.; Stello, D.; Ste&şacute; licki, M.; Suran, M. D.; Yıldız, M.; Aksoy, C.; Elsworth, Y.; Gruberbauer, M.; Guenther, D. B.; Lebreton, Y.; Molaverdikhani, K.; Pricopi, D.; Simoniello, R.; White, T. R. Bibcode: 2014ApJS..214...27M Altcode: 2014arXiv1402.3614M Recently the number of main-sequence and subgiant stars exhibiting solar-like oscillations that are resolved into individual mode frequencies has increased dramatically. While only a few such data sets were available for detailed modeling just a decade ago, the Kepler mission has produced suitable observations for hundreds of new targets. This rapid expansion in observational capacity has been accompanied by a shift in analysis and modeling strategies to yield uniform sets of derived stellar properties more quickly and easily. We use previously published asteroseismic and spectroscopic data sets to provide a uniform analysis of 42 solar-type Kepler targets from the Asteroseismic Modeling Portal. We find that fitting the individual frequencies typically doubles the precision of the asteroseismic radius, mass, and age compared to grid-based modeling of the global oscillation properties, and improves the precision of the radius and mass by about a factor of three over empirical scaling relations. We demonstrate the utility of the derived properties with several applications. Title: Differential Rotation in Main-sequence Solar-like Stars: Qualitative Inference from Asteroseismic Data Authors: Lund, Mikkel N.; Miesch, Mark S.; Christensen-Dalsgaard, Jørgen Bibcode: 2014ApJ...790..121L Altcode: 2014arXiv1406.7873L; 2014arXiv1406.7873N Understanding differential rotation of Sun-like stars is of great importance for insight into the angular momentum transport in these stars. One means of gaining such information is that of asteroseismology. By a forward modeling approach we analyze in a qualitative manner the impact of different differential rotation profiles on the splittings of p-mode oscillation frequencies. The optimum modes for inference on differential rotation are identified along with the best value of the stellar inclination angle. We find that in general it is not likely that asteroseismology can be used to make an unambiguous distinction between a rotation profile such as a conical Sun-like profile and a cylindrical profile. In addition, it seems unlikely that asteroseismology of Sun-like stars will result in inferences on the radial profile of the differential rotation, such as can be done for red giants. At best, one could possibly obtain the sign of the radial differential rotation gradient. Measurements of the extent of the latitudinal differential from frequency splitting are, however, more promising. One very interesting aspect that could likely be tested from frequency splittings is whether the differential rotation is solar-like or anti-solar-like in nature, in the sense that a solar-like profile has an equator rotating faster than the poles. Title: Transiting Exoplanet Survey Satellite (TESS) Authors: Ricker, George R.; Winn, Joshua N.; Vanderspek, Roland; Latham, David W.; Bakos, Gáspár. Á.; Bean, Jacob L.; Berta-Thompson, Zachory K.; Brown, Timothy M.; Buchhave, Lars; Butler, Nathaniel R.; Butler, R. Paul; Chaplin, William J.; Charbonneau, David; Christensen-Dalsgaard, Jørgen; Clampin, Mark; Deming, Drake; Doty, John; De Lee, Nathan; Dressing, Courtney; Dunham, E. W.; Endl, Michael; Fressin, Francois; Ge, Jian; Henning, Thomas; Holman, Matthew J.; Howard, Andrew W.; Ida, Shigeru; Jenkins, Jon; Jernigan, Garrett; Johnson, John A.; Kaltenegger, Lisa; Kawai, Nobuyuki; Kjeldsen, Hans; Laughlin, Gregory; Levine, Alan M.; Lin, Douglas; Lissauer, Jack J.; MacQueen, Phillip; Marcy, Geoffrey; McCullough, P. R.; Morton, Timothy D.; Narita, Norio; Paegert, Martin; Palle, Enric; Pepe, Francesco; Pepper, Joshua; Quirrenbach, Andreas; Rinehart, S. A.; Sasselov, Dimitar; Sato, Bun'ei; Seager, Sara; Sozzetti, Alessandro; Stassun, Keivan G.; Sullivan, Peter; Szentgyorgyi, Andrew; Torres, Guillermo; Udry, Stephane; Villasenor, Joel Bibcode: 2014SPIE.9143E..20R Altcode: 2014arXiv1406.0151R The Transiting Exoplanet Survey Satellite (TESS ) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, TESS will employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with IC (approximately less than) 13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from one month to one year, depending mainly on the star's ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10-100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every four months, inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the nearest and brightest stars hosting transiting planets, which will endure as highly favorable targets for detailed investigations. Title: Improvements to stellar structure models, based on a grid of 3D convection simulations - I. T(τ) relations Authors: Trampedach, Regner; Stein, Robert F.; Christensen-Dalsgaard, Jørgen; Nordlund, Åke; Asplund, Martin Bibcode: 2014MNRAS.442..805T Altcode: 2014arXiv1405.0236T Relations between temperature, T, and optical depth, τ, are often used for describing the photospheric transition from optically thick to optically thin in stellar structure models. We show that this is well justified, but also that currently used T(τ) relations are often inconsistent with their implementation. As an outer boundary condition on the system of stellar structure equations, T(τ) relations have an undue effect on the overall structure of stars. In this age of precision asteroseismology, we need to re-assess both the method for computing and for implementing T(τ) relations, and the assumptions they rest on. We develop a formulation for proper and consistent evaluation of T(τ) relations from arbitrary 1D or 3D stellar atmospheres, and for their implementation in stellar structure and evolution models. We extract radiative T(τ) relations, as described by our new formulation, from 3D simulations of convection in deep stellar atmospheres of late-type stars from dwarfs to giants. These simulations employ realistic opacities and equation of state, and account for line blanketing. For comparison, we also extract T(τ) relations from 1DMARCSmodel atmospheres using the same formulation. T(τ) relations from our grid of 3D convection simulations display a larger range of behaviours with surface gravity, compared with those of conventional theoretical 1D hydrostatic atmosphere models based on the mixing-length theory for convection. The 1D atmospheres show little dependence on gravity. 1D atmospheres of main-sequence stars also show an abrupt transition to the diffusion approximation at τ ≃ 2.5, whereas the 3D simulations exhibit smooth transitions that occur at the same depth for M ≃ 0.8 M⊙, and higher in the atmosphere for both more and less massive main-sequence stars. Based on these results, we recommend no longer using scaled solar T(τ) relations. Files with T(τ) relations for our grid of simulations are made available to the community, together with routines for interpolating in this irregular grid. We also provide matching tables of atmospheric opacity, for consistent implementation in stellar structure models. Title: Kepler-93b: A Terrestrial World Measured to within 120 km, and a Test Case for a New Spitzer Observing Mode Authors: Ballard, Sarah; Chaplin, William J.; Charbonneau, David; Désert, Jean-Michel; Fressin, Francois; Zeng, Li; Werner, Michael W.; Davies, Guy R.; Silva Aguirre, Victor; Basu, Sarbani; Christensen-Dalsgaard, Jørgen; Metcalfe, Travis S.; Stello, Dennis; Bedding, Timothy R.; Campante, Tiago L.; Handberg, Rasmus; Karoff, Christoffer; Elsworth, Yvonne; Gilliland, Ronald L.; Hekker, Saskia; Huber, Daniel; Kawaler, Steven D.; Kjeldsen, Hans; Lund, Mikkel N.; Lundkvist, Mia Bibcode: 2014ApJ...790...12B Altcode: 2014arXiv1405.3659B We present the characterization of the Kepler-93 exoplanetary system, based on three years of photometry gathered by the Kepler spacecraft. The duration and cadence of the Kepler observations, in tandem with the brightness of the star, enable unusually precise constraints on both the planet and its host. We conduct an asteroseismic analysis of the Kepler photometry and conclude that the star has an average density of 1.652 ± 0.006 g cm-3. Its mass of 0.911 ± 0.033 M ⊙ renders it one of the lowest-mass subjects of asteroseismic study. An analysis of the transit signature produced by the planet Kepler-93b, which appears with a period of 4.72673978 ± 9.7 × 10-7 days, returns a consistent but less precise measurement of the stellar density, 1.72+0.02-0.28 g cm-3. The agreement of these two values lends credence to the planetary interpretation of the transit signal. The achromatic transit depth, as compared between Kepler and the Spitzer Space Telescope, supports the same conclusion. We observed seven transits of Kepler-93b with Spitzer, three of which we conducted in a new observing mode. The pointing strategy we employed to gather this subset of observations halved our uncertainty on the transit radius ratio RP /R sstarf. We find, after folding together the stellar radius measurement of 0.919 ± 0.011 R ⊙ with the transit depth, a best-fit value for the planetary radius of 1.481 ± 0.019 R ⊕. The uncertainty of 120 km on our measurement of the planet's size currently renders it one of the most precisely measured planetary radii outside of the solar system. Together with the radius, the planetary mass of 3.8 ± 1.5 M ⊕ corresponds to a rocky density of 6.3 ± 2.6 g cm-3. After applying a prior on the plausible maximum densities of similarly sized worlds between 1 and 1.5 R ⊕, we find that Kepler-93b possesses an average density within this group. Title: Angular Momentum Transport within Evolved Low-mass Stars Authors: Cantiello, Matteo; Mankovich, Christopher; Bildsten, Lars; Christensen-Dalsgaard, Jørgen; Paxton, Bill Bibcode: 2014ApJ...788...93C Altcode: 2014arXiv1405.1419C Asteroseismology of 1.0-2.0 M ⊙ red giants by the Kepler satellite has enabled the first definitive measurements of interior rotation in both first ascent red giant branch (RGB) stars and those on the helium burning clump. The inferred rotation rates are 10-30 days for the ≈0.2 M ⊙ He degenerate cores on the RGB and 30-100 days for the He burning core in a clump star. Using the Modules for Experiments in Stellar Evolution code, we calculate state-of-the-art stellar evolution models of low mass rotating stars from the zero-age main sequence to the cooling white dwarf (WD) stage. We include transport of angular momentum due to rotationally induced instabilities and circulations, as well as magnetic fields in radiative zones (generated by the Tayler-Spruit dynamo). We find that all models fail to predict core rotation as slow as observed on the RGB and during core He burning, implying that an unmodeled angular momentum transport process must be operating on the early RGB of low mass stars. Later evolution of the star from the He burning clump to the cooling WD phase appears to be at nearly constant core angular momentum. We also incorporate the adiabatic pulsation code, ADIPLS, to explicitly highlight this shortfall when applied to a specific Kepler asteroseismic target, KIC8366239. Title: Non-radial Oscillations in M-giant Semi-regular Variables: Stellar Models and Kepler Observations Authors: Stello, Dennis; Compton, Douglas L.; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen; Kiss, Laszlo L.; Kjeldsen, Hans; Bellamy, Beau; García, Rafael A.; Mathur, Savita Bibcode: 2014ApJ...788L..10S Altcode: 2014arXiv1406.0003S The success of asteroseismology relies heavily on our ability to identify the frequency patterns of stellar oscillation modes. For stars like the Sun this is relatively easy because the mode frequencies follow a regular pattern described by a well-founded asymptotic relation. When a solar-like star evolves off the main sequence and onto the red giant branch its structure changes dramatically, resulting in changes in the frequency pattern of the modes. We follow the evolution of the adiabatic frequency pattern from the main sequence to near the tip of the red giant branch for a series of models. We find a significant departure from the asymptotic relation for the non-radial modes near the red giant branch tip, resulting in a triplet frequency pattern. To support our investigation we analyze almost four years of Kepler data of the most luminous stars in the field (late K and early M type) and find that their frequency spectra indeed show a triplet pattern dominated by dipole modes even for the most luminous stars in our sample. Our identification explains previous results from ground-based observations reporting fine structure in the Petersen diagram and sub-ridges in the period-luminosity diagram. Finally, we find "new ridges" of non-radial modes with frequencies below the fundamental mode in our model calculations, and we speculate they are related to f modes. Title: VizieR Online Data Catalog: T(tau) relations code (Trampedach+, 2014) Authors: Trampedach, R.; Stein, R. F.; Christensen-Dalsgaard, J.; Nordlund, A.; Asplund, M. Bibcode: 2014yCat..74420805T Altcode: Radiative T({tau})-relations, in the form of generalised Hopf functions, computed from a grid of 37, solar metallicity, realistic, 3D convection simulations with radiative transfer.

(6 data files). Title: VizieR Online Data Catalog: Small Kepler planets radial velocities (Marcy+, 2014) Authors: Marcy, G. W.; Isaacson, H.; Howard, A. W.; Rowe, J. F.; Jenkins, J. M.; Bryson, S. T.; Latham, D. W.; Howell, S. B.; Gautier, T. N., III; Batalha, N. M.; Rogers, L.; Ciardi, D.; Fischer, D. A.; Gilliland, R. L.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Huber, D.; Chaplin, W. J.; Basu, S.; Buchhave, L. A.; Quinn, S. N.; Borucki, W. J.; Koch, D. G.; Hunter, R.; Caldwell, D. A.; van Cleve, J.; Kolbl, R.; Weiss, L. M.; Petigura, E.; Seager, S.; Morton, T.; Johnson, J. A.; Ballard, S.; Burke, C.; Cochran, W. D.; Endl, M.; MacQueen, P.; Everett, M. E.; Lissauer, J. J.; Ford, E. B.; Torres, G.; Fressin, F.; Brown, T. M.; Steffen, J. H.; Charbonneau, D.; Basri, G. S.; Sasselov, D. D.; Winn, J.; Sanchis-Ojeda, R.; Christiansen, J.; Adams, E.; Henze, C.; Dupree, A.; Fabrycky, D. C.; Fortney, J. J.; Tarter, J.; Holman, M. J.; Tenenbaum, P.; Shporer, A.; Lucas, P. W.; Welsh, W. F.; Orosz, J. A.; Bedding, T. R.; Campante, T. L.; Davies, G. R.; Elsworth, Y.; Handberg, R.; Hekker, S.; Karoff, C.; Kawaler, S. D.; Lund, M. N.; Lundkvist, M.; Metcalfe, T. S.; Miglio, A.; Silva Aguirre, V.; Stello, D.; White, T. R.; Boss, A.; Devore, E.; Gould, A.; Prsa, A.; Agol, E.; Barclay, T.; Coughlin, J.; Brugamyer, E.; Mullally, F.; Quintana, E. V.; Still, M.; Thompson, S. E.; Morrison, D.; Twicken, J. D.; Desert, J. -M.; Carter, J.; Crepp, J. R.; Hebrard, G.; Santerne, A.; Moutou, C.; Sobeck, C.; Hudgins, D.; Haas, M. R.; Robertson, P.; Lillo-Box, J.; Barrado, D. Bibcode: 2014yCat..22100020M Altcode: Here we report measured masses, radii, and densities (or upper limits on those values) for 42 transiting planet candidates contained within 22 bright Kepler Objects of Interest (KOIs) from Batalha et al. (2013, Cat. J/ApJS/204/24). We carried out multiple Doppler-shift measurements of the host stars using the Keck 1 telescope. From the spectroscopy and Doppler measurements, we compute self-consistent measurements of stellar and planet radii, employing either stellar structure models or asteroseismology measurements from the Kepler photometry. We also search for (and report) 7 additional non-transiting planets revealed by the precise radial velocities (RVs), for a total of 49 planets.

We carried out "reconnaissance" high-resolution spectroscopy on ~1000 KOIs with spectral resolution, R~50000, and S/N=20-100 per pixel. The dual goals were searching for false positives and refining the stellar parameters. We obtained one or two such reconnaissance spectra using one of four facilities: the McDonald Observatory 2.7m, the Tillinghast 1.5m on Mt. Hopkins, the Lick Observatory 3m, and the 2.6m Nordic Optical Telescope.

Speckle imaging of each of the selected 22 KOIs was obtained using the two-color DSSI speckle camera at the WIYN 3.5m telescope on Kitt Peak.

All 22 KOIs were observed with the Keck NIRC2-AO system.

(3 data files). Title: Seismic constraints on the radial dependence of the internal rotation profiles of six Kepler subgiants and young red giants Authors: Deheuvels, S.; Doğan, G.; Goupil, M. J.; Appourchaux, T.; Benomar, O.; Bruntt, H.; Campante, T. L.; Casagrande, L.; Ceillier, T.; Davies, G. R.; De Cat, P.; Fu, J. N.; García, R. A.; Lobel, A.; Mosser, B.; Reese, D. R.; Regulo, C.; Schou, J.; Stahn, T.; Thygesen, A. O.; Yang, X. H.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Eggenberger, P.; Gizon, L.; Mathis, S.; Molenda-Żakowicz, J.; Pinsonneault, M. Bibcode: 2014A&A...564A..27D Altcode: 2014arXiv1401.3096D Context. We still do not understand which physical mechanisms are responsible for the transport of angular momentum inside stars. The recent detection of mixed modes that contain the clear signature of rotation in the spectra of Kepler subgiants and red giants gives us the opportunity to make progress on this question.
Aims: Our aim is to probe the radial dependence of the rotation profiles for a sample of Kepler targets. For this purpose, subgiants and early red giants are particularly interesting targets because their rotational splittings are more sensitive to the rotation outside the deeper core than is the case for their more evolved counterparts.
Methods: We first extracted the rotational splittings and frequencies of the modes for six young Kepler red giants. We then performed a seismic modeling of these stars using the evolutionary codes Cesam2k and astec. By using the observed splittings and the rotational kernels of the optimal models, we inverted the internal rotation profiles of the six stars.
Results: We obtain estimates of the core rotation rates for these stars, and upper limits to the rotation in their convective envelope. We show that the rotation contrast between the core and the envelope increases during the subgiant branch. Our results also suggest that the core of subgiants spins up with time, while their envelope spins down. For two of the stars, we show that a discontinuous rotation profile with a deep discontinuity reproduces the observed splittings significantly better than a smooth rotation profile. Interestingly, the depths that are found to be most probable for the discontinuities roughly coincide with the location of the H-burning shell, which separates the layers that contract from those that expand.
Conclusions: We characterized the differential rotation pattern of six young giants with a range of metallicities, and with both radiative and convective cores on the main sequence. This will bring observational constraints to the scenarios of angular momentum transport in stars. Moreover, if the existence of sharp gradients in the rotation profiles of young red giants is confirmed, it is expected to help in distinguishing between the physical processes that could transport angular momentum in the subgiant and red giant branches.

Appendices and Tables 3-9 are available in electronic form at http://www.aanda.org Title: The PLATO 2.0 Mission Authors: Pagano, I.; Rauer, H.; Aerts, C.; Appourchaux, T.; Benz, W.; Brandeker, A.; Christensen-Dalsgaard, J.; Deleuil, M.; Gizon, L.; Goupil, M. -J.; Guedel, M.; Heras, A.; Janot-Pacheco, E.; Mas-Hesse, M.; Piotto, G.; Pollaco, D.; Ragazzoni, R.; Santos, N. C.; Smith, A.; Suarez, J. C.; Szabo, R.; Udry, S. Bibcode: 2014EPSC....9..789P Altcode: PLATO 2.0 is the M class mission selected by ESA for its M3 launch slot in the framework of the Cosmic Vision 2015-2025 program. The main goals of PLATO 2.0 are the detection of terrestrial exoplanets in the habitable zone of solar-type stars and the characterization of their bulk properties needed to determine their habitability. Moreover, PLATO 2.0 will be key in understanding the formation, architecture, and evolution of planetary systems thanks to a thorough inventory of the physical properties of thousands of rocky, icy, and gaseous giant planets. We will illustrate the PLATO 2.0 science goals, how the instrument is conceived to fulfil the science requirements, and how the project is organized to implement the instrument, plan the observations, and exploit the resulting data. Title: Old Puzzle, New Insights: A Lithium-rich Giant Quietly Burning Helium in Its Core Authors: Silva Aguirre, V.; Ruchti, G. R.; Hekker, S.; Cassisi, S.; Christensen-Dalsgaard, J.; Datta, A.; Jendreieck, A.; Jessen-Hansen, J.; Mazumdar, A.; Mosser, B.; Stello, D.; Beck, P. G.; de Ridder, J. Bibcode: 2014ApJ...784L..16S Altcode: 2014arXiv1402.6339S About 1% of giant stars have been shown to have large surface Li abundances, which is unexpected according to standard stellar evolution models. Several scenarios for lithium production have been proposed, but it is still unclear why these Li-rich giants exist. A missing piece in this puzzle is the knowledge of the exact stage of evolution of these stars. Using low- and-high-resolution spectroscopic observations, we have undertaken a survey of lithium-rich giants in the Kepler field. In this Letter, we report the finding of the first confirmed Li-rich core-helium-burning giant, as revealed by asteroseismic analysis. The evolutionary timescales constrained by its mass suggest that Li production most likely took place through non-canonical mixing at the RGB tip, possibly during the helium flash.

Based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofísica de Canarias. Title: Limits on Surface Gravities of Kepler Planet-candidate Host Stars from Non-detection of Solar-like Oscillations Authors: Campante, T. L.; Chaplin, W. J.; Lund, M. N.; Huber, D.; Hekker, S.; García, R. A.; Corsaro, E.; Handberg, R.; Miglio, A.; Arentoft, T.; Basu, S.; Bedding, T. R.; Christensen-Dalsgaard, J.; Davies, G. R.; Elsworth, Y. P.; Gilliland, R. L.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Lundkvist, M.; Metcalfe, T. S.; Silva Aguirre, V.; Stello, D. Bibcode: 2014ApJ...783..123C Altcode: 2014arXiv1401.6324C We present a novel method for estimating lower-limit surface gravities (log g) of Kepler targets whose data do not allow the detection of solar-like oscillations. The method is tested using an ensemble of solar-type stars observed in the context of the Kepler Asteroseismic Science Consortium. We then proceed to estimate lower-limit log g for a cohort of Kepler solar-type planet-candidate host stars with no detected oscillations. Limits on fundamental stellar properties, as provided by this work, are likely to be useful in the characterization of the corresponding candidate planetary systems. Furthermore, an important byproduct of the current work is the confirmation that amplitudes of solar-like oscillations are suppressed in stars with increased levels of surface magnetic activity. Title: Study of KIC 8561221 observed by Kepler: an early red giant showing depressed dipolar modes Authors: García, R. A.; Pérez Hernández, F.; Benomar, O.; Silva Aguirre, V.; Ballot, J.; Davies, G. R.; Doğan, G.; Stello, D.; Christensen-Dalsgaard, J.; Houdek, G.; Lignières, F.; Mathur, S.; Takata, M.; Ceillier, T.; Chaplin, W. J.; Mathis, S.; Mosser, B.; Ouazzani, R. M.; Pinsonneault, M. H.; Reese, D. R.; Régulo, C.; Salabert, D.; Thompson, M. J.; van Saders, J. L.; Neiner, C.; De Ridder, J. Bibcode: 2014A&A...563A..84G Altcode: 2013arXiv1311.6990G Context. The continuous high-precision photometric observations provided by the CoRoT and Kepler space missions have allowed us to understand the structure and dynamics of red giants better using asteroseismic techniques. A small fraction of these stars show dipole modes with unexpectedly low amplitudes. The reduction in amplitude is more pronounced for stars with a higher frequency of maximum power, νmax.
Aims: In this work we want to characterise KIC 8561221 in order to confirm that it is currently the least evolved star among this peculiar subset and to discuss several hypotheses that could help explain the reduction of the dipole mode amplitudes.
Methods: We used Kepler short- and long-cadence data combined with spectroscopic observations to infer the stellar structure and dynamics of KIC 8561221. We then discussed different scenarios that could contribute to reducing the dipole amplitudes, such as a fast-rotating interior or the effect of a magnetic field on the properties of the modes. We also performed a detailed study of the inertia and damping of the modes.
Results: We have been able to characterise 36 oscillations modes, in particular, a few dipole modes above νmax that exhibit nearly normal amplitudes. The frequencies of all the measured modes were used to determine the overall properties and the internal structure of the star. We have inferred a surface rotation period of ~91 days and uncovered a variation in the surface magnetic activity during the last 4 years. The analysis of the convective background did not reveal any difference compared to "normal" red giants. As expected, the internal regions of the star probed by the ℓ = 2 and 3 modes spin 4 to 8 times faster than the surface.
Conclusions: With our grid of standard models we are able to properly fit the observed frequencies. Our model calculation of mode inertia and damping give no explanation for the depressed dipole modes. A fast-rotating core is also ruled out as a possible explanation. Finally, we do not have any observational evidence of a strong deep magnetic field inside the star.

Table 3 and Appendix A are available in electronic form at http://www.aanda.org Title: On the inference of stellar ages and convective-core properties in main-sequence solar-like pulsators Authors: Brandão, I. M.; Cunha, M. S.; Christensen-Dalsgaard, J. Bibcode: 2014MNRAS.438.1751B Altcode: 2013arXiv1311.7600B; 2013MNRAS.tmp.2970B Particular diagnostic tools may isolate the signature left on the oscillation frequencies by the presence of a small convective core. Their frequency derivative is expected to provide information about convective core's properties and stellar age. The main goal of this work is to study the potential of the diagnostic tools with regard to the inference of stellar age and stellar core's properties. For that, we computed diagnostic tools and their frequency derivatives from the oscillation frequencies of main-sequence models with masses between 1.0 and 1.6 M⊙ and with different physics. We considered the dependence of the diagnostic tools on stellar age and on the size of the relative discontinuity in the squared sound speed at the edge of the convectively unstable region. We find that the absolute value of the frequency derivatives of the diagnostic tools increases as the star evolves on the main sequence. The fraction of stellar main-sequence evolution for models with masses >1.2 M⊙ may be estimated from the frequency derivatives of two of the diagnostic tools. For lower mass models, constraints on the convective core's overshoot can potentially be derived based on the analysis of the same derivatives. For at least 35 per cent of our sample of stellar models, the frequency derivative of the diagnostic tools takes its maximum absolute value on the frequency range where observed oscillations may be expected. Title: Accurate Parameters of the Oldest Known Rocky-exoplanet Hosting System: Kepler-10 Revisited Authors: Fogtmann-Schulz, Alexandra; Hinrup, Brian; Van Eylen, Vincent; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans; Silva Aguirre, Víctor; Tingley, Brandon Bibcode: 2014ApJ...781...67F Altcode: 2013arXiv1311.6336F Since the discovery of Kepler-10, the system has received considerable interest because it contains a small, rocky planet which orbits the star in less than a day. The system's parameters, announced by the Kepler team and subsequently used in further research, were based on only five months of data. We have reanalyzed this system using the full span of 29 months of Kepler photometric data, and obtained improved information about its star and the planets. A detailed asteroseismic analysis of the extended time series provides a significant improvement on the stellar parameters: not only can we state that Kepler-10 is the oldest known rocky-planet-harboring system at 10.41 ± 1.36 Gyr, but these parameters combined with improved planetary parameters from new transit fits gives us the radius of Kepler-10b to within just 125 km. A new analysis of the full planetary phase curve leads to new estimates on the planetary temperature and albedo, which remain degenerate in the Kepler band. Our modeling suggests that the flux level during the occultation is slightly lower than at the transit wings, which would imply that the nightside of this planet has a non-negligible temperature. Title: Concluding remarks Authors: Christensen-Dalsgaard, Jørgen; Kawaler, Steven D. Bibcode: 2014IAUS..301..359C Altcode: We cannot presume to summarize all of the science we've discussed in the talks, posters, and informal discussions. Here, we discuss a few of the themes that emerged, concentrating on the theoretical basis that Wojtek Dziembowiski and his colleagues have developed and explored over the past 40+ years. We connect those with observational results - especially those from recent ground-based surveys and space-based missions that have revolutionized the study of stellar variability. Title: Stellar Observations Network Group: The prototype is nearly ready Authors: Grundahl, Frank; Christensen-Dalsgaard, Jørgen; Pallé, Pere L.; Andersen, Mads F.; Frandsen, Søren; Harpsøe, Kennet; Jørgensen, Uffe Gråe; Kjeldsen, Hans; Rasmussen, Per K.; Skottfelt, Jesper; Sørensen, Anton N.; Hage, Andrea Triviño Bibcode: 2014IAUS..301...69G Altcode: The prototype telescope and instruments for the Stellar Observations Network Group (SONG) are nearing completion at the Observatorio del Teide on Tenerife. In this contribution we describe the current status (autumn 2013) of the telescope and its instrumentation. Preliminary performance characteristics are presented for the high-resolution spectrograph based on daytime observations of the Sun and a 4 hour test series obtained for the sub-giant β Aquilae. Title: Detection of l = 4 and l = 5 Modes in 12 Years of Solar VIRGO-SPM Data—Tests on Kepler Observations of 16 Cyg A and B Authors: Lund, Mikkel Nørup; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen; Handberg, Rasmus; Silva Aguirre, Victor Bibcode: 2014ApJ...782....2L Altcode: 2014arXiv1401.7003N We present the detection of l = 4 and l = 5 modes in power spectra of the Sun, constructed from 12 yr full-disk VIRGO-SPM data sets. A method for enhancing the detectability of these modes in asteroseismic targets is presented and applied to Kepler data of the two solar analogues 16 Cyg A and B. For these targets, we see indications of a signal from l = 4 modes, while nothing is yet seen for l = 5 modes. We further simulate the power spectra of these stars and from this we estimate that it should indeed be possible to see such indications of l = 4 modes at the present length of the data sets. In the simulation process, we briefly look into the apparent misfit between observed and calculated mode visibilities. We predict that firm detections of at least l = 4 should be possible in any case at the end of the Kepler mission. For l = 5, we do not predict any firm detections from Kepler data. Title: Measurement of Acoustic Glitches in Solar-type Stars from Oscillation Frequencies Observed by Kepler Authors: Mazumdar, A.; Monteiro, M. J. P. F. G.; Ballot, J.; Antia, H. M.; Basu, S.; Houdek, G.; Mathur, S.; Cunha, M. S.; Silva Aguirre, V.; García, R. A.; Salabert, D.; Verner, G. A.; Christensen-Dalsgaard, J.; Metcalfe, T. S.; Sanderfer, D. T.; Seader, S. E.; Smith, J. C.; Chaplin, W. J. Bibcode: 2014ApJ...782...18M Altcode: 2013arXiv1312.4907M For the very best and brightest asteroseismic solar-type targets observed by Kepler, the frequency precision is sufficient to determine the acoustic depths of the surface convective layer and the helium ionization zone. Such sharp features inside the acoustic cavity of the star, which we call acoustic glitches, create small oscillatory deviations from the uniform spacing of frequencies in a sequence of oscillation modes with the same spherical harmonic degree. We use these oscillatory signals to determine the acoustic locations of such features in 19 solar-type stars observed by the Kepler mission. Four independent groups of researchers utilized the oscillation frequencies themselves, the second differences of the frequencies and the ratio of the small and large separation to locate the base of the convection zone and the second helium ionization zone. Despite the significantly different methods of analysis, good agreement was found between the results of these four groups, barring a few cases. These results also agree reasonably well with the locations of these layers in representative models of the stars. These results firmly establish the presence of the oscillatory signals in the asteroseismic data and the viability of several techniques to determine the location of acoustic glitches inside stars. Title: Asteroseismology of red giants Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2014aste.book..194C Altcode: 2011arXiv1106.5946C Red-giant stars are emerging as one of the most interesting areas of space asteroseismology. Even a relatively basic analysis leads to the determination of the global parameters of the stars, such as their mass and radius, and the very extensive space-based data now available for a large number of stars allow detailed investigation of the deep interiors of red giants, including distinguishing between stars that do and do not have helium fusion in the core, on the basis of periods of gravity waves partially trapped in the core. Here I review the theoretical background for these new developments and provide a simple explanation for the effect on the period spacing of central helium fusion. Title: The evolution of the internal rotation of solar-type stars Authors: Di Mauro, Maria Pia; Ventura, Rita; Cardini, Daniela; Christensen-Dalsgaard, Jørgen; Dziembowski, Wojciech A.; Paternò, Lucio Bibcode: 2014IAUS..301..345D Altcode: We discuss the potential of asteroseismic inversion to study the internal dynamics of solar-type stars and to reconstruct the evolution of the internal rotation from the main sequence to the red-giant phase. In particular, we consider the use of gravity and mixed modes and the application of different inversion methods. Title: What Asteroseismology can do for Exoplanets: Kepler-410A b is a Small Neptune around a Bright Star, in an Eccentric Orbit Consistent with Low Obliquity Authors: Van Eylen, V.; Lund, M. N.; Silva Aguirre, V.; Arentoft, T.; Kjeldsen, H.; Albrecht, S.; Chaplin, W. J.; Isaacson, H.; Pedersen, M. G.; Jessen-Hansen, J.; Tingley, B.; Christensen-Dalsgaard, J.; Aerts, C.; Campante, T. L.; Bryson, S. T. Bibcode: 2014ApJ...782...14V Altcode: 2013arXiv1312.4938V We confirm the Kepler planet candidate Kepler-410A b (KOI-42b) as a Neptune-sized exoplanet on a 17.8 day, eccentric orbit around the bright (K p = 9.4) star Kepler-410A (KOI-42A). This is the third brightest confirmed planet host star in the Kepler field and one of the brightest hosts of all currently known transiting exoplanets. Kepler-410 consists of a blend between the fast rotating planet host star (Kepler-410A) and a fainter star (Kepler-410B), which has complicated the confirmation of the planetary candidate. Employing asteroseismology, using constraints from the transit light curve, adaptive optics and speckle images, and Spitzer transit observations, we demonstrate that the candidate can only be an exoplanet orbiting Kepler-410A. We determine via asteroseismology the following stellar and planetary parameters with high precision; M sstarf = 1.214 ± 0.033 M ⊙, R sstarf = 1.352 ± 0.010 R ⊙, age =2.76 ± 0.54 Gyr, planetary radius (2.838 ± 0.054 R ⊕), and orbital eccentricity (0.17^{+0.07}_{-0.06}). In addition, rotational splitting of the pulsation modes allows for a measurement of Kepler-410A's inclination and rotation rate. Our measurement of an inclination of 82.5^{+7.5}_{-2.5} [°] indicates a low obliquity in this system. Transit timing variations indicate the presence of at least one additional (non-transiting) planet (Kepler-410A c) in the system. Title: Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets Authors: Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W.; Rowe, Jason F.; Jenkins, Jon M.; Bryson, Stephen T.; Latham, David W.; Howell, Steve B.; Gautier, Thomas N., III; Batalha, Natalie M.; Rogers, Leslie; Ciardi, David; Fischer, Debra A.; Gilliland, Ronald L.; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen; Huber, Daniel; Chaplin, William J.; Basu, Sarbani; Buchhave, Lars A.; Quinn, Samuel N.; Borucki, William J.; Koch, David G.; Hunter, Roger; Caldwell, Douglas A.; Van Cleve, Jeffrey; Kolbl, Rea; Weiss, Lauren M.; Petigura, Erik; Seager, Sara; Morton, Timothy; Johnson, John Asher; Ballard, Sarah; Burke, Chris; Cochran, William D.; Endl, Michael; MacQueen, Phillip; Everett, Mark E.; Lissauer, Jack J.; Ford, Eric B.; Torres, Guillermo; Fressin, Francois; Brown, Timothy M.; Steffen, Jason H.; Charbonneau, David; Basri, Gibor S.; Sasselov, Dimitar D.; Winn, Joshua; Sanchis-Ojeda, Roberto; Christiansen, Jessie; Adams, Elisabeth; Henze, Christopher; Dupree, Andrea; Fabrycky, Daniel C.; Fortney, Jonathan J.; Tarter, Jill; Holman, Matthew J.; Tenenbaum, Peter; Shporer, Avi; Lucas, Philip W.; Welsh, William F.; Orosz, Jerome A.; Bedding, T. R.; Campante, T. L.; Davies, G. R.; Elsworth, Y.; Handberg, R.; Hekker, S.; Karoff, C.; Kawaler, S. D.; Lund, M. N.; Lundkvist, M.; Metcalfe, T. S.; Miglio, A.; Silva Aguirre, V.; Stello, D.; White, T. R.; Boss, Alan; Devore, Edna; Gould, Alan; Prsa, Andrej; Agol, Eric; Barclay, Thomas; Coughlin, Jeff; Brugamyer, Erik; Mullally, Fergal; Quintana, Elisa V.; Still, Martin; Thompson, Susan E.; Morrison, David; Twicken, Joseph D.; Désert, Jean-Michel; Carter, Josh; Crepp, Justin R.; Hébrard, Guillaume; Santerne, Alexandre; Moutou, Claire; Sobeck, Charlie; Hudgins, Douglas; Haas, Michael R.; Robertson, Paul; Lillo-Box, Jorge; Barrado, David Bibcode: 2014ApJS..210...20M Altcode: 2014arXiv1401.4195M We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify six planets with densities above 5 g cm-3, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than ~2 R ⊕. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O).

Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Title: VizieR Online Data Catalog: Asteroseismic study of solar-type stars (Chaplin+, 2014) Authors: Chaplin, W. J.; Basu, S.; Huber, D.; Serenelli, A.; Casagrande, L.; Silva Aguirre, V.; Ball, W. H.; Creevey, O. L.; Gizon, L.; Handberg, R.; Karoff, C.; Lutz, R.; Marques, J. P.; Miglio, A.; Stello, D.; Suran, M. D.; Pricopi, D.; Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Molenda-Zakowicz, J.; Appourchaux, T.; Christensen-Dalsgaard, J.; Elsworth, Y.; Garcia, R. A.; Houdek, G.; Kjeldsen, H.; Bonanno, A.; Campante, T. L.; Corsaro, E.; Gaulme, P.; Hekker, S.; Mathur, S.; Mosser, B.; Regulo, C.; Salabert, D. Bibcode: 2014yCat..22100001C Altcode: During the first 10 months of science operations more than 2000 solar-type stars were selected by the Kepler Asteroseismic Science Consortium (KASC) to be observed as part of an asteroseismic survey of the Sun-like population in the Kepler field of view. Solar-like oscillations were detected by Kepler in more than 500 stars (Chaplin et al. 2011Sci...332..213C), and from these data robust global or average asteroseismic parameters were determined for all targets in the sample. These asteroseismic parameters allow us to estimate fundamental properties of the stars. In this paper we present stellar properties - namely masses, radii, surface gravities, mean densities and ages - of this asteroseismic sample of main-sequence and subgiant stars.

(5 data files). Title: Asteroseismic Fundamental Properties of Solar-type Stars Observed by the NASA Kepler Mission Authors: Chaplin, W. J.; Basu, S.; Huber, D.; Serenelli, A.; Casagrande, L.; Silva Aguirre, V.; Ball, W. H.; Creevey, O. L.; Gizon, L.; Handberg, R.; Karoff, C.; Lutz, R.; Marques, J. P.; Miglio, A.; Stello, D.; Suran, M. D.; Pricopi, D.; Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Molenda-Żakowicz, J.; Appourchaux, T.; Christensen-Dalsgaard, J.; Elsworth, Y.; García, R. A.; Houdek, G.; Kjeldsen, H.; Bonanno, A.; Campante, T. L.; Corsaro, E.; Gaulme, P.; Hekker, S.; Mathur, S.; Mosser, B.; Régulo, C.; Salabert, D. Bibcode: 2014ApJS..210....1C Altcode: 2013arXiv1310.4001C We use asteroseismic data obtained by the NASA Kepler mission to estimate the fundamental properties of more than 500 main-sequence and sub-giant stars. Data obtained during the first 10 months of Kepler science operations were used for this work, when these solar-type targets were observed for one month each in survey mode. Stellar properties have been estimated using two global asteroseismic parameters and complementary photometric and spectroscopic data. Homogeneous sets of effective temperatures, T eff, were available for the entire ensemble from complementary photometry; spectroscopic estimates of T eff and [Fe/H] were available from a homogeneous analysis of ground-based data on a subset of 87 stars. We adopt a grid-based analysis, coupling six pipeline codes to 11 stellar evolutionary grids. Through use of these different grid-pipeline combinations we allow implicitly for the impact on the results of stellar model dependencies from commonly used grids, and differences in adopted pipeline methodologies. By using just two global parameters as the seismic inputs we are able to perform a homogenous analysis of all solar-type stars in the asteroseismic cohort, including many targets for which it would not be possible to provide robust estimates of individual oscillation frequencies (due to a combination of low signal-to-noise ratio and short dataset lengths). The median final quoted uncertainties from consolidation of the grid-based analyses are for the full ensemble (spectroscopic subset) approximately 10.8% (5.4%) in mass, 4.4% (2.2%) in radius, 0.017 dex (0.010 dex) in log g, and 4.3% (2.8%) in mean density. Around 36% (57%) of the stars have final age uncertainties smaller than 1 Gyr. These ages will be useful for ensemble studies, but should be treated carefully on a star-by-star basis. Future analyses using individual oscillation frequencies will offer significant improvements on up to 150 stars, in particular for estimates of the ages, where having the individual frequency data is most important. Title: Benefits of multiple sites for asteroseismic detections Authors: Arentoft, T.; Tingley, B.; Christensen-Dalsgaard, J.; Kjeldsen, H.; White, T. R.; Grundahl, F. Bibcode: 2014MNRAS.437.1318A Altcode: 2013arXiv1310.2845A; 2013MNRAS.tmp.2654A While Kepler has pushed the science of asteroseismology to limits unimaginable a decade ago, the need for asteroseismic studies of individual objects remains. This is primarily due to the limitations of single-colour intensity variations, which are much less sensitive to certain asteroseismic signals. The best way to obtain the necessary data is via very high resolution ground-based spectrography. Such observations measure the perceived radial-velocity shifts that arise due to stellar oscillations, which exhibit a much better signal-to-noise ratio than those for intensity observations. Stellar Observations Network Group (SONG), a proposed network of 1 m telescopes with spectrographs that can reach R = 110 000, was designed with this need in mind. With one node under commissioning in Tenerife and another under construction in China, an analysis of the scientific benefits of constructing additional nodes for the network is warranted. By convolving models of asteroseismic observables (mean densities, small separations) with the anticipated window functions for different node configurations, we explore the impact of the number of nodes in the SONG network on the anticipated results, across the areas of the Hertzsprung-Russell diagram where solar-like oscillations are found. We find that although time series from two SONG nodes, or in some cases even one node, will allow us to detect oscillations; the full SONG network, providing full temporal coverage, is needed for obtaining the science goals of SONG, including analysis of modes of spherical harmonic degree l = 3. Title: Inferring properties of small convective cores in main-sequence solar-like pulsators Authors: Brandão, I. M.; Cunha, M. S.; Christensen-Dalsgaard, J. Bibcode: 2013EAS....63..115B Altcode: 2014arXiv1401.1832B This work concerns the study of the properties of convective cores in main-sequence models of solar-like pulsators and what information they may hold about stellar ages. We verified that the maximum absolute frequency derivative of particular combinations of frequencies, which we name "the slopes", provides information on the relative size of the discontinuity in the sound-speed profile at the border of the convectively mixed region. Since the latter is related to the evolutionary state of stars, we show that for models with masses above 1.3M⊙, it may be possible to estimate the fraction of stellar main-sequence evolution from the slopes. Moreover, for models with masses below 1.2M⊙ we verified that it may be possible to use the slopes to discriminate against models with small amounts of core overshoot. Title: The Torsional Oscillation and the Timing of the Solar Cycle: Is it Maximum Yet? Authors: Howe, R.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R.; Larson, T. P.; Schou, J.; Thompson, M. J. Bibcode: 2013ASPC..478..303H Altcode: After the late start to Cycle 24 there are some indications that activity may have peaked as early as late 2011 and that the polar-field reversal has already occurred in the North. We use helioseismic measurements of the migrating zonal flow pattern known as the torsional oscillation to estimate the length of the solar cycle, and find that it has held steady at about 12.3 years since late 2009, which would point to solar maximum in 2013 as expected. Title: The new era of asteroseismology Authors: Christensen-Dalsgaard, J. Bibcode: 2013EAS....63...91C Altcode: New observations of stellar pulsations, particularly from the CoRoT and Kepler space missions, have opened completely new possibilities for asteroseismic investigations for stars in large parts of the Hertzsprung-Russell diagram. Particularly dramatic has been the development of asteroseismology of stars showing solar-like oscillations, where hundreds of stars near the main sequence and tens of thousands of red giants can now be investigated. Although the analysis of the data have yielded extensive information about the global properties of the stars we are still only at the beginning of learning how to use the data for more profound studies of stellar interiors. Here I give a brief overview of the observations and discuss the potential contributions to the understanding of stellar physics. Title: Stellar Spin-Orbit Misalignment in a Multiplanet System Authors: Huber, Daniel; Carter, Joshua A.; Barbieri, Mauro; Miglio, Andrea; Deck, Katherine M.; Fabrycky, Daniel C.; Montet, Benjamin T.; Buchhave, Lars A.; Chaplin, William J.; Hekker, Saskia; Montalbán, Josefina; Sanchis-Ojeda, Roberto; Basu, Sarbani; Bedding, Timothy R.; Campante, Tiago L.; Christensen-Dalsgaard, Jørgen; Elsworth, Yvonne P.; Stello, Dennis; Arentoft, Torben; Ford, Eric B.; Gilliland, Ronald L.; Handberg, Rasmus; Howard, Andrew W.; Isaacson, Howard; Johnson, John Asher; Karoff, Christoffer; Kawaler, Steven D.; Kjeldsen, Hans; Latham, David W.; Lund, Mikkel N.; Lundkvist, Mia; Marcy, Geoffrey W.; Metcalfe, Travis S.; Silva Aguirre, Victor; Winn, Joshua N. Bibcode: 2013Sci...342..331H Altcode: 2013arXiv1310.4503H Stars hosting hot Jupiters are often observed to have high obliquities, whereas stars with multiple coplanar planets have been seen to have low obliquities. This has been interpreted as evidence that hot-Jupiter formation is linked to dynamical disruption, as opposed to planet migration through a protoplanetary disk. We used asteroseismology to measure a large obliquity for Kepler-56, a red giant star hosting two transiting coplanar planets. These observations show that spin-orbit misalignments are not confined to hot-Jupiter systems. Misalignments in a broader class of systems had been predicted as a consequence of torques from wide-orbiting companions, and indeed radial velocity measurements revealed a third companion in a wide orbit in the Kepler-56 system. Title: Kepler White Paper: Asteroseismology of Solar-Like Oscillators in a 2-Wheel Mission Authors: Chaplin, W. J; Kjeldsen, H.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Basu, S.; De Ridder, J.; Huber, D.; Arentoft, T.; Schou, J.; Garcia, R. A.; Metcalfe, T. S.; Brogaard, K.; Campante, T. L.; Elsworth, Y.; Miglio, A.; Appourchaux, T.; Bedding, T. R.; Hekker, S.; Houdek, G.; Karoff, C.; Molenda-Zakowicz, J.; Monteiro, M. J. P. F. G.; Silva Aguirre, V.; Stello, D.; Ball, W.; Beck, P. G.; Birch, A. C.; Buzasi, D. L.; Casagrande, L.; Cellier, T.; Corsaro, E.; Creevey, O. L.; Davies, G. R.; Deheuvels, S.; Dogan, G.; Gizon, L.; Grundahl, F.; Guzik, J.; Handberg, R.; Jimenez, A.; Kallinger, T.; Lund, M. N.; Lundkvist, M.; Mathis, S.; Mathur, S.; Mazumdar, A.; Mosser, B.; Neiner, C.; Nielsen, M. B.; Palle, P. L.; Pinsonneault, M. H.; Salabert, D.; Serenelli, A. M.; Shunker, H.; White, T. R. Bibcode: 2013arXiv1309.0702C Altcode: We comment on the potential for continuing asteroseismology of solar-type and red-giant stars in a 2-wheel Kepler Mission. Our main conclusion is that by targeting stars in the ecliptic it should be possible to perform high-quality asteroseismology, as long as favorable scenarios for 2-wheel pointing performance are met. Targeting the ecliptic would potentially facilitate unique science that was not possible in the nominal Mission, notably from the study of clusters that are significantly brighter than those in the Kepler field. Our conclusions are based on predictions of 2-wheel observations made by a space photometry simulator, with information provided by the Kepler Project used as input to describe the degraded pointing scenarios. We find that elevated levels of frequency-dependent noise, consistent with the above scenarios, would have a significant negative impact on our ability to continue asteroseismic studies of solar-like oscillators in the Kepler field. However, the situation may be much more optimistic for observations in the ecliptic, provided that pointing resets of the spacecraft during regular desaturations of the two functioning reaction wheels are accurate at the < 1 arcsec level. This would make it possible to apply a post-hoc analysis that would recover most of the lost photometric precision. Without this post-hoc correction---and the accurate re-pointing it requires---the performance would probably be as poor as in the Kepler-field case. Critical to our conclusions for both fields is the assumed level of pointing noise (in the short-term jitter and the longer-term drift). We suggest that further tests will be needed to clarify our results once more detail and data on the expected pointing performance becomes available, and we offer our assistance in this work. Title: Seismic study of solar convection and overshooting: results of nonlocal convection Authors: Zhang, Chun-Guang; Deng, Li-Cai; Xiong, Da-Run; Christensen-Dalsgaard, Jørgen Bibcode: 2013RAA....13.1127Z Altcode: 2013arXiv1305.2085Z Local mixing-length theory is incapable of describing nonlocal phenomena in stellar convection, such as overshooting. Therefore standard solar models constructed with local mixing-length theory significantly deviate from the Sun at the boundariesof the convection zone, where convection becomes less efficient and nonlocal effects are important. The differences between observed and computed frequencies mainly come from the region near the surface, while the localized difference in sound speed is just below the convective envelope. We compute a solar envelope model using Xiong's nonlocal convection theory, and carry out helioseismic analysis. The nonlocal model has a smooth transition at the base of the convection zone, as revealed by helioseismology. It reproduces solar frequencies more accurately, and reduces the localized difference in sound speed between the Sun and standard solar models. Title: Sounding stellar cycles with Kepler - II. Ground-based observations Authors: Karoff, C.; Metcalfe, T. S.; Chaplin, W. J.; Frandsen, S.; Grundahl, F.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Nielsen, M. B.; Frimann, S.; Thygesen, A. O.; Arentoft, T.; Amby, T. M.; Sousa, S. G.; Buzasi, D. L. Bibcode: 2013MNRAS.433.3227K Altcode: 2013arXiv1306.3306K; 2013MNRAS.tmp.1612K We have monitored 20 Sun-like stars in the Kepler field-of-view for excess flux with the Fibre-fed Echelle Spectrograph on the Nordic Optical Telescope since the launch of Kepler spacecraft in 2009. These 20 stars were selected based on their asteroseismic properties to sample the parameter space (effective temperature, surface gravity, activity level, etc.) around the Sun. Though the ultimate goal is to improve stellar dynamo models, we focus the present paper on the combination of space-based and ground-based observations that can be used to test the age-rotation-activity relations. In this paper we describe the considerations behind the selection of these 20 Sun-like stars and present an initial asteroseismic analysis, which includes stellar age estimates. We also describe the observations from the Nordic Optical Telescope and present mean values of measured excess fluxes. These measurements are combined with estimates of the rotation periods obtained from a simple analysis of the modulation in photometric observations from Kepler caused by starspots, and asteroseismic determinations of stellar ages, to test relations between age, rotation and activity. Title: Astrophysics: Twinkling stars Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2013Natur.500..405C Altcode: A correlation between stellar brightness variations and the gravitational acceleration at a star's surface has been observed that allows this acceleration to be measured with a precision of better than 25%. See Letter p.427 Title: Observations of the radial velocity of the Sun as measured with the novel SONG spectrograph: results from a 1-week campaign Authors: Pallé, P. L.; Grundahl, F.; Triviño Hage, A.; Christensen-Dalsgaard, J.; Frandsen, S.; García, R. A.; Uytterhoeven, K.; Andersen, M. F.; Rasmussen, P. K.; Sørensen, A. N.; Kjeldsen, H.; Spano, P.; Nilsson, H.; Hartman, H.; Jørgensen, U. G.; Skottfelt, J.; Harpsøe, K.; Andersen, M. I. Bibcode: 2013JPhCS.440a2051P Altcode: Deployment of the prototype node of the SONG project took place in April 2012 at Observatorio del Teide (Canary Islands). Its key instrument (echelle spectrograph) was installed and operational a few weeks later while its 1 m feeding telescope suffered a considerable delay to meet the required specifications. Using a fibre-feed, solar light could be fed to the spectrograph and we carried out a 1-week observing campaign in June 2012 to evaluate its performance for measuring precision radial velocities. In this work we present the first results of this campaign by comparing the sensitivity of the SONG spectrograph with other helioseismology reference instruments (Mark-I and GOLF) when simultaneous data are considered. Title: Stellar Ages and Convective Cores in Field Main-sequence Stars: First Asteroseismic Application to Two Kepler Targets Authors: Silva Aguirre, V.; Basu, S.; Brandão, I. M.; Christensen-Dalsgaard, J.; Deheuvels, S.; Doğan, G.; Metcalfe, T. S.; Serenelli, A. M.; Ballot, J.; Chaplin, W. J.; Cunha, M. S.; Weiss, A.; Appourchaux, T.; Casagrande, L.; Cassisi, S.; Creevey, O. L.; García, R. A.; Lebreton, Y.; Noels, A.; Sousa, S. G.; Stello, D.; White, T. R.; Kawaler, S. D.; Kjeldsen, H. Bibcode: 2013ApJ...769..141S Altcode: 2013arXiv1304.2772S Using asteroseismic data and stellar evolution models we obtain the first detection of a convective core in a Kepler field main-sequence star, putting a stringent constraint on the total size of the mixed zone and showing that extra mixing beyond the formal convective boundary exists. In a slightly less massive target the presence of a convective core cannot be conclusively discarded, and thus its remaining main-sequence lifetime is uncertain. Our results reveal that best-fit models found solely by matching individual frequencies of oscillations corrected for surface effects do not always properly reproduce frequency combinations. Moreover, slightly different criteria to define what the best-fit model is can lead to solutions with similar global properties but very different interior structures. We argue that the use of frequency ratios is a more reliable way to obtain accurate stellar parameters, and show that our analysis in field main-sequence stars can yield an overall precision of 1.5%, 4%, and 10% in radius, mass, and age, respectively. We compare our results with those obtained from global oscillation properties, and discuss the possible sources of uncertainties in asteroseismic stellar modeling where further studies are still needed. Title: Kepler-62: A Five-Planet System with Planets of 1.4 and 1.6 Earth Radii in the Habitable Zone Authors: Borucki, William J.; Agol, Eric; Fressin, Francois; Kaltenegger, Lisa; Rowe, Jason; Isaacson, Howard; Fischer, Debra; Batalha, Natalie; Lissauer, Jack J.; Marcy, Geoffrey W.; Fabrycky, Daniel; Désert, Jean-Michel; Bryson, Stephen T.; Barclay, Thomas; Bastien, Fabienne; Boss, Alan; Brugamyer, Erik; Buchhave, Lars A.; Burke, Chris; Caldwell, Douglas A.; Carter, Josh; Charbonneau, David; Crepp, Justin R.; Christensen-Dalsgaard, Jørgen; Christiansen, Jessie L.; Ciardi, David; Cochran, William D.; DeVore, Edna; Doyle, Laurance; Dupree, Andrea K.; Endl, Michael; Everett, Mark E.; Ford, Eric B.; Fortney, Jonathan; Gautier, Thomas N.; Geary, John C.; Gould, Alan; Haas, Michael; Henze, Christopher; Howard, Andrew W.; Howell, Steve B.; Huber, Daniel; Jenkins, Jon M.; Kjeldsen, Hans; Kolbl, Rea; Kolodziejczak, Jeffery; Latham, David W.; Lee, Brian L.; Lopez, Eric; Mullally, Fergal; Orosz, Jerome A.; Prsa, Andrej; Quintana, Elisa V.; Sanchis-Ojeda, Roberto; Sasselov, Dimitar; Seader, Shawn; Shporer, Avi; Steffen, Jason H.; Still, Martin; Tenenbaum, Peter; Thompson, Susan E.; Torres, Guillermo; Twicken, Joseph D.; Welsh, William F.; Winn, Joshua N. Bibcode: 2013Sci...340..587B Altcode: 2013arXiv1304.7387B We present the detection of five planets—Kepler-62b, c, d, e, and f—of size 1.31, 0.54, 1.95, 1.61 and 1.41 Earth radii (R⊕), orbiting a K2V star at periods of 5.7, 12.4, 18.2, 122.4, and 267.3 days, respectively. The outermost planets, Kepler-62e and -62f, are super-Earth-size (1.25 R⊕ < planet radius ≤ 2.0 R⊕) planets in the habitable zone of their host star, respectively receiving 1.2 ± 0.2 times and 0.41 ± 0.05 times the solar flux at Earth’s orbit. Theoretical models of Kepler-62e and -62f for a stellar age of ~7 billion years suggest that both planets could be solid, either with a rocky composition or composed of mostly solid water in their bulk. Title: Erratum: A sub-Mercury-sized exoplanet Authors: Barclay, Thomas; Rowe, Jason F.; Lissauer, Jack J.; Huber, Daniel; Fressin, François; Howell, Steve B.; Bryson, Stephen T.; Chaplin, William J.; Désert, Jean-Michel; Lopez, Eric D.; Marcy, Geoffrey W.; Mullally, Fergal; Ragozzine, Darin; Torres, Guillermo; Adams, Elisabeth R.; Agol, Eric; Barrado, David; Basu, Sarbani; Bedding, Timothy R.; Buchhave, Lars A.; Charbonneau, David; Christiansen, Jessie L.; Christensen-Dalsgaard, Jørgen; Ciardi, David; Cochran, William D.; Dupree, Andrea K.; Elsworth, Yvonne; Everett, Mark; Fischer, Debra A.; Ford, Eric B.; Fortney, Jonathan J.; Geary, John C.; Haas, Michael R.; Handberg, Rasmus; Hekker, Saskia; Henze, Christopher E.; Horch, Elliott; Howard, Andrew W.; Hunter, Roger C.; Isaacson, Howard; Jenkins, Jon M.; Karoff, Christoffer; Kawaler, Steven D.; Kjeldsen, Hans; Klaus, Todd C.; Latham, David W.; Li, Jie; Lillo-Box, Jorge; Lund, Mikkel N.; Lundkvist, Mia; Metcalfe, Travis S.; Miglio, Andrea; Morris, Robert L.; Quintana, Elisa V.; Stello, Dennis; Smith, Jeffrey C.; Still, Martin; Thompson, Susan E. Bibcode: 2013Natur.496..252B Altcode: No abstract at ADS Title: Fundamental Properties of Kepler Planet-candidate Host Stars using Asteroseismology Authors: Huber, Daniel; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Gilliland, Ronald L.; Kjeldsen, Hans; Buchhave, Lars A.; Fischer, Debra A.; Lissauer, Jack J.; Rowe, Jason F.; Sanchis-Ojeda, Roberto; Basu, Sarbani; Handberg, Rasmus; Hekker, Saskia; Howard, Andrew W.; Isaacson, Howard; Karoff, Christoffer; Latham, David W.; Lund, Mikkel N.; Lundkvist, Mia; Marcy, Geoffrey W.; Miglio, Andrea; Silva Aguirre, Victor; Stello, Dennis; Arentoft, Torben; Barclay, Thomas; Bedding, Timothy R.; Burke, Christopher J.; Christiansen, Jessie L.; Elsworth, Yvonne P.; Haas, Michael R.; Kawaler, Steven D.; Metcalfe, Travis S.; Mullally, Fergal; Thompson, Susan E. Bibcode: 2013ApJ...767..127H Altcode: 2013arXiv1302.2624H We have used asteroseismology to determine fundamental properties for 66 Kepler planet-candidate host stars, with typical uncertainties of 3% and 7% in radius and mass, respectively. The results include new asteroseismic solutions for four host stars with confirmed planets (Kepler-4, Kepler-14, Kepler-23 and Kepler-25) and increase the total number of Kepler host stars with asteroseismic solutions to 77. A comparison with stellar properties in the planet-candidate catalog by Batalha et al. shows that radii for subgiants and giants obtained from spectroscopic follow-up are systematically too low by up to a factor of 1.5, while the properties for unevolved stars are in good agreement. We furthermore apply asteroseismology to confirm that a large majority of cool main-sequence hosts are indeed dwarfs and not misclassified giants. Using the revised stellar properties, we recalculate the radii for 107 planet candidates in our sample, and comment on candidates for which the radii change from a previously giant-planet/brown-dwarf/stellar regime to a sub-Jupiter size or vice versa. A comparison of stellar densities from asteroseismology with densities derived from transit models in Batalha et al. assuming circular orbits shows significant disagreement for more than half of the sample due to systematics in the modeled impact parameters or due to planet candidates that may be in eccentric orbits. Finally, we investigate tentative correlations between host-star masses and planet-candidate radii, orbital periods, and multiplicity, but caution that these results may be influenced by the small sample size and detection biases. Title: Properties of Oscillation Modes in Subgiant Stars Observed by Kepler Authors: Benomar, O.; Bedding, T. R.; Mosser, B.; Stello, D.; Belkacem, K.; Garcia, R. A.; White, T. R.; Kuehn, C. A.; Deheuvels, S.; Christensen-Dalsgaard, J. Bibcode: 2013ApJ...767..158B Altcode: 2013arXiv1302.4143B Mixed modes seen in evolved stars carry information on their deeper layers that can place stringent constraints on their physics and on their global properties (mass, age, etc.). In this study, we present a method to identify and measure all oscillatory mode characteristics (frequency, height, width). Analyzing four subgiant stars, we present the first measure of the effect of the degree of mixture on the l = 1 mixed mode characteristics. We also show that some stars have measurable l = 2 mixed modes and discuss the interest of their measure to constrain the deeper layers of stars. Title: Asteroseismic Determination of Obliquities of the Exoplanet Systems Kepler-50 and Kepler-65 Authors: Chaplin, W. J.; Sanchis-Ojeda, R.; Campante, T. L.; Handberg, R.; Stello, D.; Winn, J. N.; Basu, S.; Christensen-Dalsgaard, J.; Davies, G. R.; Metcalfe, T. S.; Buchhave, L. A.; Fischer, D. A.; Bedding, T. R.; Cochran, W. D.; Elsworth, Y.; Gilliland, R. L.; Hekker, S.; Huber, D.; Isaacson, H.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Latham, D. W.; Lund, M. N.; Lundkvist, M.; Marcy, G. W.; Miglio, A.; Barclay, T.; Lissauer, J. J. Bibcode: 2013ApJ...766..101C Altcode: 2013arXiv1302.3728C Results on the obliquity of exoplanet host stars—the angle between the stellar spin axis and the planetary orbital axis—provide important diagnostic information for theories describing planetary formation. Here we present the first application of asteroseismology to the problem of stellar obliquity determination in systems with transiting planets and Sun-like host stars. We consider two systems observed by the NASA Kepler mission which have multiple transiting small (super-Earth sized) planets: the previously reported Kepler-50 and a new system, Kepler-65, whose planets we validate in this paper. Both stars show rich spectra of solar-like oscillations. From the asteroseismic analysis we find that each host has its rotation axis nearly perpendicular to the line of sight with the sines of the angles constrained at the 1σ level to lie above 0.97 and 0.91, respectively. We use statistical arguments to show that coplanar orbits are favored in both systems, and that the orientations of the planetary orbits and the stellar rotation axis are correlated. Title: The High-latitude Branch of the Solar Torsional Oscillation in the Rising Phase of Cycle 24 Authors: Howe, R.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R.; Larson, T. P.; Rempel, M.; Schou, J.; Thompson, M. J. Bibcode: 2013ApJ...767L..20H Altcode: We use global heliseismic data from the Global Oscillation Network Group, the Michelson Doppler Imager on board the Solar and Heliospheric Observatory, and the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, to examine the behavior, during the rising phase of Solar Cycle 24, of the migrating zonal flow pattern known as the torsional oscillation. Although the high-latitude part of the pattern appears to be absent in the new cycle when the flows are derived by subtracting a mean across a full solar cycle, it can be seen if we subtract the mean over a shorter period in the rising phase of each cycle, and these two mean rotation profiles differ significantly at high latitudes. This indicates that the underlying high-latitude rotation has changed; we speculate that this is in response to weaker polar fields, as suggested by a recent model. Title: Kepler-68: Three Planets, One with a Density between that of Earth and Ice Giants Authors: Gilliland, Ronald L.; Marcy, Geoffrey W.; Rowe, Jason F.; Rogers, Leslie; Torres, Guillermo; Fressin, Francois; Lopez, Eric D.; Buchhave, Lars A.; Christensen-Dalsgaard, Jørgen; Désert, Jean-Michel; Henze, Christopher E.; Isaacson, Howard; Jenkins, Jon M.; Lissauer, Jack J.; Chaplin, William J.; Basu, Sarbani; Metcalfe, Travis S.; Elsworth, Yvonne; Handberg, Rasmus; Hekker, Saskia; Huber, Daniel; Karoff, Christoffer; Kjeldsen, Hans; Lund, Mikkel N.; Lundkvist, Mia; Miglio, Andrea; Charbonneau, David; Ford, Eric B.; Fortney, Jonathan J.; Haas, Michael R.; Howard, Andrew W.; Howell, Steve B.; Ragozzine, Darin; Thompson, Susan E. Bibcode: 2013ApJ...766...40G Altcode: 2013arXiv1302.2596G NASA's Kepler Mission has revealed two transiting planets orbiting Kepler-68. Follow-up Doppler measurements have established the mass of the innermost planet and revealed a third Jovian-mass planet orbiting beyond the two transiting planets. Kepler-68b, in a 5.4 day orbit, has M_P=8.3^{+2.2}_{-2.4} M ⊕, R_P=2.31^{+0.06}_{-0.09} R ⊕, and \rho _P=3.32^{+0.86}_{-0.98} g cm-3, giving Kepler-68b a density intermediate between that of the ice giants and Earth. Kepler-68c is Earth-sized, with a radius R_P=0.953^{+0.037}_{-0.042} R ⊕ and transits on a 9.6 day orbit; validation of Kepler-68c posed unique challenges. Kepler-68d has an orbital period of 580 ± 15 days and a minimum mass of M Psin i = 0.947 ± 0.035MJ . Power spectra of the Kepler photometry at one minute cadence exhibit a rich and strong set of asteroseismic pulsation modes enabling detailed analysis of the stellar interior. Spectroscopy of the star coupled with asteroseismic modeling of the multiple pulsation modes yield precise measurements of stellar properties, notably T eff = 5793 ± 74 K, M sstarf = 1.079 ± 0.051 M ⊙, R sstarf = 1.243 ± 0.019 R ⊙, and ρsstarf = 0.7903 ± 0.0054 g cm-3, all measured with fractional uncertainties of only a few percent. Models of Kepler-68b suggest that it is likely composed of rock and water, or has a H and He envelope to yield its density ~3 g cm-3. Title: VizieR Online Data Catalog: Kepler planetary candidates. III. (Batalha+, 2013) Authors: Batalha, N. M.; Rowe, J. F.; Bryson, S. T.; Barclay, T.; Burke, C. J.; Caldwell, D. A.; Christiansen, J. L.; Mullally, F.; Thompson, S. E.; Brown, T. M.; Dupree, A. K.; Fabrycky, D. C.; Ford, E. B.; Fortney, J. J.; Gilliland, R. L.; Isaacson, H.; Latham, D. W.; Marcy, G. W.; Quinn, S. N.; Ragozzine, D.; Shporer, A.; Borucki, W. J.; Ciardi, D. R.; Gautier, T. N., III; Haas, M. R.; Jenkins, J. M.; Koch, D. G.; Lissauer, J. J.; Rapin, W.; Basri, G. S.; Boss, A. P.; Buchhave, L. A.; Carter, J. A.; Charbonneau, D.; Christensen-Dalsgaard, J.; Clarke, B. D.; Cochran, W. D.; Demory, B. -O.; Desert, J. -M.; DeVore, E.; Doyle, L. R.; Esquerdo, G. A.; Everett, M.; Fressin, F.; Geary, J. C.; Girouard, F. R.; Gould, A.; Hall, J. R.; Holman, M. J.; Howard, A. W.; Howell, S. B.; Ibrahim, K. A.; Kinemuchi, K.; Kjeldsen, H.; Klaus, T. C.; Li, J.; Lucas, P. W.; Meibom, S.; Morris, R. L.; Prsa, A.; Quintana, E.; Sanderfer, D. T.; Sasselov, D.; Seader, S. E.; Smith, J. C.; Steffen, J. H.; Still, M.; Stumpe, M. C.; Tarter, J. C.; Tenenbaum, P.; Torres, G.; Twicken, J. D.; Uddin, K.; van Cleve, J.; Walkowicz, L.; Welsh, W. F. Bibcode: 2013yCat..22040024B Altcode: The data employed for transit identification were acquired between 2009 May 13 00:15 UTC and 2010 Sep 22 19:03 UTC (Q1-Q6). Over 190000 stars were observed at some time during this period.

(6 data files). Title: Internal rotation of red giants by asteroseismology Authors: Di Mauro, M. P.; Cardini, D.; Ventura, R.; Stello, D.; Beck, P. G.; Davies, G.; Elsworth, Y.; García, R. A.; Hekker, S.; Mosser, B.; Christensen-Dalsgaard, J.; Bloemen, S.; Catanzaro, G.; De Smedt, K.; Tkachenko, A. Bibcode: 2013EPJWC..4303012D Altcode: 2012arXiv1212.4758D We present an asteroseismic approach to study the dynamics of the stellar interior in red giant stars by asteroseismic inversion of the splittings induced by the stellar rotation on the oscillation frequencies. We show preliminary results obtained for the red giant KIC4448777 observed by the space mission Kepler. Title: VizieR Online Data Catalog: Abundances of 93 solar-type Kepler targets (Bruntt+, 2012) Authors: Bruntt, H.; Basu, S.; Smalley, B.; Chaplin, W. J.; Verner, G. A.; Bedding, T. R.; Catala, C.; Gazzano, J. -C.; Molenda-Zakowicz, J.; Thygesen, A. O.; Uytterhoeven, K.; Hekker, S.; Huber, D.; Karoff, C.; Mathur, S.; Mosser, B.; Appourchaux, T.; Campante, T. L.; Elsworth, Y.; Garcia, R. A.; Handberg, R.; Metcalfe, T. S.; Quirion, P. -O.; Regulo, C.; Roxburgh, I. W.; Stello, D.; Christensen-Dalsgaard, J.; Kawaler, S. D.; Kjeldsen, H.; Morris, R. L.; Quintana, E. V.; Sanderfer, D. T. Bibcode: 2013yCat..74230122B Altcode: The spectra were obtained with the ESPaDOnS spectrograph at the 3.6-m Canada-France-Hawaii Telescope (CFHT) in USA and with the NARVAL spectrograph mounted on the 2-m Bernard Lyot Telescope at the Pic du Midi Observatory in France. In both the facilities, the observations were carried out as service observations from May to September in 2010.

(3 data files). Title: A sub-Mercury-sized exoplanet Authors: Barclay, Thomas; Rowe, Jason F.; Lissauer, Jack J.; Huber, Daniel; Fressin, François; Howell, Steve B.; Bryson, Stephen T.; Chaplin, William J.; Désert, Jean-Michel; Lopez, Eric D.; Marcy, Geoffrey W.; Mullally, Fergal; Ragozzine, Darin; Torres, Guillermo; Adams, Elisabeth R.; Agol, Eric; Barrado, David; Basu, Sarbani; Bedding, Timothy R.; Buchhave, Lars A.; Charbonneau, David; Christiansen, Jessie L.; Christensen-Dalsgaard, Jørgen; Ciardi, David; Cochran, William D.; Dupree, Andrea K.; Elsworth, Yvonne; Everett, Mark; Fischer, Debra A.; Ford, Eric B.; Fortney, Jonathan J.; Geary, John C.; Haas, Michael R.; Handberg, Rasmus; Hekker, Saskia; Henze, Christopher E.; Horch, Elliott; Howard, Andrew W.; Hunter, Roger C.; Isaacson, Howard; Jenkins, Jon M.; Karoff, Christoffer; Kawaler, Steven D.; Kjeldsen, Hans; Klaus, Todd C.; Latham, David W.; Li, Jie; Lillo-Box, Jorge; Lund, Mikkel N.; Lundkvist, Mia; Metcalfe, Travis S.; Miglio, Andrea; Morris, Robert L.; Quintana, Elisa V.; Stello, Dennis; Smith, Jeffrey C.; Still, Martin; Thompson, Susan E. Bibcode: 2013Natur.494..452B Altcode: 2013arXiv1305.5587B Since the discovery of the first exoplanets, it has been known that other planetary systems can look quite unlike our own. Until fairly recently, we have been able to probe only the upper range of the planet size distribution, and, since last year, to detect planets that are the size of Earth or somewhat smaller. Hitherto, no planets have been found that are smaller than those we see in the Solar System. Here we report a planet significantly smaller than Mercury. This tiny planet is the innermost of three that orbit the Sun-like host star, which we have designated Kepler-37. Owing to its extremely small size, similar to that of the Moon, and highly irradiated surface, the planet, Kepler-37b, is probably rocky with no atmosphere or water, similar to Mercury. Title: Planetary Candidates Observed by Kepler. III. Analysis of the First 16 Months of Data Authors: Batalha, Natalie M.; Rowe, Jason F.; Bryson, Stephen T.; Barclay, Thomas; Burke, Christopher J.; Caldwell, Douglas A.; Christiansen, Jessie L.; Mullally, Fergal; Thompson, Susan E.; Brown, Timothy M.; Dupree, Andrea K.; Fabrycky, Daniel C.; Ford, Eric B.; Fortney, Jonathan J.; Gilliland, Ronald L.; Isaacson, Howard; Latham, David W.; Marcy, Geoffrey W.; Quinn, Samuel N.; Ragozzine, Darin; Shporer, Avi; Borucki, William J.; Ciardi, David R.; Gautier, Thomas N., III; Haas, Michael R.; Jenkins, Jon M.; Koch, David G.; Lissauer, Jack J.; Rapin, William; Basri, Gibor S.; Boss, Alan P.; Buchhave, Lars A.; Carter, Joshua A.; Charbonneau, David; Christensen-Dalsgaard, Joergen; Clarke, Bruce D.; Cochran, William D.; Demory, Brice-Olivier; Desert, Jean-Michel; Devore, Edna; Doyle, Laurance R.; Esquerdo, Gilbert A.; Everett, Mark; Fressin, Francois; Geary, John C.; Girouard, Forrest R.; Gould, Alan; Hall, Jennifer R.; Holman, Matthew J.; Howard, Andrew W.; Howell, Steve B.; Ibrahim, Khadeejah A.; Kinemuchi, Karen; Kjeldsen, Hans; Klaus, Todd C.; Li, Jie; Lucas, Philip W.; Meibom, Søren; Morris, Robert L.; Prša, Andrej; Quintana, Elisa; Sanderfer, Dwight T.; Sasselov, Dimitar; Seader, Shawn E.; Smith, Jeffrey C.; Steffen, Jason H.; Still, Martin; Stumpe, Martin C.; Tarter, Jill C.; Tenenbaum, Peter; Torres, Guillermo; Twicken, Joseph D.; Uddin, Kamal; Van Cleve, Jeffrey; Walkowicz, Lucianne; Welsh, William F. Bibcode: 2013ApJS..204...24B Altcode: 2012arXiv1202.5852B New transiting planet candidates are identified in 16 months (2009 May-2010 September) of data from the Kepler spacecraft. Nearly 5000 periodic transit-like signals are vetted against astrophysical and instrumental false positives yielding 1108 viable new planet candidates, bringing the total count up to over 2300. Improved vetting metrics are employed, contributing to higher catalog reliability. Most notable is the noise-weighted robust averaging of multi-quarter photo-center offsets derived from difference image analysis that identifies likely background eclipsing binaries. Twenty-two months of photometry are used for the purpose of characterizing each of the candidates. Ephemerides (transit epoch, T 0, and orbital period, P) are tabulated as well as the products of light curve modeling: reduced radius (R P/R sstarf), reduced semimajor axis (d/R sstarf), and impact parameter (b). The largest fractional increases are seen for the smallest planet candidates (201% for candidates smaller than 2 R ⊕ compared to 53% for candidates larger than 2 R ⊕) and those at longer orbital periods (124% for candidates outside of 50 day orbits versus 86% for candidates inside of 50 day orbits). The gains are larger than expected from increasing the observing window from 13 months (Quarters 1-5) to 16 months (Quarters 1-6) even in regions of parameter space where one would have expected the previous catalogs to be complete. Analyses of planet frequencies based on previous catalogs will be affected by such incompleteness. The fraction of all planet candidate host stars with multiple candidates has grown from 17% to 20%, and the paucity of short-period giant planets in multiple systems is still evident. The progression toward smaller planets at longer orbital periods with each new catalog release suggests that Earth-size planets in the habitable zone are forthcoming if, indeed, such planets are abundant. Title: Stellar Pulsations Authors: Suárez, J. C.; Garrido, R.; Balona, L. A.; Christensen-Dalsgaard, J. Bibcode: 2013ASSP...31.....S Altcode: No abstract at ADS Title: List of Poster Contributions Authors: Suárez, J. C.; Garrido, R.; Balona, L. A.; Christensen-Dalsgaard, J. Bibcode: 2013ASSP...31..291S Altcode: No abstract at ADS Title: Characterizing Two Solar-type Kepler Subgiants with Asteroseismology: KIC 10920273 and KIC 11395018 Authors: Doǧan, G.; Metcalfe, T. S.; Deheuvels, S.; Di Mauro, M. P.; Eggenberger, P.; Creevey, O. L.; Monteiro, M. J. P. F. G.; Pinsonneault, M.; Frasca, A.; Karoff, C.; Mathur, S.; Sousa, S. G.; Brandão, I. M.; Campante, T. L.; Handberg, R.; Thygesen, A. O.; Biazzo, K.; Bruntt, H.; Niemczura, E.; Bedding, T. R.; Chaplin, W. J.; Christensen-Dalsgaard, J.; García, R. A.; Molenda-Żakowicz, J.; Stello, D.; Van Saders, J. L.; Kjeldsen, H.; Still, M.; Thompson, S. E.; Van Cleve, J. Bibcode: 2013ApJ...763...49D Altcode: 2012arXiv1211.6650D Determining fundamental properties of stars through stellar modeling has improved substantially due to recent advances in asteroseismology. Thanks to the unprecedented data quality obtained by space missions, particularly CoRoT and Kepler, invaluable information is extracted from the high-precision stellar oscillation frequencies, which provide very strong constraints on possible stellar models for a given set of classical observations. In this work, we have characterized two relatively faint stars, KIC 10920273 and KIC 11395018, using oscillation data from Kepler photometry and atmospheric constraints from ground-based spectroscopy. Both stars have very similar atmospheric properties; however, using the individual frequencies extracted from the Kepler data, we have determined quite distinct global properties, with increased precision compared to that of earlier results. We found that both stars have left the main sequence and characterized them as follows: KIC 10920273 is a one-solar-mass star (M = 1.00 ± 0.04 M ⊙), but much older than our Sun (t = 7.12 ± 0.47 Gyr), while KIC 11395018 is significantly more massive than the Sun (M = 1.27 ± 0.04 M ⊙) with an age close to that of the Sun (t = 4.57 ± 0.23 Gyr). We confirm that the high lithium abundance reported for these stars should not be considered to represent young ages, as we precisely determined them to be evolved subgiants. We discuss the use of surface lithium abundance, rotation, and activity relations as potential age diagnostics. Title: Asteroseismology with NASA's Kepler Mission Authors: Huber, Daniel; Chaplin, W. J.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Working Groups of Kepler Asteroseismic Science Consortium (KASC) Bibcode: 2013AAS...22130101H Altcode: The measurement of stellar oscillations - also called asteroseismology - is among the most powerful observational tools to study the structure and evolution of stars. The high precision photometry collected by the Kepler space telescope has revolutionized asteroseismology over the past few years by boosting the number of stars with detected oscillations by nearly two orders of magnitude over ground-based efforts, and delivering data with unprecedented signal-to-noise. In this talk I will highlight some of the recent breakthrough discoveries by the Kepler Mission, focusing in particular on the internal composition and rotation of red giants and the study of fundamental properties in large ensembles of stars throughout the Hertzsprung-Russell diagram. I will furthermore present results for an ensemble of ~80 Kepler Objects of Interest for which accurate host star and planet candidate properties have been determined using asteroseismology. Title: Red giant oscillations: Stellar models and mode frequency calculations Authors: Jendreieck, A.; Weiss, A.; Silva Aguirre, V.; Christensen-Dalsgaard, J.; Handberg, R.; Ruchti, G.; Jiang, C.; Thygesen, A. Bibcode: 2012AN....333..939J Altcode: 2012arXiv1210.6495J We present preliminary results on modelling KIC 7693833, the so far most metal-poor red giant star observed by Kepler. From time series spanning several months, global oscillation parameters and individual frequencies were obtained and compared to theoretical calculations. Evolution models are calculated taking into account spectroscopic and asteroseismic constraints. The oscillation frequencies of the models were computed and compared to the Kepler data. In the range of mass computed, there is no preferred model, giving an uncertainty of about 30 K in Teff, 0.02 dex in log g, 0.7R⊙ in radius, and of about 2.5 Gyrs in age. Title: Properties of extrasolar planets and their host stars: A case study of HAT-P-7 Authors: Van Eylen, V.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Aerts, C. Bibcode: 2012AN....333.1088V Altcode: 2013arXiv1301.1472V Data from the Kepler satellite (Q0-Q11) are used to study HAT-P-7. The satellite's data are extremely valuable for asteroseismic studies of stars and for observing planetary transits; in this work we do both. An asteroseismic study of the host star improves the accuracy of the stellar parameters derived by Christensen-Dalsgaard et al. (2010), who followed largely the same procedure but based the analysis on only one month of Kepler data. The stellar information is combined with transit observations, phase variations and occultations to derive planetary parameters. In particular, we confirm the presence of ellipsoidal variations as discovered by Welsh et al. (2010), but revise their magnitude, and we revise the occultation depth (Borucki et al. 2009) which leads to different planetary temperature estimates. All other stellar and planetary parameters are now more accurately determined. Title: A Bayesian approach to the modelling of α Cen A Authors: Bazot, M.; Bourguignon, S.; Christensen-Dalsgaard, J. Bibcode: 2012MNRAS.427.1847B Altcode: 2012arXiv1209.0222B Determining the physical characteristics of a star is an inverse problem consisting of estimating the parameters of models for the stellar structure and evolution, and knowing certain observable quantities. We use a Bayesian approach to solve this problem for α Cen A, which allows us to incorporate prior information on the parameters to be estimated, in order to better constrain the problem. Our strategy is based on the use of a Markov chain Monte Carlo (MCMC) algorithm to estimate the posterior probability densities of the stellar parameters: mass, age, initial chemical composition, etc. We use the stellar evolutionary code ASTEC to model the star. To constrain this model both seismic and non-seismic observations were considered. Several different strategies were tested to fit these values, using either two free parameters or five free parameters in ASTEC. We are thus able to show evidence that MCMC methods become efficient with respect to more classical grid-based strategies when the number of parameters increases. The results of our MCMC algorithm allow us to derive estimates for the stellar parameters and robust uncertainties thanks to the statistical analysis of the posterior probability densities. We are also able to compute odds for the presence of a convective core in α Cen A. When using core-sensitive seismic observational constraints, these can rise above ∼40 per cent. The comparison of results to previous studies also indicates that these seismic constraints are of critical importance for our knowledge of the structure of this star. Title: SONG-OT: The prototype SONG node at Tenerife Authors: Uytterhoeven, K.; Pallé, P. L.; Grundahl, F.; Frandsen, S.; Christensen-Dalsgaard, J.; Triviño Hage, A.; SONG Team Bibcode: 2012AN....333.1103U Altcode: The prototype SONG node, SONG-OT, is currently being installed and tested at Observatory del Teide on Tenerife. SONG will be a global network of 1-m robotic telescopes, equipped with a high-resolution échelle spectrograph and dual-colour lucky imaging cameras. The network will be devoted to the seismic study of bright stars and characterisation of low-mass planets. We present the current status of the network in general and the SONG-OT node in particular. Title: Stellar model fits and inversions Authors: Christensen-Dalsgaard, J. Bibcode: 2012AN....333..914C Altcode: 2012arXiv1211.2697C The recent asteroseismic data from the CoRoT and Kepler missions have provided an entirely new basis for investigating stellar properties. This has led to a rapid development in techniques for analysing such data, although it is probably fair to say that we are still far from having the tools required for the full use of the potential of the observations. Here I provide a brief overview of some of the issues related to the interpretation of asteroseismic data. Title: Acoustic glitches in solar-type stars from Kepler Authors: Mazumdar, A.; Monteiro, M. J. P. F. G.; Ballot, J.; Antia, H. M.; Basu, S.; Houdek, G.; Mathur, S.; Cunha, M. S.; Silva Aguirre, V.; García, R. A.; Salabert, D.; Verner, G. A.; Christensen-Dalsgaard, J.; Metcalfe, T. S.; Chaplin, W. J. Bibcode: 2012AN....333.1040M Altcode: We report the measurement of the acoustic locations of layers of sharp variation in sound speed in the interiors of 19 solar-type stars observed by the Kepler mission. The oscillatory signal in the frequencies arising due to the acoustic glitches at the base of the convection zone and the second helium ionisation zone was utilised to determine their location by four independent methods. Despite the significantly different methods of analysis, remarkable agreement was found between the results of these four methods. Further, the extracted locations of these layers were found to be consistent with representative models of the stars. Title: Fundamental Properties of Stars Using Asteroseismology from Kepler and CoRoT and Interferometry from the CHARA Array Authors: Huber, D.; Ireland, M. J.; Bedding, T. R.; Brandão, I. M.; Piau, L.; Maestro, V.; White, T. R.; Bruntt, H.; Casagrande, L.; Molenda-Żakowicz, J.; Silva Aguirre, V.; Sousa, S. G.; Barclay, T.; Burke, C. J.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Cunha, M. S.; De Ridder, J.; Farrington, C. D.; Frasca, A.; García, R. A.; Gilliland, R. L.; Goldfinger, P. J.; Hekker, S.; Kawaler, S. D.; Kjeldsen, H.; McAlister, H. A.; Metcalfe, T. S.; Miglio, A.; Monteiro, M. J. P. F. G.; Pinsonneault, M. H.; Schaefer, G. H.; Stello, D.; Stumpe, M. C.; Sturmann, J.; Sturmann, L.; ten Brummelaar, T. A.; Thompson, M. J.; Turner, N.; Uytterhoeven, K. Bibcode: 2012ApJ...760...32H Altcode: 2012arXiv1210.0012H We present results of a long-baseline interferometry campaign using the PAVO beam combiner at the CHARA Array to measure the angular sizes of five main-sequence stars, one subgiant and four red giant stars for which solar-like oscillations have been detected by either Kepler or CoRoT. By combining interferometric angular diameters, Hipparcos parallaxes, asteroseismic densities, bolometric fluxes, and high-resolution spectroscopy, we derive a full set of near-model-independent fundamental properties for the sample. We first use these properties to test asteroseismic scaling relations for the frequency of maximum power (νmax) and the large frequency separation (Δν). We find excellent agreement within the observational uncertainties, and empirically show that simple estimates of asteroseismic radii for main-sequence stars are accurate to <~ 4%. We furthermore find good agreement of our measured effective temperatures with spectroscopic and photometric estimates with mean deviations for stars between T eff = 4600-6200 K of -22 ± 32 K (with a scatter of 97 K) and -58 ± 31 K (with a scatter of 93 K), respectively. Finally, we present a first comparison with evolutionary models, and find differences between observed and theoretical properties for the metal-rich main-sequence star HD 173701. We conclude that the constraints presented in this study will have strong potential for testing stellar model physics, in particular when combined with detailed modeling of individual oscillation frequencies. Title: Sound-speed Inversion of the Sun Using a Nonlocal Statistical Convection Theory Authors: Zhang, Chunguang; Deng, Licai; Xiong, Darun; Christensen-Dalsgaard, Jørgen Bibcode: 2012ApJ...759L..14Z Altcode: 2012arXiv1210.4286Z Helioseismic inversions reveal a major discrepancy in sound speed between the Sun and the standard solar model just below the base of the solar convection zone. We demonstrate that this discrepancy is caused by the inherent shortcomings of the local mixing-length theory adopted in the standard solar model. Using a self-consistent nonlocal convection theory, we construct an envelope model of the Sun for sound-speed inversion. Our solar model has a very smooth transition from the convective envelope to the radiative interior, and the convective energy flux changes sign crossing the boundaries of the convection zone. It shows evident improvement over the standard solar model, with a significant reduction in the discrepancy in sound speed between the Sun and local convection models. Title: Asteroseismology of the Open Clusters NGC 6791, NGC 6811, and NGC 6819 from 19 Months of Kepler Photometry Authors: Corsaro, Enrico; Stello, Dennis; Huber, Daniel; Bedding, Timothy R.; Bonanno, Alfio; Brogaard, Karsten; Kallinger, Thomas; Benomar, Othman; White, Timothy R.; Mosser, Benoit; Basu, Sarbani; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Elsworth, Yvonne P.; García, Rafael A.; Hekker, Saskia; Kjeldsen, Hans; Mathur, Savita; Meibom, Søren; Hall, Jennifer R.; Ibrahim, Khadeejah A.; Klaus, Todd C. Bibcode: 2012ApJ...757..190C Altcode: 2012arXiv1205.4023C We studied solar-like oscillations in 115 red giants in the three open clusters, NGC 6791, NGC 6811, and NGC 6819, based on photometric data covering more than 19 months with NASA's Kepler space telescope. We present the asteroseismic diagrams of the asymptotic parameters δν02, δν01, and epsilon, which show clear correlation with fundamental stellar parameters such as mass and radius. When the stellar populations from the clusters are compared, we see evidence for a difference in mass of the red giant branch stars and possibly a difference in structure of the red clump stars, from our measurements of the small separations δν02 and δν01. Ensemble échelle diagrams and upper limits to the linewidths of l = 0 modes as a function of Δν of the clusters NGC 6791 and NGC 6819 are also shown, together with the correlation between the l = 0 ridge width and the T eff of the stars. Lastly, we distinguish between red giant branch and red clump stars through the measurement of the period spacing of mixed dipole modes in 53 stars among all the three clusters to verify the stellar classification from the color-magnitude diagram. These seismic results also allow us to identify a number of special cases, including evolved blue stragglers and binaries, as well as stars in late He-core burning phases, which can be potentially interesting targets for detailed theoretical modeling. Title: Kepler Asteroseismology of Red-giant Stars Authors: Christensen-Dalsgaard, J. Bibcode: 2012ASPC..462..503C Altcode: 2011arXiv1110.5012C The Kepler mission, launched in March 2009, has revolutionized asteroseismology, providing detailed observations of thousands of stars. This has allowed in-depth analyses of stars ranging from compact hot subdwarfs to red giants, and including the detection of solar-like oscillations in hundreds of stars on or near the main sequence. Here I mainly consider solar-like oscillations in red giants, where Kepler observations are yielding results of a perhaps unexpected richness. In addition to giving a brief overview of the observational and numerical results for these stars, I present a simple analysis which captures some of the properties of the observed frequencies. Title: The First Evidence for Multiple Pulsation Axes: A New roAp Star in the Kepler Field, KIC 10195926 Authors: Kurtz, D. W.; Cunha, M. S.; Saio, H.; Bigot, L.; Balona, L. A.; Elkin, V. G.; Shibahashi, H.; Brandão, I. M.; Uytterhoeven, K. : Frandsen, S.; Frimann, S.; Hatzes, A.; Lueftinger, T.; Gruberbauer, M.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Kawaler, S. D. Bibcode: 2012ASPC..462..125K Altcode: This conference talk introduced the characteristics of the rapidly oscillating Ap stars, then discussed a new rapidly oscillating Ap star discovered and published by Working Group 5 of the Kepler Asteroseismic Science Consortium, KIC 10195926. This star shows two pulsation modes with periods that are amongst the longest known for roAp stars at 17.1 min and 18.1 min, indicating that the star is near the terminal-age main-sequence. The principal pulsation mode is an oblique dipole mode that shows a rotationally split frequency septuplet that provides information on the geometry of the mode. The secondary mode also appears to be a dipole mode with a rotationally split triplet, but within the improved oblique pulsator model these two modes cannot have the same axis of pulsation. This is the first time for any pulsating star that evidence has been found for separate pulsation axes for different modes. Title: Verifying Asteroseismically Determined Parameters of Kepler Stars Using Hipparcos Parallaxes: Self-consistent Stellar Properties and Distances Authors: Silva Aguirre, V.; Casagrande, L.; Basu, S.; Campante, T. L.; Chaplin, W. J.; Huber, D.; Miglio, A.; Serenelli, A. M.; Ballot, J.; Bedding, T. R.; Christensen-Dalsgaard, J.; Creevey, O. L.; Elsworth, Y.; García, R. A.; Gilliland, R. L.; Hekker, S.; Kjeldsen, H.; Mathur, S.; Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Mosser, B.; Pinsonneault, M. H.; Stello, D.; Weiss, A.; Tenenbaum, P.; Twicken, J. D.; Uddin, K. Bibcode: 2012ApJ...757...99S Altcode: 2012arXiv1208.6294S Accurately determining the properties of stars is of prime importance for characterizing stellar populations in our Galaxy. The field of asteroseismology has been thought to be particularly successful in such an endeavor for stars in different evolutionary stages. However, to fully exploit its potential, robust methods for estimating stellar parameters are required and independent verification of the results is mandatory. With this purpose, we present a new technique to obtain stellar properties by coupling asteroseismic analysis with the InfraRed Flux Method. By using two global seismic observables and multi-band photometry, the technique allows us to obtain masses, radii, effective temperatures, bolometric fluxes, and hence distances for field stars in a self-consistent manner. We apply our method to 22 solar-like oscillators in the Kepler short-cadence sample, that have accurate Hipparcos parallaxes. Our distance determinations agree to better than 5%, while measurements of spectroscopic effective temperatures and interferometric radii also validate our results. We briefly discuss the potential of our technique for stellar population analysis and models of Galactic Chemical Evolution. Title: Fast Rotating Solar-like Stars Using Asteroseismic Datasets Authors: García, R. A.; Ceillier, T.; Campante, T. L.; Davies, G. R.; Mathur, S.; Suárez, J. C.; Ballot, J.; Benomar, O.; Bonanno, A.; Brun, A. S.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Deheuvels, S.; Elsworth, Y.; Handberg, R.; Hekker, S.; Jiménez, A.; Karoff, C.; Kjeldsen, H.; Mathis, S.; Mosser, B.; Pallé, P. L.; Pinsonneault, M.; Régulo, C.; Salabert, D.; Silva Aguirre, V.; Stello, D.; Thompson, M. J.; Verner, G.; PE11 Team of Kepler WG#1 Bibcode: 2012ASPC..462..133G Altcode: 2011arXiv1109.6488G The NASA Kepler mission is providing an unprecedented set of asteroseismic data. In particular, short-cadence light-curves (∼ 60 s samplings), allow us to study solar-like stars covering a wide range of masses, spectral types and evolutionary stages. Oscillations have been observed in around 600 out of 2000 stars observed for one month during the survey phase of the Kepler mission. The measured light curves can present features related to the surface magnetic activity (starspots) and, thus we are able to obtain a good estimate of the surface (differential) rotation. In this work we establish the basis of such research and we show a potential method to find stars with fast surface rotation. Title: Seismic Analysis of Four Solar-like Stars Observed during More Than Eight Months by Kepler Authors: Mathur, S.; Campante, T. L.; Handberg, R.; García, R. A.; Appourchaux, T.; Bedding, T. R.; Mosser, B.; Chaplin, W. J.; Ballot, J.; Benomar, O.; Bonanno, A.; Corsaro, E.; Gaulme, P.; Hekker, S.; Régulo, C.; Salabert, D.; Verner, G.; White, T. R.; Brandão, I. M.; Creevey, O. L.; Dogan, G.; Bazot, M.; Cunha, M. S.; Elsworth, Y.; Huber, D.; Hale, S. J.; Houdek, G.; Karoff, C.; Lundkvist, M.; Metcalfe, T. S.; Molenda-Zakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Stello, D.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Clarke, B. D.; Girouard, F. R.; Hall, J. R.; Quintana, E. V.; Sanderfer, D. T.; Seader, S. E. Bibcode: 2012ASPC..462..180M Altcode: 2011arXiv1110.0135M Having started science operations in May 2009, the Kepler photometer has been able to provide exquisite data for solar-like stars. Five out of the 42 stars observed continuously during the survey phase show evidence of oscillations, even though they are rather faint (magnitudes from 10.5 to 12). In this paper, we present an overview of the results of the seismic analysis of 4 of these stars observed during more than eight months. Title: Detailed Study of the Internal Structure of a Red-giant Star Observed with Kepler Authors: Di Mauro, M. P.; Ventura, R.; Cardini, D.; Catanzaro, G.; Barban, C.; Bedding, T. R.; Christensen-Dalsgaard, J.; De Ridder, J.; Hekker, S.; Huber, D.; Kallinger, T.; Kinemuchi, K.; Kjeldsen, H.; Miglio, A.; Montalbán, J.; Mosser, B.; Mullally, F.; Stello, D.; Still, M.; Uytterhoeven, K. Bibcode: 2012ASPC..462..146D Altcode: We study the internal structure and evolutionary state of KIC 4351319, a red-giant star observed with the Kepler satellite. The use of 25 individual oscillation frequencies, together with the accurate atmospheric data provided by ground-based spectroscopic observations, allowed us to estimate the main parameters of this star with a level of precision without precedents for a red giant. In addition, the excellent quality of the observations enabled us to define the location of the base of the convective envelope and to learn about the internal rotation, the helium abundance, the surface effects and extra mixing effects such as diffusion and overshooting. Title: Seismic Evidence for a Rapidly Rotating Core in a Lower-giant-branch Star Observed with Kepler Authors: Deheuvels, S.; García, R. A.; Chaplin, W. J.; Basu, S.; Antia, H. M.; Appourchaux, T.; Benomar, O.; Davies, G. R.; Elsworth, Y.; Gizon, L.; Goupil, M. J.; Reese, D. R.; Regulo, C.; Schou, J.; Stahn, T.; Casagrande, L.; Christensen-Dalsgaard, J.; Fischer, D.; Hekker, S.; Kjeldsen, H.; Mathur, S.; Mosser, B.; Pinsonneault, M.; Valenti, J.; Christiansen, J. L.; Kinemuchi, K.; Mullally, F. Bibcode: 2012ApJ...756...19D Altcode: 2012arXiv1206.3312D Rotation is expected to have an important influence on the structure and the evolution of stars. However, the mechanisms of angular momentum transport in stars remain theoretically uncertain and very complex to take into account in stellar models. To achieve a better understanding of these processes, we desperately need observational constraints on the internal rotation of stars, which until very recently was restricted to the Sun. In this paper, we report the detection of mixed modes—i.e., modes that behave both as g modes in the core and as p modes in the envelope—in the spectrum of the early red giant KIC 7341231, which was observed during one year with the Kepler spacecraft. By performing an analysis of the oscillation spectrum of the star, we show that its non-radial modes are clearly split by stellar rotation and we are able to determine precisely the rotational splittings of 18 modes. We then find a stellar model that reproduces very well the observed atmospheric and seismic properties of the star. We use this model to perform inversions of the internal rotation profile of the star, which enables us to show that the core of the star is rotating at least five times faster than the envelope. This will shed new light on the processes of transport of angular momentum in stars. In particular, this result can be used to place constraints on the angular momentum coupling between the core and the envelope of early red giants, which could help us discriminate between the theories that have been proposed over the last few decades. Title: Estimating the p-mode frequencies of the solar twin 18 Scorpii Authors: Bazot, M.; Campante, T. L.; Chaplin, W. J.; Carfantan, H.; Bedding, T. R.; Dumusque, X.; Broomhall, A. -M.; Petit, P.; Théado, S.; Van Grootel, V.; Arentoft, T.; Castro, M.; Christensen-Dalsgaard, J.; do Nascimento, J. -D., Jr.; Dintrans, B.; Kjeldsen, H.; Monteiro, M. J. P. F. G.; Santos, N. C.; Sousa, S.; Vauclair, S. Bibcode: 2012A&A...544A.106B Altcode: 2012arXiv1209.0218B Solar twins have been a focus of attention for more than a decade, because their structure is extremely close to that of the Sun. Today, thanks to high-precision spectrometers, it is possible to use asteroseismology to probe their interiors. Our goal is to use time series obtained from the HARPS spectrometer to extract the oscillation frequencies of 18 Sco, the brightest solar twin. We used the tools of spectral analysis to estimate these quantities. We estimate 52 frequencies using an MCMC algorithm. After examination of their probability densities and comparison with results from direct MAP optimization, we obtain a minimal set of 21 reliable modes. The identification of each pulsation mode is straightforwardly accomplished by comparing to the well-established solar pulsation modes. We also derived some basic seismic indicators using these values. These results offer a good basis to start a detailed seismic analysis of 18 Sco using stellar models.

Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (run ID: 183.D-0729(A)).Results of the MCMC analysis are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/544/A106 Title: Calibrating Convective Properties of Solar-like Stars in the Kepler Field of View Authors: Bonaca, Ana; Tanner, Joel D.; Basu, Sarbani; Chaplin, William J.; Metcalfe, Travis S.; Monteiro, Mário J. P. F. G.; Ballot, Jérôme; Bedding, Timothy R.; Bonanno, Alfio; Broomhall, Anne-Marie; Bruntt, Hans; Campante, Tiago L.; Christensen-Dalsgaard, Jørgen; Corsaro, Enrico; Elsworth, Yvonne; García, Rafael A.; Hekker, Saskia; Karoff, Christoffer; Kjeldsen, Hans; Mathur, Savita; Régulo, Clara; Roxburgh, Ian; Stello, Dennis; Trampedach, Regner; Barclay, Thomas; Burke, Christopher J.; Caldwell, Douglas A. Bibcode: 2012ApJ...755L..12B Altcode: 2012arXiv1207.2765B Stellar models generally use simple parameterizations to treat convection. The most widely used parameterization is the so-called mixing-length theory where the convective eddy sizes are described using a single number, α, the mixing-length parameter. This is a free parameter, and the general practice is to calibrate α using the known properties of the Sun and apply that to all stars. Using data from NASA's Kepler mission we show that using the solar-calibrated α is not always appropriate, and that in many cases it would lead to estimates of initial helium abundances that are lower than the primordial helium abundance. Kepler data allow us to calibrate α for many other stars and we show that for the sample of stars we have studied, the mixing-length parameter is generally lower than the solar value. We studied the correlation between α and stellar properties, and we find that α increases with metallicity. We therefore conclude that results obtained by fitting stellar models or by using population-synthesis models constructed with solar values of α are likely to have large systematic errors. Our results also confirm theoretical expectations that the mixing-length parameter should vary with stellar properties. Title: Planet Occurrence within 0.25 AU of Solar-type Stars from Kepler Authors: Howard, Andrew W.; Marcy, Geoffrey W.; Bryson, Stephen T.; Jenkins, Jon M.; Rowe, Jason F.; Batalha, Natalie M.; Borucki, William J.; Koch, David G.; Dunham, Edward W.; Gautier, Thomas N., III; Van Cleve, Jeffrey; Cochran, William D.; Latham, David W.; Lissauer, Jack J.; Torres, Guillermo; Brown, Timothy M.; Gilliland, Ronald L.; Buchhave, Lars A.; Caldwell, Douglas A.; Christensen-Dalsgaard, Jørgen; Ciardi, David; Fressin, Francois; Haas, Michael R.; Howell, Steve B.; Kjeldsen, Hans; Seager, Sara; Rogers, Leslie; Sasselov, Dimitar D.; Steffen, Jason H.; Basri, Gibor S.; Charbonneau, David; Christiansen, Jessie; Clarke, Bruce; Dupree, Andrea; Fabrycky, Daniel C.; Fischer, Debra A.; Ford, Eric B.; Fortney, Jonathan J.; Tarter, Jill; Girouard, Forrest R.; Holman, Matthew J.; Johnson, John Asher; Klaus, Todd C.; Machalek, Pavel; Moorhead, Althea V.; Morehead, Robert C.; Ragozzine, Darin; Tenenbaum, Peter; Twicken, Joseph D.; Quinn, Samuel N.; Isaacson, Howard; Shporer, Avi; Lucas, Philip W.; Walkowicz, Lucianne M.; Welsh, William F.; Boss, Alan; Devore, Edna; Gould, Alan; Smith, Jeffrey C.; Morris, Robert L.; Prsa, Andrej; Morton, Timothy D.; Still, Martin; Thompson, Susan E.; Mullally, Fergal; Endl, Michael; MacQueen, Phillip J. Bibcode: 2012ApJS..201...15H Altcode: 2011arXiv1103.2541H We report the distribution of planets as a function of planet radius, orbital period, and stellar effective temperature for orbital periods less than 50 days around solar-type (GK) stars. These results are based on the 1235 planets (formally "planet candidates") from the Kepler mission that include a nearly complete set of detected planets as small as 2 R ⊕. For each of the 156,000 target stars, we assess the detectability of planets as a function of planet radius, R p, and orbital period, P, using a measure of the detection efficiency for each star. We also correct for the geometric probability of transit, R sstarf/a. We consider first Kepler target stars within the "solar subset" having T eff = 4100-6100 K, log g = 4.0-4.9, and Kepler magnitude Kp < 15 mag, i.e., bright, main-sequence GK stars. We include only those stars having photometric noise low enough to permit detection of planets down to 2 R ⊕. We count planets in small domains of R p and P and divide by the included target stars to calculate planet occurrence in each domain. The resulting occurrence of planets varies by more than three orders of magnitude in the radius-orbital period plane and increases substantially down to the smallest radius (2 R ⊕) and out to the longest orbital period (50 days, ~0.25 AU) in our study. For P < 50 days, the distribution of planet radii is given by a power law, df/dlog R = kRR α with kR = 2.9+0.5 - 0.4, α = -1.92 ± 0.11, and R ≡ R p/R ⊕. This rapid increase in planet occurrence with decreasing planet size agrees with the prediction of core-accretion formation but disagrees with population synthesis models that predict a desert at super-Earth and Neptune sizes for close-in orbits. Planets with orbital periods shorter than 2 days are extremely rare; for R p > 2 R ⊕ we measure an occurrence of less than 0.001 planets per star. For all planets with orbital periods less than 50 days, we measure occurrence of 0.130 ± 0.008, 0.023 ± 0.003, and 0.013 ± 0.002 planets per star for planets with radii 2-4, 4-8, and 8-32 R ⊕, in agreement with Doppler surveys. We fit occurrence as a function of P to a power-law model with an exponential cutoff below a critical period P 0. For smaller planets, P 0 has larger values, suggesting that the "parking distance" for migrating planets moves outward with decreasing planet size. We also measured planet occurrence over a broader stellar T eff range of 3600-7100 K, spanning M0 to F2 dwarfs. Over this range, the occurrence of 2-4 R ⊕ planets in the Kepler field increases with decreasing T eff, with these small planets being seven times more abundant around cool stars (3600-4100 K) than the hottest stars in our sample (6600-7100 K).

Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Title: Kepler-36: A Pair of Planets with Neighboring Orbits and Dissimilar Densities Authors: Carter, Joshua A.; Agol, Eric; Chaplin, William J.; Basu, Sarbani; Bedding, Timothy R.; Buchhave, Lars A.; Christensen-Dalsgaard, Jørgen; Deck, Katherine M.; Elsworth, Yvonne; Fabrycky, Daniel C.; Ford, Eric B.; Fortney, Jonathan J.; Hale, Steven J.; Handberg, Rasmus; Hekker, Saskia; Holman, Matthew J.; Huber, Daniel; Karoff, Christopher; Kawaler, Steven D.; Kjeldsen, Hans; Lissauer, Jack J.; Lopez, Eric D.; Lund, Mikkel N.; Lundkvist, Mia; Metcalfe, Travis S.; Miglio, Andrea; Rogers, Leslie A.; Stello, Dennis; Borucki, William J.; Bryson, Steve; Christiansen, Jessie L.; Cochran, William D.; Geary, John C.; Gilliland, Ronald L.; Haas, Michael R.; Hall, Jennifer; Howard, Andrew W.; Jenkins, Jon M.; Klaus, Todd; Koch, David G.; Latham, David W.; MacQueen, Phillip J.; Sasselov, Dimitar; Steffen, Jason H.; Twicken, Joseph D.; Winn, Joshua N. Bibcode: 2012Sci...337..556C Altcode: 2012arXiv1206.4718C In the solar system, the planets’ compositions vary with orbital distance, with rocky planets in close orbits and lower-density gas giants in wider orbits. The detection of close-in giant planets around other stars was the first clue that this pattern is not universal and that planets’ orbits can change substantially after their formation. Here, we report another violation of the orbit-composition pattern: two planets orbiting the same star with orbital distances differing by only 10% and densities differing by a factor of 8. One planet is likely a rocky “super-Earth,” whereas the other is more akin to Neptune. These planets are 20 times more closely spaced and have a larger density contrast than any adjacent pair of planets in the solar system. Title: VizieR Online Data Catalog: p-mode frequencies of the solar twin 18 Sco (Bazot+, 2012) Authors: Bazot, M.; Campante, T. L.; Chaplin, W. J.; Carfantan, H.; Bedding, T. R.; Dumusque, X.; Broomhall, A. -M.; Petit, P.; Theado, S.; Van Grootel, V.; Arentoft, T.; Castro, M.; Christensen-Dalsgaard, J.; Do Nascimento, J. -D., Jr.; Dintrans, B.; Kjeldsen, H.; Monteiro, M. J. P. F. G.; Santos, N. C.; Sousa, S.; Vauclair, S. Bibcode: 2012yCat..35440106B Altcode: 2012yCat..35449106B Results from the estimation of the parameter of the spectrum model using the Markov Chain Monte-Carlo (MCMC) algorithm described in Sect.4. A burn-in sequence has been removed. The data is stored in the form of an array [1975001x54] The first 52 columns give the frequencies of the modes order by degree (13 l=0 modes, 13 l=1 modes, 13 l=2 modes, 13 l=3 modes). For each mode, they are sorted in ascending order. The last two columns of each line give the parameters Gamma1 and Gamma2.

(1 data file). Title: Oscillation mode frequencies of 61 main-sequence and subgiant stars observed by Kepler Authors: Appourchaux, T.; Chaplin, W. J.; García, R. A.; Gruberbauer, M.; Verner, G. A.; Antia, H. M.; Benomar, O.; Campante, T. L.; Davies, G. R.; Deheuvels, S.; Handberg, R.; Hekker, S.; Howe, R.; Régulo, C.; Salabert, D.; Bedding, T. R.; White, T. R.; Ballot, J.; Mathur, S.; Silva Aguirre, V.; Elsworth, Y. P.; Basu, S.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Uddin, K.; Stumpe, M. C.; Barclay, T. Bibcode: 2012A&A...543A..54A Altcode: 2012arXiv1204.3147A Context. Solar-like oscillations have been observed by Kepler and CoRoT in several solar-type stars, thereby providing a way to probe the stars using asteroseismology
Aims: We provide the mode frequencies of the oscillations of various stars required to perform a comparison with those obtained from stellar modelling.
Methods: We used a time series of nine months of data for each star. The 61 stars observed were categorised in three groups: simple, F-like, and mixed-mode. The simple group includes stars for which the identification of the mode degree is obvious. The F-like group includes stars for which the identification of the degree is ambiguous. The mixed-mode group includes evolved stars for which the modes do not follow the asymptotic relation of low-degree frequencies. Following this categorisation, the power spectra of the 61 main-sequence and subgiant stars were analysed using both maximum likelihood estimators and Bayesian estimators, providing individual mode characteristics such as frequencies, linewidths, and mode heights. We developed and describe a methodology for extracting a single set of mode frequencies from multiple sets derived by different methods and individual scientists. We report on how one can assess the quality of the fitted parameters using the likelihood ratio test and the posterior probabilities.
Results: We provide the mode frequencies of 61 stars (with their 1-σ error bars), as well as their associated échelle diagrams.

Appendices are available in electronic form at http://www.aanda.org Title: Accurate fundamental parameters and detailed abundance patterns from spectroscopy of 93 solar-type Kepler targets Authors: Bruntt, H.; Basu, S.; Smalley, B.; Chaplin, W. J.; Verner, G. A.; Bedding, T. R.; Catala, C.; Gazzano, J. -C.; Molenda-Żakowicz, J.; Thygesen, A. O.; Uytterhoeven, K.; Hekker, S.; Huber, D.; Karoff, C.; Mathur, S.; Mosser, B.; Appourchaux, T.; Campante, T. L.; Elsworth, Y.; García, R. A.; Handberg, R.; Metcalfe, T. S.; Quirion, P. -O.; Régulo, C.; Roxburgh, I. W.; Stello, D.; Christensen-Dalsgaard, J.; Kawaler, S. D.; Kjeldsen, H.; Morris, R. L.; Quintana, E. V.; Sanderfer, D. T. Bibcode: 2012MNRAS.423..122B Altcode: 2012arXiv1203.0611B; 2012MNRAS.tmp.3037B We present a detailed spectroscopic study of 93 solar-type stars that are targets of the NASA/Kepler mission and provide detailed chemical composition of each target. We find that the overall metallicity is well represented by Fe lines. Relative abundances of light elements (CNO) and α elements are generally higher for low-metallicity stars. Our spectroscopic analysis benefits from the accurately measured surface gravity from the asteroseismic analysis of the Kepler light curves. The accuracy on the log g parameter is better than 0.03 dex and is held fixed in the analysis. We compare our Teff determination with a recent colour calibration of VT-KS [TYCHO V magnitude minus Two Micron All Sky Survey (2MASS) KS magnitude] and find very good agreement and a scatter of only 80 K, showing that for other nearby Kepler targets, this index can be used. The asteroseismic log g values agree very well with the classical determination using Fe I-Fe II balance, although we find a small systematic offset of 0.08 dex (asteroseismic log g values are lower). The abundance patterns of metals, α elements and the light elements (CNO) show that a simple scaling by [Fe/H] is adequate to represent the metallicity of the stars, except for the stars with metallicity below -0.3, where α-enhancement becomes important. However, this is only important for a very small fraction of the Kepler sample. We therefore recommend that a simple scaling with [Fe/H] be employed in the asteroseismic analyses of large ensembles of solar-type stars. Title: Solving the Mode Identification Problem in Asteroseismology of F Stars Observed with Kepler Authors: White, Timothy R.; Bedding, Timothy R.; Gruberbauer, Michael; Benomar, Othman; Stello, Dennis; Appourchaux, Thierry; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Elsworth, Yvonne P.; García, Rafael A.; Hekker, Saskia; Huber, Daniel; Kjeldsen, Hans; Mosser, Benoît; Kinemuchi, Karen; Mullally, Fergal; Still, Martin Bibcode: 2012ApJ...751L..36W Altcode: 2012arXiv1205.0544W Asteroseismology of F-type stars has been hindered by an ambiguity in identification of their oscillation modes. The regular mode pattern that makes this task trivial in cooler stars is masked by increased line widths. The absolute mode frequencies, encapsulated in the asteroseismic variable epsilon, can help solve this impasse because the values of epsilon implied by the two possible mode identifications are distinct. We find that the correct epsilon can be deduced from the effective temperature and the line widths and we apply these methods to a sample of solar-like oscillators observed with Kepler. Title: Seismic evidence for non-synchronization in two close sdb+dM binaries from Kepler photometry Authors: Pablo, Herbert; Kawaler, Steven D.; Reed, M. D.; Bloemen, S.; Charpinet, S.; Hu, H.; Telting, J.; Østensen, R. H.; Baran, A. S.; Green, E. M.; Hermes, J. J.; Barclay, T.; O'Toole, S. J.; Mullally, Fergal; Kurtz, D. W.; Christensen-Dalsgaard, J.; Caldwell, Douglas A.; Christiansen, Jessie L.; Kinemuchi, K. Bibcode: 2012MNRAS.422.1343P Altcode: 2012arXiv1202.3649P We report on extended photometry of two pulsating subdwarf B (sdB) stars in close binaries. For both cases, we use rotational splitting of the pulsation frequencies to show that the sdB component rotates much too slowly to be in synchronous rotation. We use a theory of tidal interaction in binary stars to place limits on the mass ratios that are independent of estimates based on the radial velocity curves. The companions have masses below 0.26 M⊙. The pulsation spectra show the signature of high-overtone g-mode pulsation. One star, KIC 11179657, has a clear sequence of g modes with equal period spacings as well as several periodicities that depart from that trend. KIC 02991403 shows a similar sequence, but has many more modes that do not fit the simple pattern. Title: A Uniform Asteroseismic Analysis of 22 Solar-type Stars Observed by Kepler Authors: Mathur, S.; Metcalfe, T. S.; Woitaszek, M.; Bruntt, H.; Verner, G. A.; Christensen-Dalsgaard, J.; Creevey, O. L.; Doǧan, G.; Basu, S.; Karoff, C.; Stello, D.; Appourchaux, T.; Campante, T. L.; Chaplin, W. J.; García, R. A.; Bedding, T. R.; Benomar, O.; Bonanno, A.; Deheuvels, S.; Elsworth, Y.; Gaulme, P.; Guzik, J. A.; Handberg, R.; Hekker, S.; Herzberg, W.; Monteiro, M. J. P. F. G.; Piau, L.; Quirion, P. -O.; Régulo, C.; Roth, M.; Salabert, D.; Serenelli, A.; Thompson, M. J.; Trampedach, R.; White, T. R.; Ballot, J.; Brandão, I. M.; Molenda-Żakowicz, J.; Kjeldsen, H.; Twicken, J. D.; Uddin, K.; Wohler, B. Bibcode: 2012ApJ...749..152M Altcode: 2012arXiv1202.2844M Asteroseismology with the Kepler space telescope is providing not only an improved characterization of exoplanets and their host stars, but also a new window on stellar structure and evolution for the large sample of solar-type stars in the field. We perform a uniform analysis of 22 of the brightest asteroseismic targets with the highest signal-to-noise ratio observed for 1 month each during the first year of the mission, and we quantify the precision and relative accuracy of asteroseismic determinations of the stellar radius, mass, and age that are possible using various methods. We present the properties of each star in the sample derived from an automated analysis of the individual oscillation frequencies and other observational constraints using the Asteroseismic Modeling Portal (AMP), and we compare them to the results of model-grid-based methods that fit the global oscillation properties. We find that fitting the individual frequencies typically yields asteroseismic radii and masses to ~1% precision, and ages to ~2.5% precision (respectively, 2, 5, and 8 times better than fitting the global oscillation properties). The absolute level of agreement between the results from different approaches is also encouraging, with model-grid-based methods yielding slightly smaller estimates of the radius and mass and slightly older values for the stellar age relative to AMP, which computes a large number of dedicated models for each star. The sample of targets for which this type of analysis is possible will grow as longer data sets are obtained during the remainder of the mission. Title: Commission 12: Solar Radiation and Structure Authors: Kosovichev, Alexander; Cauzzi, Gianna; Pillet, Valentin Martinez; Asplund, Martin; Brandenburg, Axel; Chou, Dean-Yi; Christensen-Dalsgaard, Jorgen; Gan, Weiqun; Kuznetsov, Vladimir D.; Rovira, Marta G.; Shchukina, Nataliya; Venkatakrishnan, P. Bibcode: 2012IAUTA..28...81K Altcode: 2012IAUTB..28...81K Commission 12 of the International Astronomical Union encompasses investigations of the internal structure and dynamics of the Sun, mostly accessible through the techniques of local and global helioseismology, the quiet solar atmosphere, solar radiation and its variability, and the nature of relatively stable magnetic structures like sunspots, faculae and the magnetic network. The Commission sees participation of over 350 scientists worldwide. Title: Asteroseismology with Kepler and SONG Authors: Christensen-Dalsgaard, J. Bibcode: 2012AfrSk..16...74C Altcode: No abstract at ADS Title: Asteroseismology of the Solar Analogs 16 Cyg A and B from Kepler Observations Authors: Metcalfe, T. S.; Chaplin, W. J.; Appourchaux, T.; García, R. A.; Basu, S.; Brandão, I.; Creevey, O. L.; Deheuvels, S.; Doǧan, G.; Eggenberger, P.; Karoff, C.; Miglio, A.; Stello, D.; Yıldız, M.; Çelik, Z.; Antia, H. M.; Benomar, O.; Howe, R.; Régulo, C.; Salabert, D.; Stahn, T.; Bedding, T. R.; Davies, G. R.; Elsworth, Y.; Gizon, L.; Hekker, S.; Mathur, S.; Mosser, B.; Bryson, S. T.; Still, M. D.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Ibrahim, K. A.; Klaus, T. C.; Li, J. Bibcode: 2012ApJ...748L..10M Altcode: 2012arXiv1201.5966M The evolved solar-type stars 16 Cyg A and B have long been studied as solar analogs, yielding a glimpse into the future of our own Sun. The orbital period of the binary system is too long to provide meaningful dynamical constraints on the stellar properties, but asteroseismology can help because the stars are among the brightest in the Kepler field. We present an analysis of three months of nearly uninterrupted photometry of 16 Cyg A and B from the Kepler space telescope. We extract a total of 46 and 41 oscillation frequencies for the two components, respectively, including a clear detection of octupole (l = 3) modes in both stars. We derive the properties of each star independently using the Asteroseismic Modeling Portal, fitting the individual oscillation frequencies and other observational constraints simultaneously. We evaluate the systematic uncertainties from an ensemble of results generated by a variety of stellar evolution codes and fitting methods. The optimal models derived by fitting each component individually yield a common age (t = 6.8 ± 0.4 Gyr) and initial composition (Z i = 0.024 ± 0.002, Y i = 0.25 ± 0.01) within the uncertainties, as expected for the components of a binary system, bolstering our confidence in the reliability of asteroseismic techniques. The longer data sets that will ultimately become available will allow future studies of differential rotation, convection zone depths, and long-term changes due to stellar activity cycles. Title: Kepler-22b: A 2.4 Earth-radius Planet in the Habitable Zone of a Sun-like Star Authors: Borucki, William J.; Koch, David G.; Batalha, Natalie; Bryson, Stephen T.; Rowe, Jason; Fressin, Francois; Torres, Guillermo; Caldwell, Douglas A.; Christensen-Dalsgaard, Jørgen; Cochran, William D.; DeVore, Edna; Gautier, Thomas N.; Geary, John C.; Gilliland, Ronald; Gould, Alan; Howell, Steve B.; Jenkins, Jon M.; Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Sasselov, Dimitar; Boss, Alan; Charbonneau, David; Ciardi, David; Kaltenegger, Lisa; Doyle, Laurance; Dupree, Andrea K.; Ford, Eric B.; Fortney, Jonathan; Holman, Matthew J.; Steffen, Jason H.; Mullally, Fergal; Still, Martin; Tarter, Jill; Ballard, Sarah; Buchhave, Lars A.; Carter, Josh; Christiansen, Jessie L.; Demory, Brice-Olivier; Désert, Jean-Michel; Dressing, Courtney; Endl, Michael; Fabrycky, Daniel; Fischer, Debra; Haas, Michael R.; Henze, Christopher; Horch, Elliott; Howard, Andrew W.; Isaacson, Howard; Kjeldsen, Hans; Johnson, John Asher; Klaus, Todd; Kolodziejczak, Jeffery; Barclay, Thomas; Li, Jie; Meibom, Søren; Prsa, Andrej; Quinn, Samuel N.; Quintana, Elisa V.; Robertson, Paul; Sherry, William; Shporer, Avi; Tenenbaum, Peter; Thompson, Susan E.; Twicken, Joseph D.; Van Cleve, Jeffrey; Welsh, William F.; Basu, Sarbani; Chaplin, William; Miglio, Andrea; Kawaler, Steven D.; Arentoft, Torben; Stello, Dennis; Metcalfe, Travis S.; Verner, Graham A.; Karoff, Christoffer; Lundkvist, Mia; Lund, Mikkel N.; Handberg, Rasmus; Elsworth, Yvonne; Hekker, Saskia; Huber, Daniel; Bedding, Timothy R.; Rapin, William Bibcode: 2012ApJ...745..120B Altcode: 2011arXiv1112.1640B A search of the time-series photometry from NASA's Kepler spacecraft reveals a transiting planet candidate orbiting the 11th magnitude G5 dwarf KIC 10593626 with a period of 290 days. The characteristics of the host star are well constrained by high-resolution spectroscopy combined with an asteroseismic analysis of the Kepler photometry, leading to an estimated mass and radius of 0.970 ± 0.060 M ⊙ and 0.979 ± 0.020 R ⊙. The depth of 492 ± 10 ppm for the three observed transits yields a radius of 2.38 ± 0.13 Re for the planet. The system passes a battery of tests for false positives, including reconnaissance spectroscopy, high-resolution imaging, and centroid motion. A full BLENDER analysis provides further validation of the planet interpretation by showing that contamination of the target by an eclipsing system would rarely mimic the observed shape of the transits. The final validation of the planet is provided by 16 radial velocities (RVs) obtained with the High Resolution Echelle Spectrometer on Keck I over a one-year span. Although the velocities do not lead to a reliable orbit and mass determination, they are able to constrain the mass to a 3σ upper limit of 124 M ⊕, safely in the regime of planetary masses, thus earning the designation Kepler-22b. The radiative equilibrium temperature is 262 K for a planet in Kepler-22b's orbit. Although there is no evidence that Kepler-22b is a rocky planet, it is the first confirmed planet with a measured radius to orbit in the habitable zone of any star other than the Sun. Title: Masses of Subgiant Stars from Asteroseismology Using the Coupling Strengths of Mixed Modes Authors: Benomar, O.; Bedding, T. R.; Stello, D.; Deheuvels, S.; White, T. R.; Christensen-Dalsgaard, J. Bibcode: 2012ApJ...745L..33B Altcode: 2012arXiv1201.1067B For a few decades now, asteroseismology, the study of stellar oscillations, has enabled us to probe the interiors of stars with great precision. It allows stringent tests of stellar models and can provide accurate radii, masses, and ages for individual stars. Of particular interest are the mixed modes that occur in subgiant solar-like stars since they can place very strong constraints on stellar ages. Here, we measure the characteristics of the mixed modes, particularly the coupling strength, using a grid of stellar models for stars with masses between 0.9 and 1.5 M ⊙. We show that the coupling strength of the l = 1 mixed modes is predominantly a function of stellar mass and appears to be independent of metallicity. This should allow an accurate mass evaluation, further increasing the usefulness of mixed modes in subgiants as asteroseismic tools. Title: Kepler-21b: A 1.6 R Earth Planet Transiting the Bright Oscillating F Subgiant Star HD 179070 Authors: Howell, Steve B.; Rowe, Jason F.; Bryson, Stephen T.; Quinn, Samuel N.; Marcy, Geoffrey W.; Isaacson, Howard; Ciardi, David R.; Chaplin, William J.; Metcalfe, Travis S.; Monteiro, Mario J. P. F. G.; Appourchaux, Thierry; Basu, Sarbani; Creevey, Orlagh L.; Gilliland, Ronald L.; Quirion, Pierre-Olivier; Stello, Denis; Kjeldsen, Hans; Christensen-Dalsgaard, Jörgen; Elsworth, Yvonne; García, Rafael A.; Houdek, Günter; Karoff, Christoffer; Molenda-Żakowicz, Joanna; Thompson, Michael J.; Verner, Graham A.; Torres, Guillermo; Fressin, Francois; Crepp, Justin R.; Adams, Elisabeth; Dupree, Andrea; Sasselov, Dimitar D.; Dressing, Courtney D.; Borucki, William J.; Koch, David G.; Lissauer, Jack J.; Latham, David W.; Buchhave, Lars A.; Gautier, Thomas N., III; Everett, Mark; Horch, Elliott; Batalha, Natalie M.; Dunham, Edward W.; Szkody, Paula; Silva, David R.; Mighell, Ken; Holberg, Jay; Ballot, Jerôme; Bedding, Timothy R.; Bruntt, Hans; Campante, Tiago L.; Handberg, Rasmus; Hekker, Saskia; Huber, Daniel; Mathur, Savita; Mosser, Benoit; Régulo, Clara; White, Timothy R.; Christiansen, Jessie L.; Middour, Christopher K.; Haas, Michael R.; Hall, Jennifer R.; Jenkins, Jon M.; McCaulif, Sean; Fanelli, Michael N.; Kulesa, Craig; McCarthy, Don; Henze, Christopher E. Bibcode: 2012ApJ...746..123H Altcode: 2011arXiv1112.2165H We present Kepler observations of the bright (V = 8.3), oscillating star HD 179070. The observations show transit-like events which reveal that the star is orbited every 2.8 days by a small, 1.6 R Earth object. Seismic studies of HD 179070 using short cadence Kepler observations show that HD 179070 has a frequency-power spectrum consistent with solar-like oscillations that are acoustic p-modes. Asteroseismic analysis provides robust values for the mass and radius of HD 179070, 1.34 ± 0.06 M ⊙ and 1.86 ± 0.04 R ⊙, respectively, as well as yielding an age of 2.84 ± 0.34 Gyr for this F5 subgiant. Together with ground-based follow-up observations, analysis of the Kepler light curves and image data, and blend scenario models, we conservatively show at the >99.7% confidence level (3σ) that the transit event is caused by a 1.64 ± 0.04 R Earth exoplanet in a 2.785755 ± 0.000032 day orbit. The exoplanet is only 0.04 AU away from the star and our spectroscopic observations provide an upper limit to its mass of ~10 M Earth (2σ). HD 179070 is the brightest exoplanet host star yet discovered by Kepler.

Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology, the Mayall telescope at Kitt Peak National Observatory, and the WIYN Observatory which is a joint facility of NOAO, University of Wisconsin-Madison, Indiana University, and Yale University. Title: VizieR Online Data Catalog: Kepler compact pulsator candidates (Ostensen+, 2011) Authors: Ostensen, R. H.; Silvotti, R.; Charpinet, S.; Oreiro, R.; Bloemen, S.; Baran, A. S.; Reed, M. D.; Kawaler, S. D.; Telting, J. H.; Green, E. M.; O'Toole, S. J.; Aerts, C.; Gansicke, B. T.; Marsh, T. R.; Breedt, E.; Heber, U.; Koester, D.; Quint, A. C.; Kurtz, D. W.; Rodriguez-Lopez, C.; Vuckovic, M.; Ottosen, T. A.; Frimann, S.; Somero, A.; Wilson, P. A.; Thygesen, A. O.; Lindberg, J. E.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Allen, C.; McCauliff, S.; Middour, C. K. Bibcode: 2012yCat..74142860O Altcode: We present results from the final 6 months of a survey to search for pulsations in white dwarfs (WDs) and hot subdwarf stars with the Kepler spacecraft. Spectroscopic observations are used to separate the objects into accurate classes, and we explore the physical parameters of the subdwarf B (sdB) stars and white dwarfs in the sample. From the Kepler photometry and our spectroscopic data, we find that the sample contains five new pulsators of the V1093 Her type, one AM CVn type cataclysmic variable and a number of other binary systems.

(1 data file). Title: Fundamental properties of five Kepler stars using global asteroseismic quantities and ground-based observations Authors: Creevey, O. L.; Doǧan, G.; Frasca, A.; Thygesen, A. O.; Basu, S.; Bhattacharya, J.; Biazzo, K.; Brandão, I. M.; Bruntt, H.; Mazumdar, A.; Niemczura, E.; Shrotriya, T.; Sousa, S. G.; Stello, D.; Subramaniam, A.; Campante, T. L.; Handberg, R.; Mathur, S.; Bedding, T. R.; García, R. A.; Régulo, C.; Salabert, D.; Molenda-Żakowicz, J.; Quirion, P. -O.; White, T. R.; Bonanno, A.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Christiansen, J. L.; Elsworth, Y.; Fanelli, M. N.; Karoff, C.; Kinemuchi, K.; Kjeldsen, H.; Gai, N.; Monteiro, M. J. P. F. G.; Suárez, J. C. Bibcode: 2012A&A...537A.111C Altcode: 2011arXiv1111.4615C We present an asteroseismic study of the solar-like stars KIC 11395018, KIC 10273246, KIC 10920273, KIC 10339342, and KIC 11234888 using short-cadence time series of more than eight months from the Kepler satellite. For four of these stars, we derive atmospheric parameters from spectra acquired with the Nordic Optical Telescope. The global seismic quantities (average largefrequency separation and frequency of maximum power), combined with the atmospheric parameters, yield the mean density and surface gravity with precisions of 2% and ~0.03 dex, respectively. We also determine the radius, mass, and age with precisions of 2-5%, 7-11%, and ~35%, respectively, using grid-based analyses. Coupling the stellar parameters with photometric data yields an asteroseismic distance with a precision better than 10%. A vsini measurement provides a rotational period-inclination correlation, and using the rotational periods from the recent literature, we constrain the stellar inclination for three of the stars. An Li abundance analysis yields an independent estimate of the age, but this is inconsistent with the asteroseismically determined age for one of the stars. We assess the performance of five grid-based analysis methods and find them all to provide consistent values of the surface gravity to ~0.03 dex when both atmospheric and seismic constraints are at hand. The different grid-based analyses all yield fitted values of radius and mass to within 2.4σ, and taking the mean of these results reduces it to 1.5σ. The absence of a metallicity constraint when the average large frequency separation is measured with a precision of 1% biases the fitted radius and mass for the stars with non-solar metallicity (metal-rich KIC 11395018 and metal-poor KIC 10273246), while including a metallicity constraint reduces the uncertainties in both of these parameters by almost a factor of two. We found that including the average small frequency separation improves the determination of the age only for KIC 11395018 and KIC 11234888, and for the latter this improvement was due to the lack of strong atmospheric constraints. Title: Fast core rotation in red-giant stars as revealed by gravity-dominated mixed modes Authors: Beck, Paul G.; Montalban, Josefina; Kallinger, Thomas; De Ridder, Joris; Aerts, Conny; García, Rafael A.; Hekker, Saskia; Dupret, Marc-Antoine; Mosser, Benoit; Eggenberger, Patrick; Stello, Dennis; Elsworth, Yvonne; Frandsen, Søren; Carrier, Fabien; Hillen, Michel; Gruberbauer, Michael; Christensen-Dalsgaard, Jørgen; Miglio, Andrea; Valentini, Marica; Bedding, Timothy R.; Kjeldsen, Hans; Girouard, Forrest R.; Hall, Jennifer R.; Ibrahim, Khadeejah A. Bibcode: 2012Natur.481...55B Altcode: 2011arXiv1112.2825B When the core hydrogen is exhausted during stellar evolution, the central region of a star contracts and the outer envelope expands and cools, giving rise to a red giant. Convection takes place over much of the star's radius. Conservation of angular momentum requires that the cores of these stars rotate faster than their envelopes; indirect evidence supports this. Information about the angular-momentum distribution is inaccessible to direct observations, but it can be extracted from the effect of rotation on oscillation modes that probe the stellar interior. Here we report an increasing rotation rate from the surface of the star to the stellar core in the interiors of red giants, obtained using the rotational frequency splitting of recently detected `mixed modes'. By comparison with theoretical stellar models, we conclude that the core must rotate at least ten times faster than the surface. This observational result confirms the theoretical prediction of a steep gradient in the rotation profile towards the deep stellar interior. Title: Nitty-gritty Modeling Details - Geeking Out on Precision Frequencies for Comparison Sake Authors: Christensen-Dalsgaard, Jörgen; Hu, Haili Bibcode: 2011asa..progE..23C Altcode: No abstract at ADS Title: Calculating Asteroseismic Diagrams for Solar-like Oscillations Authors: White, Timothy R.; Bedding, Timothy R.; Stello, Dennis; Christensen-Dalsgaard, Jørgen; Huber, Daniel; Kjeldsen, Hans Bibcode: 2011ApJ...743..161W Altcode: 2011arXiv1109.3455W With the success of the Kepler and CoRoT missions, the number of stars with detected solar-like oscillations has increased by several orders of magnitude; for the first time we are able to perform large-scale ensemble asteroseismology of these stars. In preparation for this golden age of asteroseismology we have computed expected values of various asteroseismic observables from models of varying mass and metallicity. The relationships between these asteroseismic observables, such as the separations between mode frequencies, are able to significantly constrain estimates of the ages and masses of these stars. We investigate the scaling relation between the large frequency separation, Δν, and mean stellar density. Furthermore we present model evolutionary tracks for several asteroseismic diagrams. We have extended the so-called C-D diagram beyond the main sequence to the subgiants and the red giant branch. We also consider another asteroseismic diagram, the epsilon diagram, which is more sensitive to variations in stellar properties at the subgiant stages and can aid in determining the correct mode identification. The recent discovery of gravity-mode period spacings in red giants forms the basis for a third asteroseismic diagram. We compare the evolutionary model tracks in these asteroseismic diagrams with results from pre-Kepler studies of solar-like oscillations and early results from Kepler. Title: Testing Scaling Relations for Solar-like Oscillations from the Main Sequence to Red Giants Using Kepler Data Authors: Huber, D.; Bedding, T. R.; Stello, D.; Hekker, S.; Mathur, S.; Mosser, B.; Verner, G. A.; Bonanno, A.; Buzasi, D. L.; Campante, T. L.; Elsworth, Y. P.; Hale, S. J.; Kallinger, T.; Silva Aguirre, V.; Chaplin, W. J.; De Ridder, J.; García, R. A.; Appourchaux, T.; Frandsen, S.; Houdek, G.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Broomhall, A. M.; Corsaro, E.; Salabert, D.; Sanderfer, D. T.; Seader, S. E.; Smith, J. C. Bibcode: 2011ApJ...743..143H Altcode: 2011arXiv1109.3460H We have analyzed solar-like oscillations in ~1700 stars observed by the Kepler Mission, spanning from the main sequence to the red clump. Using evolutionary models, we test asteroseismic scaling relations for the frequency of maximum power (νmax), the large frequency separation (Δν), and oscillation amplitudes. We show that the difference of the Δν-νmax relation for unevolved and evolved stars can be explained by different distributions in effective temperature and stellar mass, in agreement with what is expected from scaling relations. For oscillation amplitudes, we show that neither (L/M) s scaling nor the revised scaling relation by Kjeldsen & Bedding is accurate for red-giant stars, and demonstrate that a revised scaling relation with a separate luminosity-mass dependence can be used to calculate amplitudes from the main sequence to red giants to a precision of ~25%. The residuals show an offset particularly for unevolved stars, suggesting that an additional physical dependency is necessary to fully reproduce the observed amplitudes. We investigate correlations between amplitudes and stellar activity, and find evidence that the effect of amplitude suppression is most pronounced for subgiant stars. Finally, we test the location of the cool edge of the instability strip in the Hertzsprung-Russell diagram using solar-like oscillations and find the detections in the hottest stars compatible with a domain of hybrid stochastically excited and opacity driven pulsation. Title: Modeling Kepler Observations of Solar-like Oscillations in the Red Giant Star HD 186355 Authors: Jiang, C.; Jiang, B. W.; Christensen-Dalsgaard, J.; Bedding, T. R.; Stello, D.; Huber, D.; Frandsen, S.; Kjeldsen, H.; Karoff, C.; Mosser, B.; Demarque, P.; Fanelli, M. N.; Kinemuchi, K.; Mullally, F. Bibcode: 2011ApJ...742..120J Altcode: 2011arXiv1109.0962J We have analyzed oscillations of the red giant star HD 186355 observed by the NASA Kepler satellite. The data consist of the first five quarters of science operations of Kepler, which cover about 13 months. The high-precision time-series data allow us to accurately extract the oscillation frequencies from the power spectrum. We find that the frequency of the maximum oscillation power, νmax, and the mean large frequency separation, Δν, are around 106 and 9.4 μHz, respectively. A regular pattern of radial and non-radial oscillation modes is identified by stacking the power spectra in an echelle diagram. We use the scaling relations of Δν and νmax to estimate the preliminary asteroseismic mass, which is confirmed with the modeling result (M = 1.45 ± 0.05 M ⊙) using the Yale Rotating stellar Evolution Code (YREC7). In addition, we constrain the effective temperature, luminosity, and radius from comparisons between observational constraints and models. A number of mixed l = 1 modes are also detected and taken into account in our model comparisons. We find a mean observational period spacing for these mixed modes of about 58 s, suggesting that this red giant branch star is in the shell hydrogen-burning phase. Title: Spin-Orbit Alignment for the Circumbinary Planet Host Kepler-16 A Authors: Winn, Joshua N.; Albrecht, Simon; Johnson, John Asher; Torres, Guillermo; Cochran, William D.; Marcy, Geoffrey W.; Howard, Andrew W.; Isaacson, Howard; Fischer, Debra; Doyle, Laurance; Welsh, William; Carter, Joshua A.; Fabrycky, Daniel C.; Ragozzine, Darin; Quinn, Samuel N.; Shporer, Avi; Howell, Steve B.; Latham, David W.; Orosz, Jerome; Prsa, Andrej; Slawson, Robert W.; Borucki, William J.; Koch, David; Barclay, Thomas; Boss, Alan P.; Christensen-Dalsgaard, Jørgen; Girouard, Forrest R.; Jenkins, Jon; Klaus, Todd C.; Meibom, Søren; Morris, Robert L.; Sasselov, Dimitar; Still, Martin; Van Cleve, Jeffrey Bibcode: 2011ApJ...741L...1W Altcode: 2011arXiv1109.3198W Kepler-16 is an eccentric low-mass eclipsing binary with a circumbinary transiting planet. Here, we investigate the angular momentum of the primary star, based on Kepler photometry and Keck spectroscopy. The primary star's rotation period is 35.1 ± 1.0 days, and its projected obliquity with respect to the stellar binary orbit is 1fdg6 ± 2fdg4. Therefore, the three largest sources of angular momentum—the stellar orbit, the planetary orbit, and the primary's rotation—are all closely aligned. This finding supports a formation scenario involving accretion from a single disk. Alternatively, tides may have realigned the stars despite their relatively wide separation (0.2 AU), a hypothesis that is supported by the agreement between the measured rotation period and the "pseudosynchronous" period of tidal evolution theory. The rotation period, chromospheric activity level, and fractional light variations suggest a main-sequence age of 2-4 Gyr. Evolutionary models of low-mass stars can match the observed masses and radii of the primary and secondary stars to within about 3%. Title: The SONG project and the prototype node at Tenerife Authors: Uytterhoeven, K.; Palle, P. L.; Grundahl, F.; Frandsen, S.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Fredslund Andersen, M.; Weiss, E.; Joergensen, U. G.; Rasmussen, P. K.; Soerensen, A. N.; Harpsoee, K.; Skottfelt, J. Bibcode: 2011arXiv1111.1834U Altcode: SONG (Stellar Observations Network Group) is a global network of 1-m class robotic telescopes that is under development. The SONG prototype will shortly be operational at Observatorio del Teide, Tenerife, and first light is expected by December 2011. The main scientific goals of the SONG project are asteroseismology of bright stars and follow-up and characterization of exo-planets by means of precise measurements of stellar surface motions and brightness variations. We present the Tenerife SONG node and its instruments. Title: VizieR Online Data Catalog: BVRI light curves of KIC Cepheids (Szabo+, 2011) Authors: Szabo, R.; Szabados, L.; Ngeow, C. -C.; Smolec, R.; Derekas, A.; Moskalik, P.; Nuspl, J.; Lehmann, H.; Furesz, G.; Molenda-Zakowicz, J.; Bryson, S. T.; Henden, A. A.; Kurtz, D. W.; Stello, D.; Nemec, J. M.; Benko, J. M.; Berdnikov, L.; Bruntt, H.; Evans, N. R.; Gorynya, N. A.; Pastukhova, E. N.; Simcoe, R. J.; Grindlay, J. E.; Los, E. J.; Doane, A.; Laycock, S. G.; Mink, D. J.; Champine, G.; Sliski, A.; Handler, G.; Kiss, L. L.; Kollath, Z.; Kovacs, J.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Allen, C.; Thompson, S. E.; van Cleve, J. Bibcode: 2011yCat..74132709S Altcode: We report results of initial work done on selected candidate Cepheids to be observed with the Kepler space telescope. Prior to the launch, 40 candidates were selected from previous surveys and data bases. The analysis of the first 322d of Kepler photometry, and recent ground-based follow-up multicolour photometry and spectroscopy allowed us to confirm that one of these stars, V1154 Cyg (KIC 7548061), is indeed a 4.9d Cepheid. Using the phase lag method, we show that this star pulsates in the fundamental mode. New radial velocity data are consistent with previous measurements, suggesting that a long-period binary component is unlikely. No evidence is seen in the ultraprecise, nearly uninterrupted Kepler photometry for non-radial or stochastically excited modes at the micromagnitude level. The other candidates are not Cepheids, but an interesting mix of possible spotted stars, eclipsing systems and flare stars.

(5 data files). Title: VizieR Online Data Catalog: Kepler planetary candidates. I. (Borucki+, 2011) Authors: Borucki, W. J.; Koch, D. G.; Basri, G.; Batalha, N.; Boss, A.; Brown, T. M.; Caldwell, D.; Christensen-Dalsgaard, J.; Cochran, W. D.; DeVore, E.; Dunham, E. W.; Dupree, A. K.; Gautier, T. N., III; Geary, J. C.; Gilliland, R.; Gould, A.; Howell, S. B.; Jenkins, J. M.; Kjeldsen, H.; Latham, D. W.; Lissauer, J. J.; Marcy, G. W.; Monet, D. G.; Sasselov, D.; Tarter, J.; Charbonneau, D.; Doyle, L.; Ford, E. B.; Fortney, J.; Holman, M. J.; Seager, S.; Steffen, J. H.; Welsh, W. F.; Allen, C.; Bryson, S. T.; Buchhave, L.; Chandrasekaran, H.; Christiansen, J. L.; Ciardi, D.; Clarke, B. D.; Dotson, J. L.; Endl, M.; Fischer, D.; Fressin, F.; Haas, M.; Horch, E.; Howard, A.; Isaacson, H.; Kolodziejczak, J.; Li, J.; MacQueen, P.; Meibom, S.; Prsa, A.; Quintana, E. V.; Rowe, J.; Sherry, W.; Tenenbaum, P.; Torres, G.; Twicken, J. D.; van Cleve, J.; Walkowicz, L.; Wu, H. Bibcode: 2011yCat..17280117B Altcode: In the spring of 2009, the Kepler Mission commenced high-precision photometry on nearly 156000 stars to determine the frequency and characteristics of small exoplanets, conduct a guest observer program, and obtain asteroseismic data on a wide variety of stars. On 2010 June 15, the Kepler Mission released most of the data from the first quarter of observations. At the time of this data release, 705 stars from this first data set have exoplanet candidates with sizes from as small as that of Earth to larger than that of Jupiter. Here we give the identity and characteristics of 305 released stars with planetary candidates. Data for the remaining 400 stars with planetary candidates will be released in 2011 February. More than half the candidates on the released list have radii less than half that of Jupiter. Five candidates are present in and near the habitable zone; two near super-Earth size, and three bracketing the size of Jupiter. The released stars also include five possible multi-planet systems. One of these has two Neptune-size (2.3 and 2.5 Earth radius) candidates with near-resonant periods.

(1 data file). Title: VizieR Online Data Catalog: Kepler planetary candidates. II. (Borucki+, 2011) Authors: Borucki, W. J.; Koch, D. G.; Basri, G.; Batalha, N.; Brown, T. M.; Bryson, S. T.; Caldwell, D.; Christensen-Dalsgaard, J.; Cochran, W. D.; DeVore, E.; Dunham, E. W.; Gautier, T. N.; Geary, J. C.; Gilliland, R.; Gould, A.; Howell, S. B.; Jenkins, J. M.; Latham, D. W.; Lissauer, J. J.; Marcy, G. W.; Rowe, J.; Sasselov, D.; Boss, A.; Charbonneau, D.; Ciardi, D.; Doyle, L.; Dupree, A. K.; Ford, E. B.; Fortney, J.; Holman, M. J.; Seager, S.; Steffen, J. H.; Tarter, J.; Welsh, W. F.; Allen, C.; Buchhave, L. A.; Christiansen, J. L.; Clarke, B. D.; Das, S.; Desert, J. -M.; Endl, M.; Fabrycky, D.; Fressin, F.; Haas, M.; Horch, E.; Howard, A.; Isaacson, H.; Kjeldsen, H.; Kolodziejczak, J.; Kulesa, C.; Li, J.; Lucas, P. W.; Machalek, P.; McCarthy, D.; MacQueen, P.; Meibom, S.; Miquel, T.; Prsa, A.; Quinn, S. N.; Quintana, E. V.; Ragozzine, D.; Sherry, W.; Shporer, A.; Tenenbaum, P.; Torres, G.; Twicken, J. D.; van Cleve, J.; Walkowicz, L.; Witteborn, F. C.; Still, M. Bibcode: 2011yCat..17360019B Altcode: The results discussed in this paper are based on three data segments: the first segment (labeled Q0) started on JD 2454953.53 and ended on 2454963.25 and was taken during commissioning operations, the second data segment (labeled Q1) taken at the beginning of science operations that started on JD 2454964.50 and finished on JD 2454997.99, and a third segment (labeled Q2) starting on JD 2455002.51 and finishing on JD 2455091.48. The durations of the segments are 9.7, 33.5, and 89.0 days, respectively. The observations span a total period of 137.95 days including the gaps. A total of 156097 long cadence (LC) targets in Q1, and 166247 LC and 1492 short cadence (SC) targets in Q2 were observed. The results reported here are for the LC observations of 153196 stars observed during Q2. The selected stars are primarily main-sequence dwarfs chosen from the Kepler Input Catalog (KIC, Cat. V/133).

(4 data files). Title: Asteroseismic Diagrams from a Survey of Solar-like Oscillations with Kepler Authors: White, Timothy R.; Bedding, Timothy R.; Stello, Dennis; Appourchaux, Thierry; Ballot, Jérôme; Benomar, Othman; Bonanno, Alfio; Broomhall, Anne-Marie; Campante, Tiago L.; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Corsaro, Enrico; Doǧan, Gülnur; Elsworth, Yvonne P.; Fletcher, Stephen T.; García, Rafael A.; Gaulme, Patrick; Handberg, Rasmus; Hekker, Saskia; Huber, Daniel; Karoff, Christoffer; Kjeldsen, Hans; Mathur, Savita; Mosser, Benoit; Monteiro, Mario J. P. F. G.; Régulo, Clara; Salabert, David; Silva Aguirre, Victor; Thompson, Michael J.; Verner, Graham; Morris, Robert L.; Sanderfer, Dwight T.; Seader, Shawn E. Bibcode: 2011ApJ...742L...3W Altcode: 2011arXiv1110.1375W Photometric observations made by the NASA Kepler Mission have led to a dramatic increase in the number of main-sequence and subgiant stars with detected solar-like oscillations. We present an ensemble asteroseismic analysis of 76 solar-type stars. Using frequencies determined from the Kepler time-series photometry, we have measured three asteroseismic parameters that characterize the oscillations: the large frequency separation (Δν), the small frequency separation between modes of l = 0 and l = 2 (δν02), and the dimensionless offset (epsilon). These measurements allow us to construct asteroseismic diagrams, namely the so-called Christensen-Dalsgaard diagram of δν02 versus Δν, and the recently re-introduced epsilon diagram. We compare the Kepler results with previously observed solar-type stars and with theoretical models. The positions of stars in these diagrams places constraints on their masses and ages. Additionally, we confirm the observational relationship between epsilon and T eff that allows for the unambiguous determination of radial order and should help resolve the problem of mode identification in F stars. Title: The Observatorio del Teide welcomes SONG:the Stellar Observations Network Group Authors: Creevey, O. L.; Grundahl, F.; Pallé, P. L.; Gråe Jørgensen, U.; Belmonte, J. A.; Christensen-Dalsgaard, J.; Frandsen, S.; Kjeldsen, H.; Kjærgaard, P. Bibcode: 2011hsa6.conf..686C Altcode: 2011arXiv1112.5539C The Stellar Observations Network Group (SONG) is an internationalnetwork project aiming to place eight 1 m robotic telescopes around the globe,with the primary objectives of studying stellar oscillations and planetsusing ultra-precision radial velocity measurements.The prototype of SONG will be installed and running at the Observatoriodel Teide by Summer 2011. In these proceedings we present the project, primary scientific objectives, and instrument, and discussthe observing possibilities for the Spanish community. Title: Constructing a One-solar-mass Evolutionary Sequence Using Asteroseismic Data from Kepler Authors: Silva Aguirre, V.; Chaplin, W. J.; Ballot, J.; Basu, S.; Bedding, T. R.; Serenelli, A. M.; Verner, G. A.; Miglio, A.; Monteiro, M. J. P. F. G.; Weiss, A.; Appourchaux, T.; Bonanno, A.; Broomhall, A. M.; Bruntt, H.; Campante, T. L.; Casagrande, L.; Corsaro, E.; Elsworth, Y.; García, R. A.; Gaulme, P.; Handberg, R.; Hekker, S.; Huber, D.; Karoff, C.; Mathur, S.; Mosser, B.; Salabert, D.; Schönrich, R.; Sousa, S. G.; Stello, D.; White, T. R.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Houdek, G.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Thompson, M. J.; Caldwell, D. A.; Christiansen, J. L.; Wohler, B. Bibcode: 2011ApJ...740L...2S Altcode: 2011arXiv1108.2031S Asteroseismology of solar-type stars has entered a new era of large surveys with the success of the NASA Kepler mission, which is providing exquisite data on oscillations of stars across the Hertzsprung-Russell diagram. From the time-series photometry, the two seismic parameters that can be most readily extracted are the large frequency separation (Δν) and the frequency of maximum oscillation power (νmax). After the survey phase, these quantities are available for hundreds of solar-type stars. By scaling from solar values, we use these two asteroseismic observables to identify for the first time an evolutionary sequence of 1 M sun field stars, without the need for further information from stellar models. Comparison of our determinations with the few available spectroscopic results shows an excellent level of agreement. We discuss the potential of the method for differential analysis throughout the main-sequence evolution and the possibility of detecting twins of very well-known stars. Title: The Kepler characterization of the variability among A- and F-type stars. I. General overview Authors: Uytterhoeven, K.; Moya, A.; Grigahcène, A.; Guzik, J. A.; Gutiérrez-Soto, J.; Smalley, B.; Handler, G.; Balona, L. A.; Niemczura, E.; Fox Machado, L.; Benatti, S.; Chapellier, E.; Tkachenko, A.; Szabó, R.; Suárez, J. C.; Ripepi, V.; Pascual, J.; Mathias, P.; Martín-Ruíz, S.; Lehmann, H.; Jackiewicz, J.; Hekker, S.; Gruberbauer, M.; García, R. A.; Dumusque, X.; Díaz-Fraile, D.; Bradley, P.; Antoci, V.; Roth, M.; Leroy, B.; Murphy, S. J.; De Cat, P.; Cuypers, J.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Breger, M.; Pigulski, A.; Kiss, L. L.; Still, M.; Thompson, S. E.; van Cleve, J. Bibcode: 2011A&A...534A.125U Altcode: 2011arXiv1107.0335U Context. The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds of A-F type stars.
Aims: We present a first general characterization of the pulsational behaviour of A-F type stars as observed in the Kepler light curves of a sample of 750 candidate A-F type stars, and observationally investigate the relation between γ Doradus (γ Dor), δ Scuti (δ Sct), and hybrid stars.
Methods: We compile a database of physical parameters for the sample stars from the literature and new ground-based observations. We analyse the Kepler light curve of each star and extract the pulsational frequencies using different frequency analysis methods. We construct two new observables, "energy" and "efficiency", related to the driving energy of the pulsation mode and the convective efficiency of the outer convective zone, respectively.
Results: We propose three main groups to describe the observed variety in pulsating A-F type stars: γ Dor, δ Sct, and hybrid stars. We assign 63% of our sample to one of the three groups, and identify the remaining part as rotationally modulated/active stars, binaries, stars of different spectral type, or stars that show no clear periodic variability. 23% of the stars (171 stars) are hybrid stars, which is a much higher fraction than what has been observed before. We characterize for the first time a large number of A-F type stars (475 stars) in terms of number of detected frequencies, frequency range, and typical pulsation amplitudes. The majority of hybrid stars show frequencies with all kinds of periodicities within the γ Dor and δ Sct range, also between 5 and 10 d-1, which is a challenge for the current models. We find indications for the existence of δ Sct and γ Dor stars beyond the edges of the current observational instability strips. The hybrid stars occupy the entire region within the δ Sct and γ Dor instability strips and beyond. Non-variable stars seem to exist within the instability strips. The location of γ Dor and δ Sct classes in the (Teff, log g)-diagram has been extended. We investigate two newly constructed variables, "efficiency" and "energy", as a means to explore the relation between γ Dor and δ Sct stars.
Conclusions: Our results suggest a revision of the current observational instability strips of δ Sct and γ Dor stars and imply an investigation of pulsation mechanisms to supplement the κ mechanism and convective blocking effect to drive hybrid pulsations. Accurate physical parameters for all stars are needed to confirm these findings. Title: Fourier analysis of non-Blazhko ab-type RR Lyrae stars observed with the Kepler space telescope Authors: Nemec, J. M.; Smolec, R.; Benkő, J. M.; Moskalik, P.; Kolenberg, K.; Szabó, R.; Kurtz, D. W.; Bryson, S.; Guggenberger, E.; Chadid, M.; Jeon, Y. -B.; Kunder, A.; Layden, A. C.; Kinemuchi, K.; Kiss, L. L.; Poretti, E.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Caldwell, D.; Ripepi, V.; Derekas, A.; Nuspl, J.; Mullally, F.; Thompson, S. E.; Borucki, W. J. Bibcode: 2011MNRAS.417.1022N Altcode: 2011arXiv1106.6120N; 2011MNRAS.tmp.1514N Nineteen of the ∼40 RR Lyr stars in the Kepler field have been identified as candidate non-Blazhko (or unmodulated) stars. In this paper we present the results of Fourier decomposition of the time-series photometry of these stars acquired during the first 417 d of operation (Q0-Q5) of the Kepler telescope. Fourier parameters based on ∼18 400 long-cadence observations per star (and ∼150 000 short-cadence observations for FN Lyr and for AW Dra) are derived. None of the stars shows the recently discovered 'period-doubling' effect seen in Blazhko variables; however, KIC 7021124 has been found to pulsate simultaneously in the fundamental and second overtone modes with a period ratio P2/P0∼ 0.593 05 and is similar to the double-mode star V350 Lyr. Period change rates are derived from O - C diagrams spanning, in some cases, over 100 years; these are compared with high-precision periods derived from the Kepler data alone. Extant Fourier correlations by Kovács, Jurcsik et al. (with minor transformations from the V to the Kp passband) have been used to derive underlying physical characteristics for all the stars. This procedure seems to be validated through comparisons of the Kepler variables with Galactic and Large Magellanic Cloud (LMC) RR Lyr stars. The most metal-poor star in the sample is NR Lyr, with [Fe/H] =-2.3 dex; and the four most metal-rich stars have [Fe/H] ranging from -0.6 to +0.1 dex. Pulsational luminosities and masses are found to be systematically smaller than L and ? values derived from stellar evolution models, and are favoured over the evolutionary values when periods are computed with the Warsaw linear hydrodynamics code. Finally, the Fourier parameters are compared with theoretical values derived using the Warsaw non-linear convective pulsation code. Title: Asteroseismology from multi-month Kepler photometry: the evolved Sun-like stars KIC 10273246 and KIC 10920273 Authors: Campante, T. L.; Handberg, R.; Mathur, S.; Appourchaux, T.; Bedding, T. R.; Chaplin, W. J.; García, R. A.; Mosser, B.; Benomar, O.; Bonanno, A.; Corsaro, E.; Fletcher, S. T.; Gaulme, P.; Hekker, S.; Karoff, C.; Régulo, C.; Salabert, D.; Verner, G. A.; White, T. R.; Houdek, G.; Brandão, I. M.; Creevey, O. L.; Doǧan, G.; Bazot, M.; Christensen-Dalsgaard, J.; Cunha, M. S.; Elsworth, Y.; Huber, D.; Kjeldsen, H.; Lundkvist, M.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Stello, D.; Clarke, B. D.; Girouard, F. R.; Hall, J. R. Bibcode: 2011A&A...534A...6C Altcode: 2011arXiv1108.3807C Context. The evolved main-sequence Sun-like stars KIC 10273246 (F-type) and KIC 10920273 (G-type) were observed with the NASA Kepler satellite for approximately ten months with a duty cycle in excess of 90%. Such continuous and long observations are unprecedented for solar-type stars other than the Sun.
Aims: We aimed mainly at extracting estimates of p-mode frequencies - as well as of other individual mode parameters - from the power spectra of the light curves of both stars, thus providing scope for a full seismic characterization.
Methods: The light curves were corrected for instrumental effects in a manner independent of the Kepler science pipeline. Estimation of individual mode parameters was based both on the maximization of the likelihood of a model describing the power spectrum and on a classic prewhitening method. Finally, we employed a procedure for selecting frequency lists to be used in stellar modeling.
Results: A total of 30 and 21 modes of degree l = 0,1,2 - spanning at least eight radial orders - have been identified for KIC 10273246 and KIC 10920273, respectively. Two avoided crossings (l = 1 ridge) have been identified for KIC 10273246, whereas one avoided crossing plus another likely one have been identified for KIC 10920273. Good agreement is found between observed and predicted mode amplitudes for the F-type star KIC 10273246, based on a revised scaling relation. Estimates are given of the rotational periods, the parameters describing stellar granulation and the global asteroseismic parameters Δν and νmax. Title: An Asteroseismic Membership Study of the Red Giants in Three Open Clusters Observed by Kepler: NGC 6791, NGC 6819, and NGC 6811 Authors: Stello, Dennis; Meibom, Søren; Gilliland, Ronald L.; Grundahl, Frank; Hekker, Saskia; Mosser, Benoît; Kallinger, Thomas; Mathur, Savita; García, Rafael A.; Huber, Daniel; Basu, Sarbani; Bedding, Timothy R.; Brogaard, Karsten; Chaplin, William J.; Elsworth, Yvonne P.; Molenda-Żakowicz, Joanna; Szabó, Robert; Still, Martin; Jenkins, Jon M.; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans; Serenelli, Aldo M.; Wohler, Bill Bibcode: 2011ApJ...739...13S Altcode: 2011arXiv1107.1234S Studying star clusters offers significant advances in stellar astrophysics due to the combined power of having many stars with essentially the same distance, age, and initial composition. This makes clusters excellent test benches for verification of stellar evolution theory. To fully exploit this potential, it is vital that the star sample is uncontaminated by stars that are not members of the cluster. Techniques for determining cluster membership therefore play a key role in the investigation of clusters. We present results on three clusters in the Kepler field of view based on a newly established technique that uses asteroseismology to identify fore- or background stars in the field, which demonstrates advantages over classical methods such as kinematic and photometry measurements. Four previously identified seismic non-members in NGC 6819 are confirmed in this study, and three additional non-members are found—two in NGC 6819 and one in NGC 6791. We further highlight which stars are, or might be, affected by blending, which needs to be taken into account when analyzing these Kepler data. Title: The excitation of solar-like oscillations in a δSct star by efficient envelope convection Authors: Antoci, V.; Handler, G.; Campante, T. L.; Thygesen, A. O.; Moya, A.; Kallinger, T.; Stello, D.; Grigahcène, A.; Kjeldsen, H.; Bedding, T. R.; Lüftinger, T.; Christensen-Dalsgaard, J.; Catanzaro, G.; Frasca, A.; De Cat, P.; Uytterhoeven, K.; Bruntt, H.; Houdek, G.; Kurtz, D. W.; Lenz, P.; Kaiser, A.; van Cleve, J.; Allen, C.; Clarke, B. D. Bibcode: 2011Natur.477..570A Altcode: 2011arXiv1109.4285A Delta Scuti (δSct) stars are opacity-driven pulsators with masses of 1.5-2.5Msolar, their pulsations resulting from the varying ionization of helium. In less massive stars such as the Sun, convection transports mass and energy through the outer 30per cent of the star and excites a rich spectrum of resonant acoustic modes. Based on the solar example, with no firm theoretical basis, models predict that the convective envelope in δSct stars extends only about 1per cent of the radius, but with sufficient energy to excite solar-like oscillations. This was not observed before the Kepler mission, so the presence of a convective envelope in the models has been questioned. Here we report the detection of solar-like oscillations in the δSct star HD187547, implying that surface convection operates efficiently in stars about twice as massive as the Sun, as the ad hoc models predicted. Title: Verification of the Kepler Input Catalog from Asteroseismology of Solar-type Stars Authors: Verner, G. A.; Chaplin, W. J.; Basu, S.; Brown, T. M.; Hekker, S.; Huber, D.; Karoff, C.; Mathur, S.; Metcalfe, T. S.; Mosser, B.; Quirion, P. -O.; Appourchaux, T.; Bedding, T. R.; Bruntt, H.; Campante, T. L.; Elsworth, Y.; García, R. A.; Handberg, R.; Régulo, C.; Roxburgh, I. W.; Stello, D.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Allen, C.; Clarke, B. D.; Girouard, F. R. Bibcode: 2011ApJ...738L..28V Altcode: 2011arXiv1109.0869V We calculate precise stellar radii and surface gravities from the asteroseismic analysis of over 500 solar-type pulsating stars observed by the Kepler space telescope. These physical stellar properties are compared with those given in the Kepler Input Catalog (KIC), determined from ground-based multi-color photometry. For the stars in our sample, we find general agreement but we detect an average overestimation bias of 0.23 dex in the KIC determination of log (g) for stars with log (g)KIC > 4.0 dex, and a resultant underestimation bias of up to 50% in the KIC radii estimates for stars with R KIC < 2 R sun. Part of the difference may arise from selection bias in the asteroseismic sample; nevertheless, this result implies there may be fewer stars characterized in the KIC with R ~ 1 R sun than is suggested by the physical properties in the KIC. Furthermore, if the radius estimates are taken from the KIC for these affected stars and then used to calculate the size of transiting planets, a similar underestimation bias may be applied to the planetary radii. Title: ADIPLS: Aarhus Adiabatic Oscillation Package (ADIPACK) Authors: Christensen-Dalsgaard, J. Bibcode: 2011ascl.soft09002C Altcode: The goal of the development of the Aarhus Adiabatic Oscillation Package was to have a simple and efficient tool for the computation of adiabatic oscillation frequencies and eigenfunctions for general stellar models, emphasizing also the accuracy of the results. The Fortran code offers considerable flexibility in the choice of integration method as well as ability to determine all frequencies of a given model, in a given range of degree and frequency. Development of the Aarhus adiabatic pulsation code started around 1978. Although the main features have been stable for more than a decade, development of the code is continuing, concerning numerical properties and output. The code has been provided as a generally available package and has seen substantial use at a number of installations. Further development of the package, including bringing the documentation closer to being up to date, is planned as part of the HELAS Coordination Action. Title: Amplitudes of Solar-like Oscillations: Constraints from Red Giants in Open Clusters Observed by Kepler Authors: Stello, Dennis; Huber, Daniel; Kallinger, Thomas; Basu, Sarbani; Mosser, Benoît; Hekker, Saskia; Mathur, Savita; García, Rafael A.; Bedding, Timothy R.; Kjeldsen, Hans; Gilliland, Ronald L.; Verner, Graham A.; Chaplin, William J.; Benomar, Othman; Meibom, Søren; Grundahl, Frank; Elsworth, Yvonne P.; Molenda-Żakowicz, Joanna; Szabó, Robert; Christensen-Dalsgaard, Jørgen; Tenenbaum, Peter; Twicken, Joseph D.; Uddin, Kamal Bibcode: 2011ApJ...737L..10S Altcode: 2011arXiv1107.0490S Scaling relations that link asteroseismic quantities to global stellar properties are important for gaining understanding of the intricate physics that underpins stellar pulsations. The common notion that all stars in an open cluster have essentially the same distance, age, and initial composition implies that the stellar parameters can be measured to much higher precision than what is usually achievable for single stars. This makes clusters ideal for exploring the relation between the mode amplitude of solar-like oscillations and the global stellar properties. We have analyzed data obtained with NASA's Kepler space telescope to study solar-like oscillations in 100 red giant stars located in either of the three open clusters, NGC 6791, NGC 6819, and NGC 6811. By fitting the measured amplitudes to predictions from simple scaling relations that depend on luminosity, mass, and effective temperature, we find that the data cannot be described by any power of the luminosity-to-mass ratio as previously assumed. As a result we provide a new improved empirical relation which treats luminosity and mass separately. This relation turns out to also work remarkably well for main-sequence and subgiant stars. In addition, the measured amplitudes reveal the potential presence of a number of previously unknown unresolved binaries in the red clump in NGC 6791 and NGC 6819, pointing to an interesting new application for asteroseismology as a probe into the formation history of open clusters. Title: Non-Blazhko RR Lyrae Stars Observed with the KEPLER Space Telescope Authors: Nemec, J. M.; Smolec, R.; Benko, J. M.; Moskalik, P.; Kolenberg, K.; Szabó, R.; Kurtz, D. W.; Bryson, S.; Guggenberger, E.; Chadid, M.; Jeon, Y. -B.; Kunder, A.; Layden, A. C.; Kinemuchi, K.; Kiss, L. L.; Poretti, E.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Caldwell, D.; Ripepi, V.; Derekas, A.; Nuspl, J.; Mullally, F.; Thompson, S. E.; Borucki, W. J. Bibcode: 2011rrls.conf...84N Altcode: 2011arXiv1108.5683N This paper summarizes the main results of our recent study of the non-Blazhko RR Lyrae stars observed with the Kepler space telescope. These stars offer the opportunity for studying the stability of the pulsations of RR Lyrae stars and for providing a reference against which the Blazhko RR Lyrae stars can be compared. Of particular interest is the stationarity of the low-dispersion (σ < 1mmag) light curves constructed from ∼18000 long-cadence (30-min) and (for FN Lyr and AW Dra) the ∼150000 short-cadence (1-min) photometric data points. Fourier-based [Fe/H] values and other physical characteristics are also derived. When the observed periods are compared with periods computed with the Warsaw non-linear convective pulsation code better agreement is achieved assuming pulsational L and M values rather than the (higher) evolutionary L and M values. Title: Using SONG to probe rapid variability and evolution of starspots Authors: Neff, James E.; Hakkila, Jon; Hill, Frank; Jackiewicz, Jason; Metcalfe, Travis S.; Christensen-Dalsgaard, Jørgen; Frandsen, Søren; Grundahl, Frank; Kjeldsen, Hans; Jørgensen, Uffe Gråe; Rasmussen, Per Kjærgaard; Gu, Sheng-Hong Bibcode: 2011IAUS..273..451N Altcode: The Stellar Observations Network Group (SONG) is being developed as a network of 1-meter spectroscopic telescopes designed for and primarily dedicated to asteroseismology. It is patterned after the highly successful GONG project. The Danish prototype telescope will be installed in Tenerife in early 2011. Ultimately we hope to have as many as 8 identical nodes providing continuous high-resolution spectroscopic observations for targets anywhere in the sky. The primary scientific goals of SONG are asteroseismology and the search for Earth-mass exoplanets. The spectroscopic requirements for these programs push the limits of current technology, but the resulting spectrograph design will enable many secondary science programs with less stringent requirements. Doppler imaging of starspots can be accomplished using continuous observations over several stellar rotations using identical instrumentation at each node. It should be possible to observe the evolution of starspot morphology in real-time, for example. We discuss the design and status of the SONG project in general, and we describe how SONG could be used to probe short timescale changes in stellar surface structure. Title: Stellar hydrodynamics caught in the act: Asteroseismology with CoRoT and Kepler Authors: Christensen-Dalsgaard, Jørgen; Thompson, Michael J. Bibcode: 2011IAUS..271...32C Altcode: 2011arXiv1104.5191C Asteroseismic investigations, particularly based on data on stellar oscillations from the CoRoT and Kepler space missions, are providing unique possibilities for investigating the properties of stellar interiors. This constitutes entirely new ways to study the effects of dynamic phenomena on stellar structure and evolution. Important examples are the extent of convection zones and the associated mixing and the direct and indirect effects of stellar rotation. In addition, the stellar oscillations themselves show very interesting dynamic behaviour. Here we discuss examples of the results obtained from such investigations, across the Hertzsprung-Russell diagram. Title: Solar-like oscillations from the depths of the red-giant star KIC 4351319 observed with Kepler Authors: di Mauro, M. P.; Cardini, D.; Catanzaro, G.; Ventura, R.; Barban, C.; Bedding, T. R.; Christensen-Dalsgaard, J.; De Ridder, J.; Hekker, S.; Huber, D.; Kallinger, T.; Miglio, A.; Montalban, J.; Mosser, B.; Stello, D.; Uytterhoeven, K.; Kinemuchi, K.; Kjeldsen, H.; Mullally, F.; Still, M. Bibcode: 2011MNRAS.415.3783D Altcode: 2011MNRAS.tmp.1166D; 2011arXiv1105.1076D We present the results of the asteroseismic analysis of the red-giant star KIC 4351319 (TYC 3124-914-1), observed for 30 d in short-cadence mode with the Kepler satellite. The analysis has allowed us to determine the large and small frequency separations, ?Hz and ?Hz, respectively, and the frequency of maximum oscillation power, ?Hz.

The high signal-to-noise ratio of the observations allowed us to identify 25 independent pulsation modes whose frequencies range approximately from 300 to ?Hz.

The observed oscillation frequencies together with the accurate determination of the atmospheric parameters (effective temperature, gravity and metallicity), provided by additional ground-based spectroscopic observations, enabled us to theoretically interpret the observed oscillation spectrum.

KIC 4351319 appears to oscillate with a well-defined solar-type p-mode pattern due to radial acoustic modes and non-radial nearly pure p modes. In addition, several non-radial mixed modes have been identified.

Theoretical models well reproduce the observed oscillation frequencies and indicate that this star, located at the base of the ascending red-giant branch, is in the hydrogen-shell-burning phase, with a mass of ∼1.3 M⊙, a radius of ? and an age of ∼5.6 Gyr. The main parameters of this star have been determined with an unprecedented level of precision for a red-giant star, with uncertainties of 2 per cent for mass, 7 per cent for age, 1 per cent for radius and 4 per cent for luminosity. Title: Characteristics of Planetary Candidates Observed by Kepler. II. Analysis of the First Four Months of Data Authors: Borucki, William J.; Koch, David G.; Basri, Gibor; Batalha, Natalie; Brown, Timothy M.; Bryson, Stephen T.; Caldwell, Douglas; Christensen-Dalsgaard, Jørgen; Cochran, William D.; DeVore, Edna; Dunham, Edward W.; Gautier, Thomas N., III; Geary, John C.; Gilliland, Ronald; Gould, Alan; Howell, Steve B.; Jenkins, Jon M.; Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Rowe, Jason; Sasselov, Dimitar; Boss, Alan; Charbonneau, David; Ciardi, David; Doyle, Laurance; Dupree, Andrea K.; Ford, Eric B.; Fortney, Jonathan; Holman, Matthew J.; Seager, Sara; Steffen, Jason H.; Tarter, Jill; Welsh, William F.; Allen, Christopher; Buchhave, Lars A.; Christiansen, Jessie L.; Clarke, Bruce D.; Das, Santanu; Désert, Jean-Michel; Endl, Michael; Fabrycky, Daniel; Fressin, Francois; Haas, Michael; Horch, Elliott; Howard, Andrew; Isaacson, Howard; Kjeldsen, Hans; Kolodziejczak, Jeffery; Kulesa, Craig; Li, Jie; Lucas, Philip W.; Machalek, Pavel; McCarthy, Donald; MacQueen, Phillip; Meibom, Søren; Miquel, Thibaut; Prsa, Andrej; Quinn, Samuel N.; Quintana, Elisa V.; Ragozzine, Darin; Sherry, William; Shporer, Avi; Tenenbaum, Peter; Torres, Guillermo; Twicken, Joseph D.; Van Cleve, Jeffrey; Walkowicz, Lucianne; Witteborn, Fred C.; Still, Martin Bibcode: 2011ApJ...736...19B Altcode: 2011arXiv1102.0541B On 2011 February 1 the Kepler mission released data for 156,453 stars observed from the beginning of the science observations on 2009 May 2 through September 16. There are 1235 planetary candidates with transit-like signatures detected in this period. These are associated with 997 host stars. Distributions of the characteristics of the planetary candidates are separated into five class sizes: 68 candidates of approximately Earth-size (R p < 1.25 R ⊕), 288 super-Earth-size (1.25 R ⊕ <= R p < 2 R ⊕), 662 Neptune-size (2 R ⊕ <= R p < 6 R ⊕), 165 Jupiter-size (6 R ⊕ <= R p < 15 R ⊕), and 19 up to twice the size of Jupiter (15 R ⊕ <= R p < 22 R ⊕). In the temperature range appropriate for the habitable zone, 54 candidates are found with sizes ranging from Earth-size to larger than that of Jupiter. Six are less than twice the size of the Earth. Over 74% of the planetary candidates are smaller than Neptune. The observed number versus size distribution of planetary candidates increases to a peak at two to three times the Earth-size and then declines inversely proportional to the area of the candidate. Our current best estimates of the intrinsic frequencies of planetary candidates, after correcting for geometric and sensitivity biases, are 5% for Earth-size candidates, 8% for super-Earth-size candidates, 18% for Neptune-size candidates, 2% for Jupiter-size candidates, and 0.1% for very large candidates; a total of 0.34 candidates per star. Multi-candidate, transiting systems are frequent; 17% of the host stars have multi-candidate systems, and 34% of all the candidates are part of multi-candidate systems. Title: First Kepler results on compact pulsators - VI. Targets in the final half of the survey phase Authors: Østensen, R. H.; Silvotti, R.; Charpinet, S.; Oreiro, R.; Bloemen, S.; Baran, A. S.; Reed, M. D.; Kawaler, S. D.; Telting, J. H.; Green, E. M.; O'Toole, S. J.; Aerts, C.; Gänsicke, B. T.; Marsh, T. R.; Breedt, E.; Heber, U.; Koester, D.; Quint, A. C.; Kurtz, D. W.; Rodríguez-López, C.; Vučković, M.; Ottosen, T. A.; Frimann, S.; Somero, A.; Wilson, P. A.; Thygesen, A. O.; Lindberg, J. E.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Allen, C.; McCauliff, S.; Middour, C. K. Bibcode: 2011MNRAS.414.2860O Altcode: 2011arXiv1101.4150O; 2011MNRAS.tmp..850O We present results from the final 6 months of a survey to search for pulsations in white dwarfs (WDs) and hot subdwarf stars with the Kepler spacecraft. Spectroscopic observations are used to separate the objects into accurate classes, and we explore the physical parameters of the subdwarf B (sdB) stars and white dwarfs in the sample. From the Kepler photometry and our spectroscopic data, we find that the sample contains five new pulsators of the V1093 Her type, one AM CVn type cataclysmic variable and a number of other binary systems.

This completes the survey for compact pulsators with Kepler. No V361 Hya type of short-period pulsating sdB stars were found in this half, leaving us with a total of one single multiperiodic V361 Hya and 13 V1093 Her pulsators for the full survey. Except for the sdB pulsators, no other clearly pulsating hot subdwarfs or white dwarfs were found, although a few low-amplitude candidates still remain. The most interesting targets discovered in this survey will be observed throughout the remainder of the Kepler mission, providing the most long-term photometric data sets ever made on such compact, evolved stars. Asteroseismic investigations of these data sets will be invaluable in revealing the interior structure of these stars and will boost our understanding of their evolutionary history. Title: The High Albedo of the Hot Jupiter Kepler-7 b Authors: Demory, Brice-Olivier; Seager, Sara; Madhusudhan, Nikku; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen; Gillon, Michaël; Rowe, Jason F.; Welsh, William F.; Adams, Elisabeth R.; Dupree, Andrea; McCarthy, Don; Kulesa, Craig; Borucki, William J.; Koch, David G. Bibcode: 2011ApJ...735L..12D Altcode: 2011arXiv1105.5143D Hot Jupiters are expected to be dark from both observations (albedo upper limits) and theory (alkali metals and/or TiO and VO absorption). However, only a handful of hot Jupiters have been observed with high enough photometric precision at visible wavelengths to investigate these expectations. The NASA Kepler mission provides a means to widen the sample and to assess the extent to which hot Jupiter albedos are low. We present a global analysis of Kepler-7 b based on Q0-Q4 data, published radial velocities, and asteroseismology constraints. We measure an occultation depth in the Kepler bandpass of 44 ± 5 ppm. If directly related to the albedo, this translates to a Kepler geometric albedo of 0.32 ± 0.03, the most precise value measured so far for an exoplanet. We also characterize the planetary orbital phase light curve with an amplitude of 42 ± 4 ppm. Using atmospheric models, we find it unlikely that the high albedo is due to a dominant thermal component and propose two solutions to explain the observed planetary flux. First, we interpret the Kepler-7 b albedo as resulting from an excess reflection over what can be explained solely by Rayleigh scattering, along with a nominal thermal component. This excess reflection might indicate the presence of a cloud or haze layer in the atmosphere, motivating new modeling and observational efforts. Alternatively, the albedo can be explained by Rayleigh scattering alone if Na and K are depleted in the atmosphere by a factor of 10-100 below solar abundances. Title: First Kepler results on compact pulsators - VIII. Mode identifications via period spacings in g-mode pulsating subdwarf B stars Authors: Reed, M. D.; Baran, A.; Quint, A. C.; Kawaler, S. D.; O'Toole, S. J.; Telting, J.; Charpinet, S.; Rodríguez-López, C.; Østensen, R. H.; Provencal, J. L.; Johnson, E. S.; Thompson, S. E.; Allen, C.; Middour, C. K.; Kjeldsen, H.; Christensen-Dalsgaard, J. Bibcode: 2011MNRAS.414.2885R Altcode: 2011arXiv1102.4286R; 2011MNRAS.tmp..852R We investigate the possibility of nearly equally spaced periods in 13 hot subdwarf B (sdB) stars observed with the Kepler spacecraft and one observed with CoRoT. Asymptotic limits for gravity (g-)mode pulsations provide relationships between equal-period spacings of modes with differing degrees ℓ and relationships between periods of the same radial order n but differing degrees ℓ. Period transforms, Kolmogorov-Smirnov tests and linear least-squares fits have been used to detect and determine the significance of equal-period spacings. We have also used Monte Carlo simulations to estimate the likelihood that the detected spacings could be produced randomly.

Period transforms for nine of the Kepler stars indicate ℓ= 1 period spacings, with five also showing peaks for ℓ= 2 modes. 12 stars indicate ℓ= 1 modes using the Kolmogorov-Smirnov test while another shows solely ℓ= 2 modes. Monte Carlo results indicate that equal-period spacings are significant in 10 stars above 99 per cent confidence, and 13 of the 14 are above 94 per cent confidence. For 12 stars, the various methods find consistent period spacings to within the errors, two others show some inconsistencies, likely caused by binarity, and the last has significant detections but the mode assignment disagrees between the methods.

We use asymptotic period spacing relationships to associate observed periods of variability with pulsation modes for ℓ= 1 and 2. From the Kepler first-year survey sample of 13 multiperiodic g-mode pulsators, five stars have several consecutive overtones making period spacings easy to detect, six others have fewer consecutive overtones but period spacings are readily detected, and two stars show marginal indications of equal-period spacings. We also examine a g-mode sdB pulsator observed by CoRoT with a rich pulsation spectrum, and our tests detect regular period spacings.

We use Monte Carlo simulations to estimate the significance of the detections in individual stars. From the simulations, it is determined that regular period spacings in 10 of the 14 stars are very unlikely to be random, another two are moderately unlikely to be random and two are mostly unconstrained.

We find a common ℓ= 1 period spacing spanning a range from 231 to 272 s allowing us to correlate pulsation modes with 222 periodicities and that the ℓ= 2 period spacings are related to the ℓ= 1 spacings by the asymptotic relationship ?. We briefly discuss the impact of equal-period spacings which indicate low-degree modes with a lack of significant mode trappings. Title: Kepler photometry of KIC 10661783: a binary star with total eclipses and δ Scuti pulsations Authors: Southworth, John; Zima, W.; Aerts, C.; Bruntt, H.; Lehmann, H.; Kim, S. -L.; Kurtz, D. W.; Pavlovski, K.; Prša, A.; Smalley, B.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Kawaler, S. D.; Kjeldsen, H.; Cote, M. T.; Tenenbaum, P.; Twicken, J. D. Bibcode: 2011MNRAS.414.2413S Altcode: 2011MNRAS.tmp..507S; 2011arXiv1102.3599S We present Kepler satellite photometry of KIC 10661783, a short-period binary star system which shows total eclipses and multiperiodic δ Scuti pulsations. A frequency analysis of the eclipse-subtracted light curve reveals at least 68 frequencies, of which 55 or more can be attributed to pulsation modes. The main limitation on this analysis is the frequency resolution within the 27-d short-cadence light curve. Most of the variability signal lies in the frequency range 18-31 d-1, with amplitudes between 0.1 and 4 mmag. One harmonic term (2f) and a few combination frequencies (fi+fj) have been detected. From a plot of the residuals versus orbital phase, we assign the pulsations to the primary star in the system. The pulsations were removed from the short-cadence data and the light curve was modelled using the Wilson-Devinney code. We are unable to get a perfect fit due to the residual effects of pulsations and also to the treatment of reflection and reprocessing in the light-curve model. A model where the secondary star fills its Roche lobe is favoured, which means that KIC 10661783 can be classified as an oEA system. Further photometric and spectroscopic observations will allow the masses and radii of the two stars to be measured to high precision and hundreds of δ Scuti pulsation frequencies to be resolved. This could lead to unique constraints on theoretical models of δ Scuti stars, if the evolutionary history of KIC 10661783 can be accounted for. Title: The first evidence for multiple pulsation axes: a new rapidly oscillating Ap star in the Kepler field, KIC 10195926 Authors: Kurtz, D. W.; Cunha, M. S.; Saio, H.; Bigot, L.; Balona, L. A.; Elkin, V. G.; Shibahashi, H.; Brandão, I. M.; Uytterhoeven, K.; Frandsen, S.; Frimann, S.; Hatzes, A.; Lueftinger, T.; Gruberbauer, M.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Kawaler, S. D. Bibcode: 2011MNRAS.414.2550K Altcode: 2011arXiv1102.4298K; 2011MNRAS.tmp..558K We have discovered a new rapidly oscillating Ap (roAp) star among the Kepler mission target stars, KIC 10195926. This star shows two pulsation modes with periods that are amongst the longest known for roAp stars at 17.1 and 18.1 min, indicating that the star is near the terminal-age main sequence. The principal pulsation mode is an oblique dipole mode that shows a rotationally split frequency septuplet that provides information on the geometry of the mode. The secondary mode also appears to be a dipole mode with a rotationally split triplet, but we are able to show within the improved oblique pulsator model that these two modes cannot have the same axis of pulsation. This is the first time for any pulsating star that evidence has been found for separate pulsation axes for different modes. The two modes are separated in frequency by 55 μHz, which we model as the large separation. The star is an α2 CVn spotted magnetic variable that shows a complex rotational light variation with a period of Prot= 5.684 59 d. For the first time for any spotted magnetic star of the upper main sequence, we find clear evidence of light variation with a period of twice the rotation period, that is, a subharmonic frequency of νrot/2. We propose that this and other subharmonics are the first observed manifestation of torsional modes in an roAp star. From high-resolution spectra, we determine Teff= 7400 K, log g= 3.6 and v sin i= 21 km s-1. We have found a magnetic pulsation model with fundamental parameters close to these values that reproduces the rotational variations of the two obliquely pulsating modes with different pulsation axes. The star shows overabundances of the rare earth elements, but these are not as extreme as most other roAp stars. The spectrum is variable with rotation, indicating surface abundance patches. Title: First Kepler results on compact pulsators - VII. Pulsating subdwarf B stars detected in the second half of the survey phase Authors: Baran, A. S.; Kawaler, S. D.; Reed, M. D.; Quint, A. C.; O'Toole, S. J.; Østensen, R. H.; Telting, J. H.; Silvotti, R.; Charpinet, S.; Christensen-Dalsgaard, J.; Still, M.; Hall, J. R.; Uddin, K. Bibcode: 2011MNRAS.414.2871B Altcode: 2011arXiv1103.1666B; 2011MNRAS.tmp..851B We present five new pulsating subdwarf B (sdB) stars discovered by the Kepler spacecraft during the asteroseismology survey phase. We perform time series analysis on the nearly continuous month-long Kepler data sets of these five objects; these data sets provide nearly alias-free time series photometry at unprecedented precision. Following an iterative pre-whitening process, we derive the pulsational frequency spectra of these stars, separating out artefacts of known instrumental origin. We find that these new pulsating sdB stars are multiperiodic long-period pulsators of the V1093 Her type, with the number of periodicities ranging from eight (KIC 8302197) to 53 (KIC 11558725). The frequencies and amplitudes are typical of g-mode pulsators of this type. We do not find any evidence for binarity in the five stars from their observed pulsation frequencies. As these are g-mode pulsators, we briefly looked for period spacings for mode identification and found average spacings of about 260 and 145 s. This may indicate l= 1 and 2 patterns. Some modes may show evidence of rotational splitting. These discoveries complete the list of compact pulsators found in the survey phase. Of the 13 compact pulsators, only one star was identified as a short-period (p-mode) V361 Hya pulsator, while all other new pulsators turned out to be V1093 Her class objects. Among the latter objects, two of them seemed to be pure V1093 Her while the others show additional low-amplitude peaks in the p-mode frequency range, suggesting their hybrid nature. Authenticity of these peaks will be tested with longer runs currently under analysis. Title: VizieR Online Data Catalog: Variability of A- and F-stars from Kepler (Uytterhoeven+ 2011) Authors: Uytterhoeven, K.; Moya, A.; Grigahcene, A.; Guzik, J. A.; Gutierrez-Soto, J.; Smalley, B.; Handler, G.; Balona, L. A.; Niemczura, E.; Fox Machado, L.; Benatti, S.; Chapellier, E.; Tkachenko, A.; Szabo, R.; Suarez, J. C.; Ripepi, V.; Pascual, J.; Mathias, P.; Martin-Ruiz, S.; Lehmann, H.; Jackiewicz, J.; Hekker, S.; Gruberbauer, M.; Garcia, R. A.; Dumusque, X.; Diaz-Fraile, D.; Bradley, P.; Antoci, V.; Roth, M.; Leroy, B.; Murphy, S. J.; De Cat, P.; Cuypers, J.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Breger, M.; Pigulski, A.; Kiss, L. L.; Still, M.; Thompson, S. E.; van Cleve, J. Bibcode: 2011yCat..35340125U Altcode: 2011yCat..35349125U We compile a database of physical parameters for the sample stars from the literature and new ground-based observations. We analyse the Kepler light curve of each star and extract the pulsational frequencies using different frequency analysis methods. We construct two new observables, 'energy' and 'efficiency', related to the driving energy of the pulsation mode and the convective efficiency of the outer convective zone, respectively.

(5 data files). Title: Cepheid investigations using the Kepler space telescope Authors: Szabó, R.; Szabados, L.; Ngeow, C. -C.; Smolec, R.; Derekas, A.; Moskalik, P.; Nuspl, J.; Lehmann, H.; Fżrész, G.; Molenda-Żakowicz, J.; Bryson, S. T.; Henden, A. A.; Kurtz, D. W.; Stello, D.; Nemec, J. M.; Benkő, J. M.; Berdnikov, L.; Bruntt, H.; Evans, N. R.; Gorynya, N. A.; Pastukhova, E. N.; Simcoe, R. J.; Grindlay, J. E.; Los, E. J.; Doane, A.; Laycock, S. G.; Mink, D. J.; Champine, G.; Sliski, A.; Handler, G.; Kiss, L. L.; Kolláth, Z.; Kovács, J.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Allen, C.; Thompson, S. E.; van Cleve, J. Bibcode: 2011MNRAS.413.2709S Altcode: 2011MNRAS.tmp..332S; 2011arXiv1101.2443S We report results of initial work done on selected candidate Cepheids to be observed with the Kepler space telescope. Prior to the launch, 40 candidates were selected from previous surveys and data bases. The analysis of the first 322 d of Kepler photometry, and recent ground-based follow-up multicolour photometry and spectroscopy allowed us to confirm that one of these stars, V1154 Cyg (KIC 7548061), is indeed a 4.9-d Cepheid. Using the phase lag method, we show that this star pulsates in the fundamental mode. New radial velocity data are consistent with previous measurements, suggesting that a long-period binary component is unlikely. No evidence is seen in the ultraprecise, nearly uninterrupted Kepler photometry for non-radial or stochastically excited modes at the micromagnitude level. The other candidates are not Cepheids, but an interesting mix of possible spotted stars, eclipsing systems and flare stars. Title: Solar-like Oscillations in KIC 11395018 and KIC 11234888 from 8 Months of Kepler Data Authors: Mathur, S.; Handberg, R.; Campante, T. L.; García, R. A.; Appourchaux, T.; Bedding, T. R.; Mosser, B.; Chaplin, W. J.; Ballot, J.; Benomar, O.; Bonanno, A.; Corsaro, E.; Gaulme, P.; Hekker, S.; Régulo, C.; Salabert, D.; Verner, G.; White, T. R.; Brandão, I. M.; Creevey, O. L.; Doǧan, G.; Elsworth, Y.; Huber, D.; Hale, S. J.; Houdek, G.; Karoff, C.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Quintana, E. V.; Sanderfer, D. T.; Seader, S. E. Bibcode: 2011ApJ...733...95M Altcode: 2011arXiv1103.4085M We analyze the photometric short-cadence data obtained with the Kepler mission during the first 8 months of observations of two solar-type stars of spectral types G and F: KIC 11395018 and KIC 11234888, respectively, the latter having a lower signal-to-noise ratio (S/N) compared with the former. We estimate global parameters of the acoustic (p) modes such as the average large and small frequency separations, the frequency of the maximum of the p-mode envelope, and the average line width of the acoustic modes. We were able to identify and to measure 22 p-mode frequencies for the first star and 16 for the second one even though the S/N of these stars are rather low. We also derive some information about the stellar rotation periods from the analyses of the low-frequency parts of the power spectral densities. A model-independent estimation of the mean density, mass, and radius is obtained using the scaling laws. We emphasize the importance of continued observations for the stars with low S/N for an improved characterization of the oscillation modes. Our results offer a preview of what will be possible for many stars with the long data sets obtained during the remainder of the mission. Title: A more realistic representation of overshoot at the base of the solar convective envelope as seen by helioseismology Authors: Christensen-Dalsgaard, J.; Monteiro, M. J. P. F. G.; Rempel, M.; Thompson, M. J. Bibcode: 2011MNRAS.414.1158C Altcode: 2011MNRAS.tmp..440C; 2011arXiv1102.0235C The stratification near the base of the Sun's convective envelope is governed by processes of convective overshooting and element diffusion, and the region is widely believed to play a key role in the solar dynamo. The stratification in that region gives rise to a characteristic signal in the frequencies of solar p modes, which has been used to determine the depth of the solar convection zone and to investigate the extent of convective overshoot. Previous helioseismic investigations have shown that the Sun's spherically symmetric stratification in this region is smoother than that in a standard solar model without overshooting, and have ruled out simple models incorporating overshooting, which extend the region of adiabatic stratification and have a more-or-less abrupt transition to subadiabatic stratification at the edge of the overshoot region. In this paper we consider physically motivated models which have a smooth transition in stratification bridging the region from the lower convection zone to the radiative interior beneath. We find that such a model is in better agreement with the helioseismic data than a standard solar model. Title: Preparation of Kepler light curves for asteroseismic analyses Authors: García, R. A.; Hekker, S.; Stello, D.; Gutiérrez-Soto, J.; Handberg, R.; Huber, D.; Karoff, C.; Uytterhoeven, K.; Appourchaux, T.; Chaplin, W. J.; Elsworth, Y.; Mathur, S.; Ballot, J.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Houdek, G.; Jenkins, J. M.; Kjeldsen, H.; McCauliff, S.; Metcalfe, T.; Middour, C. K.; Molenda-Zakowicz, J.; Monteiro, M. J. P. F. G.; Smith, J. C.; Thompson, M. J. Bibcode: 2011MNRAS.414L...6G Altcode: 2011arXiv1103.0382G The Kepler mission is providing photometric data of exquisite quality for the asteroseismic study of different classes of pulsating stars. These analyses place particular demands on the pre-processing of the data, over a range of time-scales from minutes to months. Here, we describe processing procedures developed by the Kepler Asteroseismic Science Consortium to prepare light curves that are optimized for the asteroseismic study of solar-like oscillating stars in which outliers, jumps and drifts are corrected. Title: Regularities in frequency spacings of δ Scuti stars: the Kepler star KIC 9700322 Authors: Breger, M.; Balona, L.; Lenz, P.; Hollek, J. K.; Kurtz, D. W.; Catanzaro, G.; Marconi, M.; Pamyatnykh, A. A.; Smalley, B.; Suárez, J. C.; Szabo, R.; Uytterhoeven, K.; Ripepi, V.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Fanelli, M. N.; Ibrahim, K. A.; Uddin, K. Bibcode: 2011MNRAS.414.1721B Altcode: 2010arXiv1012.4373B; 2011MNRAS.tmp..479B In the faint star KIC 9700322 observed by the Kepler satellite, 76 frequencies with amplitudes from 14 to 29 000 ppm were detected. The two dominant frequencies at 9.79 and 12.57 d-1 (113.3 and 145.5 μHz), interpreted to be radial modes, are accompanied by a large number of combination frequencies. A small additional modulation with a 0.16 d-1 frequency is also seen; this is interpreted to be the rotation frequency of the star. The corresponding prediction of slow rotation is confirmed by a spectrum from which v sin i= 19 ± 1 km s-1 is obtained. The analysis of the spectrum shows that the star is one of the coolest δ Sct variables. We also determine Teff = 6700 ± 100 K and log g = 3.7 ± 0.1, compatible with the observed frequencies of the radial modes. Normal solar abundances are found. An ℓ= 2 frequency quintuplet is also detected with a frequency separation consistent with predictions from the measured rotation rate. A remarkable result is the absence of additional independent frequencies down to an amplitude limit near 14 ppm, suggesting that the star is stable against most forms of non-radial pulsation. A low-frequency peak at 2.7763 d-1 in KIC 9700322 is the frequency difference between the two dominant modes and is repeated over and over in various frequency combinations involving the two dominant modes. The relative phases of the combination frequencies show a strong correlation with frequency, but the physical significance of this result is not clear. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München and Georg-August-Universität Göttingen. Title: Deep asteroseismic sounding of the compact hot B subdwarf pulsator KIC02697388 from Kepler time series photometry Authors: Charpinet, S.; Van Grootel, V.; Fontaine, G.; Green, E. M.; Brassard, P.; Randall, S. K.; Silvotti, R.; Østensen, R. H.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Kawaler, S. D.; Clarke, B. D.; Li, J.; Wohler, B. Bibcode: 2011A&A...530A...3C Altcode: Context. Contemporary high precision photometry from space provided by the Kepler and CoRoT satellites generates significant breakthroughs in terms of exploiting the long-period, g-mode pulsating hot B subdwarf (sdBVs) stars with asteroseismology.
Aims: We present a detailed asteroseismic study of the sdBVs star KIC02697388 monitored with Kepler, using the rich pulsation spectrum uncovered during the ~27-day-long exploratory run Q2.3.
Methods: We analyse new high-S/N spectroscopy of KIC02697388 using appropriate NLTE model atmospheres to provide accurate atmospheric parameters for this star. We also reanalyse the Kepler light curve using standard prewhitening techniques. On this basis, we apply a forward modelling technique using our latest generation of sdB models. The simultaneous match of the independent periods observed in KIC02697388 with those of models leads objectively to the identification of the pulsation modes and, more importantly, to the determination of some of the parameters of the star.
Results: The light curve analysis reveals 43 independent frequencies that can be associated with oscillation modes. All the modulations observed in this star correspond to g-mode pulsations except one high-frequency signal, which is typical of a p-mode oscillation. Although the presence of this p-mode is surprising considering the atmospheric parameters that we derive for this cool sdB star (Teff = 25 395 ± 227 K, log g = 5.500 ± 0.031 (cgs), and log N(He) /N(H) = -2.767 ± 0.122), we show that this mode can be accounted for particularly well by our optimal seismic models, both in terms of frequency match and nonadiabatic properties. The seismic analysis leads us to identify two model solutions that can both account for the observed pulsation properties of KIC02697388. Despite this remaining ambiguity, several key parameters of the star can be derived with stringent constraints, such as its mass, its H-rich envelope mass, its radius, and its luminosity. We derive the properties of the core proposing that it is a relatively young sdB star that has burnt less than ~34% (in mass) of its central helium and has a relatively large mixed He/C/O core. This latter measurement is in line with the trend already uncovered for two other g-mode sdB pulsators analysed with asteroseismology and suggests that extra mixing is occurring quite early in the evolution of He cores on the horizontal branch.
Conclusions: Additional monitoring with Kepler of this particularly interesting sdB star should reveal the inner properties of KIC02697388 and provide important information about the mode driving mechanism and the helium core properties.

Tables 3 and 4 are available in electronic form at http://www.aanda.org Title: Asteroseismic inferences on red giants in open clusters NGC 6791, NGC 6819, and NGC 6811 using Kepler Authors: Hekker, S.; Basu, S.; Stello, D.; Kallinger, T.; Grundahl, F.; Mathur, S.; García, R. A.; Mosser, B.; Huber, D.; Bedding, T. R.; Szabó, R.; De Ridder, J.; Chaplin, W. J.; Elsworth, Y.; Hale, S. J.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Still, M.; McCauliff, S.; Quintana, E. V. Bibcode: 2011A&A...530A.100H Altcode: 2011arXiv1104.4393H Context. Four open clusters are present in the Kepler field of view and timeseries of nearly a year in length are now available. These timeseries allow us to derive asteroseismic global oscillation parameters of red-giant stars in the three open clusters NGC 6791, NGC 6819 and NGC 6811. From these parameters and effective temperatures, we derive masses, radii and luminosities for the clusters as well as field red giants.
Aims: We study the influence of evolution and metallicity on the observed red-giant populations.
Methods: The global oscillation parameters are derived using different published methods and the effective temperatures are derived from 2MASS colours. The observational results are compared with BaSTI evolution models.
Results: We find that the mass has significant influence on the asteroseismic quantities Δν vs. νmax relation, while the influence of metallicity is negligible, under the assumption that the metallicity does not affect the excitation/damping of the oscillations. The positions of the stars in the H-R diagram depend on both mass and metallicity. Furthermore, the stellar masses derived for the field stars are bracketed by those of the cluster stars.
Conclusions: Both the mass and metallicity contribute to the observed difference in locations in the H-R diagram of the old metal-rich cluster NGC 6791 and the middle-aged solar-metallicity cluster NGC 6819. For the young cluster NGC 6811, the explanation of the position of the stars in the H-R diagram challenges the assumption of solar metallicity, and this open cluster might have significantly lower metallicity [Fe/H] in the range - 0.3 to - 0.7 dex. Also, nearly all the observed field stars seem to be older than NGC 6811 and younger than NGC 6791. Title: Kepler observations of the variability in B-type stars Authors: Balona, L. A.; Pigulski, A.; De Cat, P.; Handler, G.; Gutiérrez-Soto, J.; Engelbrecht, C. A.; Frescura, F.; Briquet, M.; Cuypers, J.; Daszyńska-Daszkiewicz, J.; Degroote, P.; Dukes, R. J.; Garcia, R. A.; Green, E. M.; Heber, U.; Kawaler, S. D.; Lehmann, H.; Leroy, B.; Molenda-Żaaowicz, J.; Neiner, C.; Noels, A.; Nuspl, J.; Østensen, R.; Pricopi, D.; Roxburgh, I.; Salmon, S.; Smith, M. A.; Suárez, J. C.; Suran, M.; Szabó, R.; Uytterhoeven, K.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Caldwell, D. A.; Girouard, F. R.; Sanderfer, D. T. Bibcode: 2011MNRAS.413.2403B Altcode: 2011MNRAS.tmp..298B; 2011arXiv1103.0644B The analysis of the light curves of 48 B-type stars observed by Kepler is presented. Among these are 15 pulsating stars, all of which show low frequencies, characteristic of slowly pulsating B (SPB) stars. Seven of these stars also show a few weak, isolated high frequencies and they could be considered as SPB/β Cephei (β Cep) hybrids. In all cases, the frequency spectra are quite different from what is seen from ground-based observations. We suggest that this is because most of the low frequencies are modes of high degree which are predicted to be unstable in models of mid-B stars. We find that there are non-pulsating stars within the β Cep and SPB instability strips. Apart from the pulsating stars, we can identify stars with frequency groupings similar to what is seen in Be stars but which are not Be stars. The origin of the groupings is not clear, but may be related to rotation. We find periodic variations in other stars which we attribute to proximity effects in binary systems or possibly rotational modulation. We find no evidence for pulsating stars between the cool edge of the SPB and the hot edge of the δ Sct instability strips. None of the stars shows the broad features which can be attributed to stochastically excited modes as recently proposed. Among our sample of B stars are two chemically peculiar stars, one of which is a HgMn star showing rotational modulation in the light curve. Title: Kepler observations of Am stars Authors: Balona, L. A.; Ripepi, V.; Catanzaro, G.; Kurtz, D. W.; Smalley, B.; De Cat, P.; Eyer, L.; Grigahcène, A.; Leccia, S.; Southworth, J.; Uytterhoeven, K.; van Winckel, H.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Caldwell, D. A.; van Cleve, J.; Girouard, F. R. Bibcode: 2011MNRAS.414..792B Altcode: 2011MNRAS.tmp..396B We present an analysis of high-resolution spectra for two pulsating Am stars in the Kepler field. The stellar parameters derived in this way are important because parameters derived from narrow-band photometry may be affected by the strong metal lines in these stars. We analyse the Kepler time series of ten known Am stars and find that six of them clearly show δ Scuti pulsations. The other four appear to be non-pulsating. We derive fundamental parameters for all known pulsating Am stars from ground-based observations and also for the Kepler Am stars to investigate the location of the instability strip for pulsating Am stars. We find that there is not much difference between the Am-star instability strip and the δ Scuti instability strip. We find that the observed location of pulsating Am stars in the HR diagram does not agree with the location predicted from diffusion calculations. Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fondación Galileo Galilei of the Istituto Nazionale di Astrofisica (INAF), at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, and with the Mercator Telescope operated on the island of La Palma by the Flemish Community. Title: Rotation and oblique pulsation in Kepler observations of the roAp star KIC 10483436 Authors: Balona, L. A.; Cunha, M. S.; Gruberbauer, M.; Kurtz, D. W.; Saio, H.; White, T. R.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Christiansen, J. L.; Hall, J. R.; Seader, S. E. Bibcode: 2011MNRAS.413.2651B Altcode: 2011MNRAS.tmp..526B Photometry of KIC 10483436 was obtained continuously with 1-min exposures over a 27-d period from the Kepler satellite. The light curve shows rotational variations from surface spots with a period of 4.303 ± 0.002 d, an amplitude of about 6 mmag and eight pulsation frequencies typical of roAp stars. The high-frequency pattern consists of a quintuplet of equally spaced peaks where the frequency of the dominant central peak (68 μmag amplitude) is 1353.00 μHz (P= 12.32 min). A second set of three peaks of lower amplitude are also visible. These appear to form part of a quintuplet centred on 1511.6 μHz with the central peak and one side peak missing. The equidistant frequency spacing is 2.69 μHz, which corresponds to the 4.303 d rotation period. However, the amplitudes (12 μmag) of these peaks are too close to the detection level to allow definite identification of the multiplets. Although no spectrum is available, the character of the pulsations shows that this is a roAp star with two high-frequency modes modulated in amplitude in accordance with the oblique pulsator model. The 4.303-d variation in the light curve, which is interpreted as rotational modulation, shows harmonics as high as the 26th. These harmonics are probably a result of many patches of varying surface brightness associated with surface abundance variations characteristic of Ap stars. Title: VizieR Online Data Catalog: Kepler compact pulsator candidates (Ostensen+, 2010) Authors: Ostensen, R. H.; Silvotti, R.; Charpinet, S.; Oreiro, R.; Handler, G.; Green, E. M.; Bloemen, S.; Heber, U.; Gansicke, B. T.; Marsh, T. R.; Kurtz, D. W.; Telting, J. H.; Reed, M. D.; Kawaler, S. D.; Aerts, C.; Rodriguez-Lopez, C.; Vuckovic, M.; Ottosen, T. A.; Liimets, T.; Quint, A. C.; Van Grootel, V.; Randall, S. K.; Gilliland, R. L.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Borucki, W. J.; Koch, D.; Quintana, E. V. Bibcode: 2011yCat..74091470O Altcode: For the survey phase of the Kepler Mission, three groups submitted proposals containing candidate hot subdwarf and white dwarf stars. Of the stars included in these proposals, 142 were accepted into the list of KASC survey stars. Of these, six were observed during the 9.7d commissioning run, and 57 were observed during the first four (out of 10) survey months. All 63 stars are listed in Table 1.

(1 data file). Title: VizieR Online Data Catalog: Solar-like oscillations in Kepler red giants (Hekker+, 2011) Authors: Hekker, S.; Elsworth, Y.; De Ridder, J.; Mosser, B.; Garcia, R. A.; Kallinger, T.; Mathur, S.; Huber, D.; Buzasi, D. L.; Preston, H. L.; Hale, S. J.; Ballot, J.; Chaplin, W. J.; Regulo, C.; Bedding, T. R.; Stello, D.; Borucki, W. J.; Koch, D. G.; Jenkins, J.; Allen, C.; Gilliland, R. L.; Kjeldsen, H.; Christensen-Dalsgaard, J. Bibcode: 2011yCat..35250131H Altcode: 2011yCat..35259131H For this investigation we use Kepler data obtained during the first four months of operation. These data have been analysed by different groups using already published methods and the results are compared. We also performed simulations to investigate the uncertainty on the resulting parameters due to different realizations of the stochastic signal.

(1 data file). Title: Predicting the Detectability of Oscillations in Solar-type Stars Observed by Kepler Authors: Chaplin, W. J.; Kjeldsen, H.; Bedding, T. R.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Appourchaux, T.; Elsworth, Y.; García, R. A.; Houdek, G.; Karoff, C.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Verner, G. A.; Batalha, N.; Borucki, W. J.; Brown, T. M.; Bryson, S. T.; Christiansen, J. L.; Clarke, B. D.; Jenkins, J. M.; Klaus, T. C.; Koch, D.; An, D.; Ballot, J.; Basu, S.; Benomar, O.; Bonanno, A.; Broomhall, A. -M.; Campante, T. L.; Corsaro, E.; Creevey, O. L.; Esch, L.; Gai, N.; Gaulme, P.; Hale, S. J.; Handberg, R.; Hekker, S.; Huber, D.; Mathur, S.; Mosser, B.; New, R.; Pinsonneault, M. H.; Pricopi, D.; Quirion, P. -O.; Régulo, C.; Roxburgh, I. W.; Salabert, D.; Stello, D.; Suran, M. D. Bibcode: 2011ApJ...732...54C Altcode: 2011arXiv1103.0702C Asteroseismology of solar-type stars has an important part to play in the exoplanet program of the NASA Kepler Mission. Precise and accurate inferences on the stellar properties that are made possible by the seismic data allow very tight constraints to be placed on the exoplanetary systems. Here, we outline how to make an estimate of the detectability of solar-like oscillations in any given Kepler target, using rough estimates of the temperature and radius, and the Kepler apparent magnitude. Title: Evidence for the Impact of Stellar Activity on the Detectability of Solar-like Oscillations Observed by Kepler Authors: Chaplin, W. J.; Bedding, T. R.; Bonanno, A.; Broomhall, A. -M.; García, R. A.; Hekker, S.; Huber, D.; Verner, G. A.; Basu, S.; Elsworth, Y.; Houdek, G.; Mathur, S.; Mosser, B.; New, R.; Stevens, I. R.; Appourchaux, T.; Karoff, C.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Ballot, J.; Benomar, O.; Corsaro, E.; Campante, T. L.; Gaulme, P.; Hale, S. J.; Handberg, R.; Jarvis, E.; Régulo, C.; Roxburgh, I. W.; Salabert, D.; Stello, D.; Mullally, F.; Li, J.; Wohler, W. Bibcode: 2011ApJ...732L...5C Altcode: 2011arXiv1103.5570C We use photometric observations of solar-type stars, made by the NASA Kepler Mission, to conduct a statistical study of the impact of stellar surface activity on the detectability of solar-like oscillations. We find that the number of stars with detected oscillations falls significantly with increasing levels of activity. The results present strong evidence for the impact of magnetic activity on the properties of near-surface convection in the stars, which appears to inhibit the amplitudes of the stochastically excited, intrinsically damped solar-like oscillations. Title: Large-scale Zonal Flows During the Solar Minimum -- Where Is Cycle 25? Authors: Hill, Frank; Howe, R.; Komm, R.; Christensen-Dalsgaard, J.; Larson, T. P.; Schou, J.; Thompson, M. J. Bibcode: 2011SPD....42.1610H Altcode: 2011BAAS..43S.1610H The so-called torsional oscillation is a pattern of migrating zonal flow bands that move from mid-latitudes towards the equator and poles as the magnetic cycle progresses. Helioseismology allows us to probe these flows below the solar surface. The prolonged solar minimum following Cycle 23 was accompanied by a delay of 1.5 to 2 years in the migration of bands of faster rotation towards the equator. During the rising phase of Cycle 24, while the lower-level bands match those seen in the rising phase of Cycle 23, the rotation rate at middle and higher latitudes remains slower than it was at the corresponding phase in earlier cycles, perhaps reflecting the weakness of the polar fields. In addition, there is no evidence of the poleward flow associated with Cycle 25. We will present the latest results based on nearly sixteen years of global helioseismic observations from GONG and MDI, with recent results from HMI, and discuss the implications for the development of Cycle 25. Title: Ensemble Asteroseismology of Solar-Type Stars with the NASA Kepler Mission Authors: Chaplin, W. J.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Basu, S.; Miglio, A.; Appourchaux, T.; Bedding, T. R.; Elsworth, Y.; García, R. A.; Gilliland, R. L.; Girardi, L.; Houdek, G.; Karoff, C.; Kawaler, S. D.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Verner, G. A.; Ballot, J.; Bonanno, A.; Brandão, I. M.; Broomhall, A. -M.; Bruntt, H.; Campante, T. L.; Corsaro, E.; Creevey, O. L.; Doğan, G.; Esch, L.; Gai, N.; Gaulme, P.; Hale, S. J.; Handberg, R.; Hekker, S.; Huber, D.; Jiménez, A.; Mathur, S.; Mazumdar, A.; Mosser, B.; New, R.; Pinsonneault, M. H.; Pricopi, D.; Quirion, P. -O.; Régulo, C.; Salabert, D.; Serenelli, A. M.; Silva Aguirre, V.; Sousa, S. G.; Stello, D.; Stevens, I. R.; Suran, M. D.; Uytterhoeven, K.; White, T. R.; Borucki, W. J.; Brown, T. M.; Jenkins, J. M.; Kinemuchi, K.; Van Cleve, J.; Klaus, T. C. Bibcode: 2011Sci...332..213C Altcode: 2011arXiv1109.4723C In addition to its search for extrasolar planets, the NASA Kepler mission provides exquisite data on stellar oscillations. We report the detections of oscillations in 500 solar-type stars in the Kepler field of view, an ensemble that is large enough to allow statistical studies of intrinsic stellar properties (such as mass, radius, and age) and to test theories of stellar evolution. We find that the distribution of observed masses of these stars shows intriguing differences to predictions from models of synthetic stellar populations in the Galaxy. Title: HD 181068: A Red Giant in a Triply Eclipsing Compact Hierarchical Triple System Authors: Derekas, A.; Kiss, L. L.; Borkovits, T.; Huber, D.; Lehmann, H.; Southworth, J.; Bedding, T. R.; Balam, D.; Hartmann, M.; Hrudkova, M.; Ireland, M. J.; Kovács, J.; Mező, Gy.; Moór, A.; Niemczura, E.; Sarty, G. E.; Szabó, Gy. M.; Szabó, R.; Telting, J. H.; Tkachenko, A.; Uytterhoeven, K.; Benkő, J. M.; Bryson, S. T.; Maestro, V.; Simon, A. E.; Stello, D.; Schaefer, G.; Aerts, C.; ten Brummelaar, T. A.; De Cat, P.; McAlister, H. A.; Maceroni, C.; Mérand, A.; Still, M.; Sturmann, J.; Sturmann, L.; Turner, N.; Tuthill, P. G.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Quintana, E. V.; Tenenbaum, P.; Twicken, J. D. Bibcode: 2011Sci...332..216D Altcode: 2012arXiv1202.2196D Hierarchical triple systems comprise a close binary and a more distant component. They are important for testing theories of star formation and of stellar evolution in the presence of nearby companions. We obtained 218 days of Kepler photometry of HD 181068 (magnitude of 7.1), supplemented by ground-based spectroscopy and interferometry, which show it to be a hierarchical triple with two types of mutual eclipses. The primary is a red giant that is in a 45-day orbit with a pair of red dwarfs in a close 0.9-day orbit. The red giant shows evidence for tidally induced oscillations that are driven by the orbital motion of the close pair. HD 181068 is an ideal target for studies of dynamical evolution and testing tidal friction theories in hierarchical triple systems. Title: Kepler Detected Gravity-Mode Period Spacings in a Red Giant Star Authors: Beck, P. G.; Bedding, T. R.; Mosser, B.; Stello, D.; Garcia, R. A.; Kallinger, T.; Hekker, S.; Elsworth, Y.; Frandsen, S.; Carrier, F.; De Ridder, J.; Aerts, C.; White, T. R.; Huber, D.; Dupret, M. -A.; Montalbán, J.; Miglio, A.; Noels, A.; Chaplin, W. J.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Brown, T. M.; Kawaler, S. D.; Mathur, S.; Jenkins, J. M. Bibcode: 2011Sci...332..205B Altcode: Stellar interiors are inaccessible through direct observations. For this reason, helioseismologists made use of the Sun’s acoustic oscillation modes to tune models of its structure. The quest to detect modes that probe the solar core has been ongoing for decades. We report the detection of mixed modes penetrating all the way to the core of an evolved star from 320 days of observations with the Kepler satellite. The period spacings of these mixed modes are directly dependent on the density gradient between the core region and the convective envelope. Title: VizieR Online Data Catalog: 2M1938+4603 (KIC 9472174) eclipses (Ostensen+, 2010) Authors: Ostensen, R. H.; Green, E. M.; Bloemen, S.; Marsh, T. R.; Laird, J. B.; Morris, M.; Moriyama, E.; Oreiro, R.; Reed, M. D.; Kawaler, S. D.; Aerts, C.; Vuckovic, M.; Degroote, P.; Telting, J. H.; Kjeldsen, H.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Borucki, W. J.; Koch, D. Bibcode: 2011yCat..74089051O Altcode: The discovery of the strong reflection effect with grazing eclipses was made by two of us (JBL and MM) during a photometric run in 2008 June. Here we present only the eclipse timings from the ground-based photometry, as the pulsations are too complex and have too low amplitudes to be significant in those light curves.

(4 data files). Title: Sounding Open Clusters: Asteroseismic Constraints from Kepler on the Properties of NGC 6791 and NGC 6819 Authors: Basu, Sarbani; Grundahl, Frank; Stello, Dennis; Kallinger, Thomas; Hekker, Saskia; Mosser, Benoit; García, Rafael A.; Mathur, Savita; Brogaard, Karsten; Bruntt, Hans; Chaplin, William J.; Gai, Ning; Elsworth, Yvonne; Esch, Lisa; Ballot, Jerome; Bedding, Timothy R.; Gruberbauer, Michael; Huber, Daniel; Miglio, Andrea; Yildiz, Mutlu; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen; Gilliland, Ronald L.; Fanelli, Michael M.; Ibrahim, Khadeejah A.; Smith, Jeffrey C. Bibcode: 2011ApJ...729L..10B Altcode: 2011arXiv1102.2231B We present initial results on some of the properties of open clusters NGC 6791 and NGC 6819 derived from asteroseismic data obtained by NASA's Kepler mission. In addition to estimating the mass, radius, and log g of stars on the red giant branch (RGB) of these clusters, we estimate the distance to the clusters and their ages. Our model-independent estimate of the distance modulus of NGC 6791 is (m - M)0 = 13.11 ± 0.06. We find (m - M)0 = 11.85 ± 0.05 for NGC 6819. The average mass of stars on the RGB of NGC 6791 is 1.20 ± 0.01 M sun, while that of NGC 6819 is 1.68 ± 0.03 M sun. It should be noted that we do not have data that cover the entire RGB and the actual mass will be somewhat lower. We have determined model-dependent estimates of ages of these clusters. We find ages between 6.8 and 8.6 Gyr for NGC 6791, however, most sets of models give ages around 7 Gyr. We obtain ages between 2 and 2.4 Gyr for NGC 6819. Title: Asteroseismic modelling of the solar-type subgiant star β Hydri Authors: Brandão, I. M.; Doğan, G.; Christensen-Dalsgaard, J.; Cunha, M. S.; Bedding, T. R.; Metcalfe, T. S.; Kjeldsen, H.; Bruntt, H.; Arentoft, T. Bibcode: 2011A&A...527A..37B Altcode: 2010arXiv1012.3872B Context. Comparing models and data of pulsating stars is a powerful way to understand the stellar structure better. Moreover, such comparisons are necessary to make improvements to the physics of the stellar models, since they do not yet perfectly represent either the interior or especially the surface layers of stars. Because β Hydri is an evolved solar-type pulsator with mixed modes in its frequency spectrum, it is very interesting for asteroseismic studies.
Aims: The goal of the present work is to search for a representative model of the solar-type star β Hydri, based on up-to-date non-seismic and seismic data.
Methods: We present a revised list of frequencies for 33 modes, which we produced by analysing the power spectrum of the published observations again using a new weighting scheme that minimises the daily sidelobes. We ran several grids of evolutionary models with different input parameters and different physics, using the stellar evolutionary code ASTEC. For the models that are inside the observed error box of β Hydri, we computed their frequencies with the pulsation code ADIPLS. We used two approaches to find the model that oscillates with the frequencies that are closest to the observed frequencies of β Hydri: (i) we assume that the best model is the one that reproduces the star's interior based on the radial oscillation frequencies alone, to which we have applied the correction for the near-surface effects; (ii) we assume that the best model is the one that produces the lowest value of the chi-square (χ2), i.e. that minimises the difference between the observed frequencies of all available modes and the model predictions, after all model frequencies are corrected for near-surface effects.
Results: We show that after applying a correction for near-surface effects to the frequencies of the best models, we can reproduce the observed modes well, including those that have mixed mode character. The model that gives the lowest value of the χ2 is a post-main-sequence model with a mass of 1.04 M⊙ and a metallicity slightly lower than that of the Sun. Our results underscore the importance of having individual frequencies to constrain the properties of the stellar model. Title: Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars Authors: Bedding, Timothy R.; Mosser, Benoit; Huber, Daniel; Montalbán, Josefina; Beck, Paul; Christensen-Dalsgaard, Jørgen; Elsworth, Yvonne P.; García, Rafael A.; Miglio, Andrea; Stello, Dennis; White, Timothy R.; De Ridder, Joris; Hekker, Saskia; Aerts, Conny; Barban, Caroline; Belkacem, Kevin; Broomhall, Anne-Marie; Brown, Timothy M.; Buzasi, Derek L.; Carrier, Fabien; Chaplin, William J.; di Mauro, Maria Pia; Dupret, Marc-Antoine; Frandsen, Søren; Gilliland, Ronald L.; Goupil, Marie-Jo; Jenkins, Jon M.; Kallinger, Thomas; Kawaler, Steven; Kjeldsen, Hans; Mathur, Savita; Noels, Arlette; Silva Aguirre, Victor; Ventura, Paolo Bibcode: 2011Natur.471..608B Altcode: 2011arXiv1103.5805B Red giants are evolved stars that have exhausted the supply of hydrogen in their cores and instead burn hydrogen in a surrounding shell. Once a red giant is sufficiently evolved, the helium in the core also undergoes fusion. Outstanding issues in our understanding of red giants include uncertainties in the amount of mass lost at the surface before helium ignition and the amount of internal mixing from rotation and other processes. Progress is hampered by our inability to distinguish between red giants burning helium in the core and those still only burning hydrogen in a shell. Asteroseismology offers a way forward, being a powerful tool for probing the internal structures of stars using their natural oscillation frequencies. Here we report observations of gravity-mode period spacings in red giants that permit a distinction between evolutionary stages to be made. We use high-precision photometry obtained by the Kepler spacecraft over more than a year to measure oscillations in several hundred red giants. We find many stars whose dipole modes show sequences with approximately regular period spacings. These stars fall into two clear groups, allowing us to distinguish unambiguously between hydrogen-shell-burning stars (period spacing mostly ~50seconds) and those that are also burning helium (period spacing ~100 to 300 seconds). Title: Kepler's First Rocky Planet: Kepler-10b Authors: Batalha, Natalie M.; Borucki, William J.; Bryson, Stephen T.; Buchhave, Lars A.; Caldwell, Douglas A.; Christensen-Dalsgaard, Jørgen; Ciardi, David; Dunham, Edward W.; Fressin, Francois; Gautier, Thomas N., III; Gilliland, Ronald L.; Haas, Michael R.; Howell, Steve B.; Jenkins, Jon M.; Kjeldsen, Hans; Koch, David G.; Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Rowe, Jason F.; Sasselov, Dimitar D.; Seager, Sara; Steffen, Jason H.; Torres, Guillermo; Basri, Gibor S.; Brown, Timothy M.; Charbonneau, David; Christiansen, Jessie; Clarke, Bruce; Cochran, William D.; Dupree, Andrea; Fabrycky, Daniel C.; Fischer, Debra; Ford, Eric B.; Fortney, Jonathan; Girouard, Forrest R.; Holman, Matthew J.; Johnson, John; Isaacson, Howard; Klaus, Todd C.; Machalek, Pavel; Moorehead, Althea V.; Morehead, Robert C.; Ragozzine, Darin; Tenenbaum, Peter; Twicken, Joseph; Quinn, Samuel; VanCleve, Jeffrey; Walkowicz, Lucianne M.; Welsh, William F.; Devore, Edna; Gould, Alan Bibcode: 2011ApJ...729...27B Altcode: 2011arXiv1102.0605B NASA's Kepler Mission uses transit photometry to determine the frequency of Earth-size planets in or near the habitable zone of Sun-like stars. The mission reached a milestone toward meeting that goal: the discovery of its first rocky planet, Kepler-10b. Two distinct sets of transit events were detected: (1) a 152 ± 4 ppm dimming lasting 1.811 ± 0.024 hr with ephemeris T [BJD] =2454964.57375+0.00060 -0.00082 + N*0.837495+0.000004 -0.000005 days and (2) a 376 ± 9 ppm dimming lasting 6.86 ± 0.07 hr with ephemeris T [BJD] =2454971.6761+0.0020 -0.0023 + N*45.29485+0.00065 -0.00076 days. Statistical tests on the photometric and pixel flux time series established the viability of the planet candidates triggering ground-based follow-up observations. Forty precision Doppler measurements were used to confirm that the short-period transit event is due to a planetary companion. The parent star is bright enough for asteroseismic analysis. Photometry was collected at 1 minute cadence for >4 months from which we detected 19 distinct pulsation frequencies. Modeling the frequencies resulted in precise knowledge of the fundamental stellar properties. Kepler-10 is a relatively old (11.9 ± 4.5 Gyr) but otherwise Sun-like main-sequence star with T eff = 5627 ± 44 K, M sstarf = 0.895 ± 0.060 M sun, and R sstarf = 1.056 ± 0.021 R sun. Physical models simultaneously fit to the transit light curves and the precision Doppler measurements yielded tight constraints on the properties of Kepler-10b that speak to its rocky composition: M P = 4.56+1.17 -1.29 M ⊕, R P = 1.416+0.033 -0.036 R ⊕, and ρP = 8.8+2.1 -2.9 g cm-3. Kepler-10b is the smallest transiting exoplanet discovered to date.

Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Title: Characteristics of Kepler Planetary Candidates Based on the First Data Set Authors: Borucki, William J.; Koch, David G.; Basri, Gibor; Batalha, Natalie; Boss, Alan; Brown, Timothy M.; Caldwell, Douglas; Christensen-Dalsgaard, Jørgen; Cochran, William D.; DeVore, Edna; Dunham, Edward W.; Dupree, Andrea K.; Gautier, Thomas N., III; Geary, John C.; Gilliland, Ronald; Gould, Alan; Howell, Steve B.; Jenkins, Jon M.; Kjeldsen, Hans; Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Monet, David G.; Sasselov, Dimitar; Tarter, Jill; Charbonneau, David; Doyle, Laurance; Ford, Eric B.; Fortney, Jonathan; Holman, Matthew J.; Seager, Sara; Steffen, Jason H.; Welsh, William F.; Allen, Christopher; Bryson, Stephen T.; Buchhave, Lars; Chandrasekaran, Hema; Christiansen, Jessie L.; Ciardi, David; Clarke, Bruce D.; Dotson, Jessie L.; Endl, Michael; Fischer, Debra; Fressin, Francois; Haas, Michael; Horch, Elliott; Howard, Andrew; Isaacson, Howard; Kolodziejczak, Jeffery; Li, Jie; MacQueen, Phillip; Meibom, Søren; Prsa, Andrej; Quintana, Elisa V.; Rowe, Jason; Sherry, William; Tenenbaum, Peter; Torres, Guillermo; Twicken, Joseph D.; Van Cleve, Jeffrey; Walkowicz, Lucianne; Wu, Hayley Bibcode: 2011ApJ...728..117B Altcode: 2010arXiv1006.2799B In the spring of 2009, the Kepler Mission commenced high-precision photometry on nearly 156,000 stars to determine the frequency and characteristics of small exoplanets, conduct a guest observer program, and obtain asteroseismic data on a wide variety of stars. On 2010 June 15, the Kepler Mission released most of the data from the first quarter of observations. At the time of this data release, 705 stars from this first data set have exoplanet candidates with sizes from as small as that of Earth to larger than that of Jupiter. Here we give the identity and characteristics of 305 released stars with planetary candidates. Data for the remaining 400 stars with planetary candidates will be released in 2011 February. More than half the candidates on the released list have radii less than half that of Jupiter. Five candidates are present in and near the habitable zone; two near super-Earth size, and three bracketing the size of Jupiter. The released stars also include five possible multi-planet systems. One of these has two Neptune-size (2.3 and 2.5 Earth radius) candidates with near-resonant periods. Title: Kepler photometry of the prototypical Blazhko star RR Lyr: an old friend seen in a new light Authors: Kolenberg, K.; Bryson, S.; Szabó, R.; Kurtz, D. W.; Smolec, R.; Nemec, J. M.; Guggenberger, E.; Moskalik, P.; Benkő, J. M.; Chadid, M.; Jeon, Y. -B.; Kiss, L. L.; Kopacki, G.; Nuspl, J.; Still, M.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Borucki, W. J.; Caldwell, D. A.; Jenkins, J. M.; Koch, D. Bibcode: 2011MNRAS.411..878K Altcode: 2010arXiv1011.5908K We present our analysis of the long-cadence Kepler data for the well-studied Blazhko star RR Lyr, gathered during the first two quarters of the satellite's observations and covering a total of 127 d. Besides being of great importance for our understanding of RR Lyrae stars in general, these RR Lyr data can be regarded as a case study for observations of bright stars with Kepler. Kepler can perform high-precision photometry on targets like RR Lyr, as the saturated flux is conserved to a very high degree. The Kepler data on RR Lyr are revolutionary in several respects. Even with long-cadence sampling (one measurement per 29.4 min), the unprecedented precision (< mmag) of the Kepler photometry allows the study of the star's extreme light-curve variations in detail. The multiplet structures at the main frequency and its harmonics, typical for Blazhko stars, are clearly detected up to the quintuplets. For the first time, photometric data of RR Lyr reveal the presence of half-integer frequencies, linked to a period-doubling effect. This phenomenon may be connected to the still unexplained Blazhko modulation. Moreover, with three observed Blazhko cycles at our disposal, we observe that there is no exact repetition in the light-curve changes from one modulation cycle to the next for RR Lyr. This may be due to additional periodicities in the star, or to transient or quasi-periodic changes. Title: Atmospheric parameters and pulsational properties for a sample of δ Sct, γ Dor and hybrid Kepler targets Authors: Catanzaro, G.; Ripepi, V.; Bernabei, S.; Marconi, M.; Balona, L.; Kurtz, D. W.; Smalley, B.; Borucki, W. J.; Bruntt, H.; Christensen-Dalsgaard, J.; Grigahcène, A.; Kjeldsen, H.; Koch, D. G.; Monteiro, M. J. P. F. G.; Suárez, J. C.; Szabó, R.; Uytterhoeven, K. Bibcode: 2011MNRAS.411.1167C Altcode: 2010arXiv1009.4317C; 2010MNRAS.tmp.1732C We report spectroscopic observations for 19 δ Sct candidates observed by the Kepler satellite both in long and short cadence mode. For all these stars, by using spectral synthesis, we derive the effective temperature, the surface gravity and the projected rotational velocity. An equivalent spectral-type classification has been also performed for all stars in the sample. These determinations are fundamental for modelling the frequency spectra that will be extracted from the Kepler data for asteroseismic inference. For all the 19 stars, we also present periodograms obtained from Kepler data. We find that all stars show peaks in both low- (γ Dor; g-mode) and high-frequency (δ Sct; p-mode) regions. Using the amplitudes and considering 5 cycles d-1 as a boundary frequency, we classified three stars as pure γ Dor, four as γ Dor-δ hybrid Sct, five as δ Sct-γ Dor hybrid and six as pure δ Sct. The only exception is the star KIC 05296877, which we suggest could be a binary. This work is based on spectra taken at the Loiano (INAF - OA Bologna) and Serra La Nave (INAF - OA Catania) Observatories. Title: The radius and mass of the close solar twin 18 Scorpii derived from asteroseismology and interferometry Authors: Bazot, M.; Ireland, M. J.; Huber, D.; Bedding, T. R.; Broomhall, A. -M.; Campante, T. L.; Carfantan, H.; Chaplin, W. J.; Elsworth, Y.; Meléndez, J.; Petit, P.; Théado, S.; Van Grootel, V.; Arentoft, T.; Asplund, M.; Castro, M.; Christensen-Dalsgaard, J.; Do Nascimento, J. D.; Dintrans, B.; Dumusque, X.; Kjeldsen, H.; McAlister, H. A.; Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Santos, N. C.; Sousa, S.; Sturmann, J.; Sturmann, L.; ten Brummelaar, T. A.; Turner, N.; Vauclair, S. Bibcode: 2011A&A...526L...4B Altcode: 2012arXiv1209.0217B The growing interest in solar twins is motivated by the possibility of comparing them directly to the Sun. To carry on this kind of analysis, we need to know their physical characteristics with precision. Our first objective is to use asteroseismology and interferometry on the brightest of them: 18 Sco. We observed the star during 12 nights with HARPS for seismology and used the PAVO beam-combiner at CHARA for interferometry. An average large frequency separation 134.4 ± 0.3 μHz and angular and linear radiuses of 0.6759 ± 0.0062 mas and 1.010 ± 0.009 R⊙ were estimated. We used these values to derive the mass of the star, 1.02 ± 0.03 M⊙.

Based on observations collected at the European Southern Observatory (ID 183.D-0729(A)) and at the CHARA Array, operated by Georgia State University. Title: Kepler observations of the beaming binary KPD 1946+4340 Authors: Bloemen, S.; Marsh, T. R.; Østensen, R. H.; Charpinet, S.; Fontaine, G.; Degroote, P.; Heber, U.; Kawaler, S. D.; Aerts, C.; Green, E. M.; Telting, J.; Brassard, P.; Gänsicke, B. T.; Handler, G.; Kurtz, D. W.; Silvotti, R.; Van Grootel, V.; Lindberg, J. E.; Pursimo, T.; Wilson, P. A.; Gilliland, R. L.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Borucki, W. J.; Koch, D.; Jenkins, J. M.; Klaus, T. C. Bibcode: 2011MNRAS.410.1787B Altcode: 2010arXiv1010.2747B; 2010MNRAS.tmp.1640B; 2010MNRAS.tmp.1742B The Kepler Mission has acquired 33.5 d of continuous 1-min photometry of KPD 1946+4340, a short-period binary system that consists of a subdwarf B star (sdB) and a white dwarf. In the light curve, eclipses are clearly seen, with the deepest occurring when the compact white dwarf crosses the disc of the sdB (0.4 per cent) and the more shallow ones (0.1 per cent) when the sdB eclipses the white dwarf. As expected, the sdB is deformed by the gravitational field of the white dwarf, which produces an ellipsoidal modulation of the light curve. Spectacularly, a very strong Doppler beaming (also known as Doppler boosting) effect is also clearly evident at the 0.1 per cent level. This originates from the sdB's orbital velocity, which we measure to be 164.0 ± 1.9 km s-1 from supporting spectroscopy. We present light-curve models that account for all these effects, as well as gravitational lensing, which decreases the apparent radius of the white dwarf by about 6 per cent, when it eclipses the sdB. We derive system parameters and uncertainties from the light curve using Markov chain Monte Carlo simulations. Adopting a theoretical white dwarf mass-radius relation, the mass of the subdwarf is found to be 0.47 ± 0.03 M⊙ and the mass of the white dwarf 0.59 ± 0.02 M⊙. The effective temperature of the white dwarf is 15 900 ± 300 K. With a spectroscopic effective temperature of Teff= 34 730 ± 250 K and a surface gravity of log g= 5.43 ± 0.04, the subdwarf has most likely exhausted its core helium, and is in a shell He burning stage.

The detection of Doppler beaming in Kepler light curves potentially allows one to measure radial velocities without the need of spectroscopic data. For the first time, a photometrically observed Doppler beaming amplitude is compared to a spectroscopically established value. The sdB's radial velocity amplitude derived from the photometry (168 ± 4 km s-1) is in perfect agreement with the spectroscopic value. After subtracting our best model for the orbital effects, we searched the residuals for stellar oscillations but did not find any significant pulsation frequencies. Title: Solar-like oscillations in red giants observed with Kepler: comparison of global oscillation parameters from different methods Authors: Hekker, S.; Elsworth, Y.; De Ridder, J.; Mosser, B.; García, R. A.; Kallinger, T.; Mathur, S.; Huber, D.; Buzasi, D. L.; Preston, H. L.; Hale, S. J.; Ballot, J.; Chaplin, W. J.; Régulo, C.; Bedding, T. R.; Stello, D.; Borucki, W. J.; Koch, D. G.; Jenkins, J.; Allen, C.; Gilliland, R. L.; Kjeldsen, H.; Christensen-Dalsgaard, J. Bibcode: 2011A&A...525A.131H Altcode: 2010arXiv1008.2959H Context. The large number of stars for which uninterrupted high-precision photometric timeseries data are being collected with Kepler and CoRoT initiated the development of automated methods to analyse the stochastically excited oscillations in main-sequence, subgiant and red-giant stars.
Aims: We investigate the differences in results for global oscillation parameters of G and K red-giant stars due to different methods and definitions. We also investigate uncertainties originating from the stochastic nature of the oscillations.
Methods: For this investigation we use Kepler data obtained during the first four months of operation. These data have been analysed by different groups using already published methods and the results are compared. We also performed simulations to investigate the uncertainty on the resulting parameters due to different realizations of the stochastic signal.
Results: We obtain results for the frequency of maximum oscillation power (ν_max) and the mean large separation (<Δν>) from different methods for over one thousand red-giant stars. The results for these parameters agree within a few percent and seem therefore robust to the different analysis methods and definitions used here. The uncertainties for ν_max and <Δν> due to differences in realization noise are not negligible and should be taken into account when using these results for stellar modelling.

Table 7 is only available in electronic form at http://www.aanda.org Title: The Stellar Imager (SI) - A Mission to Resolve Stellar Surfaces, Interiors, and Magnetic Activity Authors: Christensen-Dalsgaard, Jørgen; Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska, Margarita; Si Team Bibcode: 2011JPhCS.271a2085C Altcode: The Stellar Imager (SI) is a space-based, UV/Optical Interferometer (UVOI) designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and of the Universe in general. It will also probe via asteroseismology flows and structures in stellar interiors. SI will enable the development and testing of a predictive dynamo model for the Sun, by observing patterns of surface activity and imaging of the structure and differential rotation of stellar interiors in a population study of Sun-like stars to determine the dependence of dynamo action on mass, internal structure and flows, and time. SI's science focuses on the role of magnetism in the Universe and will revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in the Universe. SI is a "Landmark/Discovery Mission" in the 2005 Heliophysics Roadmap, an implementation of the UVOI in the 2006 Astrophysics Strategic Plan, and a NASA Vision Mission ("NASA Space Science Vision Missions" (2008), ed. M. Allen). We present here the science goals of the SI Mission, a mission architecture that could meet those goals, and the technology development needed to enable this mission. Additional information on SI can be found at: http://hires.gsfc.nasa.gov/si/. Title: Asteroseismology of the Transiting Exoplanet Host HD 17156 with Hubble Space Telescope Fine Guidance Sensor Authors: Gilliland, Ronald L.; McCullough, Peter R.; Nelan, Edmund P.; Brown, Timothy M.; Charbonneau, David; Nutzman, Philip; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans Bibcode: 2011ApJ...726....2G Altcode: 2010arXiv1011.0435G Observations conducted with the Fine Guidance Sensor on the Hubble Space Telescope (HST) providing high cadence and precision time-series photometry were obtained over 10 consecutive days in 2008 December on the host star of the transiting exoplanet HD 17156b. During this time, 1.0 × 1012 photons (corrected for detector dead time) were collected in which a noise level of 163 parts per million per 30 s sum resulted, thus providing excellent sensitivity to the detection of the analog of the solar 5-minute p-mode oscillations. For HD 17156, robust detection of p modes supports the determination of the stellar mean density of langρ*rang = 0.5301 ± 0.0044 g cm-3 from a detailed fit to the observed frequencies of modes of degree l = 0, 1, and 2. This is the first star for which the direct determination of langρ*rang has been possible using both asteroseismology and detailed analysis of a transiting planet light curve. Using the density constraint from asteroseismology, and stellar evolution modeling results in M * = 1.285 ± 0.026 M sun, R * = 1.507 ± 0.012 R sun, and a stellar age of 3.2 ± 0.3 Gyr.

Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. Title: Precise Estimates of the Physical Parameters for the Exoplanet System HD 17156 Enabled by Hubble Space Telescope Fine Guidance Sensor Transit and Asteroseismic Observations Authors: Nutzman, Philip; Gilliland, Ronald L.; McCullough, Peter R.; Charbonneau, David; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans; Nelan, Edmund P.; Brown, Timothy M.; Holman, Matthew J. Bibcode: 2011ApJ...726....3N Altcode: 2010arXiv1011.0440N We present observations of three distinct transits of HD 17156b obtained with the Fine Guidance Sensors on board the Hubble Space Telescope. We analyzed both the transit photometry and previously published radial velocities to find the planet-star radius ratio Rp /R sstarf = 0.07454 ± 0.00035, inclination i = 86.49+0.24 -0.20 deg, and scaled semimajor axis a/R sstarf = 23.19+0.32 -0.27. This last value translates directly to a mean stellar density determination ρsstarf = 0.522+0.021 -0.018 g cm-3. Analysis of asteroseismology observations by the companion paper of Gilliland et al. provides a consistent but significantly refined measurement of ρsstarf = 0.5308 ± 0.0040. We compare stellar isochrones to this density estimate and find M sstarf = 1.275 ± 0.018 M sun and a stellar age of 3.37+0.20 -0.47 Gyr. Using this estimate of M sstarf and incorporating the density constraint from asteroseismology, we model both the photometry and published radial velocities to estimate the planet radius Rp = 1.0870 ± 0.0066 RJ and the stellar radius R sstarf = 1.5007 ± 0.0076 R sun. The planet radius is larger than that found in previous studies and consistent with theoretical models of a solar-composition gas giant of the same mass and equilibrium temperature. For the three transits, we determine the times of mid-transit to a precision of 6.2 s, 7.6 s, and 6.9 s, and the transit times for HD 17156 do not show any significant departures from a constant period. The joint analysis of transit photometry and asteroseismology presages similar studies that will be enabled by the NASA Kepler Mission.

Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. Title: Kepler observations of rapidly oscillating Ap, δ Scuti and γ Doradus pulsations in Ap stars Authors: Balona, L. A.; Cunha, M. S.; Kurtz, D. W.; Brandão, I. M.; Gruberbauer, M.; Saio, H.; Östensen, R.; Elkin, V. G.; Borucki, W. J.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Koch, D. G.; Bryson, S. T. Bibcode: 2011MNRAS.410..517B Altcode: 2010arXiv1006.4013B; 2010MNRAS.tmp.1549B Observations of the A5p star KIC 8677585 obtained during the Kepler 10-d commissioning run with 1-min time resolution show that it is a rapidly oscillating Ap (roAp) star with several frequencies with periods near 10 min. In addition, a low frequency at 3.142 d-1 is also clearly present. Multiperiodic γ Doradus (γ Dor) and δ Scuti (δ Sct) pulsations, never before seen in any Ap star, are present in Kepler observations of at least three other Ap stars. Since γ Dor pulsations are seen in Ap stars, it is likely that the low frequency in KIC 8677585 is also a γ Dor pulsation. The simultaneous presence of both γ Dor and roAp pulsations and the unexpected detection of δ Sct and γ Dor pulsations in Ap stars present new opportunities and challenges for the interpretation of these stars. Since it is easy to confuse Am and Ap stars at classification dispersions, the nature of these Ap stars in the Kepler field needs to be confirmed. Title: First Global Rotation Inversions of HMI Data Authors: Howe, R.; Larson, T. P.; Schou, J.; Hill, F.; Komm, R.; Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 2011JPhCS.271a2061H Altcode: We present the first 2-dimensional global rotational inversions of medium-degree p-mode data from the Helioseismic and Magnetic Imager, and compare the results with inversions of Michelson Doppler Imager data for the same time period. The inferred rotation profiles show good agreement between the two instruments. Title: Discovery of a New AM CVn System with the Kepler Satellite Authors: Fontaine, G.; Brassard, P.; Green, E. M.; Charpinet, S.; Dufour, P.; Hubeny, I.; Steeghs, D.; Aerts, C.; Randall, S. K.; Bergeron, P.; Guvenen, B.; O'Malley, C. J.; Van Grootel, V.; Østensen, R. H.; Bloemen, S.; Silvotti, R.; Howell, S. B.; Baran, A.; Kepler, S. O.; Marsh, T. R.; Montgomery, M. H.; Oreiro, R.; Provencal, J.; Telting, J.; Winget, D. E.; Zima, W.; Christensen-Dalsgaard, J.; Kjeldsen, H. Bibcode: 2011ApJ...726...92F Altcode: We report the discovery of a new AM CVn system on the basis of broadband photometry obtained with the Kepler satellite supplemented by ground-based optical spectroscopy. Initially retained on Kepler target lists as a potential compact pulsator, the blue object SDSS J190817.07+394036.4 (KIC 004547333) has turned out to be a high-state AM CVn star showing the He-dominated spectrum of its accretion disk significantly reddened by interstellar absorption. We constructed new grids of NLTE synthetic spectra for accretion disks in order to analyze our spectroscopic observations. From this analysis, we infer preliminary estimates of the rate of mass transfer, the inclination angle of the disk, and the distance to the system. The AM CVn nature of the system is also evident in the Kepler light curve, from which we extracted 11 secure periodicities. The luminosity variations are dominated by a basic periodicity of 938.507 s, likely to correspond to a superhump modulation. The light curve folded on the period of 938.507 s exhibits a pulse shape that is very similar to the superhump wavefront seen in AM CVn itself, which is a high-state system and the prototype of the class. Our Fourier analysis also suggests the likely presence of a quasi-periodic oscillation similar to those already observed in some high-state AM CVn systems. Furthermore, some very low-frequency, low-amplitude aperiodic photometric activity is likely present, which is in line with what is expected in accreting binary systems. Inspired by previous work, we further looked for and found some intriguing numerical relationships between the 11 secure detected frequencies, in the sense that we can account for all of them in terms of only three basic clocks. This is further evidence in favor of the AM CVn nature of the system. Title: SONG - getting ready for the prototype Authors: Grundahl, F.; Christensen-Dalsgaard, J.; Gråe Jørgensen, U.; Frandsen, S.; Kjeldsen, H.; Kjærgaard Rasmussen, P. Bibcode: 2011JPhCS.271a2083G Altcode: The Stellar Observations Network Group, SONG, is a project which aims at building a network of eight identical telescopes distributed geographically around the globe to allow long-term, high-duty-cycle observations of stellar oscillations and to search for exoplanets via the microlensing technique. At each of the network nodes a 1 m telescope with a high-resolution spectrograph and two lucky-imaging cameras is placed. The instruments and telescope, for the prototype node, are currently being built and installation at Observatorio del Teide, Tenerife, Spain is foreseen for early 2011. Title: The torsional oscillation and the new solar cycle Authors: Howe, R.; Hill, F.; Komm, R.; Christensen-Dalsgaard, J.; Larson, T. P.; Schou, J.; Thompson, M. J.; Ulrich, R. Bibcode: 2011JPhCS.271a2074H Altcode: We present updated observations of the pattern of migrating solar zonal flows known as the torsional oscillation, covering 15 years of helioseismic measurements with GONG and MDI and 30 years of surface Doppler observations from Mount Wilson. We compare the behavior of the flows during the extended solar minimum following Cycle 23 with that in earlier minima. We demonstrate that the timing of the migration of the zonal flow belts may be of some use in predicting the start of the new cycle. We also note that the behavior of the high-latitude part of the pattern currently differs from that seen early in the previous cycle, with the high-latitude poleward-migrating branch still not established. Title: Rotation-rate variations at the tachocline: An update Authors: Howe, R.; Komm, R.; Hill, F.; Christensen-Dalsgaard, J.; Larson, T. P.; Schou, J.; Thompson, M. J.; Toomre, J. Bibcode: 2011JPhCS.271a2075H Altcode: After 15 years of GONG and MDI observations of the solar interior rotation, we revisit the issue of variations in the rotation rate near the base of the convection zone. The 1.3-year period seen in the first few years of the observations disappeared after 2000 and has still not returned. On the other hand, the agreement between GONG and MDI observations suggests that variations seen in this region have some solar origin, whether a true rotation-rate change or possibly mere stochastic variation; we present a numerical experiment supporting this contention. Title: Seismic signatures of stellar cores of solar-like pulsators: Dependence on mass and age Authors: Brandão, I. M.; Cunha, M. S.; Creevey, O. L.; Christensen-Dalsgaard, J. Bibcode: 2010AN....331..940B Altcode: 2010arXiv1008.2630B Useful information from the inner layers of stellar pulsators may be derived from the study of their oscillations. In this paper we analyse three diagnostic tools suggested in the literature built from the oscillation frequencies computed for a set of main sequence models with masses between 1.0 M⊙ and 1.6 M⊙, to check what information they may hold about stellar cores. For the models with convective cores ({M ≥ 1.2} M⊙) we find a relation between the frequency slopes of the diagnostic tools and the size of the jump in the sound speed at the edge of the core. We show that this relation is independent of the mass of the models. In practice, since the size of the jump in the sound speed is related to the age of the star, using these seismic tools we may, in principle, infer the star's evolutionary state. We also show that when combining two of the three diagnostic tools studied, we are able to distinguish models with convective cores from models without a convective core but with strong sound speed gradients in the inner layers Title: Kepler observations: Light shed on the hybrid γ Doradus - δ Scuti pulsation phenomenon Authors: Grigahcène, A.; Uytterhoeven, K.; Antoci, V.; Balona, L.; Catanzaro, G.; Daszyńska-Daszkiewicz, J.; Guzik, J. A.; Handler, G.; Houdek, G.; Kurtz, D. W.; Marconi, M.; Monteiro, M. J. P. F. G.; Moya, A.; Ripepi, V.; Suárez, J. -C.; Borucki, W. J.; Brown, T. M.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Jenkins, J. M.; Kjeldsen, H.; Koch, D.; Bernabei, S.; Bradley, P.; Breger, M.; Di Criscienzo, M.; Dupret, M. -A.; García, R. A.; García Hernández, A.; Jackiewicz, J.; Kaiser, A.; Lehmann, H.; Martín-Ruiz, S.; Mathias, P.; Molenda-Żakowicz, J.; Nemec, J. M.; Nuspl, J.; Paparó, M.; Roth, M.; Szabó, R.; Suran, M. D.; Ventura, R. Bibcode: 2010AN....331..989G Altcode: Through the observational study of stellar pulsations, the internal structure of stars can be probed and theoretical models can be tested. The main sequence γ Doradus (Dor) and δ Scuti (Sct) stars with masses 1.2-2.5 M⊙ are particularly interesting for asteroseismic study. The γ Dor stars pulsate in high-order gravity (g) modes, with pulsational periods of order of one day. The δ Sct stars, on the other hand, show low-order g and pressure (p) modes with periods of order of 2 hours. Theory predicts the existence of `hybrid' stars, i.e. stars pulsating in both types of modes, in an overlap region between the instability strips of γ Dor and δ Sct stars in the Hertzsprung-Russell diagram. Hybrid stars are particularly interesting as the two types of modes probe different regions of the stellar interior and hence provide complementary model constraints. Before the advent of Kepler, only a few hybrid stars had been confirmed. The {{Kepler}} satellite is providing a true revolution in the study of and search for hybrid stars. Analysis of the first 50 days of {{Kepler}} data of hundreds of γ Dor and δ Sct candidates reveals extremely rich frequency spectra, with most stars showing frequencies in both the δ Sct and γ Dor frequency range. As these results show that there are practically no pure δ Sct or γ Dor pulsators, a new observational classification scheme is proposed by \cite{Grig10}. We present their results and characterize 234 stars in terms of δ Sct, γ Dor, δ Sct/γ Dor or γ Dor/δ Sct hybrids. Title: The Kepler Asteroseismic Investigation: Scientific goals and first results Authors: Kjeldsen, H.; Christensen-Dalsgaard, J.; Handberg, R.; Brown, T. M.; Gilliland, R. L.; Borucki, W. J.; Koch, D. Bibcode: 2010AN....331..966K Altcode: 2010arXiv1007.1816K Kepler is a NASA mission designed to detect exoplanets and characterize the properties of exoplanetary systems. Kepler also includes an asteroseismic programme which is being conducted through the Kepler Asteroseismic Science Consortium (KASC), whose 400 members are organized into 13 working groups by type of variable star. So far data have been available from the first 7 month of the mission containing a total of 2937 targets observed at a 1-min cadence for periods between 10 days and 7 months. The goals of the asteroseismic part of the Kepler project is to perform detailed studies of stellar interiors. The first results of the asteroseismic analysis are orders of magnitude better than seen before, and this bodes well for how the future analysis of Kepler data for many types of stars will impact our general understanding of stellar structure and evolution. Title: Does Kepler unveil the mystery of the Blazhko effect? First detection of period doubling in Kepler Blazhko RR Lyrae stars Authors: Szabó, R.; Kolláth, Z.; Molnár, L.; Kolenberg, K.; Kurtz, D. W.; Bryson, S. T.; Benkő, J. M.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Borucki, W. J.; Koch, D.; Twicken, J. D.; Chadid, M.; di Criscienzo, M.; Jeon, Y. -B.; Moskalik, P.; Nemec, J. M.; Nuspl, J. Bibcode: 2010MNRAS.409.1244S Altcode: 2010MNRAS.tmp.1401S; 2010arXiv1007.3404S The first detection of the period doubling phenomenon is reported in the Kepler RR Lyrae stars RR Lyr, V808 Cyg and V355 Lyr. Interestingly, all these pulsating stars show Blazhko modulation. The period doubling manifests itself as alternating maxima and minima of the pulsational cycles in the light curve, as well as through the appearance of half-integer frequencies located halfway between the main pulsation period and its harmonics in the frequency spectrum. The effect was found to be stronger during certain phases of the modulation cycle. We were able to reproduce the period-doubling bifurcation in our non-linear RR Lyrae models computed by the Florida-Budapest hydrocode. This enabled us to trace the origin of this instability in RR Lyrae stars to a resonance, namely a 9:2 resonance between the fundamental mode and a high-order (ninth) radial overtone showing strange-mode characteristics. We discuss the connection of this new type of variation to the mysterious Blazhko effect and argue that it may give us fresh insights into solving this century-old enigma. Title: Flavours of variability: 29 RR Lyrae stars observed with Kepler Authors: Benkő, J. M.; Kolenberg, K.; Szabó, R.; Kurtz, D. W.; Bryson, S.; Bregman, J.; Still, M.; Smolec, R.; Nuspl, J.; Nemec, J. M.; Moskalik, P.; Kopacki, G.; Kolláth, Z.; Guggenberger, E.; di Criscienzo, M.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Borucki, W. J.; Koch, D.; Jenkins, J. M.; van Cleve, J. E. Bibcode: 2010MNRAS.409.1585B Altcode: 2010arXiv1007.3928B; 2010MNRAS.tmp.1514B We present our analysis of Kepler observations of 29 RR Lyrae stars, based on 138 d of observation. We report precise pulsation periods for all stars. Nine of these stars had incorrect or unknown periods in the literature. 14 of the stars exhibit both amplitude and phase Blazhko modulations, with Blazhko periods ranging from 27.7 to more than 200 d. For V445 Lyr, a longer secondary variation is also observed in addition to its 53.2-d Blazhko period. The unprecedented precision of the Kepler photometry has led to the discovery of the the smallest modulations detected so far. Moreover, additional frequencies beyond the well-known harmonics and Blazhko multiplets have been found. These frequencies are located around the half-integer multiples of the main pulsation frequency for at least three stars. In four stars, these frequencies are close to the first and/or second overtone modes. The amplitudes of these periodicities seem to vary over the Blazhko cycle. V350 Lyr, a non-Blazhko star in our sample, is the first example of a double-mode RR Lyrae star that pulsates in its fundamental and second overtone modes. Title: First Kepler results on compact pulsators - III. Subdwarf B stars with V1093 Her and hybrid (DW Lyn) type pulsations Authors: Reed, M. D.; Kawaler, S. D.; Østensen, R. H.; Bloemen, S.; Baran, A.; Telting, J. H.; Silvotti, R.; Charpinet, S.; Quint, A. C.; Handler, G.; Gilliland, R. L.; Borucki, W. J.; Koch, D. G.; Kjeldsen, H.; Christensen-Dalsgaard, J. Bibcode: 2010MNRAS.409.1496R Altcode: 2010arXiv1008.0582R; 2010MNRAS.tmp.1698R We present the discovery of non-radial pulsations in five hot subdwarf B (sdB) stars based on 27 d of nearly continuous time series photometry using the Kepler spacecraft. We find that every sdB star cooler than ≈27 500 K that Kepler has observed (seven so far) is a long-period pulsator of the V1093 Her (PG 1716) class or a hybrid star with both short and long periods. The apparently non-binary long-period and hybrid pulsators are described here. The V1093 Her periods range from 1 to 4.5 h and are associated with g-mode pulsations. Three stars also exhibit short periods indicative of p-modes with periods of 2-5 min and in addition, these stars exhibit periodicities between both classes from 15 to 45 min. We detect the coolest and longest-period V1093 Her-type pulsator to date, KIC010670103 (Teff≈ 20 900 K, Pmax≈ 4.5 h) as well as a suspected hybrid pulsator, KIC002697388, which is extremely cool (Teff≈ 23 900 K) and for the first time hybrid pulsators which have larger g-mode amplitudes than p-mode ones. All of these pulsators are quite rich with many frequencies and we are able to apply asymptotic relationships to associate periodicities with modes for KIC010670103. Kepler data are particularly well suited for these studies as they are long duration, extremely high duty cycle observations with well-behaved noise properties. Title: First Kepler results on compact pulsators - I. Survey target selection and the first pulsators Authors: Østensen, R. H.; Silvotti, R.; Charpinet, S.; Oreiro, R.; Handler, G.; Green, E. M.; Bloemen, S.; Heber, U.; Gänsicke, B. T.; Marsh, T. R.; Kurtz, D. W.; Telting, J. H.; Reed, M. D.; Kawaler, S. D.; Aerts, C.; Rodríguez-López, C.; Vučković, M.; Ottosen, T. A.; Liimets, T.; Quint, A. C.; Van Grootel, V.; Randall, S. K.; Gilliland, R. L.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Borucki, W. J.; Koch, D.; Quintana, E. V. Bibcode: 2010MNRAS.409.1470O Altcode: 2010MNRAS.409.1470A; 2010arXiv1007.3170O; 2010MNRAS.tmp.1696O We present results from the first two quarters of a survey to search for pulsations in compact stellar objects with the Kepler spacecraft. The survey sample and the various methods applied in its compilation are described, and spectroscopic observations are presented to separate the objects into accurate classes. From the Kepler photometry we clearly identify nine compact pulsators and a number of interesting binary stars. Of the pulsators, one shows the strong, rapid pulsations typical of a V361 Hya-type sdB variable (sdBV); seven show long-period pulsation characteristics of V1093 Her-type sdBVs; and one shows low-amplitude pulsations with both short and long periods. We derive effective temperatures and surface gravities for all the subdwarf B stars in the sample and demonstrate that below the boundary region where hybrid sdB pulsators are found, all our targets are pulsating. For the stars hotter than this boundary temperature a low fraction of strong pulsators (<10 per cent) is confirmed. Interestingly, the short-period pulsator also shows a low-amplitude mode in the long-period region, and several of the V1093 Her pulsators show low-amplitude modes in the short-period region, indicating that hybrid behaviour may be common in these stars, also outside the boundary temperature region where hybrid pulsators have hitherto been found. Title: Asteroseismic modelling of Procyon A: Preliminary results Authors: Doğan, G.; Bonanno, A.; Bedding, T. R.; Campante, T. L.; Christensen-Dalsgaard, J.; Kjeldsen, H. Bibcode: 2010AN....331..949D Altcode: 2010arXiv1006.5912D We present our preliminary results of the modelling of the F5 star Procyon A. The frequencies predicted by our models are compared with the frequencies extracted through a global fit to the power spectrum obtained by the latest ground-based observations, which provides two different mode identification scenarios. Title: Asteroseismology of solar-type stars with Kepler I: Data analysis Authors: Karoff, C.; Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; Garcia, R. A.; Houdek, G.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Basu, S.; Bedding, T. R.; Campante, T. L.; Eggenberger, P.; Fletcher, S. T.; Gaulme, P.; Handberg, R.; Hekker, S.; Martic, M.; Mathur, S.; Mosser, B.; Regulo, C.; Roxburgh, I. W.; Salabert, D.; Stello, D.; Verner, G. A.; Belkacem, K.; Biazzo, K.; Cunha, M. S.; Gruberbauer, M.; Guzik, J. A.; Kupka, F.; Leroy, B.; Ludwig, H. -G.; Mathis, S.; Noels, A.; Noyes, R. W.; Roca Cortes, T.; Roth, M.; Sato, K. H.; Schmitt, J.; Suran, M. D.; Trampedach, R.; Uytterhoeven, K.; Ventura, R. Bibcode: 2010AN....331..972K Altcode: 2010arXiv1005.0507K We report on the first asteroseismic analysis of solar-type stars observed by Kepler. Observations of three G-type stars, made at one-minute cadence during the first 33.5 days of science operations, reveal high signal-to-noise solar-like oscillation spectra in all three stars: About 20 modes of oscillation can clearly be distinguished in each star. We discuss the appearance of the oscillation spectra, including the presence of a possible signature of faculae, and the presence of mixed modes in one of the three stars. Title: Four years of HELAS Authors: Roth, M.; Lühe, O. v. d.; Aerts, C.; Christensen-Dalsgaard, J.; Corbard, T.; Daszyńska-Daszkiewicz, J.; Di Mauro, M. P.; Gizon, L.; Jiménez-Reyes, S.; Monteiro, M. J. P. F. G.; Pallé, P. L.; Thompson, M. J. Bibcode: 2010AN....331.1084R Altcode: The European Coordination Action on HELio- and ASteroseismology (HELAS) has completed its fourth and final year of initial funding by the European Commission. Set up as a network which combines solar and stellar physics communities in the important and vigorously evolving field of seismology, HELAS has been able to coordinate the efforts of European astronomers with remarkable success. Four large international conferences including the HELAS-IV conference on Lanzarote as well as many workshops were organized with a substantial contribution from HELAS. About a dozen workshops, addressing specialized questions in global and local helioseismology and asteroseismology were entirely organized by HELAS. Data analysis tools to prepare the European communities for the upcoming influx of data from new missions have been prepared, tested and demonstrated. Lecture notes and outreach material have been assembled and prepared for general access. As a result, HELAS has an important impact on the scientific output of the astrophysics seismology communities and significantly increased the visibility of European research in this field. This paper summarizes the activities and accomplishments of HELAS. Title: First Kepler results on compact pulsators - V. Slowly pulsating subdwarf B stars in short-period binaries Authors: Kawaler, S. D.; Reed, M. D.; Østensen, R. H.; Bloemen, S.; Kurtz, D. W.; Quint, A. C.; Silvotti, R.; Baran, A. S.; Green, E. M.; Charpinet, S.; Telting, J.; Aerts, C.; Handler, G.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Borucki, W. J.; Koch, D. G. Bibcode: 2010MNRAS.409.1509K Altcode: 2010MNRAS.tmp.1700K; 2010arXiv1008.0553K The survey phase of the Kepler Mission includes a number of hot subdwarf B (sdB) stars to search for non-radial pulsations. We present our analysis of two sdB stars that are found to be g-mode pulsators of the V1093 Her class. These two stars also display the distinct irradiation effect typical of sdB stars with a close M-dwarf companion with orbital periods of less than half a day. Because the orbital period is so short, the stars should be in synchronous rotation, and if so, the rotation period should imprint itself on the multiplet structure of the pulsations. However, we do not find clear evidence for such rotational splitting. Though the stars do show some frequency spacings that are consistent with synchronous rotation, they also display multiplets with splittings that are much smaller. Longer-duration time series photometry will be needed to determine if those small splittings are in fact rotational splitting, or caused by slow amplitude or phase modulation. Further data should also improve the signal-to-noise ratio, perhaps revealing lower-amplitude periodicities that could confirm the expectation of synchronous rotation. The pulsation periods seen in these stars show period spacings that are suggestive of high-overtone g-mode pulsations. Title: First Kepler results on compact pulsators - II. KIC 010139564, a new pulsating subdwarf B (V361 Hya) star with an additional low-frequency mode Authors: Kawaler, S. D.; Reed, M. D.; Quint, A. C.; Østensen, R. H.; Silvotti, R.; Baran, A. S.; Charpinet, S.; Bloemen, S.; Kurtz, D. W.; Telting, J.; Handler, G.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Borucki, W. J.; Koch, D. G. Bibcode: 2010MNRAS.409.1487K Altcode: 2010arXiv1008.2356K; 2010MNRAS.tmp.1701K We present the discovery of non-radial pulsations in a hot subdwarf B star based on 30.5 d of nearly continuous time series photometry using the Kepler spacecraft. KIC 010139564 is found to be a short-period pulsator of the V361 Hya (EC 14026) class with more than 10 independent pulsation modes whose periods range from 130 to 190 s. It also shows one periodicity at a period of 3165 s. If this periodicity is a high-order g-mode, then this star may be the hottest member of the hybrid DW Lyn stars. In addition to the resolved pulsation frequencies, additional periodic variations in the light curve suggest that a significant number of additional pulsation frequencies may be present. The long duration of the run, the extremely high duty cycle and the well-behaved noise properties allow us to explore the stability of the periodic variations, and to place strong constraints on how many of them are independent stellar oscillation modes. We find that most of the identified periodicities are indeed stable in phase and amplitude, suggesting a rotation period of 2-3 weeks for this star, but further observations are needed to confirm this suspicion. Title: Automatic Determination of Stellar Parameters Via Asteroseismology of Stochastically Oscillating Stars: Comparison with Direct Measurements Authors: Quirion, Pierre-Olivier; Christensen-Dalsgaard, Jørgen; Arentoft, Torben Bibcode: 2010ApJ...725.2176Q Altcode: 2010arXiv1009.5131Q Space-based projects are providing a wealth of high-quality asteroseismic data, including frequencies for a large number of stars showing solar-like oscillations. These data open the prospect for precise determinations of key stellar parameters, of particular value to the study of extra-solar planetary systems. Given the quantity of the available and expected data, it is important to develop efficient and reliable techniques for analyzing them, including the determination of stellar parameters from the observed frequencies. Here we present the SEEK package developed for the analysis of asteroseismic data from the Kepler mission. A central goal of the package is to obtain a fast and automatic determination of the stellar radius and other parameters in a form that is statistically well defined. The algorithms are tested by comparing the results of the analysis with independent measurements of stellar radius and mass for a sample of well-observed stars. We conclude that the SEEK package fixes stellar parameters with accuracy and precision. Title: Seismological challenges for stellar structure Authors: Christensen-Dalsgaard, J. Bibcode: 2010AN....331..866C Altcode: 2010arXiv1007.1720C Helioseismology has provided very detailed information about the solar interior, and extensive data on a large number of stars, although at less detail, are promised by the ongoing and upcoming asteroseismic projects. In the solar case there remain serious challenges in understanding the inferred solar structure, particularly in the light of the revised determinations of the solar surface composition. Also, a secure understanding of the origins of solar rotation as inferred from helioseismology, both in the radiative interior and in the convection zone, is still missing. In the stellar case challenges are certain to appear as the data allow more detailed inferences of the properties of stellar cores. Large remaining uncertainties in modelling concern the properties of convective cores and other processes that may cause mixing. As a result of developing asteroseismic signatures addressing these and other issues, we can look forward to a highly challenging, and hence exciting, era of stellar astrophysics. Title: Solar-like oscillations in cluster stars Authors: Stello, D.; Basu, S.; Bedding, T. R.; Brogaard, K.; Bruntt, H.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Demarque, P.; Elsworth, Y. P.; García, R. A.; Gilliland, R. L.; Hekker, S.; Huber, D.; Karoff, C.; Kjeldsen, H.; Lebreton, Y.; Mathur, S.; Meibom, S.; Molenda-Żakowicz, J.; Noels, A.; Roxburgh, I. W.; Silva Aguirre, V.; Sterken, C.; Szabó, R. Bibcode: 2010AN....331..985S Altcode: 2010arXiv1007.0009S This article summaries a talk given at the HELAS IV international meeting We present a brief overview of the history of attempts to obtain a clear detection of solar-like oscillations in cluster stars, and discuss the results on the first clear detection, which was made by the Kepler Asteroseismic Science Consortium (KASC) Working Group 2.

Data from Kepler. Title: Asteroseismology of Red Giants from the First Four Months of Kepler Data: Global Oscillation Parameters for 800 Stars Authors: Huber, D.; Bedding, T. R.; Stello, D.; Mosser, B.; Mathur, S.; Kallinger, T.; Hekker, S.; Elsworth, Y. P.; Buzasi, D. L.; De Ridder, J.; Gilliland, R. L.; Kjeldsen, H.; Chaplin, W. J.; García, R. A.; Hale, S. J.; Preston, H. L.; White, T. R.; Borucki, W. J.; Christensen-Dalsgaard, J.; Clarke, B. D.; Jenkins, J. M.; Koch, D. Bibcode: 2010ApJ...723.1607H Altcode: 2010arXiv1010.4566H We have studied solar-like oscillations in ~800 red giant stars using Kepler long-cadence photometry. The sample includes stars ranging in evolution from the lower part of the red giant branch to the helium main sequence. We investigate the relation between the large frequency separation (Δν) and the frequency of maximum power (νmax) and show that it is different for red giants than for main-sequence stars, which is consistent with evolutionary models and scaling relations. The distributions of νmax and Δν are in qualitative agreement with a simple stellar population model of the Kepler field, including the first evidence for a secondary clump population characterized by M >~ 2 M sun and νmax ~= 40-110 μHz. We measured the small frequency separations δν02 and δν01 in over 400 stars and δν03 in over 40. We present C-D diagrams for l = 1, 2, and 3 and show that the frequency separation ratios δν02/Δν and δν01/Δν have opposite trends as a function of Δν. The data show a narrowing of the l = 1 ridge toward lower νmax, in agreement with models predicting more efficient mode trapping in stars with higher luminosity. We investigate the offset epsilon in the asymptotic relation and find a clear correlation with Δν, demonstrating that it is related to fundamental stellar parameters. Finally, we present the first amplitude-νmax relation for Kepler red giants. We observe a lack of low-amplitude stars for νmax >~ 110 μHz and find that, for a given νmax between 40 and 110 μHz, stars with lower Δν (and consequently higher mass) tend to show lower amplitudes than stars with higher Δν. Title: A Precise Asteroseismic Age and Radius for the Evolved Sun-like Star KIC 11026764 Authors: Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Molenda-Żakowicz, J.; Appourchaux, T.; Chaplin, W. J.; Doǧan, G.; Eggenberger, P.; Bedding, T. R.; Bruntt, H.; Creevey, O. L.; Quirion, P. -O.; Stello, D.; Bonanno, A.; Silva Aguirre, V.; Basu, S.; Esch, L.; Gai, N.; Di Mauro, M. P.; Kosovichev, A. G.; Kitiashvili, I. N.; Suárez, J. C.; Moya, A.; Piau, L.; García, R. A.; Marques, J. P.; Frasca, A.; Biazzo, K.; Sousa, S. G.; Dreizler, S.; Bazot, M.; Karoff, C.; Frandsen, S.; Wilson, P. A.; Brown, T. M.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Campante, T. L.; Fletcher, S. T.; Handberg, R.; Régulo, C.; Salabert, D.; Schou, J.; Verner, G. A.; Ballot, J.; Broomhall, A. -M.; Elsworth, Y.; Hekker, S.; Huber, D.; Mathur, S.; New, R.; Roxburgh, I. W.; Sato, K. H.; White, T. R.; Borucki, W. J.; Koch, D. G.; Jenkins, J. M. Bibcode: 2010ApJ...723.1583M Altcode: 2010arXiv1010.4329M The primary science goal of the Kepler Mission is to provide a census of exoplanets in the solar neighborhood, including the identification and characterization of habitable Earth-like planets. The asteroseismic capabilities of the mission are being used to determine precise radii and ages for the target stars from their solar-like oscillations. Chaplin et al. published observations of three bright G-type stars, which were monitored during the first 33.5 days of science operations. One of these stars, the subgiant KIC 11026764, exhibits a characteristic pattern of oscillation frequencies suggesting that it has evolved significantly. We have derived asteroseismic estimates of the properties of KIC 11026764 from Kepler photometry combined with ground-based spectroscopic data. We present the results of detailed modeling for this star, employing a variety of independent codes and analyses that attempt to match the asteroseismic and spectroscopic constraints simultaneously. We determine both the radius and the age of KIC 11026764 with a precision near 1%, and an accuracy near 2% for the radius and 15% for the age. Continued observations of this star promise to reveal additional oscillation frequencies that will further improve the determination of its fundamental properties. Title: Stellar Imager (SI): developing and testing a predictive dynamo model for the Sun by imaging other stars Authors: Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska, Margarita; Kraemer, Steve; Lyon, Richard; Mozurkewich, David; Airapetian, Vladimir; Adams, John C.; Allen, Ronald J.; Brown, Alex; Bruhweiler, Fred; Conti, Alberto; Christensen-Dalsgaard, Joergen; Cranmer, Steve; Cuntz, Manfred; Danchi, William; Dupree, Andrea; Elvis, Martin; Evans, Nancy; Giampapa, Mark; Harper, Graham; Hartman, Kathy; Labeyrie, Antoine; Leitner, Jesse; Lillie, Chuck; Linsky, Jeffrey L.; Lo, Amy; Mighell, Ken; Miller, David; Noecker, Charlie; Parrish, Joe; Phillips, Jim; Rimmele, Thomas; Saar, Steve; Sasselov, Dimitar; Stahl, H. Philip; Stoneking, Eric; Strassmeier, Klaus; Walter, Frederick; Windhorst, Rogier; Woodgate, Bruce; Woodruff, Robert Bibcode: 2010arXiv1011.5214C Altcode: The Stellar Imager mission concept is a space-based UV/Optical interferometer designed to resolve surface magnetic activity and subsurface structure and flows of a population of Sun-like stars, in order to accelerate the development and validation of a predictive dynamo model for the Sun and enable accurate long-term forecasting of solar/stellar magnetic activity. Title: Asteroseismology of red giants from the first four months of Kepler data: Fundamental stellar parameters Authors: Kallinger, T.; Mosser, B.; Hekker, S.; Huber, D.; Stello, D.; Mathur, S.; Basu, S.; Bedding, T. R.; Chaplin, W. J.; De Ridder, J.; Elsworth, Y. P.; Frandsen, S.; García, R. A.; Gruberbauer, M.; Matthews, J. M.; Borucki, W. J.; Bruntt, H.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Koch, D. G. Bibcode: 2010A&A...522A...1K Altcode: 2010arXiv1010.4589K Context. Clear power excess in a frequency range typical for solar-type oscillations in red giants has been detected in more than 1000 stars, which have been observed during the first 138 days of the science operation of the NASA Kepler satellite. This sample includes stars in a wide mass and radius range with spectral types G and K, extending in luminosity from the bottom of the giant branch up to high-luminous red giants, including the red bump and clump. The high-precision asteroseismic observations with Kepler provide a perfect source for testing stellar structure and evolutionary models, as well as investigating the stellar population in our Galaxy.
Aims: We aim to extract accurate seismic parameters from the Kepler time series and use them to infer asteroseismic fundamental parameters from scaling relations and a comparison with red-giant models.
Methods: We fit a global model to the observed power density spectra, which allows us to accurately estimate the granulation background signal and the global oscillation parameters, such as the frequency of maximum oscillation power. We find regular patterns of radial and non-radial oscillation modes and use a new technique to automatically identify the mode degree and the characteristic frequency separations between consecutive modes of the same spherical degree. In most cases, we can also measure the small separation between l = 0, 1, and 2 modes. Subsequently, the seismic parameters are used to estimate stellar masses and radii and to place the stars in an H-R diagram by using an extensive grid of stellar models that covers a wide parameter range. Using Bayesian techniques throughout our entire analysis allows us to determine reliable uncertainties for all parameters.
Results: We provide accurate seismic parameters and their uncertainties for a large sample of red giants and determine their asteroseismic fundamental parameters. We investigate the influence of the stars' metallicities on their positions in the H-R diagram. Finally, we study the red-giant populations in the red clump and bump and compare them to a synthetic population. We find a mass and metallicity gradient in the red clump and clear evidence of a secondary-clump population. Title: 2M1938+4603: a rich, multimode pulsating sdB star with an eclipsing dM companion observed with Kepler Authors: Østensen, R. H.; Green, E. M.; Bloemen, S.; Marsh, T. R.; Laird, J. B.; Morris, M.; Moriyama, E.; Oreiro, R.; Reed, M. D.; Kawaler, S. D.; Aerts, C.; Vučković, M.; Degroote, P.; Telting, J. H.; Kjeldsen, H.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Borucki, W. J.; Koch, D. Bibcode: 2010MNRAS.408L..51O Altcode: 2010MNRAS.tmpL.126O; 2010arXiv1006.4267O 2M1938+4603 (KIC9472174) displays a spectacular light curve dominated by a strong reflection effect and rather shallow, grazing eclipses. The orbital period is 0.126 d, the second longest period yet found for an eclipsing sdB+dM, but still close to the minimum 0.1-d period among such systems. The phase-folded Kepler light curve was used to detrend the orbital effects from the data set. The amplitude spectrum of the residual light curve reveals a rich collection of pulsation peaks spanning frequencies from ~50 to 4500μHz. The presence of a complex pulsation spectrum in both the p- and g-mode regions has never before been reported in a compact pulsator.

Eclipsing sdB+dM stars are very rare, with only seven systems known and only one with a pulsating primary. Pulsating stars in eclipsing binaries are especially important since they permit masses derived from seismological model fits to be cross-checked with orbital mass constraints. We present a first analysis of this star based on the Kepler 9.7-d commissioning light curve and extensive ground-based photometry and spectroscopy that allow us to set useful bounds on the system parameters. We derive a radial-velocity amplitude K1 = 65.7 +/- 0.6 kms -1, inclination angle , and find that the masses of the components are M1 = 0.48 +/- 0.03 Msolar and M2 = 0.12 +/- 0.01 Msolar. Title: Early Asteroseismic Results from Kepler: Structural and Core Parameters of the Hot B Subdwarf KPD 1943+4058 as Inferred from g-mode Oscillations Authors: Van Grootel, V.; Charpinet, S.; Fontaine, G.; Brassard, P.; Green, E. M.; Randall, S. K.; Silvotti, R.; Østensen, R. H.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Borucki, W. J.; Koch, D. Bibcode: 2010ApJ...718L..97V Altcode: We present a seismic analysis of the pulsating hot B subdwarf KPD 1943+4058 (KIC 005807616) on the basis of the long-period, gravity-mode pulsations recently uncovered by Kepler. This is the first time that g-mode seismology can be exploited quantitatively for stars on the extreme horizontal branch, all previous successful seismic analyses having been confined so far to short-period, p-mode pulsators. We demonstrate that current models of hot B subdwarfs can quite well explain the observed g-mode periods, while being consistent with independent constraints provided by spectroscopy. We identify the 18 pulsations retained in our analysis as low-degree (ell = 1 and 2), intermediate-order (k = -9 through -58) g-modes. The periods (frequencies) are recovered, on average, at the 0.22% level, which is comparable to the best results obtained for p-mode pulsators. We infer the following structural and core parameters for KPD 1943+4058 (formal fitting uncertainties only): T eff = 28,050 ± 470 K, log g = 5.52 ± 0.03, M * = 0.496 ± 0.002 M sun, log (M env/M *) = -2.55 ± 0.07, log (1 - M core/M *) = -0.37 ± 0.01, and X core(C+O) = 0.261 ± 0.008. We additionally derive the age of the star since the zero-age extended horizontal branch 18.4 ± 1.0 Myr, the radius R = 0.203 ± 0.007 R sun, the luminosity L = 22.9 ± 3.13 L sun, the absolute magnitude MV = 4.21 ± 0.11, the reddening index E(B - V) = 0.094 ± 0.017, and the distance d = 1180 ± 95 pc. Title: Asteroseismic modelling of the solar-like star β Hydri Authors: Doğan, G.; Brandão, I. M.; Bedding, T. R.; Christensen-Dalsgaard, J.; Cunha, M. S.; Kjeldsen, H. Bibcode: 2010Ap&SS.328..101D Altcode: 2009arXiv0912.3653D; 2009Ap&SS.tmp..251D We present the results of modelling the subgiant star β Hydri using seismic observational constraints. We have computed several grids of stellar evolutionary tracks using the Aarhus STellar Evolution Code (ASTEC, Christensen-Dalsgaard in Astrophys. Space Sci. 316:13, 2008a), with and without helium diffusion and settling. For those models on each track that are located at the observationally determined position of β Hydri in the Hertzsprung-Russell (HR) diagram, we have calculated the oscillation frequencies using the Aarhus adiabatic pulsation package (ADIPLS, Christensen-Dalsgaard in Astrophys. Space Sci. 316:113, 2008b). Applying the near-surface corrections to the calculated frequencies using the empirical law presented by Kjeldsen et al. (Astrophys. J. 683:L175, 2008), we have compared the corrected model frequencies with the observed frequencies of the star. We show that after correcting the frequencies for the near-surface effects, we have a fairly good fit for both l=0 and l=2 frequencies. We also have good agreement between the observed and calculated l=1 mode frequencies, although there is room for improvement in order to fit all the observed mixed modes simultaneously. Title: Prospects for asteroseismology Authors: Christensen-Dalsgaard, Jørgen; Houdek, Günter Bibcode: 2010Ap&SS.328...51C Altcode: 2009Ap&SS.tmp..264C; 2009Ap&SS.tmp..287C; 2009Ap&SS.tmp..286C; 2009Ap&SS.tmp..276C; 2009arXiv0911.4629C The observational basis for asteroseismology is being dramatically strengthened, through more than two years of data from the CoRoT satellite, the flood of data coming from the Kepler mission and, in the slightly longer term, from dedicated ground-based facilities. Our ability to utilize these data depends on further development of techniques for basic data analysis, as well as on an improved understanding of the relation between the observed frequencies and the underlying properties of the stars. Also, stellar modelling must be further developed, to match the increasing diagnostic potential of the data. Here we discuss some aspects of data interpretation and modelling, focusing on the important case of stars with solar-like oscillations. Title: Division v: Variable Stars Authors: Gimenez, Alvaro; Kawaler, Steven; Christensen-Dalsgaard, Jørgen; Breger, Michel; Guinan, Edward; Rucinski, Slavek Bibcode: 2010IAUTB..27..207G Altcode: Division V organized a brief Business meeting during the XXVIIth General Assembly, prior to Business meetings (reported separately) of Commissions 27 and 42. The Division V Business Meeting began at 11:00 on 5 August 2009. Title: Asteroseismic Investigation of Known Planet Hosts in the Kepler Field Authors: Christensen-Dalsgaard, J.; Kjeldsen, H.; Brown, T. M.; Gilliland, R. L.; Arentoft, T.; Frandsen, S.; Quirion, P. -O.; Borucki, W. J.; Koch, D.; Jenkins, J. M. Bibcode: 2010ApJ...713L.164C Altcode: 2010arXiv1001.0032C In addition to its great potential for characterizing extra-solar planetary systems, the Kepler Mission is providing unique data on stellar oscillations. A key aspect of Kepler asteroseismology is the application to solar-like oscillations of main-sequence stars. As an example, we here consider an initial analysis of data for three stars in the Kepler field for which planetary transits were known from ground-based observations. For one of these, HAT-P-7, we obtain a detailed frequency spectrum and hence strong constraints on the stellar properties. The remaining two stars show definite evidence for solar-like oscillations, yielding a preliminary estimate of their mean densities. Title: Detection of Solar-like Oscillations from Kepler Photometry of the Open Cluster NGC 6819 Authors: Stello, Dennis; Basu, Sarbani; Bruntt, Hans; Mosser, Benoît; Stevens, Ian R.; Brown, Timothy M.; Christensen-Dalsgaard, Jørgen; Gilliland, Ronald L.; Kjeldsen, Hans; Arentoft, Torben; Ballot, Jérôme; Barban, Caroline; Bedding, Timothy R.; Chaplin, William J.; Elsworth, Yvonne P.; García, Rafael A.; Goupil, Marie-Jo; Hekker, Saskia; Huber, Daniel; Mathur, Savita; Meibom, Søren; Sangaralingam, Vinothini; Baldner, Charles S.; Belkacem, Kevin; Biazzo, Katia; Brogaard, Karsten; Suárez, Juan Carlos; D'Antona, Francesca; Demarque, Pierre; Esch, Lisa; Gai, Ning; Grundahl, Frank; Lebreton, Yveline; Jiang, Biwei; Jevtic, Nada; Karoff, Christoffer; Miglio, Andrea; Molenda-Żakowicz, Joanna; Montalbán, Josefina; Noels, Arlette; Roca Cortés, Teodoro; Roxburgh, Ian W.; Serenelli, Aldo M.; Silva Aguirre, Victor; Sterken, Christiaan; Stine, Peter; Szabó, Robert; Weiss, Achim; Borucki, William J.; Koch, David; Jenkins, Jon M. Bibcode: 2010ApJ...713L.182S Altcode: 2010arXiv1001.0026S Asteroseismology of stars in clusters has been a long-sought goal because the assumption of a common age, distance, and initial chemical composition allows strong tests of the theory of stellar evolution. We report results from the first 34 days of science data from the Kepler Mission for the open cluster NGC 6819—one of the four clusters in the field of view. We obtain the first clear detections of solar-like oscillations in the cluster red giants and are able to measure the large frequency separation, Δν, and the frequency of maximum oscillation power, νmax. We find that the asteroseismic parameters allow us to test cluster membership of the stars, and even with the limited seismic data in hand, we can already identify four possible non-members despite their having a better than 80% membership probability from radial velocity measurements. We are also able to determine the oscillation amplitudes for stars that span about 2 orders of magnitude in luminosity and find good agreement with the prediction that oscillation amplitudes scale as the luminosity to the power of 0.7. These early results demonstrate the unique potential of asteroseismology of the stellar clusters observed by Kepler. Title: Solar-like Oscillations in Low-luminosity Red Giants: First Results from Kepler Authors: Bedding, T. R.; Huber, D.; Stello, D.; Elsworth, Y. P.; Hekker, S.; Kallinger, T.; Mathur, S.; Mosser, B.; Preston, H. L.; Ballot, J.; Barban, C.; Broomhall, A. M.; Buzasi, D. L.; Chaplin, W. J.; García, R. A.; Gruberbauer, M.; Hale, S. J.; De Ridder, J.; Frandsen, S.; Borucki, W. J.; Brown, T.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Jenkins, J. M.; Kjeldsen, H.; Koch, D.; Belkacem, K.; Bildsten, L.; Bruntt, H.; Campante, T. L.; Deheuvels, S.; Derekas, A.; Dupret, M. -A.; Goupil, M. -J.; Hatzes, A.; Houdek, G.; Ireland, M. J.; Jiang, C.; Karoff, C.; Kiss, L. L.; Lebreton, Y.; Miglio, A.; Montalbán, J.; Noels, A.; Roxburgh, I. W.; Sangaralingam, V.; Stevens, I. R.; Suran, M. D.; Tarrant, N. J.; Weiss, A. Bibcode: 2010ApJ...713L.176B Altcode: 2010arXiv1001.0229B We have measured solar-like oscillations in red giants using time-series photometry from the first 34 days of science operations of the Kepler Mission. The light curves, obtained with 30 minute sampling, reveal clear oscillations in a large sample of G and K giants, extending in luminosity from the red clump down to the bottom of the giant branch. We confirm a strong correlation between the large separation of the oscillations (Δν) and the frequency of maximum power (νmax). We focus on a sample of 50 low-luminosity stars (νmax > 100 μHz, L <~ 30 L sun) having high signal-to-noise ratios and showing the unambiguous signature of solar-like oscillations. These are H-shell-burning stars, whose oscillations should be valuable for testing models of stellar evolution and for constraining the star formation rate in the local disk. We use a new technique to compare stars on a single échelle diagram by scaling their frequencies and find well-defined ridges corresponding to radial and non-radial oscillations, including clear evidence for modes with angular degree l = 3. Measuring the small separation between l = 0 and l = 2 allows us to plot the so-called C-D diagram of δν02 versus Δν. The small separation δν01 of l = 1 from the midpoint of adjacent l = 0 modes is negative, contrary to the Sun and solar-type stars. The ridge for l = 1 is notably broadened, which we attribute to mixed modes, confirming theoretical predictions for low-luminosity giants. Overall, the results demonstrate the tremendous potential of Kepler data for asteroseismology of red giants. Title: Automated Classification of Variable Stars in the Asteroseismology Program of the Kepler Space Mission Authors: Blomme, J.; Debosscher, J.; De Ridder, J.; Aerts, C.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Brown, T. M.; Borucki, W. J.; Koch, D.; Jenkins, J. M.; Kurtz, D. W.; Stello, D.; Stevens, I. R.; Suran, M. D.; Derekas, A. Bibcode: 2010ApJ...713L.204B Altcode: 2010arXiv1001.0507B We present the first results of the application of supervised classification methods to the Kepler Q1 long-cadence light curves of a subsample of 2288 stars measured in the asteroseismology program of the mission. The methods, originally developed in the framework of the CoRoT and Gaia space missions, are capable of identifying the most common types of stellar variability in a reliable way. Many new variables have been discovered, among which a large fraction are eclipsing/ellipsoidal binaries unknown prior to launch. A comparison is made between our classification from the Kepler data and the pre-launch class based on data from the ground, showing that the latter needs significant improvement. The noise properties of the Kepler data are compared to those of the exoplanet program of the CoRoT satellite. We find that Kepler improves on CoRoT by a factor of 2-2.3 in point-to-point scatter. Title: Kepler Mission Design, Realized Photometric Performance, and Early Science Authors: Koch, David G.; Borucki, William J.; Basri, Gibor; Batalha, Natalie M.; Brown, Timothy M.; Caldwell, Douglas; Christensen-Dalsgaard, Jørgen; Cochran, William D.; DeVore, Edna; Dunham, Edward W.; Gautier, Thomas N., III; Geary, John C.; Gilliland, Ronald L.; Gould, Alan; Jenkins, Jon; Kondo, Yoji; Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey; Monet, David; Sasselov, Dimitar; Boss, Alan; Brownlee, Donald; Caldwell, John; Dupree, Andrea K.; Howell, Steve B.; Kjeldsen, Hans; Meibom, Søren; Morrison, David; Owen, Tobias; Reitsema, Harold; Tarter, Jill; Bryson, Stephen T.; Dotson, Jessie L.; Gazis, Paul; Haas, Michael R.; Kolodziejczak, Jeffrey; Rowe, Jason F.; Van Cleve, Jeffrey E.; Allen, Christopher; Chandrasekaran, Hema; Clarke, Bruce D.; Li, Jie; Quintana, Elisa V.; Tenenbaum, Peter; Twicken, Joseph D.; Wu, Hayley Bibcode: 2010ApJ...713L..79K Altcode: 2010arXiv1001.0268K The Kepler Mission, launched on 2009 March 6, was designed with the explicit capability to detect Earth-size planets in the habitable zone of solar-like stars using the transit photometry method. Results from just 43 days of data along with ground-based follow-up observations have identified five new transiting planets with measurements of their masses, radii, and orbital periods. Many aspects of stellar astrophysics also benefit from the unique, precise, extended, and nearly continuous data set for a large number and variety of stars. Early results for classical variables and eclipsing stars show great promise. To fully understand the methodology, processes, and eventually the results from the mission, we present the underlying rationale that ultimately led to the flight and ground system designs used to achieve the exquisite photometric performance. As an example of the initial photometric results, we present variability measurements that can be used to distinguish dwarf stars from red giants. Title: First Kepler Results on RR Lyrae Stars Authors: Kolenberg, K.; Szabó, R.; Kurtz, D. W.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Brown, T. M.; Benkő, J. M.; Chadid, M.; Derekas, A.; Di Criscienzo, M.; Guggenberger, E.; Kinemuchi, K.; Kunder, A.; Kolláth, Z.; Kopacki, G.; Moskalik, P.; Nemec, J. M.; Nuspl, J.; Silvotti, R.; Suran, M. D.; Borucki, W. J.; Koch, D.; Jenkins, J. M. Bibcode: 2010ApJ...713L.198K Altcode: 2010arXiv1001.0417K We present the first results of our analyses of selected RR Lyrae stars for which data have been obtained by the Kepler Mission. As expected, we find a significant fraction of the RRab stars to show the Blazhko effect, a still unexplained phenomenon that manifests itself as periodic amplitude and phase modulations of the light curve, on timescales of typically tens to hundreds of days. The long time span of the Kepler Mission of 3.5 yr and the unprecedentedly high precision of its data provide a unique opportunity for the study of RR Lyrae stars. Using data of a modulated star observed in the first roll as a showcase, we discuss the data, our analyses, findings, and their implications for our understanding of RR Lyrae stars and the Blazhko effect. With at least 40% of the RR Lyrae stars in our sample showing modulation, we confirm the high incidence rate that was only found in recent high-precision studies. Moreover, we report the occurrence of additional frequencies, beyond the main pulsation mode and its modulation components. Their half-integer ratio to the main frequency is reminiscent of a period doubling effect caused by resonances, observed for the first time in RR Lyrae stars. Title: Hybrid γ Doradus-δ Scuti Pulsators: New Insights into the Physics of the Oscillations from Kepler Observations Authors: Grigahcène, A.; Antoci, V.; Balona, L.; Catanzaro, G.; Daszyńska-Daszkiewicz, J.; Guzik, J. A.; Handler, G.; Houdek, G.; Kurtz, D. W.; Marconi, M.; Monteiro, M. J. P. F. G.; Moya, A.; Ripepi, V.; Suárez, J. -C.; Uytterhoeven, K.; Borucki, W. J.; Brown, T. M.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Jenkins, J. M.; Kjeldsen, H.; Koch, D.; Bernabei, S.; Bradley, P.; Breger, M.; Di Criscienzo, M.; Dupret, M. -A.; García, R. A.; García Hernández, A.; Jackiewicz, J.; Kaiser, A.; Lehmann, H.; Martín-Ruiz, S.; Mathias, P.; Molenda-Żakowicz, J.; Nemec, J. M.; Nuspl, J.; Paparó, M.; Roth, M.; Szabó, R.; Suran, M. D.; Ventura, R. Bibcode: 2010ApJ...713L.192G Altcode: 2010arXiv1001.0747G Observations of the pulsations of stars can be used to infer their interior structure and test theoretical models. The main-sequence γ Doradus (Dor) and δ Scuti (Sct) stars with masses 1.2-2.5 M sun are particularly useful for these studies. The γ Dor stars pulsate in high-order g-modes with periods of order 1 day, driven by convective blocking at the base of their envelope convection zone. The δ Sct stars pulsate in low-order g- and p-modes with periods of order 2 hr, driven by the κ mechanism operating in the He II ionization zone. Theory predicts an overlap region in the Hertzsprung-Russell diagram between instability regions, where "hybrid" stars pulsating in both types of modes should exist. The two types of modes with properties governed by different portions of the stellar interior provide complementary model constraints. Among the known γ Dor and δ Sct stars, only four have been confirmed as hybrids. Now, analysis of combined Quarter 0 and Quarter 1 Kepler data for hundreds of variable stars shows that the frequency spectra are so rich that there are practically no pure δ Sct or γ Dor pulsators, i.e., essentially all of the stars show frequencies in both the δ Sct and the γ Dor frequency range. A new observational classification scheme is proposed that takes into account the amplitude as well as the frequency and is applied to categorize 234 stars as δ Sct, γ Dor, δ Sct/γ Dor or γ Dor/δ Sct hybrids. Title: A Multi-Site Campaign to Measure Solar-Like Oscillations in Procyon. II. Mode Frequencies Authors: Bedding, Timothy R.; Kjeldsen, Hans; Campante, Tiago L.; Appourchaux, Thierry; Bonanno, Alfio; Chaplin, William J.; Garcia, Rafael A.; Martić, Milena; Mosser, Benoit; Butler, R. Paul; Bruntt, Hans; Kiss, László L.; O'Toole, Simon J.; Kambe, Eiji; Ando, Hiroyasu; Izumiura, Hideyuki; Sato, Bun'ei; Hartmann, Michael; Hatzes, Artie; Barban, Caroline; Berthomieu, Gabrielle; Michel, Eric; Provost, Janine; Turck-Chièze, Sylvaine; Lebrun, Jean-Claude; Schmitt, Jerome; Bertaux, Jean-Loup; Benatti, Serena; Claudi, Riccardo U.; Cosentino, Rosario; Leccia, Silvio; Frandsen, Søren; Brogaard, Karsten; Glowienka, Lars; Grundahl, Frank; Stempels, Eric; Arentoft, Torben; Bazot, Michaël; Christensen-Dalsgaard, Jørgen; Dall, Thomas H.; Karoff, Christoffer; Lundgreen-Nielsen, Jens; Carrier, Fabien; Eggenberger, Patrick; Sosnowska, Danuta; Wittenmyer, Robert A.; Endl, Michael; Metcalfe, Travis S.; Hekker, Saskia; Reffert, Sabine Bibcode: 2010ApJ...713..935B Altcode: 2010arXiv1003.0052B We have analyzed data from a multi-site campaign to observe oscillations in the F5 star Procyon. The data consist of high-precision velocities that we obtained over more than three weeks with 11 telescopes. A new method for adjusting the data weights allows us to suppress the sidelobes in the power spectrum. Stacking the power spectrum in a so-called échelle diagram reveals two clear ridges, which we identify with even and odd values of the angular degree (l = 0 and 2, and l = 1 and 3, respectively). We interpret a strong, narrow peak at 446 μHz that lies close to the l = 1 ridge as a mode with mixed character. We show that the frequencies of the ridge centroids and their separations are useful diagnostics for asteroseismology. In particular, variations in the large separation appear to indicate a glitch in the sound-speed profile at an acoustic depth of ~1000 s. We list frequencies for 55 modes extracted from the data spanning 20 radial orders, a range comparable to the best solar data, which will provide valuable constraints for theoretical models. A preliminary comparison with published models shows that the offset between observed and calculated frequencies for the radial modes is very different for Procyon than for the Sun and other cool stars. We find the mean lifetime of the modes in Procyon to be 1.29+0.55 -0.49 days, which is significantly shorter than the 2-4 days seen in the Sun. Title: The Asteroseismic Potential of Kepler: First Results for Solar-Type Stars Authors: Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; García, R. A.; Houdek, G.; Karoff, C.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Brown, T. M.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Borucki, W. J.; Koch, D.; Jenkins, J. M.; Ballot, J.; Basu, S.; Bazot, M.; Bedding, T. R.; Benomar, O.; Bonanno, A.; Brandão, I. M.; Bruntt, H.; Campante, T. L.; Creevey, O. L.; Di Mauro, M. P.; Doǧan, G.; Dreizler, S.; Eggenberger, P.; Esch, L.; Fletcher, S. T.; Frandsen, S.; Gai, N.; Gaulme, P.; Handberg, R.; Hekker, S.; Howe, R.; Huber, D.; Korzennik, S. G.; Lebrun, J. C.; Leccia, S.; Martic, M.; Mathur, S.; Mosser, B.; New, R.; Quirion, P. -O.; Régulo, C.; Roxburgh, I. W.; Salabert, D.; Schou, J.; Sousa, S. G.; Stello, D.; Verner, G. A.; Arentoft, T.; Barban, C.; Belkacem, K.; Benatti, S.; Biazzo, K.; Boumier, P.; Bradley, P. A.; Broomhall, A. -M.; Buzasi, D. L.; Claudi, R. U.; Cunha, M. S.; D'Antona, F.; Deheuvels, S.; Derekas, A.; García Hernández, A.; Giampapa, M. S.; Goupil, M. J.; Gruberbauer, M.; Guzik, J. A.; Hale, S. J.; Ireland, M. J.; Kiss, L. L.; Kitiashvili, I. N.; Kolenberg, K.; Korhonen, H.; Kosovichev, A. G.; Kupka, F.; Lebreton, Y.; Leroy, B.; Ludwig, H. -G.; Mathis, S.; Michel, E.; Miglio, A.; Montalbán, J.; Moya, A.; Noels, A.; Noyes, R. W.; Pallé, P. L.; Piau, L.; Preston, H. L.; Roca Cortés, T.; Roth, M.; Sato, K. H.; Schmitt, J.; Serenelli, A. M.; Silva Aguirre, V.; Stevens, I. R.; Suárez, J. C.; Suran, M. D.; Trampedach, R.; Turck-Chièze, S.; Uytterhoeven, K.; Ventura, R.; Wilson, P. A. Bibcode: 2010ApJ...713L.169C Altcode: 2010arXiv1001.0506C We present preliminary asteroseismic results from Kepler on three G-type stars. The observations, made at one-minute cadence during the first 33.5 days of science operations, reveal high signal-to-noise solar-like oscillation spectra in all three stars: about 20 modes of oscillation may be clearly distinguished in each star. We discuss the appearance of the oscillation spectra, use the frequencies and frequency separations to provide first results on the radii, masses, and ages of the stars, and comment in the light of these results on prospects for inference on other solar-type stars that Kepler will observe. Title: Near-surface effects and solar-age determination Authors: Doğan, G.; Bonanno, A.; Christensen-Dalsgaard, J. Bibcode: 2010arXiv1004.2215D Altcode: The dominant part of the difference between the observed and model frequencies of the Sun can be approximated by a power law. We show that when this empirical law is employed to correct the model frequencies and then the small frequency separations are used for solar age determination, the results are consistent with the meteoritic age (4.563 Gyr < t < 4.576 Gyr). We present the results and compare with those obtained by using the ratios of small to large frequency separations. Title: Discovery of a Red Giant with Solar-like Oscillations in an Eclipsing Binary System from Kepler Space-based Photometry Authors: Hekker, S.; Debosscher, J.; Huber, D.; Hidas, M. G.; De Ridder, J.; Aerts, C.; Stello, D.; Bedding, T. R.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Brown, T. M.; Kjeldsen, H.; Borucki, W. J.; Koch, D.; Jenkins, J. M.; Van Winckel, H.; Beck, P. G.; Blomme, J.; Southworth, J.; Pigulski, A.; Chaplin, W. J.; Elsworth, Y. P.; Stevens, I. R.; Dreizler, S.; Kurtz, D. W.; Maceroni, C.; Cardini, D.; Derekas, A.; Suran, M. D. Bibcode: 2010ApJ...713L.187H Altcode: 2010arXiv1001.0399H Oscillating stars in binary systems are among the most interesting stellar laboratories, as these can provide information on the stellar parameters and stellar internal structures. Here we present a red giant with solar-like oscillations in an eclipsing binary observed with the NASA Kepler satellite. We compute stellar parameters of the red giant from spectra and the asteroseismic mass and radius from the oscillations. Although only one eclipse has been observed so far, we can already determine that the secondary is a main-sequence F star in an eccentric orbit with a semi-major axis larger than 0.5 AU and orbital period longer than 75 days. Title: Kepler Asteroseismology Program: Introduction and First Results Authors: Gilliland, Ronald L.; Brown, Timothy M.; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans; Aerts, Conny; Appourchaux, Thierry; Basu, Sarbani; Bedding, Timothy R.; Chaplin, William J.; Cunha, Margarida S.; De Cat, Peter; De Ridder, Joris; Guzik, Joyce A.; Handler, Gerald; Kawaler, Steven; Kiss, László; Kolenberg, Katrien; Kurtz, Donald W.; Metcalfe, Travis S.; Monteiro, Mario J. P. F. G.; Szabó, Robert; Arentoft, Torben; Balona, Luis; Debosscher, Jonas; Elsworth, Yvonne P.; Quirion, Pierre-Olivier; Stello, Dennis; Suárez, Juan Carlos; Borucki, William J.; Jenkins, Jon M.; Koch, David; Kondo, Yoji; Latham, David W.; Rowe, Jason F.; Steffen, Jason H. Bibcode: 2010PASP..122..131G Altcode: 2010arXiv1001.0139G Asteroseismology involves probing the interiors of stars and quantifying their global properties, such as radius and age, through observations of normal modes of oscillation. The technical requirements for conducting asteroseismology include ultrahigh precision measured in photometry in parts per million, as well as nearly continuous time series over weeks to years, and cadences rapid enough to sample oscillations with periods as short as a few minutes. We report on results from the first 43 days of observations, in which the unique capabilities of Kepler in providing a revolutionary advance in asteroseismology are already well in evidence. The Kepler asteroseismology program holds intrinsic importance in supporting the core planetary search program through greatly enhanced knowledge of host star properties, and extends well beyond this to rich applications in stellar astrophysics. Title: Sounding stellar cycles with Kepler - preliminary results from ground-based chromospheric activity measurements† Authors: Karoff, C.; Metcalfe, T. S.; Chaplin, W. J.; Frandsen, S.; Grundahl, F.; Kjeldsen, H.; Buzasi, D.; Arentoft, T.; Christensen-Dalsgaard, J. Bibcode: 2010IAUS..264...57K Altcode: 2009arXiv0910.1436K Due to its unique long-term coverage and high photometric precision, observations from the Kepler asteroseismic investigation will provide us with the possibility to sound stellar cycles in a number of solar-type stars with asteroseismology. By comparing these measurements with conventional ground-based chromospheric activity measurements we might be able to increase our understanding of the relation between the chromospheric changes and the changes in the eigenmodes.

In parallel with the Kepler observations we have therefore started a programme at the Nordic Optical Telescope to observe and monitor chromospheric activity in the stars that are most likely to be selected for observations for the whole satellite mission. The ground-based observations presented here can be used both to guide the selection of the special Kepler targets and as the first step in a monitoring programme for stellar cycles. Also, the chromospheric activity measurements obtained from the ground-based observations can be compared with stellar parameters such as ages and rotation in order to improve stellar evolution models. Title: Kepler Planet-Detection Mission: Introduction and First Results Authors: Borucki, William J.; Koch, David; Basri, Gibor; Batalha, Natalie; Brown, Timothy; Caldwell, Douglas; Caldwell, John; Christensen-Dalsgaard, Jørgen; Cochran, William D.; DeVore, Edna; Dunham, Edward W.; Dupree, Andrea K.; Gautier, Thomas N.; Geary, John C.; Gilliland, Ronald; Gould, Alan; Howell, Steve B.; Jenkins, Jon M.; Kondo, Yoji; Latham, David W.; Marcy, Geoffrey W.; Meibom, Søren; Kjeldsen, Hans; Lissauer, Jack J.; Monet, David G.; Morrison, David; Sasselov, Dimitar; Tarter, Jill; Boss, Alan; Brownlee, Don; Owen, Toby; Buzasi, Derek; Charbonneau, David; Doyle, Laurance; Fortney, Jonathan; Ford, Eric B.; Holman, Matthew J.; Seager, Sara; Steffen, Jason H.; Welsh, William F.; Rowe, Jason; Anderson, Howard; Buchhave, Lars; Ciardi, David; Walkowicz, Lucianne; Sherry, William; Horch, Elliott; Isaacson, Howard; Everett, Mark E.; Fischer, Debra; Torres, Guillermo; Johnson, John Asher; Endl, Michael; MacQueen, Phillip; Bryson, Stephen T.; Dotson, Jessie; Haas, Michael; Kolodziejczak, Jeffrey; Van Cleve, Jeffrey; Chandrasekaran, Hema; Twicken, Joseph D.; Quintana, Elisa V.; Clarke, Bruce D.; Allen, Christopher; Li, Jie; Wu, Haley; Tenenbaum, Peter; Verner, Ekaterina; Bruhweiler, Frederick; Barnes, Jason; Prsa, Andrej Bibcode: 2010Sci...327..977B Altcode: The Kepler mission was designed to determine the frequency of Earth-sized planets in and near the habitable zone of Sun-like stars. The habitable zone is the region where planetary temperatures are suitable for water to exist on a planet’s surface. During the first 6 weeks of observations, Kepler monitored 156,000 stars, and five new exoplanets with sizes between 0.37 and 1.6 Jupiter radii and orbital periods from 3.2 to 4.9 days were discovered. The density of the Neptune-sized Kepler-4b is similar to that of Neptune and GJ 436b, even though the irradiation level is 800,000 times higher. Kepler-7b is one of the lowest-density planets (~0.17 gram per cubic centimeter) yet detected. Kepler-5b, -6b, and -8b confirm the existence of planets with densities lower than those predicted for gas giant planets. Title: The Kepler Mission and Early Results Authors: Koch, David; Borucki, William; Jenkins, Jon; Basri, Gibor; Batalha, Natalie M.; Brown, Timothy M.; Caldwell, Douglas; Christensen-Dalsgaard, Jørgen; Cochran, William D.; Devore, Edna; Dunham, Edward W.; Gautier, Thomas N., III; Geary, John C.; Gilliland, Ronald L.; Gould, Alan; Jenkins, Jon; Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey; Monet, David; Sasselov, Dimitar; Boss, Alan; Caldwell, John; Dupree, Andrea K.; Howell, Steve B.; Kjeldsen, Hans; Meibom, Søren; Morrison, David; Tarter, Jill; Bryson, Stephen T.; Dotson, Jessie L.; Haas, Michael R.; Kolodziejczak, Jeffrey; Rowe, Jason F.; van Cleve, Jeffrey E.; Buzasi, Derek; Charbonneau, David; Doyle, Lau-Rance; Ford, Eric; Fortney, Jonathan; Holman, Matthew; Seager, Sara; Steffen, Jason; Welsh, William Bibcode: 2010cosp...38.2513K Altcode: 2010cosp.meet.2513K Kepler is a Discovery-class mission designed to determine the frequency of Earth-size planets in and near the habitable zone of solar-like stars. The instrument consists of a 0.95 m aperture photometer designed to obtain high-precision photometric measurement for more than 3.5 years of more than 100,000 stars to search for patterns of transits of exoplanets. The focal plane of the Schmidt telescope contains 42 CCDs with a total of 95 megapixels that cover 115 square degrees of sky. The single star field will be viewed for the entire duration of the mission. The photometer was launched into an Earth-trailing heliocentric orbit on March 6, 2009, finished its commissioning on May 12, and is now in the science operations mode. The bases for a number of the design choices are described. Although the data have not yet been fully corrected for the presence of systematic errors and artifacts, the data show the presence of thousands of eclipsing binaries and variable stars of amazing variety. The character of stellar variability allows us to distinguish dwarf stars from giants. Astrometric stability at the sub-millipixel level of the photocenters of stars allows us in many cases to distinguish transit candidates from background eclipsing binaries. Analysis of the early data shows transits, occultations and even visible light emission from the hot exoplanet HAT-P-7b. The latest results on exoplanet detections from Kepler will be presented. Funding for this mission is provided by NASA's Science Mission Directorate. Title: Asteroseismology Authors: Aerts, Conny; Christensen-Dalsgaard, Jørgen; Kurtz, Donald W. Bibcode: 2010aste.book.....A Altcode: The recent research domain of asteroseismology studies the internal structure of stars, which is not directly observable, through the interpretation of the frequency spectra of stellar oscillations. The basic principles of asteroseismology are very similar to those developed by earth seismologists. Stellar interiors can be probed from oscillations because different oscillation modes penetrate to different depths inside the star. Asteroseismology is the only available method to derive the internal structure of the stars with high precision.

This book - the first on asteroseismology - offers a practical guide for graduate students and scientists working in stellar astrophysics. It provides a general introduction to asteroseismology and comprehensive coverage of all its aspects: fundamental theory, observations and observational techniques, methodology of data analysis and seismic interpretations of various classes of multi-periodic pulsating stars. Title: Kepler Planet Detection Mission: Introduction and First Results Authors: Borucki, William J.; Koch, D.; Basri, G.; Batalha, N. M.; Brown, T.; Caldwell, D. A.; Caldwell, J.; Christensen-Dalsgaard, J.; Cochran, W.; DeVore, E.; Dunham, E.; Dupree, A.; Gautier, T.; Geary, J.; Gilliland, R.; Gould, A.; Howell, S.; Jenkins, J.; Kjeldsen, H.; Kondo, Y.; Latham, D.; Lissauer, J.; Marcy, G.; Meibom, S.; Monet, D.; Morrison, D.; Sasselov, D.; Tarter, J. Bibcode: 2010AAS...21510101B Altcode: 2010BAAS...42..215B The Kepler Mission is designed to determine the frequency of Earth-size and terrestrial size planets in and near the HZ of solar-like stars. It was competitively selected as Discovery Mission #10 and launched on March 6, 2009. Since completion of commissioning, it has continuously observed over 145,000 main sequence stars. The photometric precision reaches 20 ppm for 12th magnitude stars on the least noisy detectors in 6.5 hours. During the first month of operation, the photometer detected transit-like signatures from over 100 stars. Careful examination of these events shows many of them to be false-positives such as background eclipsing binaries. However ground-based follow up observations confirm the discovery of exoplanets with sizes ranging from 0.6 Rj to1.5Rj and orbital periods ranging from 3 to 9 days. Observations at Keck, Hobby-Eberly, Harlan-Smith, WIYN, MMT, Tillighast, Shane, and Nordic Optic telescopes are vetting many of the candidates and measuring their masses. Discovery of the HAT-P7b occultation will be used to derive atmospheric properties and demonstrates the precision necessary to detect Earth-size planets. Asteroseismic analyses of several stars show the presence of p-mode oscillations that can be used to determine stellar size and age. This effort is being organized by the Kepler Asteroseismic Science Consortium at Aarhus University in Denmark. Stellar parallaxes are determined from the centroid motion of the stellar images and will be combined with photometric measurements to get the sizes of stars too dim for asteroseismic measurement. Four open clusters are being observed to determine rotation rates with stellar age and spectral type. Many types of stellar variability are observed with unprecedented precision and over long continuous time periods. Examples of many of these discoveries are presented. Funding by the Exoplanet Exploration Program of the NASA Astrophysics Division is gratefully acknowledged. Title: The Kepler Short Cadence Data and Applications for Asteroseismology and Transit Light Curves Authors: Gilliland, Ronald L.; Brown, T. M.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Borucki, W. J.; Bryson, S.; Caldwell, D. A.; Jenkins, J. M.; Koch, D.; Kepler Team Bibcode: 2010AAS...21530504G Altcode: 2010BAAS...42..302G The Kepler data acquisition allows 512 targets to be followed in a 'short cadence' mode with roughly 1-minute integrations as needed for asteroseismology of solar analogs having p-mode oscillations of a few minutes, and to study fine details of high S/N transits. Characteristics of these data will be described. An application of asteroseismology in support of the core Kepler mission of characterizing detected planets follows from stellar radius determinations needed to in turn provide radii for the planets. The steps from processing of Kepler short cadence data, derivation of asteroseismic frequencies from power spectra of these time series, constraint on the mean stellar density and ultimately stellar radius will be illustrated for a few planet host stars yielding radii to accuracies approaching 1%. Analysis of individual oscillation frequencies will provide information about the properties of stellar interiors, resulting in some cases in determinations of ages to about 10%. Asteroseismic results will ultimately be expected for several thousand stars ranging from the solar analog oscillations mentioned above, to oscillations in red giants and a full spectrum of classical variable stars (both at short, and the 30-minute long cadence) including delta Scuti, RR Lyrae, RoAp stars etc.

Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA, Science Mission Directorate. Title: The internal dynamics and magnetism of the sun -- the perspective from global helioseismology (Invited) Authors: Howe, R.; Hill, F.; Komm, R.; Christensen-Dalsgaard, J.; Schou, J.; Thompson, M. J. Bibcode: 2009AGUFMSH11B..04H Altcode: Helioseismology allows us to probe the interior dynamics of the Sun. Observations over the past three decades reveal the interior rotation profile, with a near-surface shear layer, differential rotation throughout the convection zone, a strong shear layer -- the tachocline -- at the base of the convection zone, and approximately uniform rotation in the radiative interior. Since the mid 1990's, continuous observations from the Global Oscillations Network Group and the Michelson Doppler Imager have allowed the study of subtle temporal variations in the rotation within the convection zone. The so-called "torsional oscillation" pattern of migrating zonal flows accompanying the surface activity migration during the solar cycle has been shown to penetrate deep within the convection zone. During the current extended solar minimum, the flow bands can be seen to migrate more slowly towards the equator than was seen in the previous minimum. There have also been (still unconfirmed) findings of shorter-term variations in the rotation rate close to the tachocline during the early years of the previous solar cycle. This review will describe the important results and give an update on the most recent observations of the interior dynamics as we await the rise of solar cycle 24. Title: The Stellar Observations Network Group—the Prototype Authors: Grundahl, F.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Jørgensen, U. G.; Arentoft, T.; Frandsen, S.; Kjærgaard, P. Bibcode: 2009ASPC..416..579G Altcode: 2009arXiv0908.0436G The Stellar Observations Network Group (SONG) has obtained full funding for the design, construction and implementation of a prototype telescope and instrumentation package for the first network node. We describe the layout of such a node and its instrumentation and expected performance for radial-velocity measurements. The instrumentation consists of a 1m telescope, equipped with two cameras for photometry of microlensing events with the lucky-imaging technique and a high-resolution spectrograph equipped with an iodine cell for obtaining high-precision radial velocities of solar-like stars, in order to do asteroseismology. The telescope will be located in a dome of ∼4.5 m diameter, with two lucky-imaging cameras at one of the Nasmyth foci and the spectrograph and instrument control computers at a Coudé focus, located in an adjacent container. Currently the prototype telescope and instrumentation is undergoing detailed design. Installation at the first site (Tenerife) is expected during mid-late 2010, followed by extensive testing during 2011. Title: Open issues in stellar modelling Authors: Christensen-Dalsgaard, J. Bibcode: 2009arXiv0912.1405C Altcode: An important goal of helio- and asteroseismology is to improve the modelling of stellar evolution. Here I provide a brief discussion of some of the uncertain issues in stellar modelling, of possible relevance to asteroseismic inferences. Title: The Torsional Oscillation and the Solar Minimum Authors: Howe, R.; Hill, F.; Komm, R.; Christensen-Dalsgaard, J.; Schou, J.; Thompson, M. J. Bibcode: 2009AGUFM.U34A..03H Altcode: The so-called torsional oscillation is a pattern of zonal flow bands, detected at the solar surface by direct Doppler measurements and within the convection zone by helioseismic measurements such as those carried out by the Global Oscillations Network Group and the Michelson Doppler Imager, that migrates from mid-latitudes towards the equator and poles with each solar cycle. In the current minimum the low-latitude branch of the pattern can be seen to have taken at least a year longer to migrate towards the equator than was the case in the previous minimum. A flow configuration matching that of the previous minimum was reached during 2008, and by early 2009 the fast-rotating belt associated with the new cycle had reached the latitude at which the onset of activity was seen in Cycle 23, but magnetic activity has remained low. We will present the most recent results and consider the implications for the new solar cycle. Title: A Stellar Model-fitting Pipeline for Solar-like Oscillations Authors: Metcalfe, T. S.; Creevey, O. L.; Christensen-Dalsgaard, J. Bibcode: 2009AIPC.1170..535M Altcode: 2009arXiv0906.4317M Over the past two decades, helioseismology has revolutionized our understanding of the interior structure and dynamics of the Sun. Asteroseismology will soon place this knowledge into a broader context by providing structural data for hundreds of Sun-like stars. Solar-like oscillations have already been detected from the ground in several stars, and NASA's Kepler mission is poised to unleash a flood of stellar pulsation data. Deriving reliable asteroseismic information from these observations demands a significant improvement in our analysis methods. We report the initial results of our efforts to develop an objective stellar model-fitting pipeline for asteroseismic data. The cornerstone of our automated approach is an optimization method using a parallel genetic algorithm. We describe the details of the pipeline and we present the initial application to Sun-as-a-star data, yielding an optimal model that accurately reproduces the known solar properties. Title: Radial Pulsations in A Stars: the Effects of Opacity Fluctuations in their Atmospheres Authors: Medupe, R.; Christensen-Dalsgaard, J.; Phorah, M. Bibcode: 2009AIPC.1170..506M Altcode: We investigate the effect of pulsational opacity fluctuations in the atmospheres of A star models and show that the opacity fluctuations are responsible for the ``bump'' often seen in the temperature eigenfunctions in the region of the hydrogen ionization zone. We also present a formula that relates perturbations in the surface flux to those in effective temperature (Teff). This formula shows that for cooler A stars, opacity fluctuations can introduce a phase difference between δH(0)/H(0) and δTeff/Teff. In addition the new formula is used to calculate multicolour pulsational amplitudes that can be compared with photometric data to perform mode discrimination. Title: A Note on the Torsional Oscillation at Solar Minimum Authors: Howe, R.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R.; Schou, J.; Thompson, M. J. Bibcode: 2009ApJ...701L..87H Altcode: 2009arXiv0907.2965H We examine the evolution of the zonal flow pattern in the upper solar convection zone during the current extended solar minimum, and compare it with that during the previous minimum. The results suggest that a configuration matching that at the previous minimum was reached during 2008, but that the flow band corresponding to the new cycle has been moving more slowly toward the equator than was observed in the previous cycle, resulting in a gradual increase in the apparent length of the cycle during the 2007-2008 period. The current position of the lower-latitude fast-rotating belt corresponds to that seen around the onset of activity in the previous cycle. Title: Kepler’s Optical Phase Curve of the Exoplanet HAT-P-7b Authors: Borucki, W. J.; Koch, D.; Jenkins, J.; Sasselov, D.; Gilliland, R.; Batalha, N.; Latham, D. W.; Caldwell, D.; Basri, G.; Brown, T.; Christensen-Dalsgaard, J.; Cochran, W. D.; DeVore, E.; Dunham, E.; Dupree, A. K.; Gautier, T.; Geary, J.; Gould, A.; Howell, S.; Kjeldsen, H.; Lissauer, J.; Marcy, G.; Meibom, S.; Morrison, D.; Tarter, J. Bibcode: 2009Sci...325..709B Altcode: Ten days of photometric data were obtained during the commissioning phase of the Kepler mission, including data for the previously known giant transiting exoplanet HAT-P-7b. The data for HAT-P-7b show a smooth rise and fall of light from the planet as it orbits its star, punctuated by a drop of 130 ± 11 parts per million in flux when the planet passes behind its star. We interpret this as the phase variation of the dayside thermal emission plus reflected light from the planet as it orbits its star and is occulted. The depth of the occultation is similar in importance to the detection of a transiting Earth-size planet for which the mission was designed. Title: Radius Determination of Solar-type Stars Using Asteroseismology: What to Expect from the Kepler Mission Authors: Stello, Dennis; Chaplin, William J.; Bruntt, Hans; Creevey, Orlagh L.; García-Hernández, Antonio; Monteiro, Mario J. P. F. G.; Moya, Andrés; Quirion, Pierre-Olivier; Sousa, Sergio G.; Suárez, Juan-Carlos; Appourchaux, Thierry; Arentoft, Torben; Ballot, Jerome; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen; Elsworth, Yvonne; Fletcher, Stephen T.; García, Rafael A.; Houdek, Günter; Jiménez-Reyes, Sebastian J.; Kjeldsen, Hans; New, Roger; Régulo, Clara; Salabert, David; Toutain, Thierry Bibcode: 2009ApJ...700.1589S Altcode: 2009arXiv0906.0766S For distant stars, as observed by the NASA Kepler satellite, parallax information is currently of fairly low quality and is not complete. This limits the precision with which the absolute sizes of the stars and their potential transiting planets can be determined by traditional methods. Asteroseismology will be used to aid the radius determination of stars observed during NASA's Kepler mission. We report on the recent asteroFLAG hare-and-hounds Exercise#2, where a group of "hares" simulated data of F-K main-sequence stars that a group of "hounds" sought to analyze, aimed at determining the stellar radii. We investigated stars in the range 9 < V < 15, both with and without parallaxes. We further test different uncertainties in T eff, and compare results with and without using asteroseismic constraints. Based on the asteroseismic large frequency spacing, obtained from simulations of 4 yr time series data from the Kepler mission, we demonstrate that the stellar radii can be correctly and precisely determined, when combined with traditional stellar parameters from the Kepler Input Catalogue. The radii found by the various methods used by each independent hound generally agree with the true values of the artificial stars to within 3%, when the large frequency spacing is used. This is 5-10 times better than the results where seismology is not applied. These results give strong confidence that radius estimation can be performed to better than 3% for solar-like stars using automatic pipeline reduction. Even when the stellar distance and luminosity are unknown we can obtain the same level of agreement. Given the uncertainties used for this exercise we find that the input log g and parallax do not help to constrain the radius, and that T eff and metallicity are the only parameters we need in addition to the large frequency spacing. It is the uncertainty in the metallicity that dominates the uncertainty in the radius. Title: A Stellar Model-fitting Pipeline for Asteroseismic Data from the Kepler Mission Authors: Metcalfe, T. S.; Creevey, O. L.; Christensen-Dalsgaard, J. Bibcode: 2009ApJ...699..373M Altcode: 2009arXiv0903.0616M Over the past two decades, helioseismology has revolutionized our understanding of the interior structure and dynamics of the Sun. Asteroseismology will soon place this knowledge into a broader context by providing structural data for hundreds of Sun-like stars. Solar-like oscillations have already been detected from the ground in several stars, and NASA's Kepler mission is poised to unleash a flood of stellar pulsation data. Deriving reliable asteroseismic information from these observations demands a significant improvement in our analysis methods. In this paper, we report the initial results of our efforts to develop an objective stellar model-fitting pipeline for asteroseismic data. The cornerstone of our automated approach is an optimization method using a parallel genetic algorithm. We describe the details of the pipeline and we present the initial application to Sun-as-a-star data, yielding an optimal model that accurately reproduces the known solar properties. Title: Concluding remarks Authors: Christensen-Dalsgaard, J. Bibcode: 2009CoAst.158..356C Altcode: The 38th Liège Colloquium covered a broad range of topics within the area of massive stars on and near the main sequence. This included the physical processes in stellar interiors and modelling of stellar evolution, as well as observational aspects with emphasis on asteroseismology and the potential of recent and coming observations. This was a fitting tribute to Arlette Noels on the occasion of her retirement. Here I provide a brief summary of some of the main points of the conference. Title: Composing the verses for SONG Authors: Grundahl, F.; Christensen-Dalsgaard, J.; Arentoft, T.; Frandsen, S.; Kjeldsen, H.; Jørgensen, U. G.; Kjærgaard, P. Bibcode: 2009CoAst.158..345G Altcode: The SONG (Stellar Observations Network Group) project aims at designing and building a global network of 1m telescopes. The primary science goals are to detect extra--solar planets (using the microlensing and radial velocity techniques) and study stellar interiors using asteroseismology. In early 2008 funding was obtained to construct a prototype network node (telescope, dome, instrumentation and software) to be ready by the end of 2011. Here we give an account of the project and the expected broad structure of the network nodes. Title: The Kepler mission Authors: Christensen-Dalsgaard, J.; Arentoft, T.; Brown, T. M.; Gilliland, R. L.; Kjeldsen, H.; Borucki, W. J.; Koch, D. Bibcode: 2009CoAst.158..328C Altcode: The Kepler mission will provide a vast improvement in the characterization of extrasolar planetary systems, and in addition give a dramatic increase in the data available for asteroseismology. The present paper gives a brief overview of the mission, emphasizing the asteroseismic aspects, and with references to more detailed presentations. Title: The Sun as a fundamental calibrator of stellar evolution Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2009IAUS..258..431C Altcode: 2009arXiv0904.0358C The Sun is unique amongst stars in having a precisely determined age which does not depend on the modelling of stellar evolution. Furthermore, other global properties of the Sun are known to much higher accuracy than for any other star. Also, helioseismology has provided detailed determination of the solar internal structure and rotation. As a result, the Sun plays a central role in the development and test of stellar modelling. Here I discuss solar modelling and its application to tests of asteroseismic techniques for stellar age determination. Title: Measurements of Stellar Properties through Asteroseismology: A Tool for Planet Transit Studies Authors: Kjeldsen, Hans; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen Bibcode: 2009IAUS..253..309K Altcode: 2008arXiv0807.0508K Oscillations occur in stars of most masses and essentially all stages of evolution. Asteroseismology is the study of the frequencies and other properties of stellar oscillations, from which we can extract fundamental parameters such as density, mass, radius, age and rotation period. We present an overview of asteroseismic analysis methods, focusing on how this technique may be used as a tool to measure stellar properties relevant to planet transit studies. We also discuss details of the Kepler Asteroseismic Investigation the use of asteroseismology on the Kepler mission in order to measure basic stellar parameters. We estimate that applying asteroseismology to stars observed by Kepler will allow the determination of stellar mean densities to an accuracy of 1%, radii to 2 3%, masses to 5%, and ages to 5 10% of the main-sequence lifetime. For rotating stars, the angle of inclination can also be determined. Title: KEPLER: Search for Earth-Size Planets in the Habitable Zone Authors: Borucki, William; Koch, David; Batalha, Natalie; Caldwell, Douglas; Christensen-Dalsgaard, Jorgen; Cochran, William D.; Dunham, Edward; Gautier, Thomas N.; Geary, John; Gilliland, Ronald; Jenkins, Jon; Kjeldsen, Hans; Lissauer, Jack J.; Rowe, Jason Bibcode: 2009IAUS..253..289B Altcode: The Kepler Mission is a space-based mission whose primary goal is to determine the frequency of Earth-size and larger planets in the habitable zone of solar-like stars. The mission will monitor more than 100,000 stars for patterns of transits with a differential photometric precision of 20 ppm at V = 12 for a 6.5 hour transit. It will also provide asteroseismic results on several thousand dwarf stars. It is specifically designed to continuously observe a single field of view of greater than 100 square degrees for 3.5 or more years.

This paper provides a short overview of the mission, a brief history of the mission development, expected results, new investigations by the recently chosen Participating Scientists, and the plans for the Guest Observer and Astrophysical Data Programs. Title: Solar-like oscillations in the G8 V star τ Ceti Authors: Teixeira, T. C.; Kjeldsen, H.; Bedding, T. R.; Bouchy, F.; Christensen-Dalsgaard, J.; Cunha, M. S.; Dall, T.; Frandsen, S.; Karoff, C.; Monteiro, M. J. P. F. G.; Pijpers, F. P. Bibcode: 2009A&A...494..237T Altcode: 2008arXiv0811.3989T We used HARPS to measure oscillations in the low-mass star τ Cet. Although the data were compromised by instrumental noise, we have been able to extract the main features of the oscillations. We found τ Cet to oscillate with an amplitude that is about half that of the Sun, and with a mode lifetime that is slightly shorter than solar. The large frequency separation is 169 μHz, and we have identified modes with degrees 0, 1, 2, and 3. We used the frequencies to estimate the mean density of the star to an accuracy of 0.45% which, combined with the interferometric radius, gives a mass of 0.783 ± 0.012 M⊙ (1.6%).

Based on observations collected at the European Southern Observatory, La Silla, Chile (ESO Programme 74.D-0380). Title: On the opacity change required to compensate for the revised solar composition Authors: Christensen-Dalsgaard, J.; di Mauro, M. P.; Houdek, G.; Pijpers, F. Bibcode: 2009A&A...494..205C Altcode: 2008arXiv0811.1001C Context: Recent revisions of the determination of the solar composition have resulted in solar models in marked disagreement with helioseismic inferences.
Aims: The effect of the inferred composition change on the models is largely caused by the change in opacity. Thus, we wish to determine an intrinsic opacity change that would compensate for the revision to the composition.
Methods: By comparing models computed with the old and revised compositions we determine the required opacity change. Models are computed with the opacity modified in this manner and used as reference in helioseismic inversions to determine the difference between the solar and model sound speed.
Results: An opacity increase ranging between around 30 per cent close to the base of the convection zone and a few percent in the solar core leads to a sound-speed profile, for the revised composition, that is essentially indistinguishable from the original solar model. As a function of the logarithm of temperature this is well represented by a simple cubic fit. The physical realism of such a change remains debatable, however. Title: Asteroseismology: The Next Frontier in Stellar Astrophysics Authors: Giampapa, Mark S.; Aerts, Conny; Bedding, Tim; Bonanno, Alfio; Brown, Timothy M.; Christensen-Dalsgaard, Jorgen; Dominik, Martin; Ge, Jian; Gilliland, Ronald L.; Harvey, J. W.; Hill, Frank; Kawaler, Steven D.; Kjeldsen, Hans; Kurtz, D. W.; Marcy, Geoffrey W.; Matthews, Jaymie M.; Monteiro, Mario Joao P. F. G.; Schou, Jesper Bibcode: 2009astro2010S..91G Altcode: No abstract at ADS Title: Division V: Vaviable Stars Authors: Giménez, Alvaro; Kawaler, Steven D.; Aerts, Conny; Christensen-Dalsgaard, Jørgen; Breger, Michael; Guinan, Edward F.; Kurtz, Donald W.; Rucinski, Slavek M. Bibcode: 2009IAUTA..27..251G Altcode: Division V deals with all aspects of stellar variability, either intrinsic or due to eclipses by its companion in a binary system. In the case of intrinsic stellar variability the analysis of pulsating stars, surface inhomogeneities, stellar activity and oscillations are considered. For close binaries, classical detached eclipsing binaries are studied as well as more interacting systems, like contact and semi-detached binaries, or those with compact components, like cataclysmic variables and X-ray binaries, including the physics of accretion processes. Title: Dynamos and magnetic fields of the Sun and other cool stars, and their role in the formation and evolution of stars and in the habitability of planets Authors: Schrijver, Karel; Carpenter, Ken; Karovska, Margarita; Ayres, Tom; Basri, Gibor; Brown, Benjamin; Christensen-Dalsgaard, Joergen; Dupree, Andrea; Guinan, Ed; Jardine, Moira; Miesch, Mark; Pevtsov, Alexei; Rempel, Matthias; Scherrer, Phil; Solanki, Sami; Strassmeier, Klaus; Walter, Fred Bibcode: 2009astro2010S.262S Altcode: No abstract at ADS Title: Commission 12: Solar Radiation and Structure Authors: Martínez Pillet, Valentin; Kosovichev, Alexander; Mariska, John T.; Bogdan, Thomas J.; Asplund, Martin; Cauzzi, Gianna; Christensen-Dalsgaard, Jørgen; Cram, Lawrence E.; Gan, Weiqun; Gizon, Laurent; Heinzl, Petr; Rovira, Marta G.; Venkatakrishnan, P. Bibcode: 2009IAUTA..27..104M Altcode: Commission 12 encompasses investigations on the internal structure and dynamics of the Sun, mostly accessible through the techniques of local and global helioseismology, the quiet solar atmosphere, solar radiation and its variability, and the nature of relatively stable magnetic structures like sunspots, faculae and the magnetic network. A revision of the progress made in these fields is presented. For some specific topics, the review has counted with the help of experts outside the Commission Organizing Committee that are leading and/or have recently presented relevant works in the respective fields. In this cases the contributor's name is given in parenthesis. Title: Kepler Authors: Christensen-Dalsgaard, J.; Arentoft, T.; Brown, T. M.; Gilliland, R. L.; Kjeldsen, H.; Borucki, W. J.; Koch, D. Bibcode: 2008CoAst.157..266C Altcode: Kepler is a NASA mission, scheduled for launch in April 2009, whose principal purpose is to investigate extra-solar planetary systems, through the detection of planetary transits across their parent star. An important goal is to determine the prevalence of Earth-size planets in Earth-like orbits. The required photometric precision also makes the mission very well- suited for asteroseismology, with the important purpose of characterizing the central stars in planetary systems. An extensive asteroseismic programme is planned for Kepler, organized in an international collaboration in the Kepler Asteroseismic Science Consortium. Title: Dipole modes of stellar oscillations Authors: Dogan, G.; Christensen-Dalsgaard, J.; Takata, M. Bibcode: 2008CoAst.157..301D Altcode: We focus on dipole mode stellar oscillations (with l=1) which have been a challenge in identifying the modes. We make use of a new mode identification scheme specific to these oscillations. Title: A Multisite Campaign to Measure Solar-like Oscillations in Procyon. I. Observations, Data Reduction, and Slow Variations Authors: Arentoft, Torben; Kjeldsen, Hans; Bedding, Timothy R.; Bazot, Michaël; Christensen-Dalsgaard, Jørgen; Dall, Thomas H.; Karoff, Christoffer; Carrier, Fabien; Eggenberger, Patrick; Sosnowska, Danuta; Wittenmyer, Robert A.; Endl, Michael; Metcalfe, Travis S.; Hekker, Saskia; Reffert, Sabine; Butler, R. Paul; Bruntt, Hans; Kiss, László L.; O'Toole, Simon J.; Kambe, Eiji; Ando, Hiroyasu; Izumiura, Hideyuki; Sato, Bun'ei; Hartmann, Michael; Hatzes, Artie; Bouchy, Francois; Mosser, Benoit; Appourchaux, Thierry; Barban, Caroline; Berthomieu, Gabrielle; Garcia, Rafael A.; Michel, Eric; Provost, Janine; Turck-Chièze, Sylvaine; Martić, Milena; Lebrun, Jean-Claude; Schmitt, Jerome; Bertaux, Jean-Loup; Bonanno, Alfio; Benatti, Serena; Claudi, Riccardo U.; Cosentino, Rosario; Leccia, Silvio; Frandsen, Søren; Brogaard, Karsten; Glowienka, Lars; Grundahl, Frank; Stempels, Eric Bibcode: 2008ApJ...687.1180A Altcode: 2008arXiv0807.3794A We have carried out a multisite campaign to measure oscillations in the F5 star Procyon A. We obtained high-precision velocity observations over more than three weeks with 11 telescopes, with almost continuous coverage for the central 10 days. This represents the most extensive campaign so far organized on any solar-type oscillator. We describe in detail the methods we used for processing and combining the data. These involved calculating weights for the velocity time series from the measurement uncertainties and adjusting them in order to minimize the noise level of the combined data. The time series of velocities for Procyon shows the clear signature of oscillations, with a plateau of excess power that is centered at 0.9 mHz and is broader than has been seen for other stars. The mean amplitude of the radial modes is 38.1 +/- 1.3 cm s-1 (2.0 times solar), which is consistent with previous detections from the ground and by the WIRE spacecraft, and also with the upper limit set by the MOST spacecraft. The variation of the amplitude during the observing campaign allows us to estimate the mode lifetime to be 1.5+ 1.9-0.8 days. We also find a slow variation in the radial velocity of Procyon, with good agreement between different telescopes. These variations are remarkably similar to those seen in the Sun, and we interpret them as being due to rotational modulation from active regions on the stellar surface. The variations appear to have a period of about 10 days, which presumably equals the stellar rotation period or, perhaps, half of it. The amount of power in these slow variations indicates that the fractional area of Procyon covered by active regions is slightly higher than for the Sun. Title: Stellar Oscillations Network Group SONG Authors: Grundahl, F.; Arentoft, T.; Christensen-Dalsgaard, J.; Frandsen, S.; Kjeldsen, H.; Rasmussen, P. K. Bibcode: 2008JPhCS.118a2041G Altcode: 2007arXiv0705.0851G The Stellar Oscillations Network Group (SONG) is an initiative which aims at designing and building a ground-based network of 1 m telescopes dedicated to the study of phenomena occurring in the time domain. In particular the study of stellar oscillations and the search for and characterisation of extra-solar planets. There will be eight identical nodes in the network, located at existing sites. Each node will have two instruments: 1) a high-resolution spectrograph for obtaining high precision radial velocities using an iodine cell as velocity reference - this will be the main instrument for asteroseismology because solar-like oscillations are much easier to detect in velocity than intensity; and 2) an optical imager which will be used for photometry and guiding. Detailed design of the network prototype node will begin in 2008, and a fully functioning and tested prototype will be ready by the end of 2011, with the goal of achieving a fully operational network around 2014. Title: Oscillations in Procyon A: First results from a multi-site campaign Authors: Hekker, S.; Arentoft, T.; Kjeldsen, H.; Bedding, T. R.; Christensen-Dalsgaard, J.; Reffert, S.; Bruntt, H.; Butler, R. P.; Kiss, L. L.; O'Toole, S. J.; Kambe, E.; Ando, H.; Izumiura, H.; Sato, B.; Hartmann, M.; Hatzes, A. P.; Appourchaux, T.; Barban, C.; Berthomieu, G.; Bouchy, F.; García, R. A.; Lebrun, J. -C.; Martić, M.; Michel, E.; Mosser, B.; Nghiem, P. A. P.; Provost, J.; Samadi, R.; Thévenin, F.; Turck-Chièze, S.; Bonanno, S. A.; Benatti, S.; Claudi, R. U.; Cosentino, R.; Leccia, S.; Frandsen, S.; Brogaard, K.; Grundahl, F.; Stempels, H. C.; Bazot, M.; Dall, T. H.; Karoff, C.; Carrier, F.; Eggenberger, P.; Sosnowska, D.; Wittenmyer, R. A.; Endl, M.; Metcalfe, T. S. Bibcode: 2008JPhCS.118a2059H Altcode: 2007arXiv0710.3772H Procyon A is a bright F5IV star in a binary system. Although the distance, mass and angular diameter of this star are all known with high precision, the exact evolutionary state is still unclear. Evolutionary tracks with different ages and different mass fractions of hydrogen in the core pass, within the errors, through the observed position of Procyon A in the Hertzsprung-Russell diagram. For more than15 years several different groups have studied the solar-like oscillations in Procyon A to determine its evolutionary state. Although several studies independently detected power excess in the periodogram, there is no agreement on the actual oscillation frequencies yet. This is probably due to either insufficient high-quality data (i.e., aliasing) or due to intrinsic properties of the star (i.e., short mode lifetimes). Now a spectroscopic multi-site campaign using 10 telescopes world-wide (minimizing aliasing effects) with a total time span of nearly 4 weeks (increase the frequency resolution) is performed to identify frequencies in this star and finally determine its properties and evolutionary state. Title: Helio- and asteroseismology Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2008IAUS..252..135C Altcode: Observations of solar and stellar oscillations are providing detailed information about stellar interiors. In the case of the Sun the set of observed frequencies is sufficiently detailed and accurate that the properties of the solar interior, such as sound speed, density and internal rotation, can be inferred with substantial precision and resolution. This allows detailed tests of solar modelling, with interesting and to some extent controversial results. Observations of solar-like oscillations in distant stars have started only recently, owing their very small amplitudes. However, developments in ground-based equipment and observations from space are revolutionizing this field, promising greatly increased insight into the structure and evolution of the stars. Title: The Kepler asteroseismic investigation Authors: Christensen-Dalsgaard, J.; Arentoft, T.; Brown, T. M.; Gilliland, R. L.; Kjeldsen, H.; Borucki, W. J.; Koch, D. Bibcode: 2008JPhCS.118a2039C Altcode: The NASA Kepler mission for studies of extra-solar planets, with expected launch early in 2009, will provide a large set of excellent data for asteroseismology. Here we provide a brief presentation of the mission and discuss some aspects of the expected results of the asteroseismic investigations and the organization of the effort in the Kepler Asteroseismic Science Consortium (KASC). Title: SONG Stellar Observations Network Group Authors: Grundahl, Frank; Christensen-Dalsgaard, J.; Kjeldsen, H.; Frandsen, S.; Arentoft, T.; Kjaergaard, P.; Jørgensen, U. G. Bibcode: 2008IAUS..252..465G Altcode: Several areas of stellar observations depend critically on nearly continuous observations of individual objects over very extended periods. Important examples are investigations of stellar oscillations to carry out asteroseismology, and the search for extra-solar planets. To meet this requirement we are establishing the SONG network, consisting of 8 sites with a 1-meter-class telescope with a suitable geographical distribution. These will be optimized for asteroseismology based on Doppler-velocity observations and the characterization of extra-solar planets with photometry, using gravitational microlensing. Funding has been obtained towards the construction of the prototype SONG telescope which will be set up on Tenerife, with first light expected in 2011. The full network will be established in parallel with the tests of the prototype and is planned to be operational in 2014. Title: AsteroFLAG — from the Sun to the stars Authors: Chaplin, W. J.; Appourchaux, T.; Arentoft, T.; Ballot, J.; Baudin, F.; Bazot, M.; Bedding, T. R.; Christensen-Dalsgaard, J.; Creevey, O. L.; Duez, V.; Elsworth, Y.; Fletcher, S. T.; García, R. A.; Gough, D. O.; Jiménez, A.; Jiménez-Reyes, S. J.; Houdek, G.; Kjeldsen, H.; Lazrek, M.; Leibacher, J. W.; Monteiro, M. J. P. F. G.; Neiner, C.; New, R.; Régulo, C.; Salabert, D.; Samadi, R.; Sekii, T.; Sousa, S. G.; Toutain, T.; Turck-Chièze, S. Bibcode: 2008JPhCS.118a2048C Altcode: We stand on the threshold of a critical expansion of asteroseismology of Sun-like stars, the study of stellar interiors by observation and analysis of their global acoustic modes of oscillation. The Sun-like oscillations give a very rich spectrum allowing the internal structure and dynamics to be probed down into the stellar cores to very high precision. Asteroseismic observations of many stars will allow multiple-point tests of crucial aspects of stellar evolution and dynamo theory. The aims of the asteroFLAG collaboration are to help the community to refine existing, and to develop new, methods for analysis of the asteroseismic data on the Sun-like oscillators. Title: The Current Status of Asteroseismology Authors: Aerts, C.; Christensen-Dalsgaard, J.; Cunha, M.; Kurtz, D. W. Bibcode: 2008SoPh..251....3A Altcode: 2008arXiv0803.3527A; 2008SoPh..tmp...80A Stellar evolution, a fundamental bedrock of modern astrophysics, is driven by the physical processes in stellar interiors. While we understand these processes in general terms, we lack some important ingredients. Seemingly small uncertainties in the input physics of the models (e.g., the opacities or the amount of mixing and of interior rotation) have large consequences for the evolution of stars. The goal of asteroseismology is to improve the description of the interior physics of stars by means of their oscillations, just as global helioseismology led to a huge step forward in our knowledge about the internal structure of the Sun. In this paper we present the current status of asteroseismology by considering case studies of stars with a variety of masses and evolutionary stages. In particular, we outline how the confrontation between the observed oscillation frequencies and those predicted by the models allows us to pinpoint limitations of the input physics of current models and improve them to a level that cannot be reached with any other current method. Title: Asteroseismology-Studying stellar structure Authors: Kjeldsen, Hans; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen Bibcode: 2008AIPC.1043..365K Altcode: Oscillations occur in stars of most masses and essentially all stages of evolution. We discuss briefly the potential of asteroseismology, i.e., the study of the frequencies and other properties of stellar oscillations with the aim of extracting fundamental parameters such as density, mass, radius, age and rotation period. We also describe the Kepler Asteroseismic Investigation-the use of asteroseismology on the NASA Kepler mission to study stellar structure and evolution and provide information on the accuracy of the frequency measurements that can be obtained by the NASA Kepler mission. The Kepler mission will provide a comprehensive overview of stellar properties across a large part of the HR diagram, including information about the excitation and damping of the modes, and detailed information about the internal structure of a substantial number of stars. Title: Correcting Stellar Oscillation Frequencies for Near-Surface Effects Authors: Kjeldsen, Hans; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen Bibcode: 2008ApJ...683L.175K Altcode: 2008arXiv0807.1769K In helioseismology, there is a well-known offset between observed and computed oscillation frequencies. This offset is known to arise from improper modeling of the near-surface layers of the Sun, and a similar effect must occur for models of other stars. Such an effect impedes progress in asteroseismology, which involves comparing observed oscillation frequencies with those calculated from theoretical models. Here, we use data for the Sun to derive an empirical correction for the near-surface offset, which we then apply to three other stars (α Cen A, α Cen B, and β Hyi). The method appears to give good results, in particular providing an accurate estimate of the mean density of each star. Title: ADIPLS—the Aarhus adiabatic oscillation package Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2008Ap&SS.316..113C Altcode: 2008Ap&SS.tmp....1C; 2007arXiv0710.3106C Development of the Aarhus adiabatic pulsation code started around 1978. Although the main features have been stable for more than a decade, development of the code is continuing, concerning numerical properties and output. The code has been provided as a generally available package and has seen substantial use at a number of installations. Further development of the package, including bringing the documentation closer to being up to date, is planned as part of the HELAS Coordination Action. Title: ASTEC—the Aarhus STellar Evolution Code Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2008Ap&SS.316...13C Altcode: 2007Ap&SS.tmp..461C; 2007arXiv0710.3114C The Aarhus code is the result of a long development, starting in 1974, and still ongoing. A novel feature is the integration of the computation of adiabatic oscillations for specified models as part of the code. It offers substantial flexibility in terms of microphysics and has been carefully tested for the computation of solar models. However, considerable development is still required in the treatment of nuclear reactions, diffusion and convective mixing. Title: CoRoT/ESTA TASK 1 and TASK 3 comparison of the internal structure and seismic properties of representative stellar models. Comparisons between the ASTEC, CESAM, CLES, GARSTEC and STAROX codes Authors: Lebreton, Yveline; Montalbán, Josefina; Christensen-Dalsgaard, Jørgen; Roxburgh, Ian W.; Weiss, Achim Bibcode: 2008Ap&SS.316..187L Altcode: 2008arXiv0801.0928L; 2008Ap&SS.tmp...39L We compare stellar models produced by different stellar evolution codes for the CoRoT/ESTA project, comparing their global quantities, their physical structure, and their oscillation properties. We discuss the differences between models and identify the underlying reasons for these differences. The stellar models are representative of potential CoRoT targets. Overall we find very good agreement between the five different codes, but with some significant deviations. We find noticeable discrepancies (though still at the per cent level) that result from the handling of the equation of state, of the opacities and of the convective boundaries. The results of our work will be helpful in interpreting future asteroseismology results from CoRoT. Title: The CoRoT evolution and seismic tools activity. Goals and tasks Authors: Lebreton, Y.; Monteiro, M. J. P. F. G.; Montalbán, J.; Moya, A.; Baglin, A.; Christensen-Dalsgaard, J.; Goupil, M. -J.; Michel, E.; Provost, J.; Roxburgh, I. W.; Scuflaire, R.; ESTA Team Bibcode: 2008Ap&SS.316....1L Altcode: 2008arXiv0805.0977L; 2008Ap&SS.tmp..157L The forthcoming data expected from space missions such as CoRoT require the capacity of the available tools to provide accurate models whose numerical precision is well above the expected observational errors. In order to secure that these tools meet the specifications, a team has been established to test and, when necessary, to improve the codes available in the community. The CoRoT Evolution and Seismic Tool Activity (ESTA) has been set up with this mission. Several groups have been involved. The present paper describes the motivation and the organisation of this activity, providing the context and the basis for the presentation of the results that have been achieved so far. This is not a finished task as future even better data will continue to demand more precise and complete tools for asteroseismology. Title: Inter-comparison of the g-, f- and p-modes calculated using different oscillation codes for a given stellar model Authors: Moya, A.; Christensen-Dalsgaard, J.; Charpinet, S.; Lebreton, Y.; Miglio, A.; Montalbán, J.; Monteiro, M. J. P. F. G.; Provost, J.; Roxburgh, I. W.; Scuflaire, R.; Suárez, J. C.; Suran, M. Bibcode: 2008Ap&SS.316..231M Altcode: 2007arXiv0711.2587M; 2008Ap&SS.tmp...49M In order to make asteroseismology a powerful tool to explore stellar interiors, different numerical codes should give the same oscillation frequencies for the same input physics. Any differences found when comparing the numerical values of the eigenfrequencies will be an important piece of information regarding the numerical structure of the code. The ESTA group was created to analyze the non-physical sources of these differences. The work presented in this report is a part of Task 2 of the ESTA group. Basically the work is devoted to test, compare and, if needed, optimize the seismic codes used to calculate the eigenfrequencies to be finally compared with observations. The first step in this comparison is presented here. The oscillation codes of nine research groups in the field have been used in this study. The same physics has been imposed for all the codes in order to isolate the non-physical dependence of any possible difference. Two equilibrium models with different grids, 2172 and 4042 mesh points, have been used, and the latter model includes an explicit modelling of semiconvection just outside the convective core. Comparing the results for these two models illustrates the effect of the number of mesh points and their distribution in particularly critical parts of the model, such as the steep composition gradient outside the convective core. A comprehensive study of the frequency differences found for the different codes is given as well. These differences are mainly due to the use of different numerical integration schemes. The number of mesh points and their distribution are crucial for interpreting the results. The use of a second-order integration scheme plus a Richardson extrapolation provides similar results to a fourth-order integration scheme. The proper numerical description of the Brunt-Väisälä frequency in the equilibrium model is also critical for some modes. This influence depends on the set of the eigenfunctions used for the solution of the differential equations. An unexpected result of this study is the high sensitivity of the frequency differences to the inconsistent use of values of the gravitational constant ( G) in the oscillation codes, within the range of the experimentally determined ones, which differ from the value used to compute the equilibrium model. This effect can provide differences for a given equilibrium model substantially larger than those resulting from the use of different codes or numerical techniques; the actual differences between the values of G used by the different codes account for much of the frequency differences found here. Title: AsteroFLAG: First results from hare-and-hounds Exercise #1 Authors: Chaplin, W. J.; Appourchaux, T.; Arentoft, T.; Ballot, J.; Christensen-Dalsgaard, J.; Creevey, O. L.; Elsworth, Y.; Fletcher, S. T.; García, R. A.; Houdek, G.; Jiménez-Reyes, S. J.; Kjeldsen, H.; New, R.; Régulo, C.; Salabert, D.; Sekii, T.; Sousa, S. G.; Toutain, T.; rest of asteroFLAG Group Bibcode: 2008AN....329..549C Altcode: 2008arXiv0803.4143C We report on initial results from the first phase of Exercise #1 of the asteroFLAG hare and hounds. The asteroFLAG group is helping to prepare for the asteroseismology component of NASA's Kepler mission, and the first phase of Exercise #1 is concerned with testing extraction of estimates of the large and small frequency spacings of the low-degree p modes from Kepler-like artificial data. These seismic frequency spacings will provide key input for complementing the exoplanet search data. Title: Finding Earth-size planets in the habitable zone: the Kepler Mission Authors: Borucki, William; Koch, David; Basri, Gibor; Batalha, Natalie; Brown, Timothy; Caldwell, Douglas; Christensen-Dalsgaard, Jørgen; Cochran, William; Dunham, Edward; Gautier, Thomas N.; Geary, John; Gilliland, Ronald; Jenkins, Jon; Kondo, Yoji; Latham, David; Lissauer, Jack J.; Monet, David Bibcode: 2008IAUS..249...17B Altcode: 2007IAUS..249...17B The Kepler Mission is a space-based mission whose primary goal is to detect Earth-size and smaller planets in the habitable zone of solar-like stars. The mission will monitor more than 100,000 stars for transits with a differential photometric precision of 20 ppm at V=12 for a 6.5 hour transit. It will also provide asteroseismic results on several thousand dwarf stars. It is specifically designed to continuously observe a single field of view of greater than 100 square degrees for 3.5 or more years.

This overview describes the mission design, its goals and capabilities, the measured performance for those photometer components that have now been tested, the Kepler Input Catalog, an overview of the analysis pipeline, the plans for the Follow-up Observing Program to validate the detections and characterize the parent stars, and finally, the plans for the Guest Observer and Astrophysical Data Program. Title: Stellar Astrophysical Fluid Dynamics Authors: Thompson, Michael J.; Christensen-Dalsgaard, Jørgen Bibcode: 2008safd.book.....T Altcode: Preface; 1. A selective overview Jørgen Christensen-Dalsgaard and Michael J. Thompson; Part I. Stellar Convection and Oscillations: 2. On the diversity of stellar pulsations Wojciech A. Dziembowski; 3. Acoustic radiation and mode excitation by turbulent convection Günter Houdek; 4. Understanding roAp stars Margarida S. Cunha; 5. Waves in the magnetised solar atmosphere Colin S. Rosenthal; Part II. Stellar Rotation and Magnetic Fields: 6. Stellar rotation: a historical survey Leon Mestel; 7. The oscillations of rapidly rotating stars Michel Rieutord; 8. Solar tachocline dynamics: eddy viscosity, anti-friction, or something in between? Michael E. McIntyre; 9. Dynamics of the solar tachocline Pascale Garaud; 10. Dynamo processes: the interaction of turbulence and magnetic fields Michael Proctor; 11. Dynamos in planets Chris Jones; Part III. Physics and Structure of Stellar Interiors: 12. Solar constraints on the equation of state Werner Däppen; 13. 3He transport and the solar neutrino problem Chris Jordinson; 14. Mixing in stellar radiation zones Jean-Paul Zahn; 15. Element settling and rotation-induced mixing in slowly rotating stars Sylvie Vauclair; Part IV. Helio- and Asteroseismology: 16. Solar structure and the neutrino problem Hiromoto Shibahashi; 17. Helioseismic data analysis Jesper Schou; 18. Seismology of solar rotation Takashi Sekii; 19. Telechronohelioseismology Alexander Kosovichev; Part V. Large-Scale Numerical Experiments: 20. Bridges between helioseismology and models of convection zone dynamics Juri Toomre; 21. Numerical simulations of the solar convection zone Julian R. Elliott; 22. Modelling solar and stellar magnetoconvection Nigel Weiss; 23. Nonlinear magnetoconvection in the presence of a strong oblique field Keith Julien, Edgar Knobloch and Steven M. Tobias; 24. Simulations of astrophysical fluids Marcus Brüggen; Part VI. Dynamics: 25. A magic electromagnetic field Donald Lynden-Bell; 26. Continuum equations for stellar dynamics Edward A. Spiegel and Jean-Luc Thiffeault; 27. Formation of planetary systems Douglas N. C. Lin; 28. The solar-cycle global warming as inferred from sky brightness variation Wasaburo Unno and Hiromoto Shibahashi. Title: Estimation of stellar parameters using Monte Carlo Markov Chains Authors: Bazot, M.; Bourguignon, S.; Christensen-Dalsgaard, J. Bibcode: 2008MmSAI..79..660B Altcode: 2008arXiv0803.2529B We apply Monte Carlo Markov Chain methods to the stellar parameter estimation problem. This technique is useful when dealing with non-linear models and allows to derive realistic error bars on the inferred parameters. We give the first results obtained for {alpha Cen A}. Title: Kepler Mission: Current Status Authors: Borucki, William J.; Koch, D. G.; Lissauer, J. J.; Bryson, S.; Natalie, B.; Caldwell, D. A.; DeVore, E.; Jenkins, J. M.; Christensen-Dalsgaard, J.; Cochran, W. D.; Dunham, E. W.; Gautier, T. N.; Geary, J. C.; Latham, D. W.; Sasselov, D.; Gilliland, R. L.; Gould, A.; Howell, S. B.; Monet, D. G. Bibcode: 2007AAS...211.3603B Altcode: 2007BAAS...39R.788B Kepler is a Discovery-class mission designed to determine the frequency of Earth-size planets in and near the habitable zone of solar-like stars. The instrument consists of a high precision photometer with Schmidt-type optics and a focal plane containing 95 million pixels to monitor over 100,000 stars to search for patterns of transits generated by planets as small as Mars. The recent reduction in the mission duration is discussed with regard to the impact on the expected science product and null statistics. Both terrestrial and giant planets discoveries will be followed up with ground-based Doppler-velocity observations to determine mass and density.

The first meeting of Kepler Asteroseismic Science Consortium was held in Paris to organize an international team to analyze the Kepler data to determine the characteristics of the brighter target stars including their size and age. Stellar size determinations accurate to a few percent are expected. These will allow very accurate planet sizes to be determined from the depth of the transit signals.

NASA HQ received thirty six proposals for the Participating Scientist Program and chose several new members to join the Science Team.

Both the 0.95 m Schmidt corrector and 1.4 m aperture primary mirror have been completed and delivered for integration into the photometer. The focal plane with forty-two science CCD detectors and their processing electronics has been assembled and tested. The spacecraft assembly has begun with the mounting of the reaction control system, reaction wheels, attitude determination & control system, and power systems. Both the photometer and spacecraft are nearing final assembly with all subsystems having passed their environmental and performance testing. The photometer to spacecraft integration will begin this spring. The Mission is on schedule for a launch in February 2009.

The Kepler Mission is funded by the NASA Astrophysics Division, Science Mission Directorate. Title: Commission 27: Variable Stars Authors: Aerts, Conny; Kawaler, Steven D.; Christensen-Dalsgaard, Jørgen; Bedding, Timothy R.; Cacciari, Carla; Cottrell, Peter L.; Cunha, Margarida; Handler, Gerald; Martinez, Peter; Sasselov, Dimitar D.; Somasundaram, Seetha; Welch, Douglas L. Bibcode: 2007IAUTB..26..168A Altcode: The meeting started at 16h00. The president welcomed the 24 participants to the business meeting of Commission 27. After the approval of the agenda, she gave an overview of the activities of Commission 27 of the past three years. Title: Commission 35: Stellar Constitution Authors: Dziembowski, Wojciech A.; D'Antona, Francesca; VandenBerg, Don A.; Charbonnel, Corinne; Christensen-Dalsgaard, Joergen; Guzik, Joyce A.; Langer, Norbert; Larson, Richard B.; Liebert, James W.; Meynet, Georges; Müller, Ewald; Saio, Hideyuki Bibcode: 2007IAUTB..26..158D Altcode: The session was brief and quite informal as there were only six participants. The agenda included my report on organizational activities of the Commission during the 2003-2006 term and Virginia Trimble's presentation Presence of binary stars in the current astronomical literature. I summarize below the most important part of my report. Title: Division v: Variable Stars Authors: Christensen-Dalsgaard, Jørgen; Giménez, Alvaro; Guinan, Edward F.; Aerts, Conny; Balona, Luis A.; Sahade, Jorge Bibcode: 2007IAUTB..26..165C Altcode: Division V provides a joint forum for the study of stellar variability in all its manifestations, whether due to pulsation, surface inhomogeneities, evolutionary changes, or to eclipses and other phenomena specifically related to double and multiple stars. Title: A spectroscopic search for non-radial pulsations in the δ Scuti star γ Bootis Authors: Ventura, R.; Catanzaro, G.; Christensen-Dalsgaard, J.; di Mauro, M. P.; Paternò, L. Bibcode: 2007MNRAS.381.1647V Altcode: 2007arXiv0708.2364V; 2007MNRAS.tmp..890V High-resolution spectroscopic observations of the rapidly rotating δScuti star γBootis have been carried out in 2005, over six consecutive nights, in order to search for line-profile variability. Time-series, consisting of flux measurements at each wavelength bin across the TiII 4571.917 Å line profile as a function of time, have been Fourier analysed.

The results confirm the early detection reported by Kennelly et al. of a dominant periodic component at frequency 21.28 cycles d-1 in the observer's frame, probably due to a high-azimuthal-order sectorial mode. Moreover, we found other periodicities at 5.06, 12.02cyclesd-1, probably present but not secure, and at 11.70 and 18.09cyclesd-1, uncertain. The latter frequency, if present, should be identifiable as another high-azimuthal-order sectorial mode and the three additional terms as low-l modes as proved by the analysis of the first three moments of the line. Owing to the short time baseline and the one-site temporal sampling we consider our results only preliminary but encouraging for a more extensive multisite campaign.

A refinement of the atmospheric physical parameters of the star has been obtained from our spectroscopic data and adopted for preliminary computations of evolutionary models of γBootis. Title: Asteroseismology and interferometry Authors: Cunha, M. S.; Aerts, C.; Christensen-Dalsgaard, J.; Baglin, A.; Bigot, L.; Brown, T. M.; Catala, C.; Creevey, O. L.; Domiciano de Souza, A.; Eggenberger, P.; Garcia, P. J. V.; Grundahl, F.; Kervella, P.; Kurtz, D. W.; Mathias, P.; Miglio, A.; Monteiro, M. J. P. F. G.; Perrin, G.; Pijpers, F. P.; Pourbaix, D.; Quirrenbach, A.; Rousselet-Perraut, K.; Teixeira, T. C.; Thévenin, F.; Thompson, M. J. Bibcode: 2007A&ARv..14..217C Altcode: 2007arXiv0709.4613C Asteroseismology provides us with a unique opportunity to improve our understanding of stellar structure and evolution. Recent developments, including the first systematic studies of solar-like pulsators, have boosted the impact of this field of research within astrophysics and have led to a significant increase in the size of the research community. In the present paper we start by reviewing the basic observational and theoretical properties of classical and solar-like pulsators and present results from some of the most recent and outstanding studies of these stars. We centre our review on those classes of pulsators for which interferometric studies are expected to provide a significant input. We discuss current limitations to asteroseismic studies, including difficulties in mode identification and in the accurate determination of global parameters of pulsating stars, and, after a brief review of those aspects of interferometry that are most relevant in this context, anticipate how interferometric observations may contribute to overcome these limitations. Moreover, we present results of recent pilot studies of pulsating stars involving both asteroseismic and interferometric constraints and look into the future, summarizing ongoing efforts concerning the development of future instruments and satellite missions which are expected to have an impact in this field of research. Title: γ Bootis: Asteroseismology with a 1-m Class Telescope Authors: di Mauro, M. P.; Catanzaro, G.; Christensen-Dalsgaard, J.; Paternò, L.; Ventimiglia, G.; Ventura, R. Bibcode: 2007AIPC..948..455D Altcode: High-resolution spectroscopic observations carried out in 2005, allowed Ventura et al. (2007) to identify oscillation modes on the rapidly rotating δ Scuti star γ Bootis. Here we consider the theoretical interpretation of the observed oscillation spectrum based on structure models and oscillation frequencies calculated by including effects due to the fast rotation. Title: Joint Discussion 17 Highlights of recent progress in the seismology of the Sun and Sun-like stars Authors: Bedding, Timothy R.; Brun, Allan S.; Christensen-Dalsgaard, Jørgen; Crouch, Ashley; De Cat, Peter; García, Raphael A.; Gizon, Laurent; Hill, Frank; Kjeldsen, Hans; Leibacher, John W.; Maillard, Jean-Pierre; Mathis, S.; Rabello-Soares, M. Cristina; Rozelot, Jean-Pierre; Rempel, Matthias; Roxburgh, Ian W.; Samadi, Réza; Talon, Suzanne; Thompson, Michael J. Bibcode: 2007HiA....14..491B Altcode: The seismology and physics of localized structures beneath the surface of the Sun takes on a special significance with the completion in 2006 of a solar cycle of observations by the ground-based Global Oscillation Network Group (GONG) and by the instruments on board the Solar and Heliospheric Observatory (SOHO). Of course, the spatially unresolved Birmingham Solar Oscillation Network (BiSON) has been observing for even longer. At the same time, the testing of models of stellar structure moves into high gear with the extension of deep probes from the Sun to other solar-like stars and other multi-mode pulsators, with ever-improving observations made from the ground, the success of the MOST satellite, and the recently launched CoRoT satellite. Here we report the current state of the two closely related and rapidly developing fields of helio- and asteroseimology. Title: The Kepler Mission and Eclipsing Binaries Authors: Koch, David; Borucki, William; Basri, Gibor; Brown, Timothy; Caldwell, Douglas; Christensen-Dalsgaard, Jorgen; Cochran, William; Devore, Edna; Dunham, Edward; Gautier, Thomas N.; Geary, John; Gilliland, Ronald; Gould, Alan; Jenkins, Jon; Kondo, Yoji; Latham, David; Lissauer, Jack; Monet, David Bibcode: 2007IAUS..240..236K Altcode: 2006IAUS..240E..21K The Kepler Mission is a photometric mission with a precision of 14 ppm ( at R= 12) that is designed to continuously observe a single field of view (FOV) of greater 100 sq deg in the Cygnus-Lyra region for four or more years. The primary goal of the mission is to monitor >100,000 stars for transits of Earth-size and smaller planets in the habitable zone of solar-like stars. In the process, many eclipsing binaries (EB) will also be detected and light curves produced. To enhance and optimize the mission results, the stellar characteristics for all the stars in the FOV with R<16 will have been determined prior to launch. As part of the verification process, stars with transit candidates will have radial velocity follow-up observations performed to determine the component masses and thereby separate eclipses caused by stellar companions from transits caused by planets. The result will be a rich database on EBs. The community will have access to the archive for further analysis, such as, for EB modeling of the high-precision light curves. A guest observer program is also planned to allow for photometric observations of objects not on the target list but within the FOV, since only the pixels of interest from those stars monitored will be transmitted to the ground. Title: Solar-like Oscillations in the G2 Subgiant β Hydri from Dual-Site Observations Authors: Bedding, Timothy R.; Kjeldsen, Hans; Arentoft, Torben; Bouchy, Francois; Brandbyge, Jacob; Brewer, Brendon J.; Butler, R. Paul; Christensen-Dalsgaard, Jørgen; Dall, Thomas; Frandsen, Søren; Karoff, Christoffer; Kiss, László L.; Monteiro, Mario J. P. F. G.; Pijpers, Frank P.; Teixeira, Teresa C.; Tinney, C. G.; Baldry, Ivan K.; Carrier, Fabien; O'Toole, Simon J. Bibcode: 2007ApJ...663.1315B Altcode: 2007astro.ph..3747B We have observed oscillations in the nearby G2 subgiant star β Hyi using high-precision velocity observations obtained over more than a week with the HARPS and UCLES spectrographs. The oscillation frequencies show a regular comb structure, as expected for solar-like oscillations, but with several l=1 modes being strongly affected by avoided crossings. These data, combined with those we obtained five years earlier, allow us to identify 28 oscillation modes. By scaling the large-frequency separation from the Sun, we measure the mean density of β Hyi to an accuracy of 0.6%. The amplitudes of the oscillations are about 2.5 times solar and the mode lifetime is 2.3 days. A detailed comparison of the mixed l=1 modes with theoretical models should allow a precise estimate of the age of the star. Title: KEPLER Mission Status Authors: Borucki, W. J.; Koch, D. G.; Lissauer, J.; Basri, G.; Brown, T.; Caldwell, D. A.; Jenkins, J. M.; Caldwell, J. J.; Christensen-Dalsgaard, J.; Cochran, W. D.; Dunham, E. W.; Gautier, T. N.; Geary, J. C.; Latham, D.; Sasselov, D.; Gilliland, R. L.; Howell, S.; Monet, D. G.; Batalha, N. Bibcode: 2007ASPC..366..309B Altcode: Kepler is a Discovery-class mission designed to determine the frequency of Earth-size and smaller planets in and near the habitable zone (HZ) of dwarf stars. The instrument consists of a 0.95-m aperture photometer capable of doing high precision photometry of more than 100,000 late-type main sequence stars to search for patterns of transits. Multi-band ground-based observation of over 2 million stars is currently underway to estimate the stellar parameters and to choose appropriate targets. The association of planet size and occurrence frequency with stellar mass and metallicity will be investigated. At the end of the four year mission, several hundred terrestrial planets (i.e., planets up to twice the diameter of the Earth) should be discovered with periods between one day and 400 days if such planets are common. As many as 100 Earth-size planets in the HZ could be discovered. A null result would imply that terrestrial planets are rare. The scientific community is invited to participate through the "Participating Scientist", "Guest Observer' and Data Analysis programs. Title: Stellar Oscillations Network Group Authors: Grundahl, F.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Arentoft, T.; Frandsen, S. Bibcode: 2007CoAst.150..300G Altcode: Stellar Oscillations Network Group (SONG) is an initiative aimed at designing and building a network of 1m-class telescopes dedicated to asteroseismology and planet hunting. SONG will have 8 identical telescope nodes each equipped with a high-resolution spectrograph and an iodine cell for obtaining precision radial velocities and a CCD camera for guiding and imaging purposes. The main asteroseismology targets for the network are the brightest (V < 6) stars. In order to improve performance and reduce maintenance costs the instrumentation will only have very few modes of operation. In this contribution we describe the motivations for establishing a network, the basic outline of SONG and the expected performance. Title: Asteroseismology with the Kepler mission Authors: Christensen-Dalsgaard, J.; Arentoft, T.; Brown, T. M.; Gilliland, R. L.; Kjeldsen, H.; Borucki, W. J.; Koch, D. Bibcode: 2007CoAst.150..350C Altcode: 2007astro.ph..1323C NASA's Kepler mission will fly a photometer based on a wide-field Schmidt camera with a 0.95 m aperture, staring at a single field continuously for at least 4 years. Although the mission's principal aim is to locate transiting extrasolar planets, it will provide an unprecedented opportunity to make asteroseismic observations on a wide variety of stars. Plans are now being developed to exploit this opportunity to the fullest. Title: A theoretical scenario for PMS δ Scuti stars Authors: Ruoppo, A.; Marconi, M.; Marques, M.; Monteiro, M. J. P. F. G.; Christensen-Dalsgaard, J.; Palla, F.; Ripepi, V. Bibcode: 2007CoAst.150...73R Altcode: Nonradial pulsation models have been computed by means of the Aarhus adiabatic code along an extensive set of CESAM PMS evolutionary tracks. A theoretical tool for the interpretation of observed periodicities is proposed. Title: Solar Cycle Changes Over 11 Years of Medium-Degree Helioseismic Observations Authors: Howe, Rachel; Komm, R. W.; Hill, F.; Christensen-Dalsgaard, J.; Schou, J.; Thompson, M. J. Bibcode: 2007AAS...210.2218H Altcode: 2007BAAS...39..127H The Global Oscillations Network Group (GONG) has now completed, and the Michelson Doppler Imager (MDI) aboard SOHO will soon complete, a full eleven years of continuous observations of the medium-degree solar oscillations. This enables us to follow changes in the acoustic mode parameters and interior dynamics over a full solar cycle. We present results from observations of convection-zone dynamics, in which the torsional oscillation pattern seen at the surface can be followed throughout most of the bulk of the convection zone, and also changes in the frequency, lifetime and amplitude of the modes which can be shown to be closely related in space and time to the migrating pattern of surface activity.

This work utilizes data obtained by the Global Oscillation Network Group (GONG) program, managed by the National Solar Observatory, which is operated by AURA, Inc. under a cooperative agreement with the National Science Foundation. SOHO is a mission of international cooperation between ESA and NASA. Title: Opportunities to Participate in the Kepler Mission Authors: Borucki, William J.; Koch, D. G.; Lissauer, J. J.; Batalha, N.; Caldwell, D. A.; DeVore, E.; Jenkins, J. M.; Christensen-Dalsgaard, J.; Cochran, W. D.; Dunham, E. T.; Gautier, T. N.; Geary, J. C.; Gilliland, R. L.; Gould, A.; Howell, S. B.; Monet, D. G.; Sasselov, D. Bibcode: 2007AAS...21011007B Altcode: 2007BAAS...39..235B Several opportunities to participate in the Kepler Mission are available; Participating Scientist Program (PSP), Guest Observer (GO) Program, and Astrophysical Data Analysis Program (ADAP).

For the PS option, investigators from the science community will propose programs that complement those developed by the PI and Co-Investigators. The proposed programs can be analytical, observational, or theoretical in nature. Examples include: modeling eclipsing binary systems to determine the characteristics of the stars and planets, measuring and modeling timing variations in the epoch of transits to detect non-transiting planets, characterizing the atmospheres of giant planets detected from transits or from reflected light, and confirmation of transits. The solicitation for the PSP is now open.

The GO program will accommodate those investigators who wish to make astrophysical measurements of the many different types of objects in the Kepler FOV. Generally, these targets will differ from those chosen for the transit search. Examples include variable stars of all types, distribution and time variation of zodiacal light, and extragalactic objects. It is expected that a total of about 3000 additional targets at any one time will be available and that these selections can be changed at intervals of 3 months. Most of the targets will be observed at a cadence of once per 30 minutes, but a small subset can be observed with a one minute cadence. All targets must be within the active area of the Kepler FOV. The FOV will not be moved to accommodate a GO request.

Investigators desiring to analyze data from targets already on the Kepler target list should apply to the ADAP. It will be an opportunity to perform data mining on the existing database.

Acknowlegement: This is funded by the Discovery Program Office, SMD. Title: Rotation of the solar convection zone from helioseismology Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2007IAUS..239..393C Altcode: 2006astro.ph.10942C Helioseismology has provided very detailed inferences about rotation of the solar interior. Within the convection zone the rotation rate roughly shares the latitudinal variation seen in the surface differential rotation. The transition to the nearly uniformly rotating radiative interior takes place in a narrow tachocline, which is likely important to the operation of the solar magnetic cycle.The convection-zone rotation displays zonal flows, regions of slightly more rapid and slow rotation, extending over much of the depth of the convection zone and converging towards the equator as the solar cycle progresses. In addition, there is some evidence for a quasi-periodic variation in rotation, with a period of around 1.3 yr, at the equator near the bottom of the convection zone. Title: A theoretical approach for the interpretation of pulsating PMS intermediate-mass stars Authors: Ruoppo, A.; Marconi, M.; Marques, J. P.; Monteiro, M. J. P. F. G.; Christensen-Dalsgaard, J.; Palla, F.; Ripepi, V. Bibcode: 2007A&A...466..261R Altcode: 2007astro.ph..2110R Context: The investigation of the pulsation properties of pre-main-sequence intermediate-mass stars is a promising tool to evaluate the intrinsic properties of these stars and to constrain current evolutionary models. Many new candidates of this class have been discovered during the last decade and very accurate data are expected from space observations obtained for example with the CoRoT satellite.
Aims: In this context we aim at developing a theoretical approach for the interpretation of observed frequencies, both from the already available ground-based observations and from the future more accurate and extensive CoRoT results.
Methods: To this purpose we have started a project devoted to the computations of fine and extensive grids of asteroseismic models of intermediate mass pre-main-sequence stars. The obtained frequencies are used to derive an analytical relation between the large frequency separation and the stellar luminosity and effective temperature and to develop a tool to compare theory and observations in the echelle diagram.
Results: The predictive capabilities of the proposed method are verified through the application to two test stars. As a second step, we apply the procedure to two true observations from multisite campaigns and we are able to constrain their stellar parameters, in particular the mass, in spite of the small number of frequencies.
Conclusions: We expect that with a significantly higher number of frequencies both the stellar mass and age could be constrained and, at the same time, the physics of the models could be tested. Title: Commission C27: Variable Stars Authors: Aerts, Conny; Kawaler, Steven; Bedding, Tim; Cacciari, Carla; Christensen-Dalsgaard, Jørgen; Cottrell, Peter; Cunha, Margarida; Handler, Gerald; Martinez, Peter; Sasselov, Dimitar; Seetha, S.; Welch, Doug Bibcode: 2007IAUTA..26..247A Altcode: We report the major highlights of variable star research within the past three years. This overview is limited to intrinsically variable stars, because the achievements in variable star research stemming from binarity, or multiplicity in general, is covered by the summary report of Commissions 26 and 42. Title: Division V: Variable Stars Authors: Christensen-Dalsgaard, Jørgen; Aerts, Conny; Giménez, Alvaro; Guinan, Edward F.; Balona, Luis A.; Sahade, Jorge Bibcode: 2007IAUTA..26..245C Altcode: Division V, "Variable Stars", consists of Commission 27, also called "Variable Stars" and Commission 42, "Close Binaries". Thus the former deals with stars whose variations are intrinsic, whereas in the latter the variations are caused by the interactions between the components in the binary. It is evident that the definition of the Division is predominantly observational, and there may be cases where the assignment of an object to one of the two commissions might be in doubt (a recent somewhat related example was the first detection of an extra-solar planet, in 54 Pegasi, where intrinsic variability of the star in the form of high-order g modes was also initially suspected). Title: Commission 12: Solar Radiation & Structure Authors: Bogdan, Thomas. J.; Martínez Pillet, Valentin; Asplund, M.; Christensen-Dalsgaard, J.; Cauzzi, G.; Cram, L. E.; Dravins, D.; Gan, W.; Henzl, P.; Kosovichev, A.; Mariska, J. T.; Rovira, M. G.; Venkatakrishnan, P. Bibcode: 2007IAUTA..26...89B Altcode: Commission 12 covers research on the internal structure and dynamics of the Sun, the "quiet" solar atmosphere, solar radiation and its variability, and the nature of relatively stable magnetic structures like sunspots, faculae and the magnetic network. There is considerable productive overlap with the other Commissions of Division II as investigations move progressively toward the fertile intellectual boundaries between traditional research disciplines. In large part, the solar magnetic field provides the linkage that connects these diverse themes. The same magnetic field that produces the more subtle variations of solar structure and radiative output over the 11 yr activity cycle is also implicated in rapid and often violent phenomena such as flares, coronal mass ejections, prominence eruptions, and episodes of sporadic magnetic reconnection.The last three years have again brought significant progress in nearly all the research endeavors touched upon by the interests of Commission 12. The underlying causes for this success remain the same: sustained advances in computing capabilities coupled with diverse observations with increasing levels of spatial, temporal and spectral resolution. It is all but impossible to deal with these many advances here in anything except a cursory and selective fashion. Thankfully, the Living Reviews in Solar Physics; has published several extensive reviews over the last two years that deal explicitly with issues relevant to the purview of Commission 12. The reader who is eager for a deeper and more complete understanding of some of these advances is directed to http://www.livingreviews.org for access to these articles. Title: Commission 35: Stellar Constitution Authors: Dziembowski, Wojciech A.; D'Antona, Francesca; Charbonnel, C.; Christensen-Dalsgaard, J.; Guzik, J.; Langer, N.; Larson, R.; Liebert, J.; Meynet, G.; Müller, E.; Saio, H.; Vandenberg, D. Bibcode: 2007IAUTA..26..205D Altcode: Ihe triennial report from Commission 35 covers its organizational activities and highlights accomplishments in various topics of stellar interior physics. Title: Diffusion and Helioseismology Authors: Christensen-Dalsgaard, J.; Di Mauro, M. Pia Bibcode: 2007EAS....26....3C Altcode: Helioseismic inferences have demonstrated very clearly the importance of including element diffusion and settling in solar modelling: models incorporating these processes are in substantially better agreement with the inferred solar sound speed than are models that neglect them. The remaining discrepancy between the models and the Sun has been taken as evidence for mixing in the region just beneath the convection zone. However, rather more serious discrepancies have resulted from a revision of solar abundances, and no obvious solution to this problem has been found so far. This perhaps demonstrates the danger of complacency when dealing with so complex a thing as a star. Hydrodynamical instabilities are likely to play a more important role than acknowledged in standard stellar modelling. An interesting example, if not relevant to modelling up to the present solar age, is the possible onset of semiconvective instability just beneath the convection zone, as first emphasized by Bahcall et al. (2001). Title: Microscopic Diffusion in Stellar Evolution Codes: First Comparisons Results of ESTA-Task 3 Authors: Lebreton, Y.; Montalbán, J.; Christensen-Dalsgaard, J.; Théado, S.; Hui-Bon-Hoa, A.; Monteiro, M. J. P. F. G.; Degl'Innocenti, S.; Marconi, M.; Morel, P.; Prada Moroni, P. G.; Weiss, A. Bibcode: 2007EAS....26..155L Altcode: 2007astro.ph..3426L We present recent work undertaken by the Evolution and Seismic Tools Activity (ESTA) team of the CoRoT Seismology Working Group. The new ESTA-Task 3 aims at testing, comparing and optimising stellar evolution codes which include microscopic diffusion of the chemical elements resulting from pressure, temperature and concentration gradients. The results already obtained are globally satisfactory, but some differences between the different numerical tools appear that require further investigations. Title: Observational results and issues concerning the tachocline Authors: Christensen-Dalsgaard, Jørgen; Thompson, Michael J. Bibcode: 2007sota.conf...53C Altcode: No abstract at ADS Title: Temporal variations in solar rotation at the bottom of the convection zone: The current status Authors: Howe, R.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R.; Schou, J.; Thompson, M. J.; Toomre, J. Bibcode: 2007AdSpR..40..915H Altcode: We present the most recent results on the short-period variations in the solar rotation rate near the base of the convection zone. The 1.3-year period which was reported in the early years of solar cycle 23 appears not to persist after 2001, but there are hints of fluctuations at a different period during the declining phase of the cycle. Title: Comparisons for ESTA-Task3: ASTEC, CESAM and CLÉS Authors: Christensen-Dalsgaard, J. Bibcode: 2007EAS....26..177C Altcode: The ESTA activity under the CoRoT project aims at testing the tools for computing stellar models and oscillation frequencies that will be used in the analysis of asteroseismic data from CoRoT and other large-scale upcoming asteroseismic projects. Here I report results of comparisons between calculations using the Aarhus code (ASTEC) and two other codes, for models that include diffusion and settling. It is found that there are likely deficiencies, requiring further study, in the ASTEC computation of models including convective cores. Title: Kepler Mission Development Authors: Borucki, William J.; Koch, D.; Batalha, N.; Brown, T.; Caldwell, D.; Christensen-Dalsgaard, J.; Dunham, E.; Gautier, T.; Geary, J.; Gilliland, R.; Jenkins, J.; Latham, D.; Monet, D. Bibcode: 2006AAS...20912406B Altcode: 2006BAAS...38.1071B Kepler is a Discovery-class mission designed to determine the frequency of Earth-size and smaller planets in and near the habitable zone of cool dwarf stars. The instrument is a wide field-of-view (FOV) differential photometer with a 100 square degree FOV that continuously and simultaneously monitors the brightness of more than 100,000 main-sequence stars with sufficient precision to detect transits by Earth-size planets.

As part of the Kepler Mission, a ground-based observation program is underway to measure the effective temperature, log(g), metallicity, and size of 107 stars in the FOV brighter than 19th magnitude. The resulting catalog allows the Kepler Mission to choose well-characterized late-type dwarfs and to exclude giants and early spectral types from the target list. The catalog will be the most comprehensive study of stars in this portion of our galaxy. An asteroseismic study of several thousand bright stars will also be conducted. It is expected to yield detailed information about the size, mass, and age of these stars.

In October, an intensive, 5-day Critical Design Review of the mission was conducted by two review teams. The teams’ findings are being used to refine the mission development as assembly and testing of the flight components progress. Development is on schedule for a launch on November 1, 2008.

In preparation for the launch, Participating Scientist and Guest Observer Programs are being developed. The first is expected to be announced in early 2007 while the latter is expected in 2008. The Participating Scientist Program will call for interested members of the science community to propose research programs that complement and enhance those of the Kepler Science Team. The following year, the Guest Observer Program will entertain astrophysical research on any of type of target in the Kepler FOV. Title: Report on the CoRoT Evolution and Seismic Tools Activity Authors: Monteiro, M. J. P. F. G.; Lebreton, Y.; Montalban, J.; Christensen-Dalsgaard, J.; Castro, M.; Degl'Innocenti, S.; Moya, A.; Roxburgh, I. W.; Scuflaire, R.; Baglin, A.; Cunha, M. S.; Eggenberger, P.; Fernandes, J.; Goupil, M. J.; Hui-Bon-Hoa, A.; Marconi, M.; Marques, J. P.; Michel, E.; Miglio, A.; Morel, P.; Pichon, B.; Prada Moroni, P. G.; Provost, J.; Ruoppo, A.; Suarez, J. -C.; Suran, M.; Teixeira, T. C. Bibcode: 2006ESASP1306..363M Altcode: 2006astro.ph..5685M We present the work undertaken by the Evolution and Seismic Tools Activity (ESTA) team of the CoRoT Seismology Working Group. We have focused on two main tasks: Task 1 now finished has aimed at testing, comparing and optimising seven stellar evolution codes which will be used to model the internal structure and evolution of the CoRoT target stars. Task 2, still underway, aims at testing, comparing and optimising different seismic codes used to calculate the oscillations of models for different types of stars. The results already obtained are quite satisfactory, showing minor differences between the different numerical tools provided the same assumptions on the physical parameters are made. This work gives us confidence on the numerical tools that will be available to interpret the future CoRoT seismic data. Title: The DynaMICS perspective Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.624E..24T Altcode: 2006soho...18E..24T No abstract at ADS Title: European helio- and asteroseismology network HELAS Authors: Roth, M.; Luhe, O. v. d.; Palle, P.; Thompson, M. J.; Christensen-Dalsgaard, J.; Monteiro, M. J. P. F. G.; Gizon, L.; Di Mauro, M. P.; Aerts, C.; Daszynska-Daszkiewicz, J.; Corbard, T. Bibcode: 2006ESASP.624E.130R Altcode: 2006soho...18E.130R The Helio- and Asteroseismology Network (HELAS) is a Coordinated Action funded by the FP6-Infrastructure-Programme of the European Commission. Currently, HELAS consists of ten members. The objective of HELAS is to co-ordinate European activities in helio- and asteroseismology. HELAS will transfer knowledge and data analysis techniques, and will prepare the European research community for important missions in the immediate future. Title: Solar Convection Zone Dynamics: How Sensitive Are Inversions to Subtle Dynamo Features? Authors: Howe, R.; Rempel, M.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R.; Larsen, R. M.; Schou, J.; Thompson, M. J. Bibcode: 2006ApJ...649.1155H Altcode: The nearly 10 year span of medium-degree helioseismic data from the Global Oscillation Network Group and the Michelson Doppler Imager has allowed us to study the evolving flows in the solar convection zone over most of solar cycle 23. Using two independent two-dimensional rotation inversion techniques and extensive studies of the resolution using artificial data from different assumed flow profiles, including those generated from sample mean field dynamo models, we attempt to assess the reality of certain features seen in the inferred rotation profiles. Our results suggest that the findings from observations of a substantial depth dependence of the phase of the zonal flow pattern in the low latitudes, and the penetration of the flows deep into the convection zone, are likely to be real rather than artifacts of the inversion process. Title: Solar rotation and zonal flows from Mount Wilson 60 ft tower data Authors: Howe, R.; Bogart, R.; Christensen-Dalsgaard, J.; Rhodes, E. J., Jr.; Rose, P.; Schou, J. Bibcode: 2006ESASP.624E..56H Altcode: 2006soho...18E..56H No abstract at ADS Title: Prospects for helio- and asteroseismology Authors: Christensen-Dalsgaard, J. Bibcode: 2006ESASP.624E..41C Altcode: 2006soho...18E..41C; 2006astro.ph.10614C Major progress has been made in helio- and asteroseismology in recent years. In helioseismology, much of the activity has been in local helioseismology. However, the recent revision of solar surface abundances, and the resulting problems in reconciling solar models with the helioseismic inferences, have lead to renewed activity in solar modelling and global helioseismology. Interesting, although perhaps not compelling, evidence has been found for solar g modes in observations with the GOLF instrument on the SOHO spacecraft. Extensive asteroseismic results have been obtained from ground-based observations as well as from the WIRE and MOST satellites, and much is expected from the upcoming launch of the CoRoT satellite and, in a few years, from the Kepler mission. In parallel, stellar modelling is being extended to take some account of hydrodynamical effects, while large-scale hydrodynamical calculations are providing increasingly realistic simulations of these effects. The outcome of these activities will undoubtedly be a far better understanding of stellar internal properties and stellar evolution, together with an improved insight into the physics of matter under the extreme conditions found in stars. Title: Kepler Mission: Mission Progress Authors: Borucki, William J.; Koch, D. G.; Lissauer, J. J.; Basri, G. S.; Caldwell, D. A.; DeVore, E.; Jenkins, J. M.; Caldwell, J. J.; Christensen-Dalsgaard, J.; Cochran, W. D.; Dunham, E. W.; Gautier, T. N.; Geary, J. C.; Latham, D. A.; Sasselov, D.; Gilliland, R. L.; Gould, A.; Howell, S. B.; Brown, T. M.; Kondo, Y.; Monet, D. G.; Batalha, N. Bibcode: 2006DPS....38.4501B Altcode: 2006BAAS...38..567B Kepler is a Discovery-class mission designed to determine the frequency of Earth-size planets in and near the habitable zone (HZ) of solar-like stars. The instrument consists of a 0.95 m aperture photometer designed to obtain high precision photometric measurements of >100,000 stars to search for patterns of transits. The focal plane of the Schmidt-telescope contains 42 CCDs with a total of 96 megapixels that cover 100 square degrees of sky.

Both the Schmidt corrector and 1.4 m aperture primary mirror have been fabricated and polished. All 50 CCD detectors have been delivered, tested and found to perform better than required, and are now being mounted in modules to be installed in the focal plane. Measurements of the ability of the first module to detect transit amplitudes expected from Earth-size planets are scheduled to start this month. A preliminary catalog classifying 11 million stars in the FOV has been produced. The science descope that replaced the articulated antenna with a body-fixed antenna still provides performance above the baseline design. A concise description of the current mission design and expected science results are presented. Title: Computational Acoustics in Spherical Geometry: Steps toward Validating Helioseismology Authors: Hanasoge, S. M.; Larsen, R. M.; Duvall, T. L., Jr.; De Rosa, M. L.; Hurlburt, N. E.; Schou, J.; Roth, M.; Christensen-Dalsgaard, J.; Lele, S. K. Bibcode: 2006ApJ...648.1268H Altcode: Throughout the past decade, detailed helioseismic analyses of observations of solar surface oscillations have led to advances in our knowledge of the structure and dynamics of the solar interior. Such analyses involve the decomposition of time series of the observed surface oscillation pattern into its constituent wave modes, followed by inversion procedures that yield inferences of properties of the solar interior. While this inverse problem has been a major focus in recent years, the corresponding forward problem has received much less attention. We aim to rectify this situation by taking the first steps toward validating and determining the efficacy of the helioseismic measurement procedure. The goal of this effort is to design a means to perform differential studies of various effects such as flows and thermal perturbations on helioseismic observables such as resonant frequencies, travel-time shifts, etc. Here we describe our first efforts to simulate wave propagation within a spherical shell, which extends from 0.2 to about 1.0004 Rsolar (where Rsolar is the radius of the Sun) and which possesses a solar-like stratification. We consider a model containing no flows that will serve as a reference model for later studies. We discuss the computational procedure, some difficulties encountered in a simulation of this kind, and the means to overcome them. We also present techniques used to validate the simulation. Title: The Kepler Mission: Astrophysics and Eclipsing Binaries Authors: Koch, D.; Borucki, W.; Basri, G.; Brown, T.; Caldwell, D.; Christensen-Dalsgaard, J.; Cochran, W.; Dunham, E.; Gautier, T. N.; Geary, J.; Gilliland, R.; Jenkins, J.; Kondo, Y.; Latham, D.; Lissauer, J.; Monet, D. Bibcode: 2006Ap&SS.304..391K Altcode: 2006Ap&SS.tmp..467K The Kepler Mission is a photometric space mission that will continuously observe a single 100 square degree field of view (FOV) of the sky of more than 100,000 stars in the Cygnus-Lyra region for four or more years with a precision of 14 parts per million (ppm) for a 6.5 hour integration including shot noise for a twelfth magnitude star. The primary goal of the mission is to detect Earth-size planets in the habitable zone of solar-like stars. In the process, many eclipsing binaries (EB) will also be detected. Prior to launch, the stellar characteristics will have been determined for all the stars in the FOV with K<14.5. As part of the verification process, stars with transits (about 5%) will need to have follow-up radial velocity observations performed to determine the component masses and thereby separate grazing eclipses caused by stellar companions from transits caused by planets. The result will be a rich database on EBs. The community will have access to the archive for uses such as for EB modeling of the high-precision light curves. A guest observer program is also planned for objects not already on the target list. Title: A new international project: Stellar Oscillations Network Group Authors: Kjeldsen, H.; Grundahl, F.; Christensen-Dalsgaard, J. Bibcode: 2006IAUJD..17E..29K Altcode: Stellar Oscillations Network Group (SONG) is a new international project with the aim of developing a global network of automatic telescopes of ~1m aperture devoted to asteroseismology and planet hunting with a major fraction of the available time devoted to asteroseismology. The project is undergoing a conceptual design study in 2006 and is still in its very earliest phases. The network is expected to consist of 8 identical telescope-nodes, and will be operated as a single facility. A timescale for the implementation of the project is not yet developed, but it is realistic to expect that full operations can, at the earliest, commence around 2010. SONG is planned to provide high S/N data for many stars of different types, with emphasis being on long time-series work lasting several weeks to months for selected targets. The network will focus mainly on bright stars. Title: Introductory overview : a new era of asteroseismology Authors: Christensen-Dalsgaard, J. Bibcode: 2006IAUJD..17E..17C Altcode: In the last few years, asteroseismology of solar-like stars has been converted from a dream to a solid reality. New observational facilities, particularly very stable spectrographs, have allowed the detection and study of oscillations in a number of stars on, and just after, the main sequence, placing increasingly strong constraints on the modelling of stellar interiors. Further great advances are expected in the coming years, from continued ground- based efforts and from space missions. Particularly interesting will be the results from CoRoT, to be launched later this year; on a slightly longer time scale the NASA Kepler mission is expected to provide asteroseismic data for a large number of stars. The interpretation of these data will certainly start a new era of realistic stellar modelling with a strong observational base. Title: Scientific Objectives of the Novel Formation Flying Mission Aspiics Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.617E.164L Altcode: 2006soho...17E.164L No abstract at ADS Title: The EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO): Science Plan and Instrument Overview Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.617E.165W Altcode: 2006soho...17E.165W No abstract at ADS Title: Helas-European Helio- and Asteroseismology Network Authors: Roth, M.; Lühe, O. v. d.; Pallé, P.; Thompson, M.; Christensen-Dalsgaard, J.; Monteiro, M. J. P. F. G; Gizon, L.; Di Mauro, M. P.; Aerts, C.; Daszynska-Daszkiewicz, J.; Corbard, T. Bibcode: 2006ESASP.617E.157R Altcode: 2006soho...17E.157R No abstract at ADS Title: The Dynamics Project Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.617E.162T Altcode: 2006soho...17E.162T No abstract at ADS Title: Asteroseismology: the SONG of the Stars Authors: Christensen-Dalsgaard, Jorgen Bibcode: 2006kas..confE..14C Altcode: No abstract at ADS Title: Pinpointing isochrones in clusters . Authors: Grundahl, F.; Arentoft, T.; Bruntt, H.; Christensen-Dalsgaard, J.; Clausen, J. V.; Frandsen, S.; Glowienka, L.; Jensen, H. R.; Kjeldsen, H.; Lefever, K.; Meibom, S.; Nielsen, T. B.; Pigulski, A.; Southworth, J. Bibcode: 2006MmSAI..77..433G Altcode: Detached eclipsing binaries allow the determination of accurate stellar masses and radii. Here we present the first results of a programme which aims at using such systems for the determination of accurate stellar parameters in open star clusters and discuss this in relation to the study of pulsating stars. As an example we show results for a detached eclipsing system in the old open cluster NGC 188 and briefly discuss the two intermediate age open clusters NGC 1817 and NGC 2506 which both contains pulsating stars and detached eclipsing binaries. Title: SONG: Stellar Oscillations Network Group . A global network of small telescopes for asteroseismology and planet searches. Authors: Grundahl, F.; Kjeldsen, H.; Frandsen, S.; Andersen, M.; Bedding, T.; Arentoft, T.; Christensen-Dalsgaard, J. Bibcode: 2006MmSAI..77..458G Altcode: One of the limiting factors in current asteroseismic investigations of solar type stars is the limited time coverage of single-site observations. To remedy this problem we are studying the design of a global network based on 16-24 inch telescopes equipped with fibre fed high-efficiency and high-resolution spectrographs and iodine cells. These will measure precise radial velocity time-series for stars in order to carry out asteroseismic analyses and search for low-mass planets in short period orbits around our targets. Title: Probing the internal magnetic field of slowly pulsating B-stars through g modes Authors: Hasan, S. S.; Zahn, J. -P.; Christensen-Dalsgaard, J. Bibcode: 2005A&A...444L..29H Altcode: 2005astro.ph.11472H Context: .
Aims: .We suggest that high-order g modes can be used as a probe of the internal magnetic field of SPB (slowly pulsating B) stars. The idea is based on earlier work by the authors hich analytically investigated the effect of a vertical magnetic field on p and g modes in a plane-parallel isothermal stratified atmosphere. It was found that even a weak field can significantly shift the g-mode frequencies - the effect increases with mode order.
Methods: .In the present study we adopt the classical perturbative approach to estimate the internal field of a 4 solar mass SPB star by looking at its effect on a low-degree (l=1) and high-order (n=20) g mode with a period of about 1.5 d.
Results: .We find that a polar field strength of about 110 kG on the edge of the convective core is required to produce a frequency shift of 1%. Frequency splittings of that order have been observed in several SPB variables, in some cases clearly too small to be ascribed to rotation. We suggest that they may be due to a poloidal field with a strength of order 100 kG, buried in the deep interior of the star.
Conclusions: . Title: Jets in the Solar Tachocline as Diagnostics of Global MHD Processes Authors: Christensen-Dalsgaard, J.; Corbard, T.; Dikpati, M.; Gilman, P. A.; Thompson, M. J. Bibcode: 2005ASPC..346..115C Altcode: Multiple theories predict the existence of prograde fluid jets in the solar tachocline. We find helioseismic evidence of a prograde jet near 60° latitude in N and S hemispheres that persists through almost all of the current solar cycle. This evidence favors a hydrodynamic origin for the jet, from global instability of the differential rotation of the tachocline. We see no evidence for jets that migrate toward the equator with the advancing solar cycle, which tends to rule out jets associated with toroidal field bands in the tachocline. Title: Kepler Mission Design Authors: Koch, D. G.; Borucki, W. J.; Lissauer, J. J.; Basri, G. S.; Gould, A. D.; Brown, T. M.; Caldwell, D. A.; DeVore, E. K.; Jenkins, J. M.; Christensen-Dalsgaard, J.; Cochran, W. D.; Dunham, E. W.; Gautier, T. N.; Geary, J. C.; Latham, D. W.; Gilliland, R. L.; Kondo, Y.; Monet, D. G. Bibcode: 2005AAS...20711009K Altcode: 2005BAAS...37.1339K The Kepler Mission is in the development phase with launch planned for 2008. The mission goal is to reliably detect a significant number of Earth-size and smaller planets in the habitable zone of solar-like stars. (see W. Borucki, et al, this meeting.) The mission design allows for exploring the diversity of planetary sizes and orbital periods for a wide variety of stellar spectral types, (see posters by D. Latham, et al and T. Brown, et al, this meeting on stellar catalog preparation). In this poster we describe the technical approach taken for the mission design; describing the flight and ground system, the detection methodology, the photometer design and capabilities, the way the data are taken and processed, the Guest Observer opportunity and the EPO aspects (see paper by E. DeVore, et al). Finally the detection capability in terms of planet size is presented as a function of planetary orbital period, mission duration, stellar type and combined differential photometric precision. Title: Solar-like Oscillations in α Centauri B Authors: Kjeldsen, Hans; Bedding, Timothy R.; Butler, R. Paul; Christensen-Dalsgaard, Jørgen; Kiss, Laszlo L.; McCarthy, Chris; Marcy, Geoffrey W.; Tinney, Christopher G.; Wright, Jason T. Bibcode: 2005ApJ...635.1281K Altcode: 2005astro.ph..8609K We have made velocity observations of the star α Centauri B from two sites, allowing us to identify 37 oscillation modes with l=0-3. Fitting to these modes gives the large and small frequency separations as a function of frequency. The mode lifetime, as measured from the scatter of the oscillation frequencies about a smooth trend, is similar to that in the Sun. Limited observations of the star δ Pav show oscillations centered at 2.3 mHz, with peak amplitudes close to solar. We introduce a new method of measuring oscillation amplitudes from heavily smoothed power density spectra, from which we estimated amplitudes for α Cen α and B, β Hyi, δ Pav, and the Sun. We point out that the oscillation amplitudes may depend on which spectral lines are used for the velocity measurements.

Based on observations collected at the European Southern Observatory, Paranal, Chile (ESO Programme 71.D-0618). Title: Solar Convection-Zone Dynamics, 1995-2004 Authors: Howe, R.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R.; Schou, J.; Thompson, M. J. Bibcode: 2005ApJ...634.1405H Altcode: The nine-year span of medium-degree helioseismic data from the Global Oscillation Network Group (GONG) and the Michelson Doppler Imager (MDI) allows us to study the evolving zonal flows in the solar convection zone over the rising phase, maximum, and early declining phase of solar cycle 23. Using two independent two-dimensional rotation inversion techniques, we investigate the depth profile of the flow pattern known as the torsional oscillation. The observations suggest that the flows penetrate deep within the convection zone-perhaps to its base-even at low latitudes, and that the phase of the pattern is approximately constant along lines of constant rotation rather than lines of constant latitude. Title: Kepler Mission: Current Status Authors: Borucki, W. J.; Koch, D. G.; Lissauer, J. J.; Basri, G. S.; Caldwell, D. A.; DeVore, E.; Jenkins, J. M.; Caldwell, J. J.; Christensen-Dalsgaard, J.; Cochran, W. D.; Dunham, E. W.; Gautier, T. N.; Geary, J. C.; Latham, D. A.; Sasselov, D.; Gilliland, R. L.; Gould, A.; Howell, S. B.; Kondo, Y.; Monet, D. G. Bibcode: 2005AAS...20715301B Altcode: 2005BAAS...37Q1412B Kepler is a Discovery-class mission designed to determine the frequency of Earth-size planets in and near the habitable zone (HZ) of solar-like stars. The instrument consists of a 0.95 m aperture photometer designed to obtain high precision photometric measurements of >100,000 stars to search for patterns of transits. The depth and repetition time of transits provide the size of the planet relative to the star and its orbital period. At the end of the four year mission, several hundred terrestrial planets should be discovered if such planets are common.

Multi-band ground-based observation of 5x106 stars in the Kepler FOV is currently underway to estimate stellar parameters and choose appropriate targets. The poster by Latham et al discusses the filter set, magnitude range, and current status of the Kepler Input Catalog. The poster by Brown et.al. describes the methods used to go from these observations and stellar models to Teff and log(g). With these parameters, dwarf stars can be selected and both the star and planet diameters can be calculated. When transit patterns are detected, the positions of discovered planets relative to the habitable zone can be estimated.

Both the Schmidt corrector and 1.4 m aperture primary mirror have been fabricated and are being polished. Forty-six CCD detectors have been delivered, tested, and are being prepared for mounting in modules that will be installed in the focal plane. As of Oct. 2005, the first CCD driver, data acquisition, and science data accumulator boards have been functionally tested. And Build 0 of the flight software has been completed and tested. These support reading out of the 96 megapixel focal plane as often as every 3 sec. A more complete discussion of the spacecraft and instrument development can be found in the poster by Koch et al. Title: How Sensitive are Rotation Inversions to Subtle Features of the Dynamo? Authors: Howe, R.; Rempel, M.; Christensen-Dalsgaard, J.; Schou, J.; Thompson, M. J.; Komm, R.; Hill, F. Bibcode: 2005ASPC..346...99H Altcode: Global rotation inversions can probe the pattern of zonal flows well into the convection zone. In this paper, we test the ability of the inversions to constrain the predictions of dynamo models. A flux-transport dynamo model, including a mean-field theory of differential rotation and allowing for feedback of the Lorentz force on differential rotation and meridional flow, was used to produce a 22-year cycle of simulated rotation profiles. These were then subjected to simulated inversions with realistic mode sets and errors, in order to test how well the subtle subsurface features of the input profile could be recovered. The preliminary results are quite encouraging. Title: The life of stars and their planets Authors: Catala, C.; Aerts, C.; Aigrain, S.; Antonello, E.; Appourchaux, T.; Auvergne, M.; Baglin, A.; Barge, P.; Barstow, M. A.; Baudin, F.; Boumier, P.; Collier Cameron, A.; Christensen-Dalsgaard, J.; Cutispoto, G.; Deeg, H.; Deleuil, M.; Desidera, S.; Donati, J. -F.; Favata, F.; Foing, B. H.; Gameiro, J. F.; Garcia, R.; Garrido, F.; Horne, K.; Lanza, A. F.; Lanzafame, A. C.; Lecavelier Des Etangs, A.; Léger, A.; Mas-Hesse, M.; Messina, S.; Micela, G.; Michel, E.; Monteiro, M. J. P. F. G.; Mosser, B.; Noels, A.; Pagano, I.; Piotto, G.; Poretti, E.; Rauer, H.; Roca-Cortes, T.; Rodono, M.; Rouan, D.; Roxburgh, I.; Schneider, J.; Strassmeier, K.; Turck-Chièze, S.; Vauclair, S.; Vidal-Madjar, A.; Weiss, W. W.; Wheatley, P. Bibcode: 2005ESASP.588...99C Altcode: 2005tssc.conf...99C We lack a reliable scenario for the formation and evolution of stars and their planetary systems, involving key factors such as magnetic fields and turbulence. We present the case for a mission concept that will clarify these problems and give us a global view of the evolution of combined star and planetary systems. This will be achieved by simultaneously addressing the search for planetary transits in front of a large number of stars, including many nearby stars, the study of their internal structure and evolution via asteroseismology, and that of their magnetic activity, via UV monitoring. Title: Influence of two updated nuclear reaction rates on the evolution of low and intermediate mass stars Authors: Weiss, A.; Serenelli, A.; Kitsikis, A.; Schlattl, H.; Christensen-Dalsgaard, J. Bibcode: 2005A&A...441.1129W Altcode: 2005astro.ph..3408W Two key reactions of hydrostatic nuclear burning in stars have recently been revised by new experimental data - the 14N(p,γ)150 and 3 α reaction rates. We investigate how much the new rates influence the evolution of low-mass, metal-poor and metal-free stars and of an intermediate-mass star of solar-type composition. We concentrate on phases of helium ignition or thermally unstable helium burning. Our global result is that the new 3 α rate has no significant influence on such stars, but that there is a noticeable though small effect of the new 14N(p,γ)150 rate, in particular on the core helium flash and the blue loop during core helium burning in the intermediate-mass star. Title: Detection of granulation in the solar-like star Procyon A Authors: Bruntt, H.; Kjeldsen, H.; Buzasi, D.; Christensen-Dalsgaard, J.; Bedding, T. R. Bibcode: 2005ESASP.560..469B Altcode: 2005csss...13..469B No abstract at ADS Title: Seismology of the Sun and solar-like stars Authors: Christensen-Dalsgaard, J. Bibcode: 2005ESASP.560...81C Altcode: 2005csss...13...81C No abstract at ADS Title: The non-detection of oscillations in Procyon by MOST: Is it really a surprise? Authors: Bedding, T. R.; Kjeldsen, H.; Bouchy, F.; Bruntt, H.; Butler, R. P.; Buzasi, D. L.; Christensen-Dalsgaard, J.; Frandsen, S.; Lebrun, J. -C.; Martić, M.; Schou, J. Bibcode: 2005A&A...432L..43B Altcode: 2005astro.ph..1662B We argue that the non-detection of oscillations in Procyon by the MOST satellite reported by [CITE] is fully consistent with published ground-based velocity observations of this star. We also examine the claims that the MOST observations represent the best photometric precision so far reported in the literature by about an order of magnitude and are the most sensitive data set for asteroseismology available for any star other than the Sun. These statements are not correct, with the most notable exceptions being observations of oscillations in α Cen A that are far superior. We further disagree that the hump of excess power seen repeatedly from velocity observations of Procyon can be explained as an artefact caused by gaps in the data. The MOST observations failed to reveal oscillations clearly because their noise level is too high, possibly from scattered Earthlight in the instrument. We did find an excess of strong peaks in the MOST amplitude spectrum that is inconsistent with a simple noise source such as granulation, and may perhaps indicate oscillations at roughly the expected level. Title: Physics of Solar-Like Oscillations Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2005HiA....13..397C Altcode: The physics of solar and stellar oscillations determine their observable properties: frequencies amplitudes lifetimes line asymmetries and phase relations. In the solar case these quantities have been measured often with high precision and much has been learned about the properties of the solar interior and the properties of the oscillations. I discuss some examples of these inferences concentrating mostly on the low-degree modes for which corresponding information may be expected for distant stars. In addition I consider the current state of investigations of solar-like oscillations in other stars and the prospects for an improved understanding of the physics of such oscillations. Title: The use of frequency-separation ratios for asteroseismology Authors: Otí Floranes, H.; Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 2005MNRAS.356..671O Altcode: 2005MNRAS.356..671F The systematic patterns of separations between frequencies of modes of different degree and order are a characteristic of p-mode oscillations of stars. The frequency separations depend on the internal structure of the star and so measuring them in the observed oscillation spectra of variable stars gives valuable diagnostics of the interior of a star. Roxburgh & Vorontsov proposed using the ratio of the so-called small frequency separation to the large frequency separation as a diagnostic of the stellar interior, and demonstrated that this ratio was less sensitive than the individual frequency separations themselves to uncertain details of the near-surface structure. Here we derive kernels relating the frequency separation ratio to structure, and show why the ratio is relatively insensitive to the near-surface structure in terms of the very small amplitude of the kernels in the near-surface layers. We also investigate the behaviour of the separation ratio for stars of different masses and ages, and demonstrate the usefulness of the ratio in the so-called asteroseismic Hertzsprung-Russell diagram. Title: On helioseismic tests of basic physics Authors: Christensen-Dalsgaard, J.; Di Mauro, M. P.; Schlattl, H.; Weiss, A. Bibcode: 2005MNRAS.356..587C Altcode: 2004MNRAS.tmp..633C An important goal of helioseismology is to provide information about the basic physics and parameters that determine the structure of the solar interior. Here we discuss the procedures applied in such analyses, using as an example attempts to obtain significant constraints on the value of Newton's gravitational constant G from helioseismology. The analysis is based on complete direct and inverse helioseismic analysis of a set of accurate observed acoustic frequencies. We confirm, as found by previous investigations based on different approaches, that the actual level of precision of the helioseismic inferences does not allow us to constrain G with a precision better than that which can be reached with direct experimental measurements. The conclusion emphasizes the importance in helioseismic inferences of considering not only the accuracy with which solar oscillations are measured, but also the effect of uncertainties in other aspects of the model computation and helioseismic analysis. Title: Detection of Jets and Associated Toroidal Fields in the Solar Tachocline Authors: Christensen-Dalsgaard, J.; Corbard, T.; Dikpati, M.; Gilman, P. A.; Thompson, M. J. Bibcode: 2004ESASP.559..376C Altcode: 2004soho...14..376C No abstract at ADS Title: How Sensitive are Rotation Inversions to Subtle Features of the Dynamo? Authors: Howe, R.; Rempel, M.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R. W.; Schou, J.; Thompson, M. J. Bibcode: 2004ESASP.559..468H Altcode: 2004soho...14..468H No abstract at ADS Title: The Phase of the Torsional Oscillation Pattern Authors: Howe, R.; Komm, R. W.; Hill, F.; Christensen-Dalsgaard, J.; Schou, J.; Thompson, M. J. Bibcode: 2004ESASP.559..476H Altcode: 2004soho...14..476H No abstract at ADS Title: An Overview of Helio- and Asteroseismology Authors: Christensen-Dalsgaard, J. Bibcode: 2004ESASP.559....1C Altcode: 2004soho...14....1C No abstract at ADS Title: An Introduction to Solar Oscillations and Helioseismology Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2004AIPC..731...18C Altcode: Helioseismology offers unique possibilities for probing the detailed internal structure of a star and, in this way, constraining the physical properties of matter under stellar conditions. Here I provide a brief introduction to stellar structure and stellar oscillations, as well as to the techniques used in helioseismic analyses. In addition, I give a few examples of the results obtained from helioseismic investigations of solar structure. Title: Asteroseismology of Sun-Like Stars Authors: Metcalfe, T. S.; Brown, T. M.; Christensen-Dalsgaard, J. Bibcode: 2004ESASP.559..567M Altcode: 2004soho...14..567M; 2004astro.ph..8127M In the past decade, helioseismology has revolutionized our understanding of the interior structure of the Sun. In the next decade, asteroseismology will place this knowledge into context, by providing structural information for dozens of pulsating stars across the H-R diagram. Solar-like oscillations have already been detected from the ground in a few stars, and several current and planned satellite missions will soon unleash a flood of stellar pulsation data. Deriving reliable seismological constraints from these observations will require a significant improvement to our current analysis methods. We are adapting a computational method, based on a parallel genetic algorithm, to help interpret forthcoming observations of Sun-like stars. This approach was originally developed for white dwarfs and ultimately led to several interesting tests of fundamental physics, including a key astrophysical nuclear reaction rate and the theory of stellar crystallization. The impact of this method on the analysis of pulsating white dwarfs suggests that seismological modeling of Sun-like stars will also benefit from this approach. Title: Convection-Zone Dynamics from GONG and MDI, 1995-2004 Authors: Howe, R.; Komm, R. W.; Hill, F.; Christensen-Dalsgaard, J.; Haber, D. A.; Schou, J.; Thompson, M. J. Bibcode: 2004ESASP.559..472H Altcode: 2004soho...14..472H No abstract at ADS Title: Astronomy: Where are Procyon's quakes? Authors: Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans Bibcode: 2004Natur.430...29C Altcode: The acoustic waves that ripple through the Sun should exist in other stars too. But a search for these 'starquakes' in the nearby star Procyon has found no evidence of them. Title: The internal solar rotation from helioseismology (Invited Review) Authors: Christensen-Dalsgaard, J. Bibcode: 2004IAUS..215..305C Altcode: No abstract at ADS Title: New theoretical developments in stellar pulsation Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2004ASPC..310....3C Altcode: 2004IAUCo.193....3C; 2004vslg.conf....3C The basic properties of stellar oscillations are reasonably well understood, allowing measurements of their frequencies to be used as probes of stellar interiors. The detailed understanding of the processes responsible for the oscillations, in the very broad range of stars observed to pulsate, has improved substantially over the past decade, as have the techinques for asteroseismic investigations on the basis of the observations. Here I provide a brief overview of the theory of stellar oscillations, emphasizing several cases of recent progress, often inspired by new observational developments. Title: Interpretation of the solar-like pulsational behaviour of η Bootis Authors: Di Mauro, Maria Pia; Christensen-Dalsgaard, JØrgen; Paternò, Lucio; D'Antona, Francesca Bibcode: 2004SoPh..220..185D Altcode: HR 5235, better known as η Bootis, is a bright and well-known star for which very accurate observations have recently enabled Kjeldsen et al. (2003) and Carrier, Bouchy, and Eggenberger (2003) not only to confirm the presence of solar-like oscillations, but also to identify the excitation in the oscillation spectrum of several p-mode frequencies with harmonic degrees l = 0 - 2. Here we show how such observational success, through the calculation and the investigation of theoretical structure models and the comparison of the observed oscillation spectra with the predicted p-mode frequencies of oscillations, permits one to draw conclusions about the actual evolutionary state of this star and on the physical properties of its internal structure. The computation of the structure models is based on the use of updated global parameters and includes overshooting from the convective core. In particular, we consider the effect on the stellar structure, and hence on the theoretical frequencies, of employing different equations of state and different formalisms to describe the convective energy transport. Title: Physics of solar-like oscillations Authors: Christensen-Dalsgaard, JØrgen Bibcode: 2004SoPh..220..137C Altcode: The physics of solar and stellar oscillations determines their observable properties: frequencies, amplitudes, lifetimes, line asymmetries and phase relations. In the solar case these quantities have been measured, often with high precision, and much has been learned about the properties of the solar interior, and the properties of the oscillations. With recent advances in observational techniques, such seismic investigations are now being extended to solar-like oscillations in distant stars. I provide a brief overview of the basic properties of stellar oscillations, and of the information about stellar properties that may be inferred from them, concentrating mostly on the low-degree modes for which information may be expected for distant stars. In addition, I consider the current state of investigations of solar-like oscillations in other stars, and the prospects for an improved understanding of the physics of such oscillations. Title: ENEAS: the European Network of Excellence in AsteroSeismology Authors: Aerts, C.; Baglin, A.; Christensen-Dalsgaard, J.; Goupil, M. J.; Houdek, G.; Kjeldsen, H.; Kollath, Z.; Kurtz, D.; Lebreton, Y.; Maceroni, C.; Noels, A.; Schwarzenberg-Czerny, A.; Škoda, P.; Solano, E.; Thompson, M. J. Bibcode: 2004ESASP.538..247A Altcode: 2004sshp.conf..247A Asteroseismology is one of the major important science topics in astrophysics in the coming decade. Several recent breakthroughs have indeed been made in Europe in this field. The observational data will improve significantly in the near future, as upgraded ground-based instruments are being built and two European asteroseismic space missions are planned for launch between 2005 and 2008. They will provide us for the first time with ultra-high-accuracy, high-temporal resoluton data from space for stars other than the Sun. A successful asteroseismic study involves many different steps, from state-of-the-art raw data treatment to theoretical physical modelling of the oscillation frequencies. Our network is set up to meet the needs of combining and exchanging the different expertises of the participating institutes, of training PhD students and of both training and exchanging post-doctoral researchers. This will guarantee the most fruitful and efficient exploitation of the very substantial investments that are being made in Europe in future observations of stellar oscillations, strengthening Europe's leading position in this research field. Also, it will be a test-bed for the development of efficient procedures for collaboration across the internet, involving a vast range of procedures and skills, as well as extensive common use of a broad variety of data. Furthermore, procedures will be incorporated for the joint training of students, which is an essential part of our project. Title: Planet Detection Capabilities of the Eddington Mission Authors: Deeg, Hans J.; Horne, Keith; Favata, Fabio; Eddington Science Team; Aerts, C.; Antonello, E.; Badiali, M.; Catala, C.; Christensen-Dalsgaard, J.; Gimenez, A.; Grenon, M.; Penny, A.; Rauer, H.; Roxburgh, I. W.; Schneider, J.; Waltham, N. R. Bibcode: 2004IAUS..202..448D Altcode: No abstract at ADS Title: A Comparison of Solar p-Mode Parameters from MDI and GONG: Mode Frequencies and Structure Inversions Authors: Basu, S.; Christensen-Dalsgaard, J.; Howe, R.; Schou, J.; Thompson, M. J.; Hill, F.; Komm, R. Bibcode: 2003ApJ...591..432B Altcode: Helioseismic analysis of solar global oscillations allows investigation of the internal structure of the Sun. One important test of the reliability of the inferences from helioseismology is that the results from independent sets of contemporaneous data are consistent with one another. Here we compare mode frequencies from the Global Oscillation Network Group and Michelson Doppler Imager on board SOHO and resulting inversion results on the Sun's internal structure. The average relative differences between the data sets are typically less than 1×10-5, substantially smaller than the formal errors in the differences; however, in some cases the frequency differences show a systematic behavior that might nonetheless influence the inversion results. We find that the differences in frequencies are not a result of instrumental effects but are almost entirely related to the data pipeline software. Inversion of the frequencies shows that their differences do not result in any significant effects on the resulting inferences on solar structure. We have also experimented with fitting asymmetric profiles to the oscillation power spectra and find that, compared with the symmetric fits, this causes no significant change in the inversion results. Title: Interferometry and asteroseismology: The radius of tau Cet Authors: Pijpers, F. P.; Teixeira, T. C.; Garcia, P. J.; Cunha, M. S.; Monteiro, M. J. P. F. G.; Christensen-Dalsgaard, J. Bibcode: 2003A&A...406L..15P Altcode: We have determined from interferometry the radius of the nearby star tau Cet, using recent observations with the VINCI instrument on VLTI using the siderostats. The limb-darkened disk diameter is determined, with an unprecedented internal precision of 0.5%, to be 1.971 +/- 0.009_(int.)+/- 0.05_(ext.) mas, corresponding to a physical radius of 0.773 +/- 0.004_(int.)+/- 0.02_(ext.) Rsun. With this determination tau Cet becomes a prime target for asteroseismic campaigns to determine its internal structure, and thereby test stellar evolution theory. We discuss implications for asteroseismology and present predictions for oscillation properties.

Based on observations collected at the European Southern Observatory, Chile. Title: Convective overshooting in the evolution and seismology of eta Bootis Authors: Di Mauro, M. P.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Bedding, T. R.; Paternò, L. Bibcode: 2003A&A...404..341D Altcode: In the near future frequencies of solar-like oscillation will be observed by the several planned space missions. In order to assess the information that will be available from such observations, we consider theoretical predictions of the frequency spectrum of oscillations of the star eta Bootis, which shows solar-type pulsations. We present results obtained by comparing ``classical'' evolution models with models computed by taking into account overshooting from the convective core. Title: Stellar Astrophysical Fluid Dynamics Authors: Thompson, Michael J.; Christensen-Dalsgaard, Jørgen Bibcode: 2003safd.book.....T Altcode: Preface; 1. A selective overview Jørgen Christensen-Dalsgaard and Michael J. Thompson; Part I. Stellar Convection and Oscillations: 2. On the diversity of stellar pulsations Wojciech A. Dziembowski; 3. Acoustic radiation and mode excitation by turbulent convection Günter Houdek; 4. Understanding roAp stars Margarida S. Cunha; 5. Waves in the magnetised solar atmosphere Colin S. Rosenthal; Part II. Stellar Rotation and Magnetic Fields: 6. Stellar rotation: a historical survey Leon Mestel; 7. The oscillations of rapidly rotating stars Michel Rieutord; 8. Solar tachocline dynamics: eddy viscosity, anti-friction, or something in between? Michael E. McIntyre; 9. Dynamics of the solar tachocline Pascale Garaud; 10. Dynamo processes: the interaction of turbulence and magnetic fields Michael Proctor; 11. Dynamos in planets Chris Jones; Part III. Physics and Structure of Stellar Interiors: 12. Solar constraints on the equation of state Werner Däppen; 13. 3He transport and the solar neutrino problem Chris Jordinson; 14. Mixing in stellar radiation zones Jean-Paul Zahn; 15. Element settling and rotation-induced mixing in slowly rotating stars Sylvie Vauclair; Part IV. Helio- and Asteroseismology: 16. Solar structure and the neutrino problem Hiromoto Shibahashi; 17. Helioseismic data analysis Jesper Schou; 18. Seismology of solar rotation Takashi Sekii; 19. Telechronohelioseismology Alexander Kosovichev; Part V. Large-Scale Numerical Experiments: 20. Bridges between helioseismology and models of convection zone dynamics Juri Toomre; 21. Numerical simulations of the solar convection zone Julian R. Elliott; 22. Modelling solar and stellar magnetoconvection Nigel Weiss; 23. Nonlinear magnetoconvection in the presence of a strong oblique field Keith Julien, Edgar Knobloch and Steven M. Tobias; 24. Simulations of astrophysical fluids Marcus Brüggen; Part VI. Dynamics: 25. A magic electromagnetic field Donald Lynden-Bell; 26. Continuum equations for stellar dynamics Edward A. Spiegel and Jean-Luc Thiffeault; 27. Formation of planetary systems Douglas N. C. Lin; 28. The solar-cycle global warming as inferred from sky brightness variation Wasaburo Unno and Hiromoto Shibahashi. Title: Transient oscillations near the solar tachocline Authors: Toomre, Juri; Christensen-Dalsgaard, Jorgen; Hill, Frank; Howe, Rachel; Komm, Rudolf W.; Schou, Jesper; Thompson, Michael J. Bibcode: 2003ESASP.517..409T Altcode: 2003soho...12..409T We report on further developments in the 1.3-yr quasi-periodic oscillations reported by Howe et al. (2000). These are small (6 to 8 nHz peak-to-peak) oscillations in the inferred rotation rate near the bottom of the convection zone and in the outer part of the radiative interior. The oscillations are strongest and most coherent at about a fractional radius of 0.72 in the equatorial region. Further monitoring of the oscillations near the equator shows that they continued for a period after the end of the data analyzed by Howe et al., but appear to have now diminished in amplitude. This is reminiscent of the transient behavior of similar (1.3 to 1.4 yr) periodicities in solar-wind and geomagnetic datasets previously reported. We speculate that the near tachocline oscillation is associated with the rising phase of the solar cycle. We discuss tests performed to eliminate various possible explanations of the oscillations due to systematic errors in the data and in their analyses. Title: Radial Oscillations in A Stars Authors: Medupe, R.; Christensen-Dalsgaard, J.; Kurtz, D. W. Bibcode: 2003ASPC..305..146M Altcode: 2003mfob.conf..146M No abstract at ADS Title: Physics of Solar-Like Oscillations Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2003IAUJD..12E..55C Altcode: The physics of solar and stellar oscillations determine their observable properties: frequencies amplitudes lifetimes line asymmetries and phase relations. In the solar case these quantities have been measured often with high precision and much has been learned about the properties of the solar interior and the properties of the oscillations. I discuss some examples of these inferences concentrating mostly on the low-degree modes for which corresponding information may be expected for distant stars. In addition I consider the current state of investigations of solar-like oscillations in other stars and the prospects for an improved understanding of the physics of such oscillations. Title: A Study of the Solar-Like Properties of β Hydri Authors: Di Mauro, Maria Pia; Christensen-Dalsgaard, Jørgen; Paternò, Lucio Bibcode: 2003Ap&SS.284..229D Altcode: We investigate properties of the internal structure of HR2021, better known as β Hydri, a G2 IV subgiant with mass close to solar and for which observations by Bedding et al. (2001) have shown the presence of solar-like oscillations. We have computed models of β Hydri, based on updated global parameters, and compared the computed frequencies for the models with the observed oscillation spectrum. Title: The European Ultra-High Precision Stellar Photometry Road Map for Asteroseismology and Planet Finding Authors: Roxburgh, Ian; Favata, Fabio; Baglin, Annie; Christensen-Dalsgaard, Jørgen Bibcode: 2003acfp.conf..479R Altcode: We give a brief description of the 3 European space missions COROT, MONS and Eddington, devoted to asteroseismology and planet finding. Title: Rotation of the solar interior Authors: Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 2003dysu.book...55C Altcode: Helioseismology allows us to infer the rotation in the greater part of the solar interior with high precision and resolution. The results show interesting conflicts with earlier theoretical expectations, indicating that the Sun is host to complex dynamical phenomena, so far hardly understood. This has important consequences for our ideas about the evolution of stellar rotation, as well as for models for the generation of the solar magnetic field. An overview of our current knowledge about solar rotation is given, much of it obtained from the SOHO spacecraft, and the broader implications are discussed. Title: Preface (Stellar astrophysical fluid dynamics) Authors: Thompson, Michael J.; Christensen-Dalsgaard, Jørgen Bibcode: 2003safd.bookD...9T Altcode: No abstract at ADS Title: On Asteroseismic Constraints for Modelling the δ Scuti Stars V480 Tau and θ2 Tau A Authors: Di Mauro, M. P.; Pijpers, F.; Christensen-Dalsgaard, J.; Paternò, L.; Teixeira, T.; Thompson, M. J. Bibcode: 2003ASPC..305..161D Altcode: 2003mfob.conf..161D We investigate the structure and evolution of δ Scuti stars and discuss how basic properties as well as global oscillation frequencies are modified by moderate rotation. We present theoretical analyses of V480 Tau, observed during the MUSICOS 1996 campaign (Hao et al. 2001), and of θ2 Tau A, monitored by the WIRE satellite (Poretti et al. 2002). We compare the observed spectra of frequencies with the theoretical oscillation frequencies calculated by including rotational effects. Title: Seismological analysis of the Helium ionization zones in low- and moderate-mass stars Authors: Miglio, A.; Christensen-Dalsgaard, J.; di Mauro, M. P.; Monteiro, M. J. P. F. G.; Thompson, M. J. Bibcode: 2003aahd.conf..537M Altcode: The region of the second ionization of helium in solar-like stars is a narrow subsurface layer whose thermodynamic properties are responsible for the presence of a characteristic signature in the oscillation frequencies of the p modes. Here, with the aim of detecting the acoustic depth of the second helium ionization zone, we consider two methods of analysing the signal generated in the oscillation frequencies by the sharp decrease in the first adiabatic exponent Γ1, which occurs where ionization takes place. The properties of the ionization zone, once determined by seismological means, may be used to put constraints on the structure of the stars, in particular on the envelope helium abundance. Title: Giant Vibrations in Dip Authors: Teixeira, T. C.; Christensen-Dalsgaard, J.; Carrier, F.; Aerts, C.; Frandsen, S.; Stello, D.; Maas, T.; Burnet, M.; Bruntt, H.; de Medeiros, J. R.; Bouchy, F.; Kjeldsen, H.; Pijpers, F. Bibcode: 2003Ap&SS.284..233T Altcode: This work reports the discovery of solar-type oscillations in the giant star ξ Hydrae. Title: The Effect of Rotation on Stellar Oscillations Authors: Karami, Kayoomars; Christensen-Dalsgaard, Joergen; Pijpers, Frank P. Bibcode: 2003IAUJD..12E..29K Altcode: Here we investigate the effect of rotation up to third order on normal 'p' and 'g' modes based on the formalism developed by Soufi Goupil and Dziembowski (1998). As demonstrated by those authors the third order perturbation formalism shows that: i) By taking into account parts of the effects of Coriolis force in the zeroth order system the computation reduces to solving the eigenvalue problem up to cubic order without having to solve successive equations for the eigenfunctions at each order and also the usual m-degeneracy occurring in the absence of rotation is removed. ii) Near-degenerate coupling due to rotation only occurs between modes with either the same degree l (and different radial orders) or with degrees which differ by ±2. The total coupling coefficients are caused by the three distinct terms including Coriolis contribution non-spherically symmetric distortion and distortion and Coriolis coupling. Our study shows that the third-order perturbation formalism presented by Soufi Goupil and Dziembowski (1998) should be revised by adding or correcting some terms in the equations. We also carry out the numerical calculations for calculating the frequency corrections up to third order for zero-age main-sequence and somewhat evolved models of β Cephi stars. Title: Solar-Like Oscillations in the Giant Star XI Hydrae Authors: Stello, Dennis; Carrier, Fabien; Aerts, Conny; Frandsen, Søren; Bouchy, Francois; Kjeldsen, Hans; Teixeira, Teresa; Pijpers, Frank; Christensen-Dalsgaard, Jørgen Bibcode: 2003IAUJD..12E..35S Altcode: The discovery of solar-like oscillations in the giant star xi Hydrae (G7III) was reported by Frandsen et al. (2002). In this talk we present a much larger and more complete analysis of the data presented by Frandsen et al. (2002) including an improved analysis containing new stellar models (models for helium core burning stars). We also present a large number of simulations that are used to quantify the alias problem in the data set (caused by single site observations) and hence making it possible to distinguish between detected frequencies which should be trusted as real modes and those that are probably due to sideband structures. Title: Problems, Connections and Expectations of Asteroseismology: a Summary of the Workshop Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2003Ap&SS.284..277C Altcode: The workshop took place at the beginning of what promises to be a golden age of asteroseismology. Ground-based instrumentation is finally reaching a level of stability which allows detailed investigations of solar-like oscillations in at least bright, slowly rotating main-sequence stars. Very extensive results are expected from the coming space missions, including data on a broad range of stars from the Eddington mission. The observational situation is therefore extremely promising. To make full use of these promises, major efforts are required towards the efficient utilization of the data, through the development of techniques for the analysis and interpretation of the data. A broad range of topics related to these issues is discussed in the present proceedings. Here I review some of the relevant problems, relate the asteroseismic investigations to broader areas of astrophysics and consider briefly the basis for our great expectations for the development of the field. Title: Commission 27: Variable stars (Etoiles variables) Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2003IAUTA..25..271C Altcode: 2003IAUTr..25A.271C No abstract at ADS Title: A Danish space project: MONS - measuring oscillations in nearby stars Authors: Kjeldsen, H.; Christensen-Dalsgaard, J.; Bedding, T. R. Bibcode: 2003AdSpR..31..363K Altcode: The MONS (Measuring Oscillations in Nearby Stars) project on the Rømer satellite aims at studying properties of stellar interiors through observations of oscillations in stellar luminosity and surface temperature. The main targets are stars exhibiting oscillations similar to those observed in the Sun, with very low amplitudes. During the planned two-year life time of the mission, around 20 such stars will be observed with the MONS Main Telescope. Additional data on variability of a large number of stars of a broad range of types may be obtained from the parallel science programme. This part of the programme will use two instruments; The Star Trackers and the Field Monitor. The following paper aims at describing some aspects of the MONS project. Title: A selective overview Authors: Christensen-Dalsgaard, Jørgen; Thompson, Michael J. Bibcode: 2003safd.book....1C Altcode: Contents: 1. Introduction. 2. On taking mixing-length theory seriously. 3. The solar spoon. 4. Deep roots of solar cycles. 5. Helioseismology: oscillations as a diagnostic of the solar interior. 6. Inverting helioseismic data. 7. On the detection of subphotospheric convective velocities and temperature fluctuations. 8. Prospects for asteroseismic inference. Title: The Effect of Rotation on Stellar Oscillations Authors: Karami, Kayoomars; Christensen-Dalsgaard, Joergen; Pijpers, Frank P. Bibcode: 2003IAUJD..12E..28K Altcode: Here we investigate the effect of rotation up to third order in terms of the angular velocity of a star on normal 'p' and 'g' modes based on the formalism developed by Soufi et al. (1998). Third order perturbation formalism shows that: i) By taking into account parts of the effects of Coriolis force in the zeroth order system the computation reduces to solving the eigenvalue problem up to cubic order without having to solve successive equations for the eigenfunctions at each order and also the usual m-degeneracy occurring in the absence of rotation is removed. ii) Near-degenerate coupling due to rotation only occurs between modes with either the same degree l (and different radial orders) or with degrees which differ by ±2. The total coupling coefficients are caused by the three distinct terms including Coriolis contribution non-spherically symmetric distortion and distortion and Coriolis coupling. Our study shows that the third-order perturbation formalism presented by Soufi et al. (1998) should be revised by adding or correcting some terms in the equations. We also carry out the numerical calculations for calculating the frequency corrections up to third order for zero-age main-sequence and somewhat evolved models of β Cephi stars. Title: The Internal Rotation of the Sun Authors: Thompson, Michael J.; Christensen-Dalsgaard, Jørgen; Miesch, Mark S.; Toomre, Juri Bibcode: 2003ARA&A..41..599T Altcode: Helioseismology has transformed our knowledge of the Sun's rotation. Earlier studies revealed the Sun's surface rotation, but now a detailed observational picture has been built up of the internal rotation of our nearest star. Unlike the predictions of stellar-evolution models, the radiative interior is found to rotate roughly uniformly. The rotation within the convection zone is also very different from prior expectations, which had been that the rotation rate would depend primarily on the distance from the rotation axis. Layers of rotational shear have been discovered at the base of the convection zone and in the subphotospheric layers. Studies of the time variation of rotation have uncovered zonal-flow bands, extending through a substantial fraction of the convection zone, which migrate over the course of the solar cycle, and there are hints of other temporal variations and of a jet-like structure. At the same time, building on earlier work with mean-field models, researchers have made great progress in supercomputer simulations of the intricate interplay between turbulent convection and rotation in the Sun's interior. Such studies are beginning to transform our understanding of how rotation organizes itself in a stellar interior. Title: HARPS: ESO's coming planet searcher. Chasing exoplanets with the La Silla 3.6-m telescope Authors: Pepe, F.; Mayor, M.; Rupprecht, G.; Avila, G.; Ballester, P.; Beckers, J. -L.; Benz, W.; Bertaux, J. -L.; Bouchy, F.; Buzzoni, B.; Cavadore, C.; Deiries, S.; Dekker, H.; Delabre, B.; D'Odorico, S.; Eckert, W.; Fischer, J.; Fleury, M.; George, M.; Gilliotte, A.; Gojak, D.; Guzman, J. -C.; Koch, F.; Kohler, D.; Kotzlowski, H.; Lacroix, D.; Le Merrer, J.; Lizon, J. -L.; Lo Curto, G.; Longinotti, A.; Megevand, D.; Pasquini, L.; Petitpas, P.; Pichard, M.; Queloz, D.; Reyes, J.; Richaud, P.; Sivan, J. -P.; Sosnowska, D.; Soto, R.; Udry, S.; Ureta, E.; van Kesteren, A.; Weber, L.; Weilenmann, U.; Wicenec, A.; Wieland, G.; Christensen-Dalsgaard, J.; Dravins, D.; Hatzes, A.; Kürster, M.; Paresce, F.; Penny, A. Bibcode: 2002Msngr.110....9P Altcode: An extensive review of past, present and future research on extrasolar planets is given in the article “Extrasolar Planets” by N. Santos et al. in the present issue of The Messenger. Here we want to mention only that the search for extrasolar planets and the interpretation of the scientific results have evolved in recent years into one of the most exciting and dynamic research topics in modern astronomy. Title: Helioseismic investigation of the solar envelope Authors: di Mauro, M. P.; Christensen-Dalsgaard, J. Bibcode: 2002ESASP.506..879D Altcode: 2002svco.conf..879D; 2002ESPM...10..879D It has already been demonstrated that the solar envelope can be probed with sufficiently high spatial resolution through inversion of high-degree acoustic modes, which unfortunately appear strongly affected by uncertainties of the surface layers. In order to suppress those uncertainties, we introdue the use of a suitable procedure to be adopted in the helioseismic inversions of high-degree modes and show new results on the properties of the Sun's interior. Title: Helioseismology Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2002RvMP...74.1073C Altcode: 2002astro.ph..7403C Oscillations detected on the solar surface provide a unique opportunity for investigations of the interior properties of a star. Through major observational efforts, including extensive observations from space, as well as through the development of sophisticated tools for the analysis and interpretation of the data, we have been able to infer the large-scale structure and rotation of the solar interior with substantial accuracy. In addition, information is emerging about the complex subsurface structure and dynamics of sunspot regions, which dominate the magnetic activity in the solar atmosphere and beyond. The results provide a detailed test of the modeling of stellar structure and evolution, and hence of the physical properties of matter assumed in the models. In this way the basis for using stellar modeling in other branches of science is substantially strengthened; an important example is the use of observations of solar neutrinos to constrain the properties of the neutrino. Title: Detection of Solar-like oscillations in the G7 giant star ξ Hya Authors: Frandsen, S.; Carrier, F.; Aerts, C.; Stello, D.; Maas, T.; Burnet, M.; Bruntt, H.; Teixeira, T. C.; de Medeiros, J. R.; Bouchy, F.; Kjeldsen, H.; Pijpers, F.; Christensen-Dalsgaard, J. Bibcode: 2002A&A...394L...5F Altcode: 2002astro.ph..9325F We report the firm discovery of solar-like oscillations in a giant star. We monitored the star xi Hya (G7III) continuously during one month with the CORALIE spectrograph attached to the 1.2 m Swiss Euler telescope. The 433 high-precision radial-velocity measurements clearly reveal multiple oscillation frequencies in the range 50-130 muHz, corresponding to periods between 2.0 and 5.5 hours. The amplitudes of the strongest modes are slightly smaller than 2 ms. Current model calculations are compatible with the detected modes.

Based on observations obtained with the CORALIE spectrograph on the 1.2-m Swiss Euler telescope at La Silla, Chile. Title: Solar internal rotation as seen from SOHO MIDI data Authors: Vorontsov, S. V.; Christensen-Dalsgaard, J.; Schou, J.; Strakhov, V. N.; Thompson, M. J. Bibcode: 2002ESASP.508..111V Altcode: 2002soho...11..111V We report results of inverting the rotational splittings of solar p-mode frequencies measured from the MDI data, using an adaptive regularization technique as described by Strakhov & Vorontsov (2001). We analyse the spatial and temporal structure of the variations in the internal rotation, which constitute the 11-yr solar torsional oscillations. We employ all the data collected over half a solar cycle to analyse further the time-independent component of the differential rotation, particularly focusing on the solar tachocline region. We address systematic errors in the rotational splitting measurements, as indicated by the inversion residuals, which appear to restrict the accuracy of the current helioseismic measurements. Title: Helioseismic Measurement of Solar Torsional Oscillations Authors: Vorontsov, S. V.; Christensen-Dalsgaard, J.; Schou, J.; Strakhov, V. N.; Thompson, M. J. Bibcode: 2002Sci...296..101V Altcode: Bands of slower and faster rotation, the so-called torsional oscillations, are observed at the Sun's surface to migrate in latitude over the 11-year solar cycle. Here, we report on the temporal variations of the Sun's internal rotation from solar p-mode frequencies obtained over nearly 6 years by the Michelson Doppler Imager (MDI) instrument on board the Solar and Heliospheric Observatory (SOHO) satellite. The entire solar convective envelope appears to be involved in the torsional oscillations, with phase propagating poleward and equatorward from midlatitudes at all depths throughout the convective envelope. Title: Inferences on the solar envelope with high-degree modes Authors: Di Mauro, M. P.; Christensen-Dalsgaard, J.; Rabello-Soares, M. C.; Basu, S. Bibcode: 2002A&A...384..666D Altcode: We investigate the structure of the Sun by helioseismic inversion of a set of p-mode frequencies which includes new precise observations of modes with high degree (l < 1000) obtained from the MDI instrument on the SOHO satellite (Rhodes et al. \cite{rh98}). Such data have the potential to improve the resolution of the solar structure in the near-surface region, to provide detailed tests of the equation of state and constrain the envelope helium abundance. In order to suppress the uncertainties in the treatment of the surface layers in helioseismic inversion procedures, we introduce here the use of a new surface term, developed on the basis of higher-order asymptotic theory of acoustic modes and suitable for the handling of high-degree mode frequencies. Title: A Comparison of Solar p-Mode Parameters from the Michelson Doppler Imager and the Global Oscillation Network Group: Splitting Coefficients and Rotation Inversions Authors: Schou, J.; Howe, R.; Basu, S.; Christensen-Dalsgaard, J.; Corbard, T.; Hill, F.; Komm, R.; Larsen, R. M.; Rabello-Soares, M. C.; Thompson, M. J. Bibcode: 2002ApJ...567.1234S Altcode: Using contemporaneous helioseismic data from the Global Oscillation Network Group (GONG) and Michelson Doppler Imager (MDI) onboard SOHO, we compare frequency-splitting data and resulting inversions about the Sun's internal rotation. Helioseismology has been very successful in making detailed and subtle inferences about the solar interior. But there are some significant differences between inversion results obtained from the MDI and GONG projects. It is important for making robust inferences about the solar interior that these differences are located and their causes eliminated. By applying the different analysis pipelines developed by the projects not only to their own data but also to the data from the other project, we conclude that the most significant differences arise not from the observations themselves but from the different frequency estimation analyses used by the projects. We find that the GONG pipeline results in substantially fewer fitted modes in certain regions. The most serious systematic differences in the results, with regard to rotation, appear to be an anomaly in the MDI odd-order splitting coefficients around a frequency of 3.5 mHz and an underestimation of the low-degree rotational splittings in the GONG algorithm. Title: Mini-ASTROD: mission concept Authors: Ni, Wei-Tou; Zhu, Jin; Wu, Xiang-Ping; Chu, Guey-Bo; Yang, Bin; Gao, Jian; Guan, Min; Tang, Chien-Jen; Chou, Yi; Chang, Chung-Hao; Huang, Tian-Yi; Qu, Qin-Yue; Yi, Zhao-Hua; Li, Guang-Yu; Tao, Jin-He; Wu, An-Ming; Luo, Jun; Yeh, Hsien-Chi; Zhou, Ze-Bing; Xiong, Yao-Heng; Bi, Shao-Lan; Xu, Chong-Ming; Wu, Xue-Jun; Tang, Meng-Xi, Bao, Yun; Li, Fang-Yu; Huang, Cheng; Yang, Fu-Min; Ye, Shu-Hua; Zhang, Shu-Lian; Zhang, Yuan-Zhong; Nie, Yu-Xin; Chen, Guang; Christensen-Dalsgaard, Joergen; Dittus, Hansjoerg; Fujii, Yasunori; Laemmerzahl, Claus; Mangin, Jean Francois; Peters, Achim; Ruediger, Albrecht; Samain, Etienne; Schiller, Stephan Bibcode: 2002PYunO..91..123N Altcode: Advances in laser physics and its applications triggered the proposition and development of Laser Astrodynamics. Mini-ASTROD is a down-scaled version of ASTROD (Astrodynamical Space Test of Relativity using Optical Devices). This mission concept has one spacecraft carrying a payload of a telescope, six lasers, and a clock together with ground stations (ODSN: Optical Deep Space Network) to test the optical scheme and yet give important scientific results. These scientific results include a better measurement of the relativistic parameters (gamma to 1 ppm, beta to a few ppm and others with improvement), a better sensitivity in using optical Doppler tracking method for detecting gravitational waves, a potential of measuring the solar angular momentum via Lense-Thirring effect and measurement of many solar system parameters more precisely. These enable us to build a more precise ephemeris and astrodynamics. The weight of this spacecraft is estimated to be about 300 - 350 kg with a payload of about 100 - 120 kg. The spacecraft goes into an inner solar orbit with several options. We discuss the payload configuration and outlook for technological developments to reach the mission goals, and summarize the conclusions and recommendations of the first and second organizational meetings for Mini-ASTROD study. Title: Solar g-Mode Oscillations Authors: Christensen-Dalsgaard, Jørgen Bibcode: 2002IJMPD..11..995C Altcode: In the early days of helioseismology, around 1975, independent detections of an oscillation with a period of 160 min in solar spectral line-shift data caused very substantial interest: it was suggested that this resulted from a solar g mode, whose frequency would then provide a tight constraint on the structure of the solar core. Also, it was noted that such modes, which involve a substantial fraction of the solar mass, might lead to a detectable gravitational-wave signal. Later observations have, however, failed to confirm the solar nature of the originally detected oscillation. Extensive data on the low-frequency part of the solar oscillation spectrum have been obtained from several experiments over the last decade, including instruments on the SOHO spacecraft. These have provided stringent limits on amplitudes of solar g modes and a few tentative detections, although so far not independently confirmed. Theoretical estimates of g-mode amplitudes, while highly uncertain, suggest that direct detection of the modes on the solar surface may be difficult. However, detection with the ASTROD mission may be possible, although identification of the solar signal will require careful analysis. Title: Radial and Nonradial Pulsations as Probes of Stellar Physics Authors: Aerts, Conny; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen Bibcode: 2002ASPC..259.....A Altcode: 2002IAUCo.185.....A; 2002rnpp.conf.....A No abstract at ADS Title: Mini-ASTROD Authors: Ni, Wei-Tou; Zhu, Jin; Wu, Xiang-Ping; Chu, Guey-Bo; Yang, Bin; Gao, Jian; Guan, Min; Tang, Chien-Jen; Chou, Yi; Chang, Chung-Hao; Huang, Tianyi; Qu, Qin-Yue; Yi, Zhao-Hua; Li, Guangyu; Tao, Jinhe; Wu, An-Ming; Luo, Jun; Yeh, Hsien-Chi; Zhou, Ze-Bing; Xiong, Yaoheng; Bi, Shao-Lan; Xu, Chongming; Wu, Xue-Jun; Tang, Meng-Xi; Bao, Yun; Li, Fangyu; Huang, Cheng; Yang, Fu-Min; Ye, Shu-Hua; Zhang, Shu-Lian; Zhang, Yuan-Zhong; Nie, Yuxin; Chen, Guang; Christensen-Dalsgaard, Jørgen; Dittus, Hansjörg; Fujii, Yasunori; Lämmerzahl, Claus; Mangin, Jean François; Peters, Achim; Rüdiger, Albrecht; Samain, Étienne; Schiller, Stephan Bibcode: 2002IJMPD..11.1035N Altcode: Advances in laser physics and its applications triggered the proposition and development of Laser Astrodynamics. Mini-ASTROD is a down-scaled version of ASTROD (Astro-dynamical Space Test of Relativity using Optical Devices). This mission concept has one spacecraft carrying a payload of a telescope, six lasers, and a clock together with ground stations (ODSN: Optical Deep Space Network) to test the optical scheme and yet give important scientific results. These scientific results include a better measurement of the relativistic parameters (γ to 1 ppm, β to a few ppm and others with improvement), a better sensitivity (several times better) in using the optical Doppler tracking method for detecting gravitational waves, a potential of measuring the solar angular momentum via the Lense-Thirring effect and measurement of many solar system parameters more precisely. These enable us to build a more precise ephemeris and astrodynamics. The weight of this spacecraft is estimated to be about 300-350 kg with a payload of about 100-120 kg. The spacecraft goes into an inner solar orbit with several options. One option is with period 304 days as for the inner spacecraft of the standard two-spacecraft ASTROD mission concept and it takes about 900 days to reach the other side of the Sum relative to the Earth. Another option is to launch with initial period about 290 days and to pass by Venus twice to receive gravity-assistance for achieving shorter periods. For a launch on November 15, 2008, after two encounters with Venus, the orbital period can be shortened to 165 days. After about 400 days from launch, the spacecraft will arrive at the other side of the Sun and the relativistic parameter γ can be determined to 1 ppm. We discuss the payload configuration and outlook for technological developments to reach the mission goals, and summarize the conclusions and recommendations of the first and second organizational meeting for the Mini-ASTROD study. Title: SOLA inversions for the core structure of solar-type stars Authors: Basu, S.; Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 2002ESASP.485..249B Altcode: 2002sshp.conf..249B; 2001astro.ph.10446B The Subtractive Optimally Localized Averages (SOLA) method, developed and extensively used in helioseismology, is applied to artificial data to obtain measures of the sound speed inside a solar-type star. In contrast to inversion methods which fit models to some aspect of the data, methods such as SOLA provide an honest assessment of what can truly be resolved using seismic data, without introducing additional assumptions such as that the space of admissible stellar models is small. The resulting measures obtained from SOLA inversion can subsequently be used to eliminate putative stellar models. Here we present results of experiments to test the reliability of SOLA inferences using solar models and models of solar-type stars. Title: On inverting asteroseismic data Authors: Thompson, M. J.; Christensen-Dalsgaard, J. Bibcode: 2002ESASP.485...95T Altcode: 2002sshp.conf...95T; 2001astro.ph.10447T Some issues of inverting asteroseismic frequency data are discussed, including the use of model calibration and linearized inversion. An illustrative inversion of artificial data for solar-type stars, using least-squares fitting of a small set of basis functions, is presented. A few details of kernel construction are also given. Title: Asteroseismic inference for solar-type stars Authors: Monteiro, M. J. P. F. G.; Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 2002ESASP.485..291M Altcode: 2001astro.ph.10445M; 2002sshp.conf..291M The oscillation spectra of solar-type stars may in the not-too-distant future be used to constrain certain properties of the stars. The C-D diagram of large versus small frequency separations is one of the powerful tools available to infer the properties - including perhaps masses and ages - of stars which display a detectable spectrum of oscillation. Also, the border of a convective region in a solar-type star gives rise to a characteristic periodic signal in the star's low-degree p-mode frequencies. Such a signature contains information about the location and nature of the transition between convective and non-convective regions in the star. In this work we address some of the uncertainties associated with the direct use of the C-D diagram to evaluate the mass and age of the star due to the unknown contributions that make the stars different from the evolutionary models used to construct our reference grid. We also explore the possibility of combining an amplitude versus period diagram with the C-D diagram to evaluate the properties of convective borders within solar-type stars. Title: MONS on the Danish Rømer satellite: measuring oscillations in nearby stars Authors: Christensen-Dalsgaard, J. Bibcode: 2002ESASP.485...25C Altcode: 2002sshp.conf...25C; 2001astro.ph.10444C MONS (for Measuring Oscillations in Nearby Stars) is the scientific project on the Danish Rømer satellite mission, which is being developed as part of the Danish Small Satellite Programme. The principal goal is to study solar-like oscillations in around 20 bright stars, with a precision that in the best cases will be limited only by the intrinsic stellar "noise". The baseline orbit, a so-called Molniya orbit, allows access to essentially the entire sky during the planned 2-year mission. The main instrument is a short-focus reflecting telescope with an aperture of 32 cm, making two-colour measurements. A focused Field Monitor will be used to detect and correct for possible faint variable stars of substantial amplitude near the main target. In addition the Field Monitor, and the Star Trackers on the platform, may be used to observe a broad range of variable phenomena. The project has concluded the Systems Definition Phase by a successful review, and launch is scheduled for the middle of 2005. Title: Stellar Evolution Authors: Christensen-Dalsgaard, J. Bibcode: 2002eaa..bookE1879C Altcode: Stars evolve because they lose energy through radiation from their hot surfaces. As a result, there is a general tendency for the star to contract under gravity. This is partly stopped by the release of energy from nuclear reactions. However, once the nuclear fuel is exhausted, gravity gets the upper hand and the star ends its life as a compact object: a white dwarf, a neutron star or a black hol... Title: Applications of Non-Adiabatic Radial Pulsation Equations to roAp Stars Authors: Medupe, R.; Christensen-Dalsgaard, J.; Kurtz, D. W. Bibcode: 2002ASPC..259..296M Altcode: 2002IAUCo.185..296M; 2002rnpp.conf..296M No abstract at ADS Title: An Attempt at Mode Identification for V480 Tau Authors: Di Mauro, M. P.; Christensen-Dalsgaard, J.; Pijpers, F.; Hao, J. Bibcode: 2002ASPC..259..336D Altcode: 2002IAUCo.185..336D; 2002rnpp.conf..336D Spectroscopic observations of the delta Scuti star V480 Tau, obtained during the MUSICOS 1996 campaign (Hao et al. 2001), detected a large number of modes. In order to assess the information available from such data, we compare the observed spectrum of frequencies with the theoretical predictions obtained for models computed by including the effect of fast rotation on global oscillations. Title: Solar-like Oscillations of Semiregular Variables Authors: Christensen-Dalsgaard, J.; Kjeldsen, H.; Mattei, J. A. Bibcode: 2001ApJ...562L.141C Altcode: 2001astro.ph.10475C Oscillations of the Sun and solar-like stars are believed to be excited stochastically by convection near the stellar surface. Theoretical modeling predicts that the resulting amplitude increases rapidly with the luminosity of the star. Thus, one might expect oscillations of substantial amplitudes in red giants with high luminosities and vigorous convection. Here we present evidence that such oscillations may in fact have been detected in the so-called semiregular variables, extensive observations of which have been made by amateur astronomers in the American Association for Variable Star Observers. This may offer a new opportunity for studying the physical processes that give rise to the oscillations, possibly leading to further information about the properties of convection in these stars. Title: Rotation of the solar interior Authors: Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 2001astro.ph.10607C Altcode: Helioseismology has allowed us to infer the rotation in the greater part of the solar interior with high precision and resolution. The results show interesting conflicts with earlier theoretical expectations, indicating that the the Sun is host to complex dynamical phenomena, so far hardly understood. This has important consequences for our ideas about the evolution of stellar rotation, as well as for models for the generation of the solar magnetic field. Here we provide an overview of our current knowledge about solar rotation, much of it obtained from observations from the SOHO spacecraft, and discuss the broader implications. Title: Changes in convective properties over the solar cycle: effect on p-mode damping rates Authors: Houdek, G.; Chaplin, W. J.; Appourchaux, T.; Christensen-Dalsgaard, J.; Däppen, W.; Elsworth, Y.; Gough, D. O.; Isaak, G. R.; New, R.; Rabello-Soares, M. C. Bibcode: 2001MNRAS.327..483H Altcode: Measurements of both solar irradiance and p-mode oscillation frequencies indicate that the structure of the Sun changes with the solar cycle. Balmforth, Gough & Merryfield investigated the effect of symmetrical thermal disturbances on the solar structure and the resulting pulsation frequency changes. They concluded that thermal perturbations alone cannot account for the variations in both irradiance and p-mode frequencies, and that the presence of a magnetic field affecting acoustical propagation is the most likely explanation of the frequency change, in the manner suggested earlier by Gough & Thompson and by Goldreich et al. Numerical simulations of Boussinesq convection in a magnetic field have shown that at high Rayleigh number the magnetic field can modify the preferred horizontal length scale of the convective flow. Here, we investigate the effect of changing the horizontal length scale of convective eddies on the linewidths of the acoustic resonant mode peaks observed in helioseismic power spectra. The turbulent fluxes in these model computations are obtained from a time-dependent, non-local generalization of the mixing-length formalism. The modelled variations are compared with p-mode linewidth changes revealed by the analysis of helioseismic data collected by the Birmingham Solar-Oscillations Network (BiSON); these low-degree (low-l) observations cover the complete falling phase of solar activity cycle 22. The results are also discussed in the light of observations of solar-cycle variations of the horizontal size of granules and with results from 2D simulations by Steffen of convective granules. Title: On the dipolar f mode of stellar oscillation Authors: Christensen-Dalsgaard, J.; Gough, D. O. Bibcode: 2001MNRAS.326.1115C Altcode: The classification of adiabatic modes of non-radial stellar oscillation was established by Cowling in 1941. In addition to acoustic and gravity modes he identified an intermediate mode, which he labelled the f mode, and which in simple stellar models has no radial node. The motion of a dipolar f mode (of spherical-harmonic degree l=1) shifts the centre of mass, and must have zero frequency. On the other hand, if the perturbation to the gravitational potential is neglected (the case considered by Cowling) the f mode has a frequency intermediate between those of the gravity and acoustic modes; this is true of modes of any degree (l>=1). Here we consider the properties of the dipolar f mode, elucidating the origin of these differences through continuous transformations between the various relevant cases; in addition, we discuss the broader issues of the classification of modes of non-radial oscillation. Title: Solar Neutrino Emission Deduced from a Seismic Model Authors: Turck-Chièze, S.; Couvidat, S.; Kosovichev, A. G.; Gabriel, A. H.; Berthomieu, G.; Brun, A. S.; Christensen-Dalsgaard, J.; García, R. A.; Gough, D. O.; Provost, J.; Roca-Cortes, T.; Roxburgh, I. W.; Ulrich, R. K. Bibcode: 2001ApJ...555L..69T Altcode: Three helioseismic instruments on the Solar and Heliospheric Observatory have observed the Sun almost continuously since early 1996. This has led to detailed study of the biases induced by the instruments that measure intensity or Doppler velocity variation. Photospheric turbulence hardly influences the tiny signature of conditions in the energy-generating core in the low-order modes, which are therefore very informative. We use sound-speed and density profiles inferred from GOLF and MDI data including these modes, together with recent improvements to stellar model computations, to build a spherically symmetric seismically adjusted model in agreement with the observations. The model is in hydrostatic and thermal balance and produces the present observed luminosity. In constructing the model, we adopt the best physics available, although we adjust some fundamental ingredients, well within the commonly estimated errors, such as the p-p reaction rate (+1%) and the heavy-element abundance (+3.5%); we also examine the sensitivity of the density profile to the nuclear reaction rates. Then, we deduce the corresponding emitted neutrino fluxes and consequently demonstrate that it is unlikely that the deficit of the neutrino fluxes measured on Earth can be explained by a spherically symmetric classical model without neutrino flavor transitions. Finally, we discuss the limitations of our results and future developments. Title: Imaging an Emerging Active Region with Helioseismic Tomography Authors: Jensen, Jesper Munk; Duvall, Thomas L., Jr.; Jacobsen, Bo Holm; Christensen-Dalsgaard, Jørgen Bibcode: 2001ApJ...553L.193J Altcode: The wave-speed structure beneath an emerging active region is derived from helioseismic time-distance data using inversion techniques developed in geophysics. We use Fresnel zone-based sensitivity kernels along with a Fourier domain-based regularized least-squares inversion technique. The results show that wave-speed anomalies extend down to 20 Mm below active regions. We also see some evidence of deeper anomalies that appear around 16-20 hr after the emergence of an active region and then disappear within 8 hr. These anomalies could be the signature of a change in the subsurface structure of the active region. Title: SX Phœnicis stars in the core of 47 Tucanae Authors: Bruntt, H.; Frandsen, S.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Petersen, J. O.; Guhathakurta, P.; Edmonds, P. D.; Bono, G. Bibcode: 2001A&A...371..614B Altcode: 2001astro.ph..4178B We present new results on five of six known SX Phœnicis stars in the core of the globular cluster 47 Tucanae. We give interpretations of the light curves in the V and I bands from 8.3 days of observations with the Hubble Space Telescope near the core of 47 Tuc. The most evolved SX Phe star in the cluster is a double-mode pulsator (V2) and we determine its mass to be (1.54+/-0.05) Msun from its position in the Hertzsprung-Russell diagram and by comparing observed periods with current theoretical pulsation models. For V14 we do not detect any pulsation signal. For the double-mode pulsators V3, V15, and V16 we cannot give a safe identification of the modes. We also describe the photometric techniques we have used to extract the light curves of stars in the crowded core. Some of the SX Phœnicis are saturated and we demonstrate that even for stars that show signs of a bleeding signal we can obtain a point-to-point accuracy of 1-3%. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy Inc., under NASA contract NAS5-26555. Title: Comparing Global Solar Rotation Results from MDI and GONG Authors: Howe, R.; Komm, R. W.; Hill, F.; Christensen-Dalsgaard, J.; Schou, J.; Thompson, M. J.; Corbard, T. Bibcode: 2001AGUSM..SP31A14H Altcode: The GONG (Global Oscillations Network Group) project and the Solar Oscillations Investigation (SOI) using the Michelson Doppler Imager (MDI) instrument aboard the SOHO spacecraft have jointly accumulated more than five years of data on medium-degree solar p-modes, including nearly four years of contemporaneous observations. The inferences of interior solar rotation from the two projects are broadly consistent and show similar temporal variations, but there are also significant systematic differences. We report here on the results of an ongoing attempt to cross-compare the results and analysis techniques of the two projects. Three 108-day periods, at low, medium and high solar activity epochs, have been analysed, with both MDI and GONG analysis being applied to each data set, and the results are compared. Title: Inversion of Time-Distance Data Using Non-ray-Theoretical Sensitivity Kernels Authors: Jensen, J. M.; Duvall, T. L.; Jacobsen, B. H.; Pijpers, F. P.; Christensen-Dalsgaard, J. Bibcode: 2001AGUSM..SP31A23J Altcode: Inversions of Helioseismic Time-Distance data present unique views of the three-dimensional wave-speed variations in the solar interior. It has e.g. become possible to image the subsurface wave-speed structures beneath active regions and thus explore the magnetic activity of the sun in a new way. Since the solar oscillations have long wavelengths compared to the spatial extent of the features we wish to investigate, the ray approximation is inadequate in such imaging. We present inversions of Helioseismic Time-Distance data using non-ray-theoretical sensitivity kernels. The kernels are obtained using the Rytov approximation and have the so-called banana-doughnut shape. They are zero along the raypath and most of the sensitivity is located in an area corresponding to the first Fresnel zone around the ray. For the inversion we use a Fourier-domain based regularized least-squares method. We present results obtained using this inversion procedure, along with averaging kernels and error estimates of the results. We also present first results obtained using a SOLA inversion algorithm. Title: Variations in Rotation Rate Within the Solar Convection Zone From GONG and MDI 1995-2000 Authors: Howe, R.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R. W.; Schou, J.; Thompson, M. J.; Toomre, J. Bibcode: 2001AGUSM..SP31A15H Altcode: Helioseismic measurements with the Michelson Doppler Imager (MDI) instrument aboard SOHO, and complementary measurements from the Global Oscillation Network Group (GONG) project, are revealing changes deep within the Sun as the solar cycle progresses. We will present the latest results based on recent data from both experiments, including flows in the upper part of the convection zone and variations in the rotation rate near its base. Title: Seismology of solar-type stars Authors: Basu, S.; Christensen-Dalsgaard, J.; Monteiro, M. J. P. F. G.; Thompson, M. J. Bibcode: 2001ESASP.464..407B Altcode: 2001soho...10..407B Seismology of solar-type stars other than the Sun becomes a realistic possibly with the upcoming MOST, COROT and MONS missions, and the ESA mission Eddington. We report on the results of experiments with artificial data from models of solar-type stars to assess further what we might learn about the internal structure of such stars. Title: Non-ideal effects on the solar equation of state Authors: Bi, S. L.; di Mauro, M. P.; Christensen-Dalsgaard, J. Bibcode: 2001ESASP.464..499B Altcode: 2001soho...10..499B This paper presents a simple and efficient equation of state which can be used for quick and accurate computation of the thermodynamic functions of partly ionized and weakly coupled plasmas (Bi, Di Mauro and Christensen-Dalsgaard 2000). Based on the free energy minimization method, the improvement of the equation of state includes a detailed account of the physical processes of non-ideal effects consisting of electron degeneracy, Coulomb coupling and pressure ionization. The non-ideal corrections to the equation of state are calculated under solar interior conditions. The result reveals that the contribution is quite significant, and hence modifies the thermodynamic properties of the plasma substantially. Title: Inversion for the solar internal rotation with an adaptive regularization technique Authors: Vorontsov, S. V.; Christensen-Dalsgaard, J.; Schou, J.; Strakhov, V. N.; Thompson, M. J. Bibcode: 2001ESASP.464..559V Altcode: 2001soho...10..559V We report the first preliminary results of applying the adaptive regularization technique (Strakhov and Vorontsov 2000) to the inversion for the solar internal rotation. The 360d SOHO MDI data set with 18-th degree fit to the rotational splittings is used in the 1.5-D and 2-D inversions, and we used the 72d data sets (Schou 1999) to trace the possible variations with solar activity. Title: Comparing mode frequencies from MDI and GONG Authors: Howe, R.; Hill, F.; Basu, S.; Christensen-Dalsgaard, J.; Komm, R. W.; Munk Larsen, R.; Roth, M.; Schou, J.; Thompson, M. J.; Toomre, J. Bibcode: 2001ESASP.464..137H Altcode: 2001soho...10..137H We present results of analyses of MDI and GONG time series covering the same time intervals, and using both the MDI and GONG peakbagging algorithms. We discuss some of the likely causes of differences between the inferred frequencies and frequency splittings. In addition, we consider the effect of these differences on the results of inversions for the solar internal rotation and sound speed. Title: Solar cycle changes in convection zone dynamics from MDI and GONG 1995 - 2000 Authors: Howe, R.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R. W.; Munk Larsen, R.; Schou, J.; Thompson, M. J.; Toomre, J. Bibcode: 2001ESASP.464...19H Altcode: 2001soho...10...19H The combined GONG and MDI medium-degree helioseismic data sets now cover just over 5 years and allow us to probe the changing dynamics of the convection zone in unprecedented detail. Here we present the latest results from both projects, showing the evolution of the migrating zonal flows close to the surface and also changes close to and below the base of the convection zone. Title: Convective overshooting in the evolution and seismology of η Bootis Authors: di Mauro, M. P.; Christensen-Dalsgaard, J. Bibcode: 2001ESASP.464..373D Altcode: 2001soho...10..373D In the near future frequencies of solar-like oscillations will be observed by the several planned space missions, including MONS (Measuring Oscillations in Nearby Stars), which will fly on board the Danish Rømer satellite. In order to assess the information that will be available from such observations, we consider theoretical predictions of the frequency spectrum of oscillations of the star η Bootis, which seems to show solar-type pulsations. We present results obtained by comparing "classical" evolution models with models computed by taking into account overshooting from the convective core. Title: Structure of Procyon A by a Seismological Approach Authors: di Mauro, M. P.; Christensen-Dalsgaard, J. Bibcode: 2001IAUS..203...94D Altcode: The success of helioseismology has spurred investigators to search for similar oscillations in other Sun-like stars and extend this diagnostic technique to become ``asteroseismology''. In anticipation of data that several planned space missions, including MONS satellite (Measuring Oscillations in Nearby Stars), will be soon devoted to provide, we consider the theoretical prediction of the power spectrum of oscillations of Procyon A, which shows solar-type pulsations, comparing models computed by taking into account an overshooting from the convective core, as well as a diffusion of helium and heavy-elements. We also calculate the frequency modification due to a given internal rotational behaviour, in order to examine the potential of asteroseismology to recognize, and with which accuracy, the possible signature of differential rotation. Title: Recent Progress in Asteroseismology Authors: Christensen-Dalsgaard, J. Bibcode: 2001IAUS..203...50C Altcode: Asteroseismology, the study of stellar interiors on the basis of observations of multi-mode stellar oscillations, extends over a large part of the Hertzsprung-Russell diagram. Extensive observational results have been obtained for δ Scuti stars, although the lack of reliable mode identifications has so far precluded the use of the data for detailed investigations. The recently discovered EC14026 stars (or pulsating subdwarf B stars) promise information about the properties of stars on the horizontal branch. Solar-like oscillations, i.e., oscillations excited stochastically by convection, have been tentatively identified in a few cases, including through observations from the WIRE satellite. Promising cases are giant stars, where the expected amplitudes may make ground-based observations of the oscillations relatively straightforward. Major advances can be expected from the upcoming asteroseismic space projects under development or study; the most ambitious of the latter is the Eddington mission, recently proposed to ESA and up for selection later this year. Title: New Inferences on the Sun from High-degree Modes: the External Layers and the Equation of State Authors: di Mauro, M. P.; Christensen-Dalsgaard, J. Bibcode: 2001IAUS..203..177D Altcode: We investigate the structure of the Sun by helioseismic inversion of a set of p-mode frequencies which include new accurate observations of modes with high degree (l < 1000) obtained from MDI instrument flying on board of SOHO satellite. The use of high-degree frequencies highly improves the resolution of the solar structure in the near-surface region, where effects of the equation of state are felt more strongly. In particular, we show the potential of such data to test the solar equation of state and to constrain the solar envelope helium abundance. Title: Interior Solar-Cycle Changes Detected by Helioseismology Authors: Howe, R.; Hill, F.; Komm, R. W.; Christensen-Dalsgaard, J.; Munk Larsen, R.; Schou, J.; Thompson, M. J.; Toomre, J. Bibcode: 2001IAUS..203...40H Altcode: Helioseismic measurements with the MDI instrument aboard SOHO, and complementary measurements from the GONG network, are revealing changes deep within the Sun as the solar cycle progresses. We will present results based on recent data from both experiments, including variations in the rotation rate deep inside the convection zone. Title: On the signature of the solar activity at the base of the convective envelope Authors: Monteiro, M. J. P. F. G.; Christensen-Dalsgaard, J.; Schou, J.; Thompson, M. J. Bibcode: 2001ESASP.464..535M Altcode: 2001soho...10..535M A we approach the solar maximum for the current cycle it is timely to establish what helioseismology can tell us about the internal changes the Sun undergoes as the cycle progresses. In this work we use SOI-MDI data in order to identify changes occurring to the stratification of the Sun at the base of the convective envelope. Both changes with time (averaged over colatitude) and changes over time at different colatitudes are addressed. These are discussed in terms of the changes in the properties of the convection at the base of the envelope in the region where the tachocline is present. Those variations could be attributed to the interaction between convection, rotation and magnetic fields, which must be intrinsically time-dependent phenomena, possibly correlated with the observed changes occurring over the cycle in the envelope up to the surface. Title: Coulomb corrections to the equation of state for a weakly-coupled plasma Authors: Bi, S. L.; Di Mauro, M. P.; Christensen-Dalsgaard, J. Bibcode: 2000A&A...364..157B Altcode: Coulomb corrections to the equation of state of degenerate matter are usually described by Debye-Hückel theory; however, recent studies have considered modifications of thermodynamic quantities which are caused by the interactions of charged particles beyond the Debye-Hückel approximation. Based on the weakly-coupled plasma limit, the formulae for the physical properties of non-ideal effects on the equation of state are derived. The treatment of the non-ideal effects due to Coulomb coupling combines the results of quantum-statistic calculations for the electrons, N-body semianalytic theory for ions, and the extended Debye-Hückel theory with hard-core correction for the electron-ion interaction. The leading Coulomb correction not only can be applied to the weak-coupling region, but also preserves the well-known Debye-Hückel limit at Gamma << 1. We examine the Coulomb correction to the thermodynamic quantities of a weakly coupled and fully ionized plasma. The result reveals that the contribution is quite significant, and hence modifies the thermodynamic properties of the plasma substantially. Title: An improved equation of state under solar interior conditions Authors: Bi, S. L.; Di Mauro, M. P.; Christensen-Dalsgaard, J. Bibcode: 2000A&A...364..879B Altcode: This paper presents a simple and efficient equation of state which can be used for quick and accurate computing of the thermodynamic functions of partly ionized and weakly coupled plasmas. Based on the free energy minimization method, the improvement of the equation of state includes a detailed account of the physical processes of non-ideal effects consisting of electron degeneracy, Coulomb coupling and pressure ionization. The treatment of Coulomb coupling combines the results of the quantum exchange effect of degenerate electrons at finite temperature, N-body semi-analytic theory and the extended Debye-Hückel theory with hard-sphere correction. For the complicated physical processes of pressure ionization an approximate model is adopted. The nonideal corrections to equation of state are calculated under solar interior conditions. Title: Helioseismology: Theory Authors: Christensen-Dalsgaard, J. Bibcode: 2000eaa..bookE2249C Altcode: Observations have shown that the solar surface is in a state of continual oscillation, involving a very large number of different modes (see HELIOSEISMIC OBSERVATIONS). The observed frequencies depend in a relatively simple manner on the structure and rotation of the solar interior. To use this information to probe the Sun we need to understand how the properties of the oscillations reflect cond... Title: Nuclei in the Cosmos 2000 Authors: Christensen-Dalsgaard, Jørgen; Langanke, Karlheinz Bibcode: 2000PASP..112.1514C Altcode: Conference was held in Århus, Denmark, in 2000 June. Proceedings will be edited by J. Christensen-Dalsgaard and K. Langanke and published as a regular volume in Nuclear Physics A. Title: The effect of diffusion on pulsations of stars on the upper main sequence --- δ Scuti and metallic A stars Authors: Turcotte, S.; Richer, J.; Michaud, G.; Christensen-Dalsgaard, J. Bibcode: 2000A&A...360..603T Altcode: 2000astro.ph..6272T Recent dramatic improvements in the modeling of abundance evolution due to diffusion in A stars have been achieved with the help of monochromatic opacity tables from the OPAL group. An important result in the context of stellar pulsations is the substantial helium abundance shown to be left over in the driving region of δ Scuti-type pulsations in chemically peculiar Am stars. An accurate opacity profile in the entire stellar envelope including the full effect of heavy elements is also now available for the first time. Pulsations are shown to be excluded for young Am stars but occur naturally when these stars evolve off the ZAMS. The predicted variable metallic A stars all lie towards the red edge of the instability strip, in qualitative agreement with the observed variable δ Delphini and mild Am stars. Results show little direct excitation from iron-peak elements in A-type stars. The main abundance effect is due to the settling of helium, along with a marginal effect due to the enhancement of hydrogen. Title: Seismic study of stellar convective regions: the base of the convective envelope in low-mass stars Authors: Monteiro, Mário J. P. F. G.; Christensen-Dalsgaard, Jørgen; Thompson, Michael J. Bibcode: 2000MNRAS.316..165M Altcode: The possibility of observing solar-type oscillations on other stars is of great relevance to investigating the uncertain aspects of the internal structure of stars. One of these aspects is the convective overshoot that takes place at the borders of the envelopes of stars of mass similar to, or lower than, the Sun. It affects the temperature stratification, mixing, rotation and magnetic-field generation. Asteroseismology can provide an observational test for the studies of the structure of such overshoot regions. The seismic study of the transition in the Sun, located at the base of the convection zone, has been successful in determining the characteristics of this layer in the Sun. In this work we consider the extension of the analysis to other solar-type stars (of mass between 0.85 and 1.2Msolar) in order to establish a method for determining the characteristics of their convective envelopes. In particular, we hope to be able to establish seismologically that a star does indeed possess a convective envelope, to measure the size of the convective region and also to constrain the properties of an overshoot layer at the bottom of the envelope. The limitations in terms of observational uncertainties and stellar characteristics, and the detectability of an overshoot layer, are discussed. Title: Structure of the Solar Core: Effect of Asymmetry of Peak Profiles Authors: Basu, S.; Turck-Chièze, S.; Berthomieu, G.; Brun, A. S.; Corbard, T.; Gonczi, G.; Christensen-Dalsgaard, J.; Provost, J.; Thiery, S.; Gabriel, A. H.; Boumier, P. Bibcode: 2000ApJ...535.1078B Altcode: 2000astro.ph..1208B Recent studies have established that peaks in solar oscillation power spectra are not Lorentzian in shape but have a distinct asymmetry. Fitting a symmetric Lorentzian profile to the peaks, therefore, produces a shift in frequency of the modes. Accurate determination of low-frequency modes is essential to infer the structure of the solar core by inversion of the mode frequencies. In this paper we investigate how the changes in frequencies of low-degree modes obtained by fitting symmetric and asymmetric peak profiles change the inferred properties of the solar core. We use data obtained by the Global Oscillations at Low Frequencies (GOLF) project on board the SOHO spacecraft. Two different solar models and inversion procedures are used to invert the data in order to determine the sound speed in the solar core. We find that for a given set of modes no significant difference in the inferred sound speed results from taking asymmetry into account when fitting the low-degree modes. Title: Solar-Cycle Changes in Convection-Zone Dynamics from SOI and GONG Data Authors: Howe, R.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R. W.; Larsen, R. M.; Schou, J.; Thompson, M. J.; Toomre, J. Bibcode: 2000SPD....31.0113H Altcode: 2000BAAS...32..803H The combined GONG and MDI medium-degree helioseismic data sets now cover more than 4.5 years and allow us to probe the changing dynamics of the convection zone in unprecedented detail. Here we present the latest results from both projects, showing the evolution of the migrating zonal flows close to the surface and also changes close to and below the base of the convection zone. This work utilizes data obtained by the Global Oscillation Network Group (GONG) project, managed by the National Solar Observatory, a Division of the National Optical Astronomy Observatories, which is operated by AURA, Inc. under a cooperative agreement with the National Science Foundation. SOHO is a joint project of ESA and NASA. Title: The potential of solar high-degree modes for structure inversion Authors: Rabello-Soares, M. C.; Basu, Sarbani; Christensen-Dalsgaard, J.; Di Mauro, M. P. Bibcode: 2000SoPh..193..345R Altcode: It is likely that precise and reliable frequencies of high-degree modes will soon be available from the SOI/MDI experiment. Here we examine the ability of such modes (with l>300) to resolve the solar structure in the near-surface region. In particular, we investigate inversions to determine the adiabatic exponent Γ1 as a test of the solar equation of state, as well as the potential of such data to constrain the solar envelope helium abundance. Title: US Mission of Opportunity on MONS Authors: Schou, J.; Scherrer, P. H.; Bogart, R. S.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Buzasi, D. L. Bibcode: 2000mons.proc..123S Altcode: The Measuring Oscillations in Nearby Stars (MONS) Survey Telescope (MONS-ST) is a Mission of Opportunity that will study the interior of a large number of stars using stellar oscillations. MONS-ST will provide additional hardware and/or extend the lifetime of the Danish MONS micro satellite, which has been selected for flight in 2003. The additional hardware provided by MONS-ST will enhance the MONS mission by increasing the number of stars observable and extending the lifetime of the mission. A Guest Investigator program, allowing a number of scientists to propose targets and analyze data, will be part of the mission. Title: Deeply Penetrating Banded Zonal Flows in the Solar Convection Zone Authors: Howe, R.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R. W.; Larsen, R. M.; Schou, J.; Thompson, M. J.; Toomre, J. Bibcode: 2000ApJ...533L.163H Altcode: 2000astro.ph..3121H Helioseismic observations have detected small temporal variations of the rotation rate below the solar surface that correspond to the so-called ``torsional oscillations'' known from Doppler measurements of the surface. These appear as bands of slower- and faster-than-average rotation moving equatorward. Here we establish, using complementary helioseismic observations over 4 yr from the GONG network and from the MDI instrument on board SOHO, that the banded flows are not merely a near-surface phenomenon: rather, they extend downward at least 60 Mm (some 8% of the total solar radius) and thus are evident over a significant fraction of the nearly 200 Mm depth of the solar convection zone. Title: Eddington: a proposal to ESA for asteroseismology and planet-finding Authors: Favata, F.; Roxburgh, I.; Christensen-Dalsgaard, J. Bibcode: 2000mons.proc...49F Altcode: Eddington is a proposal to the European Space Agency (ESA) for a moderate-size (d~= 1.2 m), wide-field (Ω >= 6 sq. deg) optical telescope, which will be used for asteroseismic investigations as well as for extra-solar planet finding. The mission has been proposed to ESA in the framework of the F2/F3 mission opportunity and has recently been selected for a study, with a final selection due in September 2000. This paper briefly describes the proposed mission, as well as the current study baseline and organization. Title: Evolution, Seismology and Internal Dynamics of Procyon Authors: di Mauro, M. P.; Christensen-Dalsgaard, J.; Weiss, A. Bibcode: 2000mons.proc..151D Altcode: We consider the theoretical prediction of the power spectrum of oscillations of Procyon A which shows solar-like pulsations. We also calculate the frequency modification due to a given internal rotational behaviour, in order to examine the potential of asteroseismology to recognize, and with which accuracy, the possible signature of differential rotation. Title: Time Variability of Rotation in Solar Convection Zone From soi-mdi Authors: Toomre, J.; Christensen-Dalsgaard, J.; Howe, R.; Larsen, R. M.; Schou, J.; Thompson, M. J. Bibcode: 2000SoPh..192..437T Altcode: The variation of rotation in the convection zone over a period of two years from mid-1996 is studied using inversions of SOI-MDI data. We confirm the existence of near-surface banded zonal flows migrating towards the equator from higher latitudes, and reveal that these banded flows extend substantially beneath the surface, possibly to depths as great as 70 Mm (10% of the solar radius). Our results also reveal apparently significant temporal variations in the rotation rate at high latitudes and in the vicinity of the tachocline over the period of study. Title: Dynamic Variations at the Base of the Solar Convection Zone Authors: Howe, R.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R. W.; Larsen, R. M.; Schou, J.; Thompson, M. J.; Toomre, J. Bibcode: 2000Sci...287.2456H Altcode: We have detected changes in the rotation of the sun near the base of its convective envelope, including a prominent variation with a period of 1.3 years at low latitudes. Such helioseismic probing of the deep solar interior has been enabled by nearly continuous observation of its oscillation modes with two complementary experiments. Inversion of the global-mode frequency splittings reveals that the largest temporal changes in the angular velocity Ω are of the order of 6 nanohertz and occur above and below the tachocline that separates the sun's differentially rotating convection zone (outer 30% by radius) from the nearly uniformly rotating deeper radiative interior beneath. Such changes are most pronounced near the equator and at high latitudes and are a substantial fraction of the average 30-nanohertz difference in Ω with radius across the tachocline at the equator. The results indicate variations of rotation close to the presumed site of the solar dynamo, which may generate the 22-year cycles of magnetic activity. Title: Sensitivity Kernels for Time-Distance Inversion Authors: Jensen, Jesper Munk; Jacobsen, Bo Holm; Christensen-Dalsgaard, Jørgen Bibcode: 2000SoPh..192..231J Altcode: Inversion of local-area helioseismic time-distance data has so far only been done in the ray approximation (Kosovichev, 1996). Since this is a high-frequency approximation its applicability can be questioned for the solar case. Bogdan (1997) showed that for a simple solar model the localized wave packets do follow, but are not confined to, the ray path. We use an approximation based on the first Fresnel zone that has been developed in geophysics by Snieder and Lomax (1996) to go beyond the ray approximation in the inversions. We have calculated sensitivity kernels using both approximations. To test them we use a finite-difference forward modeling of the whole wave field in an acoustic medium reminiscent of the Sun. We use the finite-difference modeling to calculate sensitivity kernels for the full wave field and compare this with the other kernels. The results show that the Fresnel-zone-based kernels are in good agreement with the sensitivity obtained from the modeling. Thus these new kernels represent a significant step forward in the inversion of time-distance data. Title: MONS: Measuring Oscillations in Nearby Stars Authors: Kjeldsen, H.; Bedding, T. R.; Christensen-Dalsgaard, J. Bibcode: 2000ASPC..203...73K Altcode: 2000ilss.conf...73K; 2000IAUCo.176...73K Asteroseismology on δ Scuti stars has until now produced very few convincing results -- if we aim at doing strong tests of details of stellar modelling. The main reason for the lack of success is probably that these stars often rotate, which split nonradial oscillation frequencies into many more frequencies. These many frequencies and the fact that the more evolved δ Scuti stars contain a strong chemical composition gradient at the edge of the convective core, produce a very complicated eigenfrequency spectrum. In contrast to this, we expect, in principle, seismological studies of δ Scuti stars to be a very simple task: One has to compare theoretical oscillations in model stars with the observed oscillations. However, in order to produce convincing asteroseismological results, we need to do three things: (1) Detect as many eigenfrequencies as possible at high precision, (2) identify the eigenmodes and (3) improve the theoretical models. By observing δ Scuti stars in open clusters using CCDs, we have a possibility to improve on (1) and (2) as well as providing an opening for an improvement in the theoretical models by doing accurate calibrations of the basic cluster properties. In this paper I shall describe some of the results from CCD studies of δ Scuti stars in open clusters and identify some future prospects for this technique. Title: Studies of Non-adiabatic Effects on Radial Pulsations in the Atmospheres of Rapidly Oscillating Ap Stars Authors: Medupe, R.; Kurtz, D. W.; Christensen-Dalsgaard, J. Bibcode: 2000ASPC..203..451M Altcode: 2000ilss.conf..451M; 2000IAUCo.176..451M A code for solving non-adiabatic radial pulsation equations with consistent treatment of radiative transfer is used to study the oscillations in the atmospheres of the rapidly oscillating Ap stars. We find that our results are consistent with the presence of an observable node in the temperature eigenfunction. Title: Implications of helioseismology for stellar structure and evolution Authors: Christensen-Dalsgaard, J. Bibcode: 2000ASPC..198...31C Altcode: 2000scac.conf...31C No abstract at ADS Title: An Introduction to Helioseismology Authors: Christensen-Dalsgaard, J.; Däppen, W.; Dziembowski, W. A.; Guzik, J. A. Bibcode: 2000ASIC..544...59C Altcode: 2000vsea.conf...59C No abstract at ADS Title: Basic Aspects of Stellar Structure and Pulsation Authors: Christensen-Dalsgaard, J.; Dziembowski, W. A. Bibcode: 2000ASIC..544....1C Altcode: 2000vsea.conf....1C No abstract at ADS Title: Commission 27: Variable Stars: (Les Etoiles Variables) Authors: Kurtz, D. W.; Christensen-Dalsgaard, J.; Cacciari, C.; Cottrell, P.; Harmanec, P.; Jerzykiewicz, M.; Matthews, J.; Moskalik, P.; Sasselov, D.; Welch, D. Bibcode: 2000IAUTA..24..255K Altcode: No abstract at ADS Title: An Introduction to the Theory of δ Scuti Stars Authors: Christensen-Dalsgaard, J. Bibcode: 2000ASPC..210..187C Altcode: 2000dsrs.conf..187C No abstract at ADS Title: Helioseismic detection of temporal variations of solar rotation rate near the base of the convection zone Authors: Howe, R.; Christensen-Dalsgaard, J.; Hill, F.; Komm, R. W.; Larsen, R. M.; Schou, J.; Thompson, M. J.; Toomre, J. Bibcode: 1999AAS...19510702H Altcode: 1999BAAS...31R1530H The differential rotation of the Sun and its ability to generate large-scale magnetic fields through cyclic dynamo action appear to be intimately linked. It is now commonly thought that the global dynamo behavior responsible for the emergence of active regions is derived from strong organized toroidal magnetic fields generated by rotational shear in a thin region (the tachocline) at the base of the convection zone. The magnetic field could well have a feedback effect on the fluid motions in the region. We are thus motivated to use helioseismology to look for changes in rotation profiles near the tachocline as the Sun's magnetic cycle progresses. This approach has become possible using frequency-splitting data for p- and f-mode oscillations derived over four years (from May 1995 to Sept 1999) of full-disk Doppler observations from the ground-based Global Oscillation Network Group (GONG) project and from the Michelson Doppler Imager (MDI) experiment aboard the SOHO spacecraft. Inversions using two different methods of the splittings from these two independent data sets reveal systematic variations of the rotation rate close to the base of the convection zone, with different behavior at low and high latitudes. Notable are variations of order 6 nHz in rotation rates near the equator, to be compared with the radial angular velocity contrast across the tachocline of about 30 nHz. These exhibit several nearly repetitive changes with a period of about 1.2-1.4 years and appear to be real changes in the deep convection zone and tachocline rotation rates that need to be followed as the solar cycle progresses. The GONG project is managed by the National Solar Observatory, a Division of the National Optical Astronomy Observatories, which is operated by AURA, Inc. under a cooperative agreement with the National Science Foundation. SOHO is a joint project of ESA and NASA. Title: Helioseismic Constraints on the Structure of the Solar Tachocline Authors: Charbonneau, P.; Christensen-Dalsgaard, J.; Henning, R.; Larsen, R. M.; Schou, J.; Thompson, M. J.; Tomczyk, S. Bibcode: 1999ApJ...527..445C Altcode: This paper presents a series of helioseismic inversions aimed at determining with the highest possible confidence and accuracy the structure of the rotational shear layer (the tachocline) located beneath the base of the solar convective envelope. We are particularly interested in identifying features of the inversions that are robust properties of the data, in the sense of not being overly influenced by the choice of analysis methods. Toward this aim we carry out two types of two-dimensional linear inversions, namely Regularized Least-Squares (RLS) and Subtractive Optimally Localized Averages (SOLA), the latter formulated in terms of either the rotation rate or its radial gradient. We also perform nonlinear parametric least-squares fits using a genetic algorithm-based forward modeling technique. The sensitivity of each method is thoroughly tested on synthetic data. The three methods are then used on the LOWL 2 yr frequency-splitting data set. The tachocline is found to have an equatorial thickness of w/Rsolar=0.039+/-0.013 and equatorial central radius rc/Rsolar=0.693+/-0.002. All three techniques also indicate that the tachocline is prolate, with a difference in central radius Δrc/Rsolar~=0.024+/-0.004 between latitude 60° and the equator. Assuming uncorrelated and normally distributed errors, a strictly spherical tachocline can be rejected at the 99% confidence level. No statistically significant variation in tachocline thickness with latitude is found. Implications of these results for hydrodynamical and magnetohydrodynamical models of the solar tachocline are discussed. Title: Rotation of the solar interior Authors: Christensen-Dalsgaard, Jørgen; Thompson, Michael J. Bibcode: 1999CSci...77.1460C Altcode: No abstract at ADS Title: Pulsation models of delta Scuti variables. II. delta Scuti stars as precise distance indicators Authors: Petersen, J. O.; Christensen-Dalsgaard, J. Bibcode: 1999A&A...352..547P Altcode: The Hipparcos period-luminosity relation for high-amplitude delta Scuti stars is discussed as an average period-luminosity-colour-metallicity relation comparing the Hipparcos sample of calibrating stars with a more representative sample taken from McNamara (1997). The Hipparcos relation includes systematic effects of both colour and metallicity and agrees with other period-luminosity relations with an accuracy of about +/- 0.10 mag. Direct stellar-evolution and pulsation modelling is used to study effects on the average period-luminosity relation from the location of the high-amplitude variables within the instability strip given as a range in effective temperature (colour term) and the metallicity given as [Fe/H]. Using accurate data for the instability strip given by McNamara precise agreement with the Hipparcos relation is found. By fitting the bolometric magnitude as a function of pulsation period, effective temperature and metallicity an accuracy of 0.02-0.03 mag is obtained both within the narrow high-amplitude strip and including a much broader strip covering most of the full {delta Sct} instability strip. Problems in practical application of this relation are briefly considered. Using uvbybeta narrow-band photometry it seems possible to obtain this accuracy in determinations of distances to e.g. the Galactic Bulge and the Magellanic Clouds. Title: Amplitudes of stochastically excited oscillations in main-sequence stars Authors: Houdek, G.; Balmforth, N. J.; Christensen-Dalsgaard, J.; Gough, D. O. Bibcode: 1999A&A...351..582H Altcode: 1999astro.ph..9107H We present estimates of the amplitudes of intrinsically stable stochastically excited radial oscillations in stars near the main sequence. The amplitudes are determined by the balance between acoustical energy generation by turbulent convection (the Lighthill mechanism) and linear damping. Convection is treated with a time-dependent, nonlocal, mixing-length model, which includes both convective heat flux and turbulent pressure in both the equilibrium model and the pulsations. Velocity and luminosity amplitudes are computed for stars with masses between 0.9 M_sun and 2.0 M_sun in the vicinity of the main sequence, for various metallicities and convection parameters. As in previous studies, the amplitudes are found to increase with stellar mass, and therefore with luminosity. Amongst those stars that are pulsationally stable, the largest amplitudes are predicted for a 1.6 M_sun model of spectral type F2; the values are approximately 15 times larger than those measured in the Sun. Title: Convective contributions to the frequencies of solar oscillations Authors: Rosenthal, C. S.; Christensen-Dalsgaard, J.; Nordlund, Å.; Stein, R. F.; Trampedach, R. Bibcode: 1999A&A...351..689R Altcode: 1998astro.ph..3206R Differences between observed and theoretical eigenfrequencies of the Sun have characteristics which identify them as arising predominantly from properties of the oscillations in the vicinity of the solar surface: in the super-adiabatic, convective boundary layer and above. These frequency differences may therefore provide useful information about the structure of these regions, precisely where the theory of solar structure is most uncertain. In the present work we use numerical simulations of the outer part of the Sun to quantify the influence of turbulent convection on solar oscillation frequencies. Separating the influence into effects on the mean model and effects on the physics of the modes, we find that the main model effects are due to the turbulent pressure that provides additional support against gravity, and thermal differences between average 3-D models and 1-D models. Surfaces of constant pressure in the visible photosphere are elevated by about 150 km, relative to a standard envelope model. As a result, the turning points of high-frequency modes are raised, while those of the low-frequency modes remain essentially unaffected. The corresponding gradual lowering of the mode frequencies accounts for most of the frequency difference between observations and standard solar models. Additional effects are expected to come primarily from changes in the physics of the modes, in particular from the modulation of the turbulent pressure by the oscillations. Title: Effects of line asymmetries on the determination of solar internal structure Authors: Rabello-Soares, M. C.; Christensen-Dalsgaard, J.; Rosenthal, C. S.; Thompson, M. J. Bibcode: 1999A&A...350..672R Altcode: 1999astro.ph..8250R Despite the strong evidence that the peaks in the spectrum of solar oscillations are asymmetric, most determinations of mode frequencies have been based on fits of symmetric Lorentzian profiles to the Fourier or power spectra of oscillation time strings. The systematic errors resulting from neglecting the line asymmetry could have serious effects on inversions for the solar internal structure and rotation. Here we analyse artificial data based on simple models of the intrinsic line asymmetry, using GONG mode parameters with asymmetries found by one of us (Rosenthal \cite{rosenthal2}). By fitting Lorentzians to the resulting spectra, we estimate the likely properties of the errors introduced in the frequencies. We discuss whether these frequency shifts have a form similar to the near-surface layers uncertainties and are therefore suppressed in the solar structure inversion. We also estimate directly their contribution, if any, in the solar sound-speed and density determinations using the SOLA technique. Title: A note on Saio's estimate of second-order effects of rotation on stellar oscillation frequencies Authors: Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 1999A&A...350..852C Altcode: In many cases, oscillating stars rotate so rapidly that second-order effects must be taken into account in analyses of the oscillation frequencies. Such investigations have commonly been based on results provided by Saio (1981) for a polytropic model. Here we compare those with frequency changes for more realistic models; we point out that a simple correction to Saio's data allows them to be used in the observationally relevant case of comparing models at fixed luminosity and effective temperature. Title: On the choice of parameters in solar-structure inversion Authors: Rabello-Soares, M. C.; Basu, Sarbani; Christensen-Dalsgaard, J. Bibcode: 1999MNRAS.309...35R Altcode: 1999astro.ph..5107R The observed solar p-mode frequencies provide a powerful diagnostic of the internal structure of the Sun and permit us to test in considerable detail the physics used in the theory of stellar structure. Among the most commonly used techniques for inverting such helioseismic data are two implementations of the optimally localized averages (OLA) method, namely the subtractive optimally localized averages (SOLA) and multiplicative optimally localized averages (MOLA). Both are controlled by a number of parameters, the proper choice of which is very important for a reliable inference of the solar internal structure. Here we make a detailed analysis of the influence of each parameter on the solution and indicate how to arrive at an optimal set of parameters for a given data set. Title: Rotation of the solar core from BiSON and LOWL frequency observations Authors: Chaplin, W. J.; Christensen-Dalsgaard, J.; Elsworth, Y.; Howe, R.; Isaak, G. R.; Larsen, R. M.; New, R.; Schou, J.; Thompson, M. J.; Tomczyk, S. Bibcode: 1999MNRAS.308..405C Altcode: Determination of the rotation of the solar core requires very accurate data on splittings for the low-degree modes which penetrate to the core, as well as for modes of higher degree to suppress the contributions from the rest of the Sun to the splittings of the low-degree modes. Here we combine low-degree data based on 32 months of observations with the BiSON network and data from the LOWL instrument. The data are analysed with a technique that specifically aims at obtaining an inference of rotation that is localized to the core. Our analysis provides what we believe is the most stringent constraint to date on the rotation of the deep solar interior. Title: Time-Variability of the Inferred Rotation in the Upper Convection Zone Authors: Toomre, J.; Christensen-Dalsgaard, J.; Howe, R.; Larsen, R. M.; Schou, J.; Thompson, M. J. Bibcode: 1999soho....9E..87T Altcode: We present results of inverting for the rotation of the upper convection zone, using frequency splittings derived from successive 72-day time series of SOI-MDI observations. Schou (1999; also Schou et al. 1998) has studied the evolution of the pattern of small-scale zonal flows in the near-surface layers using f-mode splittings and has found that this flow pattern migrates equatorward in a manner similar to that seen in the so-called torsional oscillation observed in surface Doppler measurements. In the present work we look at the time variability of the rotation at greater depth, in the upper convection zone, by inverting both f- and p-mode splittings. The evolution of the flow is less regular than is seen at the surface, but we do observe apparently significant variations in the inferred flow pattern, on latitudinal scales similar to those seen at the surface. In particular, in the subsurface shear layer we see intriguing variations, with the first year's data showing apparent emergence of zonal flows of some 10-15 m/s amplitude at around 20 degrees latitude. Title: Convective Envelopes in Solar-Type Stars: What Can We Learn from their Seismic Study? Authors: Monteiro, M. J. P. F. G.; Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 1999ASPC..173..273M Altcode: 1999sstt.conf..273M No abstract at ADS Title: The Potential of Solar High-Degree Oscillation Frequencies for Structure Inversion Authors: Rabello-Soares, M. C.; Basu, Sarbani; Christensen-Dalsgaard, J.; di Mauro, M. P. Bibcode: 1999soho....9E..78R Altcode: It is likely that precise and reliable frequencies of high-degree modes will soon be available from the SOI/MDI experiment. Here we examine the ability of such modes (with l > 300) to resolve the solar structure in the near-surface region. In particular, we investigate inversions to determine the adiabatic exponent G1 (Basu & Christensen-Dalsgaard, 1997) as a test of the solar equation of state, as well as the potential of such data to constrain the solar envelope helium abundance. Title: Probing Solar Convection with p-Mode Linewidths Authors: Rabello-Soares, M. C.; Houdek, G.; Christensen-Dalsgaard, J. Bibcode: 1999ASPC..173..301R Altcode: 1999sstt.conf..301R No abstract at ADS Title: On the Location of the Instability Strip Authors: Houdek, G.; Balmforth, N. J.; Christensen-Dalsgaard, J.; Gough, D. O. Bibcode: 1999ASPC..173..317H Altcode: 1999sstt.conf..317H No abstract at ADS Title: Sensitivity Kernels for Time-Distance Inversion Authors: Jensen, J. M.; Jacobsen, B. H.; Christensen-Dalsgaard, J. Bibcode: 1999soho....9E..67J Altcode: Inversion of local area helioseismic Time-Distance data has so far only been done in the ray approximation (Kosovichev 1996). Since this is a high frequency approximation its applicability can be questioned for the solar case. Bogdan (1997) showed that for a simple solar model the sensitivity of the wavepackets do follow the raypath but is not confined to the raypath. We use an approximation based on the first Fresnel zone that has been developed in geophysics by Snieder and Lomax (1996) to go beyond the ray approximation in the inversions. We have calculated sensitivity kernels using both approximation. To test them we used a finite difference forward modelling of the whole wave field in an acoustic medium reminiscent of the sun to calculate synthetic data. These data were inverted using both approximations. We also used the finite difference modelling to calculate sensitivity kernels using the full wave field and compared this to the other kernels. The results show that the Fresnel-zone-based kernels are in good agreement with the sensitivity obtained from the modelling, and also perform well in the inversions. Thus these new kernels represent a significant step forward in the inversion of Time-Distance data. Title: Stellar Evolution with a Variable Mixing-Length Parameter Authors: Trampedach, R.; Stein, R. F.; Christensen-Dalsgaard, J.; Nordlund, Å. Bibcode: 1999ASPC..173..233T Altcode: 1999sstt.conf..233T No abstract at ADS Title: MONS: A Proposal for a Danish Satellite Authors: Kjeldsen, H.; Bedding, T. R.; Frandsen, S.; dall, T. H.; Thomsen, B.; Christensen-Dalsgaard, J.; Clausen, J. V.; Petersen, J. O.; Andersen, M. I. Bibcode: 1999ASPC..173..353K Altcode: 1999sstt.conf..353K No abstract at ADS Title: Probing Convection with Helio- and Asteroseismology Authors: Christensen-Dalsgaard, J. Bibcode: 1999ASPC..173...51C Altcode: 1999sstt.conf...51C No abstract at ADS Title: Probing stellar interiors with MONS Authors: Christensen-Dalsgaard, J. Bibcode: 1998mons.proc...17C Altcode: The MONS satellite, under consideration within the Danish small-satellite programme, aims at carrying out high-precision photometric observations of oscillations of a limited number of relatively bright stars. The primary goal is to study solar-like oscillation in other stars, of expected very low amplitude, but observation of other types of oscillating stars will also be carried out, to attempt to detect very weak modes that may be present. Frequencies and amplitudes of the modes will be used to study the internal properties of the stars and the mechanisms responsible for the oscillations. In this way, a better understanding will be sought of the structure and evolution of the stars, and of the physical processes that controls them. Here I summarize the properties of the relevant stellar oscillations and discuss how these properties may provide information about the stellar interiors. Title: Stellar background power spectra from hydrodynamical simulations of stellar atmospheres Authors: Trampedach, R.; Christensen-Dalsgaard, J.; Nordlund, A.; Stein, R. F. Bibcode: 1998mons.proc...59T Altcode: The non-p-mode contribution to the temporal irradiance or velocity spectra of the Sun has for a long time been considered as noise, but in recent years it has gradually been appreciated as the signal of granulation. Accordingly these spectra are now referred to as background spectra. We hope that further analysis of these background spectra will serve two purposes: to provide information about convection in other stars; and, as the background still constitutes a noise source when looking for p- and in particular g-modes of solar type stars, to provide us with stricter limits as to what is observable. Based on hydrodynamical simulations of convection in the atmospheres of the Sun, alpha Cen A and Procyon, we calculate irradiance and velocity spectra and infer a few properties of these spectra. Due to the limited horizontal extent of the simulations (covering 6-8 granules each) we only get a signal from the granulation, whereas effects of meso- and supergranulation are missing in our signal. At the high-frequency end we are limited by the horizontal resolution of the simulations. Title: Helioseismic Studies of Differential Rotation in the Solar Envelope by the Solar Oscillations Investigation Using the Michelson Doppler Imager Authors: Schou, J.; Antia, H. M.; Basu, S.; Bogart, R. S.; Bush, R. I.; Chitre, S. M.; Christensen-Dalsgaard, J.; Di Mauro, M. P.; Dziembowski, W. A.; Eff-Darwich, A.; Gough, D. O.; Haber, D. A.; Hoeksema, J. T.; Howe, R.; Korzennik, S. G.; Kosovichev, A. G.; Larsen, R. M.; Pijpers, F. P.; Scherrer, P. H.; Sekii, T.; Tarbell, T. D.; Title, A. M.; Thompson, M. J.; Toomre, J. Bibcode: 1998ApJ...505..390S Altcode: The splitting of the frequencies of the global resonant acoustic modes of the Sun by large-scale flows and rotation permits study of the variation of angular velocity Ω with both radius and latitude within the turbulent convection zone and the deeper radiative interior. The nearly uninterrupted Doppler imaging observations, provided by the Solar Oscillations Investigation (SOI) using the Michelson Doppler Imager (MDI) on the Solar and Heliospheric Observatory (SOHO) spacecraft positioned at the L1 Lagrangian point in continuous sunlight, yield oscillation power spectra with very high signal-to-noise ratios that allow frequency splittings to be determined with exceptional accuracy. This paper reports on joint helioseismic analyses of solar rotation in the convection zone and in the outer part of the radiative core. Inversions have been obtained for a medium-l mode set (involving modes of angular degree l extending to about 250) obtained from the first 144 day interval of SOI-MDI observations in 1996. Drawing inferences about the solar internal rotation from the splitting data is a subtle process. By applying more than one inversion technique to the data, we get some indication of what are the more robust and less robust features of our inversion solutions. Here we have used seven different inversion methods. To test the reliability and sensitivity of these methods, we have performed a set of controlled experiments utilizing artificial data. This gives us some confidence in the inferences we can draw from the real solar data. The inversions of SOI-MDI data have confirmed that the decrease of Ω with latitude seen at the surface extends with little radial variation through much of the convection zone, at the base of which is an adjustment layer, called the tachocline, leading to nearly uniform rotation deeper in the radiative interior. A prominent rotational shearing layer in which Ω increases just below the surface is discernible at low to mid latitudes. Using the new data, we have also been able to study the solar rotation closer to the poles than has been achieved in previous investigations. The data have revealed that the angular velocity is distinctly lower at high latitudes than the values previously extrapolated from measurements at lower latitudes based on surface Doppler observations and helioseismology. Furthermore, we have found some evidence near latitudes of 75° of a submerged polar jet which is rotating more rapidly than its immediate surroundings. Superposed on the relatively smooth latitudinal variation in Ω are alternating zonal bands of slightly faster and slower rotation, each extending some 10° to 15° in latitude. These relatively weak banded flows have been followed by inversion to a depth of about 5% of the solar radius and appear to coincide with the evolving pattern of ``torsional oscillations'' reported from earlier surface Doppler studies. Title: Opacity effects on the solar interior. I. Solar structure Authors: Tripathy, S. C.; Christensen-Dalsgaard, J. Bibcode: 1998A&A...337..579T Altcode: 1997astro.ph..9206T Despite recent major advances, the opacity remains an important source of uncertainty in the calculation of solar models, and hence of solar oscillation frequencies. Hence it is of substantial interest to investigate the sensitivity of solar structure to changes in the opacity. Furthermore, we may hope from the precise helioseismic inferences of solar structure to obtain information about possible corrections to the opacities used in the model calculation. Here we carry out detailed calculations of the influence on solar models of changes in the opacity, including also evolutionary effects. We find that over the relevant range the response of the model is approximately linear in the opacity change, allowing the introduction of opacity kernels relating a general opacity change to the corresponding model changes. Changes in the convection zone can be characterized entirely by the change in the initial composition and mixing length required to calibrate the model. Title: Accurate Determination of the Solar Photospheric Radius Authors: Brown, T. M.; Christensen-Dalsgaard, J. Bibcode: 1998ApJ...500L.195B Altcode: 1998astro.ph..3131B The Solar Diameter Monitor measured the duration of solar meridian transits during the 6 years 1981-1987, spanning the declining half of solar cycle 21. We have combined these photoelectric measurements with models of the solar limb-darkening function, deriving a mean value for the solar near-equatorial radius of 695.508+/-0.026 Mm. Annual averages of the radius are identical within the measurement error of +/-0.037 Mm. Title: The 'Standard' Sun Modelling and Helioseismology Authors: Christensen-Dalsgaard, Jørgen Bibcode: 1998SSRv...85...19C Altcode: The ‘standard’ solar model is based on a number of simplifying assumptions and depends on knowledge of the physical properties of matter in the Sun. Given these assumptions, the constraint that the model have the observed surface luminosity provides an estimate of the initial solar helium abundance. From helioseismic analyses further information can be obtained about the present composition, including a fairly precise measure of the envelope helium abundance and an estimate of the hydrogen profile in the radiative interior. It must be emphasized, however, that these inferences may suffer from systematic error arising from incomplete knowledge about the equation of state and opacity of the solar interior. Title: Solar Models with Non-Standard Chemical Composition Authors: Turcotte, S.; Christensen-Dalsgaard, J. Bibcode: 1998SSRv...85..133T Altcode: The OPAL monochromatic opacity tables are used to evaluate the impact of a non-standard chemical composition on solar models. Title: The phase function for stellar acoustic oscillations - IV. Solar-like stars Authors: Perez Hernandez, F.; Christensen-Dalsgaard, J. Bibcode: 1998MNRAS.295..344P Altcode: 1997astro.ph..6062P; 1997astro.ph..6062H In recent years there has been some progress towards detecting solar-like oscillations in stars. The goal of this challenging project is to analyse frequency spectra similar to that observed for the Sun in integrated light. In this context it is important to investigate what can be learned about the structure and evolution of the stars from such future observations. Here we concentrate on the structure of the upper layers, as reflected in the phase function. We show that it is possible to obtain this function from low-degree p modes, at least for stars on the main sequence. We analyse its dependence on several uncertainties in the structure of the uppermost layers. We also investigate a filtered phase function, which has properties that depend on the layers around the second helium ionization zone. Title: The Sun is not severely deficient in heavy elements Authors: Christensen-Dalsgaard, J.; Gough, D. O. Bibcode: 1998Obs...118...25C Altcode: No abstract at ADS Title: Sensitivity of the Sound Speed to the Physical Processes Included in the Standard Solar Model Authors: Turck-Chièze, S.; Basu, S.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Gabriel, M.; Morel, P.; Provost, J.; Turcotte, S.; GOLF Team Bibcode: 1998ESASP.418..555T Altcode: 1998soho....6..555T The accuracy of the present seismic data allows us to check the solar internal sound speed down to the core. This is a great support to check the hypothesis of the classical stellar evolution and to predict the neutrino fluxes. The interpretation of these measurements supposes an accurate determination of the structure of the standard solar model as a first step. It is why a continuing effort has been devoted to the knowledge of the physical quantities included in this framework. In this poster we present 6 different solar models calculated by different groups of the GOLF consortium. These models include the most recent progress in atomic physics and nuclear physics. Then, we discuss the sensitivity of the sound speed difference, between GOLF+MDI observations and models, to different ingredients, in peculiar to the opacity coefficients and the determination of the solar age. Title: Slow Poles and Shearing Flows from Heliospheric Observations with MDI and GONG Spanning a Year Authors: Schou, J.; Christensen-Dalsgaard, J.; Howe, R.; Larsen, R. M.; Thompson, M. J.; Toomre, J. Bibcode: 1998ESASP.418..845S Altcode: 1998soho....6..845S We invert one year of coeval high-resolution rotational splitting data (up to degree l 250) from GONG and SOI-MDI. The first 4 months of MDI data uncovered several new features in the rotation of the solar convective envelope: surface and subsurface zonal bands corresponding to the so-called torsional oscillations, superimposed on the overall smooth latitudinal surface rotation; a drop in the near-polar surface rotation rate below the rate extrapolated from lower latitudes; and an indication of a prograde jet-like feature at high latitudes at a depth of about 5 percent of the solar radius. Using the 1 year of data from the MDI and GONG instruments, we test the robustness and stationarity of these features. As an aid to testing the robustness of our inferences, we use two independent inversion methods (2-D regularized least squares and SOLA) and apply them to the splitting data obtained from both GONG and MDI. Title: Problems, Prospects and Promises of Helio- and Asteroseismology: A Summary of the Workshop Authors: Christensen-Dalsgaard, J. Bibcode: 1998ESASP.418...17C Altcode: 1998soho....6...17C No abstract at ADS Title: Theoretical aspects of asteroseismology Authors: Christensen-Dalsgaard, J. Bibcode: 1998IAUS..185..245C Altcode: Unlike the solar case, seismic investigations of the distant stars must be based on data for modes of relatively low degree. On the other hand, stars display a much broader range of modes than so far observed in the Sun, including g modes in several types of stars. Furthermore, the ability to probe the conditions in a broad range of stars, covering different stellar masses and evolutionary stages, is crucial for tests of stellar evolution theory and information about the properties of stellar interiors. I discuss the properties of the observed or expected oscillations in stars, with special emphasis on the diagnostic potential of the frequencies. In some cases inversion for aspects of the stellar internal rotation and structure might be possible, for example by analyzing a combination of g modes and low-order p modes. However, this requires identification of the modes in the complex spectra of oscillations, which still presents severe problems. Title: Rotation of the Solar Core Inferred from GONG Data Authors: Rabello-Soares, M. C.; Appourchaux, T.; Christensen-Dalsgaard, J. Bibcode: 1998ESASP.418..837R Altcode: 1998soho....6..837R We present inferences of the solar core rotation derived from GONG frequency splittings. The GONG data for the low-degree modes (l <= 6) are for the one year period Aug. 1995-1996; these splittings were determined using a new method of fitting heliosismic spectra (Rabello-Soares & Appourchaux 1998). These are combined with GONG data for higher degree modes, as obtained by the GONG team (Hill et al. 1996). We have employed a new two-dimensional implementation of the optimally localized averages (OLA) inversion method (Chaplin et al. 1998). As in one dimension, the OLA produces better-localized averaging kernels than do least-squares techniques. This is particularly beneficial in the deep interior, where it is in any case difficult to obtain localized information. Title: The Stellar and Planetary Explorer (SPEX) Mission Authors: Schou, J.; Scherrer, P. H.; Brown, T. M.; Frandsen, S.; Horner, S. D.; Korzennik, S. G.; Noyes, R. W.; Tarbell, T. D.; Title, A. M.; Walker, A. B. C., II; Weiss, W. W.; Bogart, R. S.; Bush, R. I.; Christensen-Dalsgaard, J.; Hoeksema, J. T.; Jones, A.; Kjeldsen, H. Bibcode: 1998ESASP.418..401S Altcode: 1998soho....6..401S The Stellar and Planetary Explorer (SPEX) is a mission designed to search for terrestrial sized planets around sun-like stars using precise photometry. The planets will be detected by searching for the decrease in brightness associated with transits of the planets in front of their parent stars. One of the secondary scientific objective of SPEX is to do asteroseismology on a number of sun-like stars. SPEX is designed as a secondary payload on a commercial communications satellite and will have a design life time of three years. We will provide an overview of the SPEX scientific objectives and design, with particular emphasis on the prospects for doing asteroseismology. Title: Seismic Constraints on Sound Speed in the Solar Core Authors: Rabello-Soares, M. C.; Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 1998ESASP.418..511R Altcode: 1998soho....6..511R Direct seismic information about the structure of the solar core from measured p-mode frequencies is based on only a modest number of modes of low degree. Hence it is difficult to obtain local measures of, for example, the variation of the sound speed in the core. However, even averages of the central sound-speed difference between the Sun and a model would be of considerable diagnostic value, provided that these averages could be effectively restricted to a sufficiently small region. Chaplin et al. (1998) developed a technique, based on the method of optimally localized averages introduced by Backus & Gilbert, to construct an average of the rotation of the solar core, and this was applied with some success to combined BiSON and LOWL data. Here we investigate a similar procedure for constructing averages of the sound-speed difference between the Sun and a reference model, localized to the core. These provide seismic constraints on core structure that are only minimally sensitive to uncertainties in other regions of the Sun. Title: Testing the helioseismic determination of opacity corrections Authors: Tripathy, S. C.; Christensen-Dalsgaard, J. Bibcode: 1998BASI...26..163T Altcode: 1997astro.ph..3170T We investigate the effect of localized opacity modifications on the sound-speed profile of solar models. The sound-speed difference between the Sun and a solar model is used to deduce the opacity correction that would be required to bring the model into agreement with the Sun. We test this procedure on artificial data for a pair of solar models and apply it to the solar sound speed as inferred from inversion of LOWL observed frequencies. We show that a solar model constructed with the appropriately modified opacity has a sound-speed profile very similar to that of the Sun. Title: The Base of the Convection Zone and the Solar Magnetic Cycle: Seismic Detection of Their Connection Authors: Monteiro, Mario J. P. F. G.; Christensen-Dalsgaard, Jorgen; Thompson, Michael J. Bibcode: 1998ESASP.418..495M Altcode: 1998soho....6..495M It is now possible to detect small variations with time of the characteristics of the transition at the bottom of the solar convection zone, as determined from the periodic signal in the frequencies (Christensen-Dalsgaard et.al. 1995, Basu 1997). Such measurements may allow us to establish whether and in what manner the deeper convection zone changes with the solar magnetic cycle. This would be important for understanding the dynamics at the base of the convection zone and the origin of the solar cycle. It will also help in understanding the physics of convective overshoot, its interaction with rotation and magnetic fields, and the effects on the stratification. In this work we investigate the limits on the detectability of small changes in the stratification at the base of the convection zone, and attempt to constrain the amplitude of the changes from currently available seismic data. Title: Asteroseismology Authors: Christensen-Dalsgaard, Jørgen Bibcode: 1998Ap&SS.261....1C Altcode: 1999Ap&SS.261....1C No abstract at ADS Title: Implications of Heavy-Element Settling for the Seismology of the αCen System Authors: Turcotte, S.; Christensen-Dalsgaard, J. Bibcode: 1998ESASP.418..407T Altcode: 1998soho....6..407T Oscillation frequencies for calibrated models of α Cen A and B are presented. The models incorporate a consistent treatment of diffusion of He and heavy elements (Turcotte et. al 1998). Previous models have neglected the impact of settling of heavy elements on the evolution of the α Cen stars. Of particular interest is its implications for the evolution of the convective core of α Cen A. Some models are considered in which the extent of the convective overshoot at the core and beneath the surface convective zones are varied to estimate their influence on the models. The oscillation frequencies for α Cen A are examined in particular to verify to what extent they can be of use to help constrain the convective core overshoot. Title: MCD Inversion for Sound Speed using Time-Distance Data Authors: Jensen, J. M.; Jacobsen, B. H.; Christensen--Dalsgaard, J. Bibcode: 1998ESASP.418..635J Altcode: 1998soho....6..635J We present an inversion technique based on a MultiChannel Deconvolution (MCD) algorithm that speeds up the calculations by doing the computational work in the Fourier domain. As a result, inversions can be done in a matter of seconds, even for high-volume data sets such as those from the SOHO satellite. This technique has been developed recently within geophysics for inversion of electromagnetic data. It is based on the Born approximation where one inverts for perturbations around a reference model. Because the reference model has horizontal translational invariance, the forward calculation becomes a convolution of the model with the Frechet kernels, which according to the convolution theorem can be performed as a simple multiplication in the Fourier domain. Also, inverse calculations speed up significantly in the Fourier domain. A reliable inversion requires correct Frechet kernels. These are currently unknown. The Frechet kernels which we have used so far are based on the Gaussian beam concept, which is a step beyond a pure ray approximation. The Fourier transformation implies periodicity. This introduces errors in the inversion near the edges of the area investigated. These errors are of the same order of magnitude as errors introduced by zero padding the data. We will show the details of the MCD technique, examples of resolution kernels and results of inversions performed on helioseismic data. Title: The influence of magnetic fields on radiative damping of magnetoatmospheric oscillations Authors: Banerjee, Dipankar; Hasan, S. S.; Christensen-Dalsgaard, J. Bibcode: 1998IAUS..185..423B Altcode: We examine the non adiabatic effects on the modes of an isothermal stratified magnetic atmosphere. The present investigation is a continuation of earlier work by Banerjee, Hasan & Christensen-Dalsgaard (1995, 1996, 1997), where the interaction of various elementary modes in a stratified magnetised atmosphere was studied in the purely adiabatic limit. The inclusion of radiative dissipation in magnetoatmospheric wave problem - even in the over simplified Newtonian Cooling approximation - is of great importance. Including Newtonian Cooling, in the weak field limit, an analytic expression for the dispersion relation is derived which allows the effect of weak magnetic field on the modes to be studied. We examine the nature of the eigen frequency curves in the diagnostic diagram and find that, similar to the previous analysis, the modes undergo avoided crossings. We study the full frequency spectrum and the interaction amongst various modes. Strong mode coupling in the avoided crossing regions permits energy leakage. Our results, find application in the analysis of waves in flux-tubes on the Sun. We study the influence of magnetoatmospheric waves on spectral line profiles. Title: The 'Standard' Sun Authors: Christensen-Dalsgaard, J. Bibcode: 1998sce..conf...19C Altcode: No abstract at ADS Title: Helioseismology and Solar Neutrinos Authors: Christensen-Dalsgaard, J. Bibcode: 1998tsra.conf..694C Altcode: 1997astro.ph..2094C Helioseismology has provided very precise information about the solar internal sound speed and density throughout most of the solar interior. The results are generally quite close to the properties of standard solar models. Since the solar oscillation frequencies do not provide direct information about temperature and composition, the helioseismic results to not completely rule out an astrophysical solution to the discrepancy between the predicted and measured neutrino fluxes from the Sun. However, such a solution does appear rather implausible. Title: Improved SOLA Inversions of MDI Data Authors: Larsen, R. M.; Christensen-Dalsgaard, J.; Kosovichev, A. G.; Schou, J. Bibcode: 1998ESASP.418..813L Altcode: 1998soho....6..813L We present a new version of 2d-SOLA, where the target functions have been modified to match the behavior of the mode kernels near the rotation axis and to minimize near-surface contributions. Inversion of artificial data show that these modifications significantly improve the effective resolution near the pole, which allows us to assess the reliability of the high-latitude features seen by other inversion methods. Most importantly, our new inversions seem to confirm the detection of a submerged polar jet previously seen in the 2d-RLS inversions reported by Schou et al. 1998. A test of the robustness of the improved method is carried out by inverting artificial data from the MDI Hare and Hounds exercise. We analyze the averaging kernels and error propagation of the method, and also describe the error-correlation between different points in the solution, the latter being a potential source of spurious features in the solutions as pointed out by Howe and Thompson, 1996. So far, helioseismic datasets given in the form of a-coefficients have been inverted under the assumption that the errors in different a-coefficients are uncorrelated. The MDI peak-bagging procedure, however, does produce estimates of the error-correlation between a-coefficients within the same multiplet. Here we investigate the effect of including this knowledge in the inversions. Title: Tests of Convective Frequency Effects with SOI/MDI High-Degree Data Authors: Rosenthal, C. S.; Christensen-Dalsgaard, J.; Kosovichev, A. G.; Nordlund, A. A.; Reiter, J.; Rhodes, E. J., Jr.; Schou, J.; Stein, R. F.; Trampedach, R. Bibcode: 1998ESASP.418..521R Altcode: 1998astro.ph..7066R; 1998soho....6..521R Advances in hydrodynamical simulations have provided new insight into the effects of convection on the frequencies of solar oscillations. As more accurate observations become available, this may lead to an improved understanding of the dynamics of convection and the interaction between convection and pulsation (Rosenthal et al. 1999). Recent high-resolution observations from the SOI/MDI instrument on the SOHO spacecraft have provided the so-far most-detailed observations of high-degree modes of solar oscillations, which are particularly sensitive to the near-surface properties of the Sun. Here we present preliminary results of a comparison between these observations and frequencies computed for models based on realistic simulations of near-surface convection. Such comparisons may be expected to help in identifying the causes for the remaining differences between the observed frequencies and those of solar models. Title: Asteroseismology and Stellar Rotation Authors: Kjeldsen, H.; Arentoft, T.; Bedding, T.; Christensen-Dalsgaard, J.; Frandsen, S.; Thompson, M. J. Bibcode: 1998ESASP.418..385K Altcode: 1998soho....6..385K Δ Scuti stars are observed to rotate with surface velocities of the order 100-200 km/s corresponding to a rotation period of about one day. Rotation removes the frequency degeneracy in the azimuthal order m of the modes and thus allows the possibility of determining the angular velocity inside the star. Rotation also perturbs the internal structure of the star, making the star oblate, as well as changing the internal stratification. Such perturbations will result in a systematic change of all frequencies, if compared with a non-rotating star of similar mass and age. In this way even the radial (l = 0) mode frequencies will be affected by the rotation of the star. We discuss how basic properties as well as frequencies of δ Scuti stars are affected by fast rotation and we investigate the impact of these changes on our interpretation of observed frequencies used in an asteroseismic analysis. We discuss the results in the light of the currently available frequency data for δ Scuti stars in the Praesepe cluster. Title: HIPPARCOS Parallaxes for eta Boo and kappa^1 Boo: Two Successes for Asteroseismology Authors: Bedding, Timothy R.; Kjeldsen, Hans; Christensen-Dalsgaard, Jorgen Bibcode: 1998ASPC..154..741B Altcode: 1998csss...10..741B; 1997astro.ph..9005B The release of the Hipparcos catalogue provides an opportunity to check results from asteroseismology. We discuss two stars: (i) Eta Boo (G subgiant), in which we have previously reported detection of solar-like oscillations; and (ii) Kappa2Boo, a multi-mode Delta Scuti variable. The Hipparcos parallaxes for both stars are in excellent agreement with oscillation results. Title: A Study of the Parameters for Solar Structure Inversion Methods Authors: Rabello-Soares, M. C.; Basu, Sarbani; Christensen-Dalsgaard, J. Bibcode: 1998ESASP.418..505R Altcode: 1998soho....6..505R The observed solar p-mode frequencies provide an extremely useful diagnostic of the internal structure of the Sun, and permit us to test in considerable detail the physics used in the theory of stellar structure. Two implementations of the optimally localized averages (OLA) method are amongst the most commonly used techniques for inverting helioseismic data, namely the Subtractive Optimally Localized Averages (SOLA) and Multiplicative Optimally Localized Averages (MOLA). In both of them, there are a number of parameters that must be chosen in order to find the solution. Proper choice of the parameters is very important to determine correctly the variation of the internal structure along the solar radius. In this work, we make a detailed analysis on the influence of each parameter on the solution and indicate how to arrive at an optimal set of parameters for a given data set. Title: Turbulence in Astrophysics: Stars Authors: Canuto, V. M.; Christensen-Dalsgaard, J. Bibcode: 1998AnRFM..30..167C Altcode: Turbulence is ubiquitous in astrophysics, ranging from cosmology, interstellar medium to stars, supernovae, accretion disks, etc. Large scales and small viscosities combine to form large Reynolds numbers. Because it is not possible in a single article to review all the above scenarios, we limit ourselves to stars, in which thermal instabilities give rise to turbulent convection as the dominant heat transport mechanism. (Accretion disks, where shear instabilities dominate the outward transport of angular momentum, will be the subject of a second article, planned for Volume 31.) Because of the lack of a satisfactory theory, turbulence constitutes a bottleneck that prevents astrophysical models from being fully predictive. Because continued use of phenomenological turbulence expressions would make astrophysical models perennially unpredictive, a way must be found to make astrophysical models as prognostic as possible. In addition to the difficulties brought about by turbulence, astrophysical settings introduce "malicious conditions," of which the most refractory to a satisfactory quantification are compressibility (caused by the large density excursions that characterize convective zones in stars) and rotation. Basic understanding of how they affect turbulence in general is still rather sketchy. Reasons for the choice of stars and accretion disks as prototype examples are the following: The underlying instabilities are very basic; laboratory and direct numerical simulations data help constrain theoretical models; and new observational data, especially from helioseismology, help discriminate among different models with unprecedented accuracy. Title: Effects of Line Asymmetries on the Determination of Solar Oscillation Frequencies Authors: Christensen-Dalsgaard, J.; Rabello-Soares, M. C.; Rosenthal, C. S.; Thompson, M. J. Bibcode: 1998ESASP.418..147C Altcode: 1998soho....6..147C Despite the strong evidence that the peaks in the spectrum of solar oscillations are asymmetric, most determinations of mode frequencies have been based on fits of symmetric Lorentzian profiles to the Fourier or power spectra of oscillation time strings. The systematic errors resulting from neglecting the line asymmetry could have serious effects on inversions for the solar internal structure and rotation. Here we analyze artificial data based on simple models of the intrinsic line asymmetry. By fitting Lorentzians to the resulting spectra, we estimate the likely properties of the errors introduced in the frequencies and consider the possible effects on the inversions. Title: Seismic detection of boundaries of stellar convective regions Authors: Monteiro, M. J. P. F. G.; Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 1998IAUS..185..315M Altcode: The seismic study of the base of the convection zone in the Sun (eg Christensen-Dalsgaard et al 1995, MNRAS 276, 283) has been successful in determining not only the position of the base of the convective envelope, but also the characteristics of this transition layer. In this poster we consider other types of star possessing convective envelopes or cores and seek to establish the conditions under which we may determine important characteristics of their convective regions. In particular we may hope to establish seismologically that a star does indeed posess a convective envelope or core and to measure the size of that convective region. The method used consists in identifying a signal in the observed frequencies whose characteristics depend on the location of the border of a convective region in the star. The limitations in terms of observational uncertainties and stellar characteristics are presented. Title: New eyes to see inside the sun and stars : pushing the limits of helio- and asteroseismology with new observations from the ground and from space Authors: Deubner, Franz-Ludwig; Christensen-Dalsgaard, Joergen; Kurtz, Don Bibcode: 1998IAUS..185.....D Altcode: No abstract at ADS Title: Detection of the Lower Boundary of Stellar Convective Envelopes from Seismic Data Authors: Monteiro, Mário J. P. F. G.; Christensen-Dalsgaard, Jørgen; Thompson, Michael J. Bibcode: 1998Ap&SS.261...41M Altcode: 1999Ap&SS.261...41M No abstract at ADS Title: Solar Models with Non-Standard Chemical Composition Authors: Turcotte, S.; Christensen-Dalsgaard, J. Bibcode: 1998sce..conf..133T Altcode: No abstract at ADS Title: Diagnostic Potential of the Solar f Modes Authors: Chitre, S. M.; Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 1998ESASP.418..141C Altcode: 1998soho....6..141C The frequencies of f modes of intermediate and high degree l of a stellar model in hydrostatic equilibrium are essentially given by ω = square root {g kh}, where to a good first approximation g is the surface gravitational acceleration G M / R2 and kh = square root {l(l+1)}/R, M and R being the mass and radius respectively of the model. More precisely, the frequency is determined not simply by the surface values of these quantities but by a weighted average over the region where the mode has appreciable amplitude. Thus the frequencies of the f modes depend on the density stratification in the near-surface region (Gough 1985, 1993). Given the very high accuracy to which the f-mode frequencies can now be determined, in particular from the SOI/MDI experiment on SOHO, this sensitivity may provide an important diagnostic of the Sun's near-surface structure. We investigate this sensitivity, in terms of numerical kernels and the simple analytical approximation derived by Gough. In addition, we consider the possibilities for investigating time variations and asphericity in solar structure on the basis of f-mode observations. Title: The Problem of Mode Identification in roAp Stars: Multi-Colour Photometry Authors: Medupe, R.; Kurtz, D. W.; Christensen-Dalsgaard, J. Bibcode: 1998ASPC..135..197M Altcode: 1998hcsp.conf..197M Dziembowski (1977) proposed a modified Baade-Wesselink method for mode identification in a non-radially pulsating star with a well determined radius. Balona & Stobie (1979) recast this technique in an observationally feasible form, and applied it to some stars. This technique works for b Cephei, 53 Persei, d Scuti, Cepheid and ZZ Ceti variables, but does not work for rapidly oscillating Ap (roAp) stars. Here we outline the problem of mode identification in roAp stars and show how we shall attempt to solve it. We also apply the linearised expression (as in Watson 1988), for non-radial light variation, combined with the latest model atmospheres of roAp stars to the light and colour variation data to show the effect of improved model atmospheres on the Baade-Wesselink method and other mode discrimination techniques. Title: The SOI-MDI High-Latitude Jet: the Evidence For and Against Authors: Howe, R.; Antia, H.; Basu, S.; Christensen-Dalsgaard, J.; Korzennik, S. G.; Schou, J.; Thompson, M. J. Bibcode: 1998ESASP.418..803H Altcode: 1998soho....6..803H The apparent detection of a prograde jet at latitude 75-circ and at a radius of about 0.95Rodot in some inversions of rotation data from SOI--MDI (Schou et al., 1998) has excited considerable interest, but whether the jet really exists in the solar interior is certainly not yet firmly established. The detection of the feature is sensitive both to the inversion techniques used and to the methods of mode parameter estimation used to generate the input data. In particular, the feature is much more apparent in Regularized Least-Squares inversions than in inversions using an Optimally Localized Average approach, and is not detected at all in the present GONG data when analysed with the GONG peakfinding algorithm, or indeed in SOI data when analysed with the GONG algorithm. Therefore in this poster we examine critically the current evidence for the source and existence of this jet in the light of forward and inverse analyses. Title: The Effect of Differential Settling and of Revised Abundances on Solar Oscillation Frequencies Authors: Turcotte, S.; Christensen--Dalsgaard, J. Bibcode: 1998ESASP.418..561T Altcode: 1998soho....6..561T The effect of including consistent diffusion of heavy elements on the predicted solar oscillation frequencies is investigated. The models are calculated using the OPAL monochromatic opacities and include the effect of differential settling of all the elements included in their database (Turcotte et. al, 1998). The impact of the newly proposed reduction of photospheric CNO abundances by 10% (Grevesse & Sauval, 1998) on the structure and oscillation frequencies is also investigated. Title: Near-surface constraints on the structure of stellar convection zones Authors: Trampedach, R.; Christensen-Dalsgaard, J.; Nordlund, A.; Stein, R. Bibcode: 1997ASSL..225...73T Altcode: 1997scor.proc...73T By simulating the convection in the upper layers of six different stars and matching these simulations to 1D-mixing length models using the same input physics, we have been able to infer the behaviour of the mixing-length parameter, $\alpha$, as the stellar parameters changes. Title: Solar internal sound speed as inferred from combined BiSON and LOWL oscillation frequencies Authors: Basu, Sarbani; Christensen-Dalsgaard, J.; Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; New, R.; Schou, J.; Thompson, M. J.; Tomczyk, S. Bibcode: 1997MNRAS.292..243B Altcode: 1997astro.ph..2105B Observations of the Sun with the LOWL instrument provide a homogeneous set of solar p-mode frequencies from low to intermediate degree that allow one to determine the structure of much of the solar interior avoiding systematic errors that are introduced when different data sets are combined, i.e., principally the effects of solar cycle changes on the frequencies. Unfortunately, the LOWL data set contains very few of the lowest-degree modes, which are essential for determining reliably the structure of the solar core - in addition, these lowest-degree data have fairly large associated uncertainties. However, observations made by the Birmingham Solar-Oscillations Network (BiSON) in integrated sunlight provide high-accuracy measurements of a large number of low-degree modes. In this paper we demonstrate that the low-degree mode set of the LOWL data can be successfully combined with the more accurate BiSON data, provided the observations are contemporaneous for those frequencies where the solar cycle induced effects are important. We show that this leads to a factor of 2 decrease in the error on the inferred sound speed in the solar core. We find that the solar sound speed is higher than in solar models for r<0.2Rsolar. The density of the solar core is, however, lower than that in solar models. Title: Rotation and Zonal Flows in the Solar Envelope from the SOHO/MDI Observations Authors: Scherrer, P. H.; Schou, J.; Bogart, R. S.; Bush, R. I.; Hoeksema, J. T.; Kosovichev, A. G.; Antia, H. M.; Chitre, S. M.; Christensen-Dalsgaard, J.; Larsen, R. M.; Pijpers, F. P.; Eff-Darwich, A.; Korzennik, S. G.; Gough, D. O.; Sekii, T.; Howe, R.; Tarbell, T.; Title, A. M.; Thompson, M. J.; Toomre, J. Bibcode: 1997AAS...191.7310S Altcode: 1997BAAS...29.1322S We report on the latest inferences concerning solar differential rotation that have been drawn from the helioseismic data that are now available from the Solar Oscillations Investigation (SOI) using the Michelson Doppler Imager (MDI) on the Solar and Heliospheric Observatory (SOHO). That spacecraft is positioned in a halo orbit near the Sun-Earth Lagrangian point L_1, in order to obtain continuous Doppler-imaged observations of the sun with high spatial fidelity. Doppler velocity, intensity and magnetic field images are recorded, based on modulations of the 676.8 nm Ni I solar absorption line. The high spatial resolution of MDI thereby permits the study of many millions of global resonant modes of solar oscillation. Determination and subsequent inversion of the frequencies of these modes, including the degeneracy-splitting by the rotation of the sun, enables us to infer how the sun's angular velocity varies throughout much of the interior. The current MDI data are providing substantial refinements to the helioseismic deductions that can be made about differential rotation both within the convection zone and in its transition to the radiative interior. The shearing layer evident in the angular velocity Omega just below the solar surface is becoming better defined, as is the adjustment layer or tachocline near the base of the convection zone. The MDI data are also revealing a prominent decrease in Omega at high latitudes from the rotation rate expressed by a simple three-term expansion in latitude that was originally deduced from surface Doppler measurements. Further, there are indications that a submerged polar vortex involving somewhat faster Omega than its surroundings exists at about 75(deg) in latitudes. Title: The influence of radiative damping on the modes of a magnetized isothermal atmosphere Authors: Banerjee, D.; Hasan, S. S.; Christensen-Dalsgaard, J. Bibcode: 1997ASSL..225..277B Altcode: 1997scor.proc..277B We examine the influence of radiative damping on the modes of an isothermal magnetized plasma. This investigation is an extension of earlier work by Hasan \& Christensen-Dalsgaard (1992) and Banerjee, Hasan \& Christensen-Dalsgaard (1995, 1996), which treated the effects of a uniform vertical magnetic field on the adiabatic modes of a stratified atmosphere. We focus on the properties of the Lamb mode and examine its interaction with a magnetic mode. We show that radiative dissipation can significantly alter the Lamb-mode frequency and lead to a enhanced damping of the waves at the avoided crossings in the $k-\omega$ diagram. This mechanism could be important for wave damping in flux tubes on the Sun. Title: Effects of convection on the mean solar structure Authors: Christensen-Dalsgaard, J. Bibcode: 1997ASSL..225....3C Altcode: 1997astro.ph..2104C; 1997scor.proc....3C The overall framework for the study of solar convection and oscillations is the spherically symmetric component of solar structure. I discuss those properties of the solar interior which depend on convection and other possible hydrodynamical motion and the increasingly detailed information about the structure which is provided by helioseismic data. The most basic dependence of solar models on convection is the calibration to fix the solar radius. The dominant causes for differences in oscillation frequencies between the Sun and solar models seem to be located near the top of the convection zone. However, there is also evidence for possible weak mixing below the convection zone and perhaps in the solar core. The former, at least, might be induced by penetration of convective motion into the stable layers below. Title: SCORe'96 : Solar Convection and Oscillations and their Relationship Authors: Pijpers, F. P.; Christensen-Dalsgaard, J.; Rosenthal, C. S. Bibcode: 1997ASSL..225.....P Altcode: 1997scor.proc.....P No abstract at ADS Title: First View of the Solar Core from GOLF Acoustic Modes Authors: Turck-Chièze, S.; Basu, S.; Brun, A. S.; Christensen-Dalsgaard, J.; Eff-Darwich, A.; Lopes, I.; Pérez Hernández, F.; Berthomieu, G.; Provost, J.; Ulrich, R. K.; Baudin, F.; Boumier, P.; Charra, J.; Gabriel, A. H.; Garcia, R. A.; Grec, G.; Renaud, C.; Robillot, J. M.; Roca Cortés, T. Bibcode: 1997SoPh..175..247T Altcode: After 8 months of nearly continuous measurements the GOLF instrument, aboard SOHO, has detected acoustic mode frequencies of more than 100 modes, extending from 1.4 mHz to 4.9 mHz. In this paper, we compare these results with the best available predictions coming from solar models. To verify the quality of the data, we examine the asymptotic seismic parameters; this confirms the improvements achieved in solar models during the last decade. Title: Performance and Early Results from the GOLF Instrument Flown on the SOHO Mission Authors: Gabriel, A. H.; Charra, J.; Grec, G.; Robillot, J. -M.; Roca Cortés, T.; Turck-Chièze, S.; Ulrich, R.; Basu, S.; Baudin, F.; Bertello, L.; Boumier, P.; Charra, M.; Christensen-Dalsgaard, J.; Decaudin, M.; Dzitko, H.; Foglizzo, T.; Fossat, E.; García, R. A.; Herreros, J. M.; Lazrek, M.; Pallé, P. L.; Pétrou, N.; Renaud, C.; Régulo, C. Bibcode: 1997SoPh..175..207G Altcode: GOLF in-flight commissioning and calibration was carried out during the first four months, most of which represented the cruise phase of SOHO towards its final L1 orbit. The initial performance of GOLF is shown to be within the design specification, for the entire instrument as well as for the separate sub-systems. Malfunctioning of the polarising mechanisms after 3 to 4 months operation has led to the adoption of an unplanned operating sequence in which these mechanisms are no longer used. This mode, which measures only the blue wing of the solar sodium lines, detracts little from the detection and frequency measurements of global oscillations, but does make more difficult the absolute velocity calibration, which is currently of the order of 20%. Data continuity in the new mode is extremely high and the instrument is producing exceptionally noise-free p-mode spectra. The data set is particularly well suited to the study of effects due to the excitation mechanism of the modes, leading to temporal variations in their amplitudes. The g modes have not yet been detected in this limited data set. In the present mode of operation, there are no indications of any degradation which would limit the use of GOLF for up to 6 years or more. Title: Equation of state and helioseismic inversions. Authors: Basu, S.; Christensen-Dalsgaard, J. Bibcode: 1997A&A...322L...5B Altcode: 1997astro.ph..2162B Inversions to determine the squared isothermal sound speed and density within the Sun often use the helium abundance Y as the second parameter. This requires the explicit use of the equation of state (EOS), thus potentially leading to systematic errors in the results if the equations of state of the reference model and the Sun are not the same. We demonstrate how this potential error can be suppressed. We also show that it is possible to invert for the intrinsic difference in the adiabatic exponent {GAMMA}_1_ between two equations of state. When applied to solar data such inversion rules out the EFF equation of state completely, while with existing data it is difficult to distinguish between other equations of state. Title: Effect of Newtonian Cooling on Waves in a Magnetized Isothermal Atmosphere Authors: Banerjee, Dipankar; Hasan, S. S.; Christensen-Dalsgaard, J. Bibcode: 1997SoPh..172...53B Altcode: 1997ESPM....8...53B We examine the influence of nonadiabatic effects on the modes of an isothermal stratified magnetic atmosphere. The present investigation is a continuation of earlier work by Hasan and Christensen-Dalsgaard (1992) and Banerjee, Hasan, and Christensen-Dalsgaard (1995, 1996), where the interaction of various elementary modes in a stratified magnetized atmosphere was studied in the purely adiabatic limit. The inclusion of radiative dissipation based on Newton's law of cooling demonstrates the importance of this effect in the study of magnetoatmospheric waves. We analyze the physical nature of magnetoacoustic gravity (or MAG) oscillations in the presence of Newtonian cooling and find that the eigenfrequency curves in the diagnostic diagram, as in the previous analysis, undergo avoided crossings. However, the qualitative nature of the mode interaction is strongly influenced by radiative dissipation, which leads to strong mode damping in the avoided-crossing regions. We demonstrate this effect for the interaction between the Lamb mode and a magnetic mode. Our results could be important in the analysis of waves in flux tubes on the Sun. Title: SVD preprocessing of helioseismic data for solar structure inversion. Authors: Basu, S.; Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 1997A&A...321..634B Altcode: Helioseismic inversion to determine solar structure is based on the analysis of very substantial numbers of modes and hence may involve considerable computational expense. This is particularly true for inversions using methods of optimally localised averages, which require inversion of matrices whose order is the number of modes in the set; yet such methods are desirable to make the full use of the data. On the other hand, there is considerable redundancy in the data, different modes carrying almost the same information about solar structure. Thus, in the unavoidable presence of data errors, the number of independent pieces of information is generally much less than the number of modes. This suggests that the mode-set can be reduced by forming suitable combinations of the data before the more computationally intensive inversion is performed. We show that such combinations may be based on singular value decomposition (SVD) of the problem, leading to a drastically reduced inverse problem whose solution is essentially indistinguishable from the solution of the original problem. In addition, the results of the SVD provide insight into the information content of the helioseismic data. Title: Structure and Rotation of the Solar Interior: Initial Results from the MDI Medium-L Program Authors: Kosovichev, A. G.; Schou, J.; Scherrer, P. H.; Bogart, R. S.; Bush, R. I.; Hoeksema, J. T.; Aloise, J.; Bacon, L.; Burnette, A.; de Forest, C.; Giles, P. M.; Leibrand, K.; Nigam, R.; Rubin, M.; Scott, K.; Williams, S. D.; Basu, Sarbani; Christensen-Dalsgaard, J.; Dappen, W.; Rhodes, E. J., Jr.; Duvall, T. L., Jr.; Howe, R.; Thompson, M. J.; Gough, D. O.; Sekii, T.; Toomre, J.; Tarbell, T. D.; Title, A. M.; Mathur, D.; Morrison, M.; Saba, J. L. R.; Wolfson, C. J.; Zayer, I.; Milford, P. N. Bibcode: 1997SoPh..170...43K Altcode: The medium-l program of the Michelson Doppler Imager instrument on board SOHO provides continuous observations of oscillation modes of angular degree, l, from 0 to ∽ 300. The data for the program are partly processed on board because only about 3% of MDI observations can be transmitted continuously to the ground. The on-board data processing, the main component of which is Gaussian-weighted binning, has been optimized to reduce the negative influence of spatial aliasing of the high-degree oscillation modes. The data processing is completed in a data analysis pipeline at the SOI Stanford Support Center to determine the mean multiplet frequencies and splitting coefficients. The initial results show that the noise in the medium-l oscillation power spectrum is substantially lower than in ground-based measurements. This enables us to detect lower amplitude modes and, thus, to extend the range of measured mode frequencies. This is important for inferring the Sun's internal structure and rotation. The MDI observations also reveal the asymmetry of oscillation spectral lines. The line asymmetries agree with the theory of mode excitation by acoustic sources localized in the upper convective boundary layer. The sound-speed profile inferred from the mean frequencies gives evidence for a sharp variation at the edge of the energy-generating core. The results also confirm the previous finding by the GONG (Gough et al., 1996) that, in a thin layer just beneath the convection zone, helium appears to be less abundant than predicted by theory. Inverting the multiplet frequency splittings from MDI, we detect significant rotational shear in this thin layer. This layer is likely to be the place where the solar dynamo operates. In order to understand how the Sun works, it is extremely important to observe the evolution of this transition layer throughout the 11-year activity cycle. Title: Are Standard Solar Models Reliable? Authors: Bahcall, John N.; Pinsonneault, M. H.; Basu, Sarbani; Christensen-Dalsgaard, J. Bibcode: 1997PhRvL..78..171B Altcode: 1996astro.ph.10250B The sound speeds of solar models that include element diffusion agree with helioseismological measurements to a rms discrepancy of better than 0.2% throughout almost the entire Sun. Models that do not include diffusion, or in which the interior of the Sun is assumed to be significantly mixed, are effectively ruled out by helioseismology. Standard solar models predict the measured properties of the Sun more accurately than is required for applications involving solar neutrinos. Title: Internal structure and rotation of the Sun: First results from MDI data Authors: Kosovichev, A. G.; Schou, J.; Scherrer, P. H.; Bogart, R. S.; Bush, R. I.; Hoeksema, J. T.; Aloise, J.; Bacon, L.; Burnette, A.; De Forest, C.; Giles, P. M.; Leibrand, K.; Nigam, R.; Rubin, M.; Scott, K.; Williams, S. D.; Basu, Sarbani; Christensen-Dalsgaard, J.; Däppen, W.; Rhodes, E. J., Jr.; Duvall, T. L., Jr.; Howe, R.; Thompson, M. J.; Gough, D. O.; Sekii, T.; Toomre, J.; Tarbell, T. D.; Title, A. M.; Mathur, D.; Morrison, M.; Saba, J. L. R.; Wolfson, C. J.; Zayer, I.; Milford, P. N. Bibcode: 1997IAUS..181..203K Altcode: No abstract at ADS Title: Constraints on stellar interior physics from helioseismology. Authors: Christensen-Dalsgaard, J. Bibcode: 1997IAUS..189..285C Altcode: 1998IAUS..189..285C; 1997astro.ph..2095C The author uses as reference the so-called Model S of Christensen-Dalsgaard et al. (1996). This, as well as other models discussed here, were calibrated to present solar luminosity and radius, as well as to the observed surface ratio Zs/Xs = 0.0245 between the heavy-element and hydrogen abundances, by adjusting the initial composition and the mixing-length parameter. Title: Three years of ANTENA: what we have done! Authors: Belmonte, J. A.; Hernández, M. M.; Pérez Hernández, F.; Vidal, I.; Roca Cortés, T.; Michel, E.; Auvergne, M.; Chevreton, M.; Goupil, M. J.; Soufi, F.; Baglin, A.; Frandsen, S.; Viskum, M.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Schmider, F. X.; Fossat, E.; Delache, Ph.; Provost, J.; Audard, N.; Berthomieu, G.; Paparó, M.; Kovács, G.; Szabados, L. Bibcode: 1997IAUS..181..357B Altcode: No abstract at ADS Title: On solar p-mode frequency shifts caused by near-surface model changes Authors: Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 1997MNRAS.284..527C Altcode: The effect on p-mode frequencies of changing the near-surface structure of solar models is investigated. As is well known, changes confined to the near-surface region have little effect on the low-frequency p modes: this is as one would expect from a simple asymptotic description which shows that these modes have upper turning points located well beneath the photosphere. However, some examples of structural changes show that, if the changes are viewed at fixed fractional radius (an Eulerian description), the small frequency shifts at low frequency come about through near-cancellation of different contributions which are individually much larger than the resultant shifts themselves; the reason is that even so-called near-surface changes extend substantially below the upper turning points of these modes. We demonstrate that the corresponding changes at fixed fractional mass (a Lagrangian description) are confined much closer to the surface, so that the small frequency shifts come about in a natural way. Title: The seismic structure of the Sun from GONG Authors: Anderson, E.; Antia, H. M.; Basu, S.; Chaboyer, B.; Chitre, S. M.; Christensen-Dalsgaard, J.; Eff-Darwich, A.; Elliott, J. R.; Giles, P. M.; Gough, D. O.; Guzik, J. A.; Harvey, J. W.; Hill, F.; Leibacher, J. W.; Kosovichev, A. G.; Monteiro, M. J. P. F. G.; Richard, O.; Sekii, T.; Shibahashi, H.; Takata, M.; Thompson, M. J.; Toomre, J.; Vauclair, S.; Vorontsov, S. V. Bibcode: 1997IAUS..181..151A Altcode: No abstract at ADS Title: Improved solar models. Authors: Chaboyer, B.; Basu, S.; Christensen-Dalsgaard, J. Bibcode: 1996JRASC..90..306C Altcode: No abstract at ADS Title: Pulsation models of δ Scuti variables. I. The high-amplitude double-mode stars. Authors: Petersen, J. O.; Christensen-Dalsgaard, J. Bibcode: 1996A&A...312..463P Altcode: The relations between high-amplitude δ Scuti stars and the much more abundant low-amplitude δ Sct variables are not clear. Both groups have similar periods and seem to have almost the same basic physical properties, although their light-curve characteristics are very different. In the last few years much improved observational data have been published, and improved theoretical physics - in particular the new OPAL/OP opacities - now allows much more accurate calculations of theoretical evolution models including the normal-mode pulsation frequencies. We here use new series of stellar envelope models to give calibrations of the first overtone-to-fundamental mode and the second-to-first overtone period ratios in terms of the primary model parameters: metal content and mass-luminosity relation. Effects of the secondary model parameters: hydrogen content, position within the instability strip and assumed efficiency of convection are also studied in detail, and shown to be small. These results combined with pulsation analysis of new stellar evolution models are applied to discuss the available information for double-mode high-amplitude δ Sct stars. We conclude that observed period ratios and positions in the HR-diagram are in agreement with the assumption that these variables are normal stars following standard evolution. Observational data for SX Phoenicis and AI Velorum are compared with theoretical evolution sequences. It is shown that the photometry and the observed two periods of SX Phe constrain the metal content to Z=0.001, the mass to 1.0 solar masses and the bolometric magnitude to about 2.70mag. The inferred distance of SX Phe gives a parallax of 0.012+/-0.002arcsec compared with that of the HIPPARCOS Input Catalogue of 0.023+/-0.008arcsec. For AI Vel the available photometry and the two primary observed periods do not provide a unique solution. Models based on OPAL opacities allow Z=0.01-0.02 with corresponding masses 1.6-2.0 solar masses. This can be understood by the compensating effects from Z and the mass-luminosity relation in the calibration of the period ratio. It is suggested that the surprisingly narrow interval in the first overtone-to-fundamental mode period ratio observed in the double-mode δ Sct stars may be due to these compensating effects. Attempting to fit low-amplitude modes observed in AI Vel in addition to the primary oscillations, it is concluded that the present models cannot explain these oscillations in terms of radial modes. The little understood relations between high- and low-amplitude δ Sct stars are briefly discussed, and the problem of mode identification is emphasized. Title: Asteroseismological calibration of open clusters Authors: Audard, N.; Brown, T. M.; Christensen-Dalsgaard, J.; Frandsen, S.; Kjeldsen, H. Bibcode: 1996BASI...24..305A Altcode: No abstract at ADS Title: Solar structure as revealed by 1 year LOWL data Authors: Basu, Sarbani; Christensen-Dalsgaard, J.; Schou, J.; Thompson, M. J.; Tomczyk, S. Bibcode: 1996BASI...24..147B Altcode: No abstract at ADS Title: An overview of the conference Authors: Christensen-Dalsgaard, Jorgen Bibcode: 1996BASI...24..379C Altcode: No abstract at ADS Title: Wave leakage in a magnetized isothermal atmosphere Authors: Banerjee, Dipankar; Hasan, S. S.; Christensen-Dalsgaard, J. Bibcode: 1996BASI...24..325B Altcode: No abstract at ADS Title: Effects on solar structure of opacity changes Authors: Tripathy, S. C.; Christensen-Dalsgaard, J. Bibcode: 1996BASI...24..129T Altcode: No abstract at ADS Title: How are the observed frequencies related to solar structure? Authors: Christensen-Dalsgaard, Jorgen Bibcode: 1996BASI...24..103C Altcode: No abstract at ADS Title: The Current State of Solar Modeling Authors: Christensen-Dalsgaard, J.; Dappen, W.; Ajukov, S. V.; Anderson, E. R.; Antia, H. M.; Basu, S.; Baturin, V. A.; Berthomieu, G.; Chaboyer, B.; Chitre, S. M.; Cox, A. N.; Demarque, P.; Donatowicz, J.; Dziembowski, W. A.; Gabriel, M.; Gough, D. O.; Guenther, D. B.; Guzik, J. A.; Harvey, J. W.; Hill, F.; Houdek, G.; Iglesias, C. A.; Kosovichev, A. G.; Leibacher, J. W.; Morel, P.; Proffitt, C. R.; Provost, J.; Reiter, J.; Rhodes, E. J., Jr.; Rogers, F. J.; Roxburgh, I. W.; Thompson, M. J.; Ulrich, R. K. Bibcode: 1996Sci...272.1286C Altcode: Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations. Title: Filtering out near-surface uncertainties from helioseismic inversions Authors: Basu, Sarbani; Christensen-Dalsgaard, J.; Perez Hernandez, F.; Thompson, M. J. Bibcode: 1996MNRAS.280..651B Altcode: The differences between observed solar p-mode frequencies and the frequencies of a reference model can be inverted to infer the structure of the Sun using a variety of linear inversion techniques. However, it is well known that the adiabatic description, which is often employed in frequency calculations, breaks down in the outermost layers of the Sun. This and other uncertainties in the treatment of the superficial layers introduce a slowly varying frequency-dependent function into the frequency differences.

We present here a technique to pre-process the frequency differences prior to applying any of the standard inversion techniques in order to eliminate the frequency dependent component which arises from the near-surface uncertainties, suppressing also the corresponding contributions from the kernels relating frequency differences to differences in structure. This is achieved by applying suitable linear filters to the frequency differences and to the mode kernels. We obtain the filtered kernels and demonstrate that the surface contribution can be successfully suppressed. We also present the results of the inversions performed after the data and mode kernels have been filtered. Title: The Seismic Structure of the Sun Authors: Gough, D. O.; Kosovichev, A. G.; Toomre, J.; Anderson, E.; Antia, H. M.; Basu, S.; Chaboyer, B.; Chitre, S. M.; Christensen-Dalsgaard, J.; Dziembowski, W. A.; Eff-Darwich, A.; Elliott, J. R.; Giles, P. M.; Goode, P. R.; Guzik, J. A.; Harvey, J. W.; Hill, F.; Leibacher, J. W.; Monteiro, M. J. P. F. G.; Richard, O.; Sekii, T.; Shibahashi, H.; Takata, M.; Thompson, M. J.; Vauclair, S.; Vorontsov, S. V. Bibcode: 1996Sci...272.1296G Altcode: Global Oscillation Network Group data reveal that the internal structure of the sun can be well represented by a calibrated standard model. However, immediately beneath the convection zone and at the edge of the energy-generating core, the sound-speed variation is somewhat smoother in the sun than it is in the model. This could be a consequence of chemical inhomogeneity that is too severe in the model, perhaps owing to inaccurate modeling of gravitational settling or to neglected macroscopic motion that may be present in the sun. Accurate knowledge of the sun's structure enables inferences to be made about the physics that controls the sun; for example, through the opacity, the equation of state, or wave motion. Those inferences can then be used elsewhere in astrophysics. Title: Differential Rotation and Dynamics of the Solar Interior Authors: Thompson, M. J.; Toomre, J.; Anderson, E. R.; Antia, H. M.; Berthomieu, G.; Burtonclay, D.; Chitre, S. M.; Christensen-Dalsgaard, J.; Corbard, T.; De Rosa, M.; Genovese, C. R.; Gough, D. O.; Haber, D. A.; Harvey, J. W.; Hill, F.; Howe, R.; Korzennik, S. G.; Kosovichev, A. G.; Leibacher, J. W.; Pijpers, F. P.; Provost, J.; Rhodes, E. J., Jr.; Schou, J.; Sekii, T.; Stark, P. B.; Wilson, P. R. Bibcode: 1996Sci...272.1300T Altcode: Splitting of the sun's global oscillation frequencies by large-scale flows can be used to investigate how rotation varies with radius and latitude within the solar interior. The nearly uninterrupted observations by the Global Oscillation Network Group (GONG) yield oscillation power spectra with high duty cycles and high signal-to-noise ratios. Frequency splittings derived from GONG observations confirm that the variation of rotation rate with latitude seen at the surface carries through much of the convection zone, at the base of which is an adjustment layer leading to latitudinally independent rotation at greater depths. A distinctive shear layer just below the surface is discernible at low to mid-latitudes. Title: Helioseismology, Solar Models and Solar Neutrinos Authors: Christensen-Dalsgaard, Jørgen Bibcode: 1996NuPhS..48..325C Altcode: Very accurate measurements of oscillation frequencies of the Sun are providing detailed information about the structure of the solar interior. Somewhat surprisingly, the results are in excellent agreement with so-called 'standard solar models', provided up-to-date physics is used and settling of helium and heavy elements is taken into account. This suggests that an 'astrophysical solution' to the solar neutrino problem may be unlikely. Title: Testing Solar Models with the GONG Data Authors: Christensen-Dalsgaard, J.; Dappen, W.; Demarque, P.; GONG Models Team Bibcode: 1996AAS...188.5302C Altcode: 1996BAAS...28..903C The wealth of very precise data from the GONG network and other helioseismic experiments provide a unique opportunity for testing the modeling of stellar interiors. Stellar modeling forms the basis for much of astrophysics. Furthermore, the application and calibration of solar models to the helioseismic data provides a test of the physics on which the models depend; thus we can investigate the thermodynamic and radiative properties of matter under the extreme conditions found in the Sun. Current models are in remarkable agreement with the helioseismic inferences within the errors in the input data; this suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the Sun is unlikely to be caused by errors in the standard solar model. However, careful analysis of the GONG data reveals subtle discrepancies that we attribute to uncertainties in some of the model input physics and the neglect of other subtle physical processes. The role of mixing inside the Sun, due for example to rotationally induced instabilities during its past evolution, the precise form of the hydrogen depletion profile near the center, the efficiency of helium and heavier element diffusion below the convection zone, and the structure of the highly superadiabatic layer just below the photosphere, are among the significant details in solar models, which the high-quality GONG data will greatly help to resolve. Comparisons between theoretical predictions of solar p-mode frequencies, previous p-mode observations and the first GONG data are used to illustrate these points. Title: The Sun's Hydrostatic Structure from LOWL Data Authors: Basu, Sarbani; Christensen-Dalsgaard, J.; Schou, J.; Thompson, M. J.; Tomczyk, S. Bibcode: 1996ApJ...460.1064B Altcode: Recent observations with the LOWL (Low-Degree [l] Oscillations Experiment) instrument have for the first time provided a uniform set of frequencies that allow detailed inversion for the structure of much of the Sun's deep interior. We present the results of inverting the LOWL data and compare them with the corresponding results obtained using inhomogeneous data sets from more than one instrument. Furthermore, improvements in the description of the required physics motivates the calculation of new solar models. Thus, we present results of inversions of the LOWL data against several reference models using up-to-date physics. In models including the gravitational settling of helium, the sound speed and density agree with the Sun to within substantially better than 1%. We test various modifications to the physics of the models in order to see if the remaining small (but significant) discrepancy between the Sun and the models can be removed. We find that none of the modifications tested can adequately account for the remaining discrepancy, though a small increase in helium diffusion in the core gives a modest improvement over the standard diffusion model. Finally, we find that the seismic data support theoretical calculations that indicate that settling of heavier elements has reduced the present surface value of Z by about 8% relative to its mean interior value. Title: Seismic properties of the Sun's superadiabatic layer. I. Theoretical modelling and parametrization of the uncertainties. Authors: Monteiro, M. J. P. F. G.; Christensen-Dalsgaard, J.; Thompson, M. J. Bibcode: 1996A&A...307..624M Altcode: Some alternatives to the traditional mixing-length theory (MLT) have recently been proposed for modelling convective heat transport inside stars. The ideal formulation is one that does not involve any free parameters. However, in our present state of ignorance we still need at least one free parameter in order to build solar models with the correct radius. Having adjusted this parameter (e.g. the mixing-length parameter α_c_) to obtain the observed radius, we cannot discriminate non-seismically between different convective theories, regardless of how low-efficiency convection is treated. In this paper we consider how the additional information provided by global p-mode frequencies can be used to investigate low-efficiency convection at the top of the solar convective envelope and discriminate between different theories. We consider a parametrization which in addition to the mixing length has two further parameters: one (β_c_) which regulates the relative degree of overadiabaticity (or inefficiency) of convection, and a second (m) that affects the transition between the regimes of efficient and inefficient convection. Our parametrization includes traditional MLT__ and the theory of Canuto & Mazzitelli as particular cases. We study the effect of varying these parameters by constructing a series of envelope models with the same depth of the convection zone and computing their oscillation frequencies. We discuss our results in terms of kernels relating frequency changes to changes in the structure of the superadiabatic region. Title: Filtering in Inversion for Solar Internal Structure Authors: Basu, Sarbani; Christensen-Dalsgaard, J.; Pérez Hernández, F.; Thompson, M. J. Bibcode: 1996imie.conf...32B Altcode: No abstract at ADS Title: On the Choice of Trade-off Parameter in Helioseismic SOLA Inversion Authors: Stepanov, A. A.; Christensen-Dalsgaard, J. Bibcode: 1996imie.conf...54S Altcode: No abstract at ADS Title: Testing a solar model: the forward problem. Authors: Christensen-Dalsgaard, J. Bibcode: 1996stsu.conf...47C Altcode: This paper addresses the forward problem, i.e., the relation between the structure of a solar model and the corresponding frequencies. As important, however, is the extent to which the frequencies reflect the physics and other assumptions underlying the model calculation. Thus the author considers some aspects of solar model computation. In addition, the understanding of the diagnostic potential of the frequencies requires information about the properties of the oscillations. He investigates the relation between the properties of solar structure and the oscillations by considering several examples of modifications to the solar models and their effects on the frequencies and considers further analyses of the observed frequencies. Finally, the prospects of extending this type of work to other stars are addressed. Title: The interfacial F mode in a spherical solar model Authors: Rosenthal, C. S.; Christensen-Dalsgaard, J. Bibcode: 1995MNRAS.276.1003R Altcode: The solar f modes are a branch of oscillations characterized by a close correspondence between their measured dispersion relation and that predicted for a pure surface gravity wave: omega^2=gk where g is the surface gravity of the Sun. However, there is now substantial evidence for deviations from this simple behaviour. We consider the hypothesis of Rosenthal & Gough that the f modes are characterized better as an interfacial wave propagating at the chromosphere-corona transition. Using a standard solar interior model, a semi-empirical atmospheric model, and a parametrized transition region model as our equilibrium state, we solve the linearized oscillation equations for the interfacial f mode. We find that the frequencies of the interfacial f mode differ from those of the classical f mode only at very high degrees. We conclude that the interfacial f-mode theory may be the correct explanation for the very high-degree data, but that some other mechanism is required to explain the lower degree data. Title: The Influence of a Vertical Magnetic Field on Oscillations in an Isothermal Stratified Atmosphere. II. Authors: Banerjee, Dipankar; Hasan, S. S.; Christensen-Dalsgaard, J. Bibcode: 1995ApJ...451..825B Altcode: We examine the effect of a uniform vertical magnetic field on the modes of an isothermal stratified atmosphere. The present investigation is a continuation of earlier work by Hasan & Christensen-Dalsgaard in which this problem was studied for rigid boundary conditions. In this paper, the earlier results are extended to different sets of boundary conditions. We demonstrate explicitly how these boundary conditions affect the various elementary wave modes present in the atmosphere. In the weak-field limit, an analytic expression for the dispersion relation is derived, which allows the effect of a weak magnetic field on the modes to be studied. We show that, to lowest order in our perturbation expansion, the oscillation spectrum can be analyzed in terms of (a) p- and g-like modes; (b) a magnetic Lamb mode; (c) magnetic or slow modes; and (d) a gravity- Lamb mode. The first three of these were present in the previous analysis for rigid boundaries, whereas the last is a consequence of the vertical gradients of the displacements at the boundaries. We focus our attention on the properties of this mode and show that it is present even in the moderate to strong field case as a magnetogravity-Lamb mode. The recognition and physical interpretation of this mode is a new feature of the present analysis. We also examine the nature of the eigenfrequency curves in the diagnostic (or K-Ω) diagram and find that, similar to the previous analysis, the modes undergo avoided crossings. However, the nature of the solutions in the present case is more complicated, especially when triple-mode interactions occur. Furthermore, the connectivity of the curves in the K-Ω diagram can be strongly influenced by the choice of boundary conditions. Our results, though somewhat idealized, find application in the analysis of waves in sunspots. It is conjectured that conditions for the existence of the magnetogravity-Lamb mode may also be satisfied in the subphotospheric layers of the Sun. Title: Helioseismic estimation of convective overshoot in the Sun Authors: Christensen-Dalsgaard, Jorgen; Monteiro, Mario J. P. F. G.; Thompson, Michael J. Bibcode: 1995MNRAS.276..283C Altcode: By using the periodic signal present in the frequencies of oscillation due to the base of the solar convection zone, Monteiro, Christensen-Dalsgaard & Thompson gave an upper limit to the extent of a layer of convective overshooting in the Sun. Alternative studies have suggested that it may not be possible to do so since the amplitude of the signal does not vary monotonically with the extent of the layer.

In this work a new more complete set of models is used to compare the values of the amplitude obtained from the fitting of the signal with the expected amplitudes. These are determined using the assumption that the rapid variation occurring at the base of the convection zone and creating the periodic signal can be described as discontinuities of the sound-speed derivatives. The amplitude of the signal due to the discontinuity of the third derivative of the sound speed is then proportional to the derivative of the radiative gradient, while the amplitude resulting from the discontinuity of the second derivative is proportional to the difference between radiative and adiabatic gradients at the position where the transition occurs. The latter is non-zero only if overshoot is present.

Asymptotic predictions of the amplitudes of the signal in the p-mode frequencies are in good agreement with the values found from fitting models with substantial overshoot regions; as was also found by Monteiro et al., the observed solar frequencies place severe limits on the extent of overshoot of this nature.