Author name code: strassmeier ADS astronomy entries on 2022-09-14 author:"Strassmeier, Klaus G." ------------------------------------------------------------------------ Title: The Great Dimming of Betelgeuse: A Surface Mass Ejection and Its Consequences Authors: Dupree, Andrea K.; Strassmeier, Klaus G.; Calderwood, Thomas; Granzer, Thomas; Weber, Michael; Kravchenko, Kateryna; Matthews, Lynn D.; Montargès, Miguel; Tappin, James; Thompson, William T. Bibcode: 2022ApJ...936...18D Altcode: 2022arXiv220801676D The bright supergiant, Betelgeuse (Alpha Orionis, HD 39801), underwent a historic optical dimming during 2020 January 27-February 13. Many imaging and spectroscopic observations across the electromagnetic spectrum were obtained prior to, during, and subsequent to this dimming event. These observations of Betelgeuse reveal that a substantial surface mass ejection (SME) occurred and moved out through the extended atmosphere of the supergiant. A photospheric shock occurred in 2019 January-March, progressed through the extended atmosphere of the star during the following 11 months and led to dust production in the atmosphere. Resulting from the substantial mass outflow, the stellar photosphere was left with lower temperatures and the chromosphere with a lower density. The mass ejected could represent a significant fraction of the total annual mass-loss rate from the star suggesting that episodic mass-loss events can contribute an amount comparable to that of the stellar wind. Following the SME, Betelgeuse was left with a cooler average photosphere, an unusual short photometric oscillation, reduced velocity excursions, and the disappearance of the ~400 day pulsation in the optical and radial velocity for more than two years following the Great Dimming. Title: The recurrent nova V3890 Sgr: a near-infrared and optical study of the red giant component and its environment Authors: Kaminsky, B.; Evans, A.; Pavlenko, Ya V.; Woodward, C. E.; Banerjee, D. P. K.; Gehrz, R. D.; Walter, F.; Starrfield, S.; Ilyin, I.; Strassmeier, K. G.; Wagner, R. M. Bibcode: 2022MNRAS.tmp.2296K Altcode: 2022arXiv220714721K We present an analysis of the red giant component of the recurrent nova V3890 Sgr, using data obtained before and after its 2019 eruption. Its effective temperature is Teff = 3050 ±200 K for log g = 0.7, although there are modest changes in Teff. There is an overabundance of both carbon (0.20 ± 0.05 dex) and sodium (1.0 ± 0.3 dex) relative to their solar values, possibly the result of ejecta from the 1990 nova eruption being entrained into the red giant photosphere. We find 12C/13C =25 ± 2, a value similar to that found in red giants in other recurrent novae. The interpretation of the quiescent spectrum in the 5-38 μm region requires the presence of photospheric SiO absorption and cool (~400 K) dust in the red giant environment. The spectrum in the region of the Na I D lines is complex, and includes at least six interstellar components, together with likely evidence for interaction between ejecta from the 2019 eruption and material accumulated in the plane of the binary. Three recurrent novae with giant secondaries have been shown to have environments with different dust content, but photospheres with similar 12C/13C ratios. The SiO fundamental bands most likely have a photospheric origin in the all three stars. Title: The Origin of Weakened Magnetic Braking in Old Solar Analogs Authors: Metcalfe, Travis S.; Finley, Adam J.; Kochukhov, Oleg; See, Victor; Ayres, Thomas R.; Stassun, Keivan G.; van Saders, Jennifer L.; Clark, Catherine A.; Godoy-Rivera, Diego; Ilyin, Ilya V.; Pinsonneault, Marc H.; Strassmeier, Klaus G.; Petit, Pascal Bibcode: 2022ApJ...933L..17M Altcode: 2022arXiv220608540M The rotation rates of main-sequence stars slow over time as they gradually lose angular momentum to their magnetized stellar winds. The rate of angular momentum loss depends on the strength and morphology of the magnetic field, the mass-loss rate, and the stellar rotation period, mass, and radius. Previous observations suggested a shift in magnetic morphology between two F-type stars with similar rotation rates but very different ages (88 Leo and ρ CrB). In this Letter, we identify a comparable transition in an evolutionary sequence of solar analogs with ages between 2-7 Gyr. We present new spectropolarimetry of 18 Sco and 16 Cyg A and B from the Large Binocular Telescope, and we reanalyze previously published Zeeman Doppler images of HD 76151 and 18 Sco, providing additional constraints on the nature and timing of this transition. We combine archival X-ray observations with updated distances from Gaia to estimate mass-loss rates, and we adopt precise stellar properties from asteroseismology and other sources. We then calculate the wind braking torque for each star in the evolutionary sequence, demonstrating that the rate of angular momentum loss drops by more than an order of magnitude between the ages of HD 76151 and 18 Sco (2.6-3.7 Gyr) and continues to decrease modestly to the age of 16 Cyg A and B (7 Gyr). We suggest that this magnetic transition may represent a disruption of the global dynamo arising from weaker differential rotation, and we outline plans to probe this phenomenon in additional stars spanning a wide range of spectral types. Title: The Spectroscopic Evolution of V1674 Hercules: The Fastest Nova Ever Authors: Starrfield, Sumner; Woodward, Charles E.; Perron, Isabelle; Wagner, R. Mark; Page, Kim; Strassmeier, Klaus; Ilyin, Ilya Bibcode: 2022AAS...24034604S Altcode: V1674 Her (Nova Her 2021) was discovered in outburst on 2021 June 12 and reached a peak brightness of V ~ 6. It then declined extremely rapidly falling 2 magnitudes in 1.2 days. It was followed at high cadence by a slew of ground and space based observatories with numerous publications ensuing. These observations found that in addition to the fastest decline on record, it was an ONe type nova exhibiting strong forbidden Ne emission lines, and it exhibited a 501 s oscillation that suggested that the outburst occurred in an intermediate polar system. Moreover, the ejection velocities were of the order of 6000 km/s. We have continued to monitor it as it returned to quiescence and will present the optical spectra collected for this nova, plus any new data at other wavelengths, that we obtain after the submission of this abstract. Our optical data have been collected on 22 epochs to date at spectral resolutions ranging from 1700 to 130,000 with facilities of the MDM, MMT, and LBT observatories. Our latest spectrum, obtained with the MDM 2.4-m Hiltner telescope and OSMOS spectrograph (2022 March 27 UT), after it emerged from solar conjunction, show a dramatic change in that the forbidden lines have disappeared and He II 4686 Ang is the strongest emission line in the spectrum superposed on a blue continuum. We will discuss the implications of this change. We are grateful to all the facilities for their support of observing time. Title: Nodal Precession and Tidal Evolution of KELT-9 b and WASP-33 b Authors: Stephan, Alexander P.; Wang, Ji; Cauley, Paul W.; Gaudi, B. Scott; Ilyin, Ilya; Johnson, Marshall; Strassmeier, Klaus Bibcode: 2022BAAS...54e4601S Altcode: Hot Jupiters provide important insights into planetary formation, migration, atmospheric composition, and star-planet tidal interactions. Of special interest are Hot Jupiters with strongly misaligned orbits to their host stars' spin axis, which generally induces strong nodal precession of the planetary orbits, measurable via the Doppler Tomography technique. Here we present new results for the nodal precession of KELT-9 b, derived from new PEPSI/LBT observations and archival data covering a time span of 7 years. We measure the stellar gravitational quadrupole moment, J2, the stellar oblateness and spin rate, and true spin-orbit misalignment to a high degree of accuracy. We confirm the validity of our methodology by also analyzing the previously studied WASP-33 system, using new PEPSI/LBT observations and archival data covering a time span of 11 years. We conclude that both KELT-9 b and WASP-33 b will cease to transit their host stars by the end of the 21st century. Based on their tidal dynamics, we estimate the expected remaining life spans of both planets as well as speculate on their likely dynamical origins. Title: Nodal Precession and Tidal Evolution of KELT-9 b and WASP-33 b Authors: Stephan, Alexander P.; Wang, Ji; Cauley, Paul W.; Gaudi, B. Scott; Ilyin, Ilya; Johnson, Marshall; Strassmeier, Klaus Bibcode: 2022AAS...24041801S Altcode: Hot Jupiters provide important insights into planetary formation, migration, atmospheric composition, and star-planet tidal interactions. Of special interest are Hot Jupiters with strongly misaligned orbits to their host stars' spin axis, which generally induces strong nodal precession of the planetary orbits, measurable via the Doppler Tomography technique. Here we present new results for the nodal precession of KELT-9 b, derived from new PEPSI/LBT observations and archival data covering a time span of 5 years. We measure the stellar gravitational quadrupole moment, J2, the stellar oblateness and spin rate, and true spin-orbit misalignment to a high degree of accuracy. We confirm the validity of our methodology by also analyzing the previously studied WASP-33 system, using new PEPSI/LBT observations and archival data covering a time span of 11 years. We conclude that both KELT-9 b and WASP-33 b will cease to transit their host stars by the end of the 21st century. Based on their tidal dynamics, we estimate the expected remaining life spans of both planets as well as speculate on their likely dynamical origins. Title: Variable and super-sonic winds in the atmosphere of an ultra-hot giant planet Authors: Pai Asnodkar, Anusha; Wang, Ji; Eastman, Jason; Cauley, Paul; Gaudi, B. Scott; Ilyin, Ilya; Strassmeier, Klaus Bibcode: 2022BAAS...54e.188P Altcode: Hot Jupiters (HJs) present an extreme case for exploring the conditions that regulate planetary atmospheres because they experience intense irradiation from their host stars that induces global-scale winds. General circulation models (GCMs) of HJ atmospheres predict day-to-nightside winds (winds flowing from the side of the planet facing its host star to the side facing away from the star) and equatorial jets (winds that entirely circulate around the planet) with speeds on the order of a few km/s. We apply high-resolution transmission spectroscopy using the PEPSI spectrograph on the Large Binocular Telescope to empirically constrain supersonic ~10 km/s day-to-nightside winds traced by Fe II features in the atmosphere of KELT-9 b, an ultra-hot Jupiter (UHJ) that remains to-date the hottest known planet. Reconciling our findings with archival HARPS-N datasets suggests multi-epoch variability ~5-8 km/s over timescales between weeks to years. We compare with the UHJ KELT-20 b to demonstrate the exceptional nature of KELT-9 b's atmospheric dynamics. A qualitative evaluation of our measured wind velocities and variability against current UHJ GCMs reveals that KELT-9 b poses unique challenges for validating giant planet atmospheric models. Title: Characterization of chromospheric activity based on Sun‑as‑a‑star spectral and disk‑resolved activity indices Authors: Dineva, Ekaterina; Pearson, Jeniveve; Ilyin, Ilya; Verma, Meetu; Diercke, Andrea; Strassmeier, Klaus G.; Denker, Carsten Bibcode: 2022AN....34323996D Altcode: 2022arXiv220606076D The strong chromospheric absorption lines Ca H & K are tightly connected to stellar surface magnetic fields. Only for the Sun, spectral activity indices can be related to evolving magnetic features on the solar disk. The Solar Disk-Integrated (SDI) telescope feeds the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) of the Large Binocular Telescope (LBT) at Mt. Graham International Observatory (MGIO), Arizona, U.S.A. We present high-resolution, high-fidelity spectra that were recorded on 184 & 82 days in 2018 & 2019 and derive the Ca H & K emission ratio, i.e., the S-index. In addition, we compile excess brightness and area indices based on full-disk Ca K line-core filtergrams of the Chromospheric Telescope (ChroTel) at Observatorio del Teide, Tenerife, Spain and full-disk ultraviolet (UV) 1600~Å images of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). Thus, Sun-as-a-star spectral indices are related to their counterparts derived from resolved images of the solar chromosphere. All indices display signatures of rotational modulation, even during the very low magnetic activity in the minimum of Solar Cycle 24. Bringing together different types of activity indices has the potential to join disparate chromospheric datasets, yielding a comprehensive description of chromospheric activity across many solar cycles. Title: A Search for Temperature Inversion Agents in KELT-20b with LBT/PEPSI Authors: Johnson, Marshall C.; Wang, Ji; Pai Asnodkar, Anusha; Strassmeier, Klaus; Ilyin, Ilya Bibcode: 2022BAAS...54e.028J Altcode: The existence of temperature inversions in the atmospheres of hot Jupiters has long been a controversial topic, but there is growing evidence that at least some ultra hot Jupiters possess inverted atmospheric profiles. In most cases, however, it is unclear what chemical agents are responsible for the inversions. Most previous searches for inversion agents have been through transmission spectroscopy, but this method typically probes lower pressure levels than those where inversion agents are expected to occur. Emission spectroscopy, on the other hand, is more technically challenging but directly probes the altitudes inhabited by inversion agents.

We present a search for inversion agents in the ultra hot Jupiter KELT-20b/MASCARA-2b using both emission and transmission spectroscopy with the PEPSI high-resolution spectrograph on LBT. An atmospheric inversion was recently detected on this planet by several authors using the spectra of several different atomic and molecular species. We search for inversion agents including TiO, VO, and FeH using cross-correlation methodology. The use of both emission and transmission data allows us to set stringent limits upon the presence of these species at multiple levels in the atmosphere. Title: The PEPSI exoplanet transit survey (PETS) I: investigating the presence of a silicate atmosphere on the super-earth 55 Cnc e Authors: Keles, Engin; Mallonn, Matthias; Kitzmann, Daniel; Poppenhaeger, Katja; Hoeijmakers, H. Jens; Ilyin, Ilya; Alexoudi, Xanthippi; Carroll, Thorsten A.; Alvarado-Gomez, Julian; Ketzer, Laura; Bonomo, Aldo S.; Borsa, Francesco; Gaudi, B. Scott; Henning, Thomas; Malavolta, Luca; Molaverdikhani, Karan; Nascimbeni, Valerio; Patience, Jennifer; Pino, Lorenzo; Scandariato, Gaetano; Schlawin, Everett; Shkolnik, Evgenya; Sicilia, Daniela; Sozzetti, Alessandro; Foster, Mary G.; Veillet, Christian; Wang, Ji; Yan, Fei; Strassmeier, Klaus G. Bibcode: 2022MNRAS.513.1544K Altcode: 2022MNRAS.tmp..838K; 2022arXiv220316856K The study of exoplanets and especially their atmospheres can reveal key insights on their evolution by identifying specific atmospheric species. For such atmospheric investigations, high-resolution transmission spectroscopy has shown great success, especially for Jupiter-type planets. Towards the atmospheric characterization of smaller planets, the super-Earth exoplanet 55 Cnc e is one of the most promising terrestrial exoplanets studied to date. Here, we present a high-resolution spectroscopic transit observation of this planet, acquired with the PEPSI instrument at the Large Binocular Telescope. Assuming the presence of Earth-like crust species on the surface of 55 Cnc e, from which a possible silicate-vapor atmosphere could have originated, we search in its transmission spectrum for absorption of various atomic and ionized species such as Fe , Fe +, Ca , Ca +, Mg, and K , among others. Not finding absorption for any of the investigated species, we are able to set absorption limits with a median value of 1.9 × RP. In conclusion, we do not find evidence of a widely extended silicate envelope on this super-Earth reaching several planetary radii. Title: Nodal Precession and Tidal Evolution of Two Hot Jupiters: WASP-33 b and KELT-9 b Authors: Stephan, Alexander P.; Wang, Ji; Cauley, P. Wilson; Gaudi, B. Scott; Ilyin, Ilya; Johnson, Marshall C.; Strassmeier, Klaus G. Bibcode: 2022ApJ...931..111S Altcode: 2022arXiv220302546S Hot Jupiters orbiting rapidly rotating stars on inclined orbits undergo tidally induced nodal precession measurable over several years of observations. The Hot Jupiters WASP-33 b and KELT-9 b are particularly interesting targets because they are among the hottest planets found to date, orbiting relatively massive stars. Here, we analyze archival and new data that span 11 and 5 yr for WASP-33 b and KELT-9 b, respectively, in order to model and improve upon their tidal precession parameters. Our work confirms the nodal precession for WASP-33 b and presents the first clear detection of the precession of KELT-9 b. We determine that WASP-33 and KELT-9 have gravitational quadrupole moments $({6.3}_{-0.8}^{+1.2})\times {10}^{-5}$ and $({3.26}_{-0.80}^{+0.93})\times {10}^{-4}$ , respectively. We estimate the planets' precession periods to be ${1460}_{-130}^{+170}$ yr and ${890}_{-140}^{+200}$ yr, respectively, and that they will cease to transit their host stars around the years ${2090}_{-10}^{+17}$ CE and ${2074}_{-10}^{+12}$ CE, respectively. Additionally, we investigate both planets' tidal and orbital evolution, suggesting that a high-eccentricity tidal migration scenario is possible to produce both system architectures and that they will most likely not be engulfed by their hosts before the end of their main-sequence lifetimes. Title: An Aligned Orbit for the Young Planet V1298 Tau b Authors: Johnson, Marshall C.; David, Trevor J.; Petigura, Erik A.; Isaacson, Howard T.; Van Zandt, Judah; Ilyin, Ilya; Strassmeier, Klaus; Mallonn, Matthias; Zhou, George; Mann, Andrew W.; Livingston, John H.; Luger, Rodrigo; Dai, Fei; Weiss, Lauren M.; Močnik, Teo; Giacalone, Steven; Hill, Michelle L.; Rice, Malena; Blunt, Sarah; Rubenzahl, Ryan; Dalba, Paul A.; Esquerdo, Gilbert A.; Berlind, Perry; Calkins, Michael L.; Foreman-Mackey, Daniel Bibcode: 2022AJ....163..247J Altcode: 2021arXiv211010707J The alignment of planetary orbits with respect to the stellar rotation preserves information on their dynamical histories. Measuring this angle for young planets helps illuminate the mechanisms that create misaligned orbits for older planets, as different processes could operate over timescales ranging from a few megayears to a gigayear. We present spectroscopic transit observations of the young exoplanet V1298 Tau b; we update the age of V1298 Tau to be 28 ± 4 Myr based on Gaia EDR3 measurements. We observed a partial transit with Keck/HIRES and LBT/PEPSI, and detected the radial velocity anomaly due to the Rossiter-McLaughlin effect. V1298 Tau b has a prograde, well-aligned orbit, with $\lambda ={4}_{-10}^{+7}$ deg. By combining the spectroscopically measured $v\sin {i}_{\star }$ and the photometrically measured rotation period of the host star we also find that the orbit is aligned in 3D, $\psi ={8}_{-7}^{+4}$ deg. Finally, we combine our obliquity constraints with a previous measurement for the interior planet V1298 Tau c to constrain the mutual inclination between the two planets to be i mut = 0° ± 19°. This measurements adds to the growing number of well-aligned planets at young ages, hinting that misalignments may be generated over timescales of longer than tens of megayears. The number of measurements, however, is still small, and this population may not be representative of the older planets that have been observed to date. We also present the derivation of the relationship between i mut, λ, and i for the two planets. Title: The PEPSI-LBT Exoplanet Transit Survey (PETS). II. A Deep Search for Thermal Inversion Agents in KELT-20 b/MASCARA-2 b with Emission and Transmission Spectroscopy Authors: Johnson, Marshall C.; Wang, Ji; Pai Asnodkar, Anusha; Bonomo, Aldo S.; Gaudi, B. Scott; Henning, Thomas; Ilyin, Ilya; Keles, Engin; Malavolta, Luca; Mallonn, Matthias; Molaverdikhani, Karan; Nascimbeni, Valerio; Patience, Jennifer; Poppenhaeger, Katja; Scandariato, Gaetano; Schlawin, Everett; Shkolnik, Evgenya; Sicilia, Daniela; Sozzetti, Alessandro; Strassmeier, Klaus G.; Veillet, Christian; Yan, Fei Bibcode: 2022arXiv220512162J Altcode: Recent observations have shown that the atmospheres of ultra hot Jupiters (UHJs) commonly possess temperature inversions, where the temperature increases with increasing altitude. Nonetheless, which opacity sources are responsible for the presence of these inversions remains largely observationally unconstrained. We used LBT/PEPSI to observe the atmosphere of the UHJ KELT-20 b in both transmission and emission in order to search for molecular agents which could be responsible for the temperature inversion. We validate our methodology by confirming a previous detection of Fe I in emission at $15.1\sigma$; however, we are unable to reproduce published detections of Fe II, Cr I, or Si I. We attribute the non-detection of Si I to the lack of lines in our bandpass, but the non-detections of Fe II and Cr I are puzzling due to our much higher signal-to-noise ratio than previous works. Our search for the inversion agents TiO, VO, FeH, and CaH results in non-detections. Using injection-recovery testing we set $4\sigma$ upper limits upon the volume mixing ratios for these constituents as low as $\sim1\times10^{-10}$ for TiO. For TiO, VO, and CaH, our limits are much lower than expectations from an equilibrium chemical model, while FeH is lower than the expectations only from a super-Solar metallicity model. We thus rule out TiO, VO, and CaH as the source of the temperature inversion in KELT-20 b, while FeH is disfavored only if KELT-20 b possesses a high-metallicity atmosphere. Title: VizieR Online Data Catalog: KELT-9 radial velocity with LBT/PEPSI (Pai Asnodkar+, 2022) Authors: Pai Asnodkar, A.; Wang, Ji; Gaudi, B. S.; Cauley, P. W.; Eastman, J. D.; Ilyin, I.; Strassmeier, K.; Beatty, T. Bibcode: 2022yCat..51630040P Altcode: We observed two transits of KELT-9 b with the high-resolution echelle spectrograph Polarimetric and Spectroscopic Instrument (PEPSI) on the Large Binocular Telescope (LBT) (two 8.4m mirrors, effective aperture of 11.8m) in Arizona. PEPSI has a blue arm (nominally 3830-5440Å) and a red arm (nominally 5440-9070Å) with six cross-dispersers for full optical coverage. In this work, we use high-resolution data from the blue arm taken with cross-disperser 3 (~4750-5430Å, R=50000) exclusively because of negligible telluric contamination.

In this work, we apply the classical techniques used to analyze SB2s to the KELT-9 system using observations from PEPSI spectrograph on LBT and the HARPS-N spectrograph on the Telescopio Nazionale Galileo (TNG). We utilize the original Tillinghast Reflector Echelle Spectrograph (TRES) data (Gaudi+, 2017Natur.546..514G) as well as additional velocities from higher-precision spectrographs.

(1 data file). Title: Variable and Supersonic Winds in the Atmosphere of an Ultrahot Giant Planet Authors: Pai Asnodkar, Anusha; Wang, Ji; Eastman, Jason D.; Cauley, P. Wilson; Gaudi, B. Scott; Ilyin, Ilya; Strassmeier, Klaus Bibcode: 2022AJ....163..155P Altcode: 2022arXiv220104154P Hot Jupiters (HJs) receive intense irradiation from their stellar hosts. The resulting extreme environments in their atmospheres allow us to study the conditions that drive planetary atmospheric dynamics, e.g., global-scale winds. General circulation models predict day-to-nightside winds and equatorial jets with speeds of the order of a few km s-1. To test these models, we apply high-resolution transmission spectroscopy using the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) spectrograph on the Large Binocular Telescope to study the atmosphere of KELT-9 b, an ultrahot Jupiter and currently the hottest known planet. We measure ~10 km s-1 day-to-nightside winds traced by Fe II features in the planet's atmosphere. This is at odds with previous literature (including data taken with PEPSI), which report no significant day-to-nightside winds on KELT-9 b. We identify the cause of this discrepancy as due to an inaccurate ephemeris for KELT-9 b in previous literature. We update the ephemeris, which shifts the midtransit time by up to 10 minutes for previous data sets, resulting in consistent detections of blueshifts in all the data sets analyzed here. Furthermore, a comparison with archival data sets from the High-accuracy Radial velocity Planet Searcher for the Northern hemisphere suggests a temporal wind variability of ~5-8 km s-1 over timescales between weeks to years. Temporal variability of atmospheric dynamics on HJs is a phenomenon anticipated by certain general circulation models that has not been observed over these timescales until now. However, such large variability as we measure on KELT-9 b challenges general circulation models, which predict much lower amplitudes of wind variability over timescales between days to weeks. Title: KELT-9 as an Eclipsing Double-lined Spectroscopic Binary: A Unique and Self-consistent Solution to the System Authors: Pai Asnodkar, Anusha; Wang, Ji; Gaudi, B. Scott; Cauley, P. Wilson; Eastman, Jason D.; Ilyin, Ilya; Strassmeier, Klaus; Beatty, Thomas Bibcode: 2022AJ....163...40P Altcode: 2021arXiv211015275P Transiting hot Jupiters present a unique opportunity to measure absolute planetary masses due to the magnitude of their radial velocity signals and known orbital inclination. Measuring planet mass is critical to understanding atmospheric dynamics and escape under extreme stellar irradiation. Here we present the ultrahot Jupiter system KELT-9 as a double-lined spectroscopic binary. This allows us to directly and empirically constrain the mass of the star and its planetary companion without reference to any theoretical stellar evolutionary models or empirical stellar scaling relations. Using data from the PEPSI, HARPS-N, and TRES spectrographs across multiple epochs, we apply least-squares deconvolution to measure out-of-transit stellar radial velocities. With the PEPSI and HARPS-N data sets, we measure in-transit planet radial velocities using transmission spectroscopy. By fitting the circular orbital solution that captures these Keplerian motions, we recover a planetary dynamical mass of 2.17 ± 0.56 M J and stellar dynamical mass of 2.11 ± 0.78 M ⊙, both of which agree with the discovery paper. Furthermore, we argue that this system, as well as systems like it, are highly overconstrained, providing multiple independent avenues for empirically cross-validating model-independent solutions to the system parameters. We also discuss the implications of this revised mass for studies of atmospheric escape. Title: Detection capability of ground-based meter-sized telescopes for shallow exoplanet transits Authors: Mallonn, M.; Poppenhaeger, K.; Granzer, T.; Weber, M.; Strassmeier, K. G. Bibcode: 2022A&A...657A.102M Altcode: 2021arXiv211014344M Meter-sized ground-based telescopes are frequently used today for the follow-up of extrasolar planet candidates. While the transit signal of a Jupiter-sized object can typically be detected to a high level of confidence with small telescope apertures as well, the shallow transit dips of planets with the size of Neptune and smaller are more challenging to reveal. We employ new observational data to illustrate the photometric follow-up capabilities of meter-sized telescopes for shallow exoplanet transits. We describe in detail the capability of distinguishing the photometric signal of an exoplanet transit from an underlying trend in the light curve. The transit depths of the six targets we observed, Kepler-94b, Kepler-63b, K2-100b, K2-138b, K2-138c, and K2-138e, range from 3.9 ppt down to 0.3 ppt. For five targets of this sample, we provide the first ground-based photometric follow-up. The timing of three targets is precisely known from previous observations, and the timing of the other three targets is uncertain and we aim to constrain it. We detect or rule out the transit features significantly in single observations for the targets that show transits of 1.3 ppt or deeper. The shallower transit depths of two targets of 0.6 and 0.8 ppt were detected tentatively in single light curves, and were detected significantly by repeated observations. Only for the target of the shallowest transit depth of 0.3 ppt were we unable to draw a significant conclusion despite combining five individual light curves. An injection-recovery test on our real data shows that we detect transits of 1.3 ppt depth significantly in single light curves if the transit is fully covered, including out-of-transit data toward both sides, in some cases down to 0.7 ppt depth. For Kepler-94b, Kepler-63b, and K2-100b, we were able to verify the ephemeris. In the case of K2-138c with a 0.6 ppt deep transit, we were able to refine it, and in the case of K2-138e, we ruled out the transit in the time interval of more than ±1.5 σ of its current literature ephemeris.

Reduced light curves are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/657/A102

Based on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated by AIP and IAC. Title: Letter from the Editor 2022 Authors: Strassmeier, Klaus G. Bibcode: 2022AN....34328001S Altcode: No abstract at ADS Title: A detailed understanding of the rotation-activity relationship using the 300 Myr old open cluster NGC 3532 Authors: Fritzewski, D. J.; Barnes, S. A.; James, D. J.; Järvinen, S. P.; Strassmeier, K. G. Bibcode: 2021A&A...656A.103F Altcode: 2021arXiv211203302F Context. The coeval stars of young open clusters provide insights into the formation of the rotation-activity relationship that elude studies of multi-age field populations.
Aims: We measure the chromospheric activity of cool stars in the 300 Myr old open cluster NGC 3532 in concert with their rotation periods to study the mass-dependent morphology of activity for this transitional coeval population.
Methods: Using multi-object spectra of the Ca II infrared triplet region obtained with the AAOmega spectrograph at the 4 m Anglo-Australian Telescope, we measure the chromospheric emission ratios RIRT' for 454 FGKM cluster members of NGC 3532.
Results: The morphology of activity against colour appears to be a near-mirror image of the cluster's rotational behaviour. In particular, we identify a group of `desaturated transitional rotators' that branches off from the main group of unsaturated FGK slow rotators, and from which it is separated by an `activity gap'. The few desaturated gap stars are identical to the ones in the rotational gap. Nevertheless, the rotation-activity diagram is completely normal. In fact, the relationship is so tight that it allows us to predict rotation periods for many additional stars. We then precisely determine these periods from our photometric light curves, allowing us to construct an enhanced colour-period diagram that represents 66% of the members in our sample. Our activity measurements show that all fast rotators of near-solar mass (F-G type) have evolved to become slow rotators, demonstrating that the absence of fast rotators in a colour-period diagram is not a detection issue but an astrophysical fact. We also identify a new population of low-activity stars among the early M dwarfs, enabling us to populate the extended slow rotator sequence in the colour-period diagram.
Conclusions: The joint analysis of chromospheric activity and photometric time series data thus enables comprehensive insights into the evolution of the rotation and activity of stars during the transitional phase between the Pleiades and Hyades ages.

Full Table 1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/656/A103

Based on data acquired through the Australian Astronomical Observatory, under program S/2017A/02.

Based on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, under proposal 2008A-0476. Title: Rapid contraction of giant planets orbiting the 20-million-year-old star V1298 Tau Authors: Suárez Mascareño, A.; Damasso, M.; Lodieu, N.; Sozzetti, A.; Béjar, V. J. S.; Benatti, S.; Zapatero Osorio, M. R.; Micela, G.; Rebolo, R.; Desidera, S.; Murgas, F.; Claudi, R.; González Hernández, J. I.; Malavolta, L.; del Burgo, C.; D'Orazi, V.; Amado, P. J.; Locci, D.; Tabernero, H. M.; Marzari, F.; Aguado, D. S.; Turrini, D.; Cardona Guillén, C.; Toledo-Padrón, B.; Maggio, A.; Aceituno, J.; Bauer, F. F.; Caballero, J. A.; Chinchilla, P.; Esparza-Borges, E.; González-Álvarez, E.; Granzer, T.; Luque, R.; Martín, E. L.; Nowak, G.; Oshagh, M.; Pallé, E.; Parviainen, H.; Quirrenbach, A.; Reiners, A.; Ribas, I.; Strassmeier, K. G.; Weber, M.; Mallonn, M. Bibcode: 2022NatAs...6..232S Altcode: 2021NatAs...6..232S; 2021NatAs.tmp..252S; 2021arXiv211109193S; 2021NatAs.tmp..234S Current theories of planetary evolution predict that infant giant planets have large radii and very low densities before they slowly contract to reach their final size after about several hundred million years1,2. These theoretical expectations remain untested so far as the detection and characterization of very young planets is extremely challenging due to the intense stellar activity of their host stars3,4. Only the recent discoveries of young planetary transiting systems allow initial constraints to be placed on evolutionary models5-7. With an estimated age of 20 million years, V1298 Tau is one of the youngest solar-type stars known to host transiting planets; it harbours a system composed of four planets, two Neptune-sized, one Saturn-sized and one Jupiter-sized8,9. Here we report a multi-instrument radial velocity campaign of V1298 Tau, which allowed us to determine the masses of two of the planets in the system. We find that the two outermost giant planets, V1298 Tau b and e (0.64 ± 0.19 and 1.16 ± 0.30 Jupiter masses, respectively), seem to contradict our knowledge of early-stages planetary evolution. According to models, they should reach their mass-radius combination only hundreds of millions of years after formation. This result suggests that giant planets can contract much more quickly than usually assumed. Title: VizieR Online Data Catalog: Searching transiting planets around halo stars. I. (Kolecki+, 2021) Authors: Kolecki, J. R.; Wang, J.; Johnson, J. A.; Zinn, J. C.; Ilyin, I.; Strassmeier, K. G. Bibcode: 2021yCat..51620125K Altcode: Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) spectrograph is located at the Large Binocular Telescope (LBT, 2x8.4m on Mt. Graham, Arizona, USA). LBT PEPSI observations were made on 2019 March 25, May 15, June 23, and June 25, UT with 200μm fiber (R=130000 and 1.75" on sky) in two spectral regions 4800-5441Å and 6278-7419Å (cross-dispersers (CD) 3 and 5) with 10-60minutes integration time depending on the star brightness.

(2 data files). Title: VizieR Online Data Catalog: NGC 3532 stars chromospheric activity (Fritzewski+, 2021) Authors: Fritzewski, D. J.; Barnes, S. A.; James, D. J.; Jarvinen, S. P.; Strassmeier, K. G. Bibcode: 2021yCat..36560103F Altcode: Measurements of chromospheric activity for cool star members of the open cluster NGC 3532. In addition to the equivalent widths and chromospheric emission ratios, the table contains photometric rotation periods for 258 stars.

(1 data file). Title: The rapidly oscillating Ap star γ Equ: linear polarization as an enhanced pulsation diagnostic? Authors: Hubrig, S.; Järvinen, S. P.; Ilyin, I.; Strassmeier, K. G.; Schöller, M. Bibcode: 2021MNRAS.508L..17H Altcode: 2021MNRAS.tmpL..86H; 2021arXiv210811272H We present the first short time-scale observations of the rapidly oscillating Ap (roAp) star γ Equ in linear polarized light obtained with the Potsdam Echelle Polarimetric and Spectroscopic Instrument installed at the Large Binocular Telescope. These observations are used to search for pulsation variability in Stokes Q and U line profiles belonging to different elements. The atmospheres of roAp stars are significantly stratified with spectral lines of different elements probing different atmospheric depths. roAp stars with strong magnetic fields, such as γ Equ with a magnetic field modulus of 4 kG and a pulsation period of 12.21 min, are of special interest because the effect of the magnetic field on the structure of their atmospheres can be studied with greatest detail and accuracy. Our results show that we may detect changes in the transversal field component in Fe I and rare earth element lines possessing large second-order Landé factors. Such variability can be due to the impact of pulsation on the transverse magnetic field, causing changes in the obliquity angles of the magnetic force lines. Further studies of roAp stars in linear polarized light and subsequent detailed modelling are necessary to improve our understanding of the involved physics. Title: VizieR Online Data Catalog: Transit events of 4 extrasolar planets (Mallonn+, 2022) Authors: Mallonn, M.; Poppenhaeger, K.; Granzer, T.; Weber, M.; Strassmeier, K. G. Bibcode: 2021yCat..36570102M Altcode: We obtained 19 photometric time series of transit events and employed them to describe the detection capability of ground-based meter-sized telescopes for shallow exoplanet transits on observational data. At second, we verified or refined the orbital ephemeris of several exoplanets.

We present 19 differential photometry time series of transit events of different extrasolar planets.

(2 data files). Title: Searching For Transiting Planets Around Halo Stars. I. Sample Selection and Validation Authors: Kolecki, Jared R.; Wang, Ji; Johnson, Jennifer A.; Zinn, Joel C.; Ilyin, Ilya; Strassmeier, Klaus G. Bibcode: 2021AJ....162..125K Altcode: 2021arXiv210613251K By measuring the elemental abundances of a star, we can gain insight into the composition of its initial gas cloud-the formation site of the star and its planets. Planet formation requires metals, the availability of which is determined by the elemental abundance. In the case where metals are extremely deficient, planet formation can be stifled. To investigate such a scenario requires a large sample of metal-poor stars and a search for planets therein. This paper focuses on the selection and validation of a halo star sample. We select ~17,000 metal-poor halo stars based on their Galactic kinematics, and confirm their low metallicities ([Fe/H] < -0.5), using spectroscopy from the literature. Furthermore, we perform high-resolution spectroscopic observations using LBT/PEPSI and conduct detailed metallicity ([Fe/H]) analyses on a sample of 13 previously-known halo stars that also have hot kinematics. We can use the halo star sample presented here to measure the frequency of planets and to test planet formation in extremely metal-poor environments. The result of the planet search and its implications will be presented and discussed in a companion paper by Boley et al. Title: H-α Variability of V1298 Tau c Authors: Schlawin, Everett; Ilyin, Ilya; Feinstein, Adina D.; Bean, Jacob; Huang, Chenliang; Gao, Peter; Strassmeier, Klaus; Poppenhaeger, Katja Bibcode: 2021RNAAS...5..195S Altcode: 2021arXiv210808851S The 23 Myr system V1298 Tau hosts four transiting planets and is a valuable laboratory for exploring the early stages of planet evolution soon after formation of the star. We observe the innermost planet, V1298 Tau c, during transit using LBT PEPSI to obtain high spectral resolution characterization of escaping material near the H-α line. We find no strong evidence for atmospheric material escaping at the orbital velocity of the planet. Instead, we find a deep stellar feature that is variable on the few percent level, similar to a previous observation of the planet and can be explained by stellar activity. We attempted to monitor the broadband optical transit with LBT MODS but do not achieve the precision needed to characterize the atmosphere or improve the ephemeris. Title: Rotation periods for cool stars in the open cluster NGC 3532. The transition from fast to slow rotation Authors: Fritzewski, D. J.; Barnes, S. A.; James, D. J.; Strassmeier, K. G. Bibcode: 2021A&A...652A..60F Altcode: 2021arXiv211203300F Context. A very rich cluster intermediate in age between the Pleiades (150 Myr) and the Hyades (600 Myr) is needed to probe the rotational evolution, especially the transition between fast and slow rotation that occurs between the two ages.
Aims: We study the rich 300 Myr-old open cluster NGC 3532 to probe this important transition and to provide constraints on angular momentum loss. Measuring the rotation periods builds on our prior work of providing spectroscopic membership information for the cluster, and it supports the chromospheric activity measurements of cluster stars that we provide in a companion paper.
Methods: Using 42 d-long photometric time series observations obtained with the Yale 1 m telescope at CTIO, we measured rotation periods for members of NGC 3532 and compared them with the predictions of angular momentum evolution models.
Results: We directly measured 176 photometric rotation periods for the cluster members. An additional 113 photometric rotation periods were identified using activity information, described fully in the companion paper, resulting in a total sample containing 279 rotation periods for FGKM stars in NGC 3532. The colour-period diagram constructed from this rich data set shows a well-populated and structured slow rotator sequence, and a fast rotator sequence evolved beyond zero-age main sequence age whose stars are in transition from fast to slow rotation. The slow rotator sequence itself is split into slightly slower and faster rotators, a feature we trace to photometric binary status. We also identify an extended slow rotator sequence extending to P ∼ 32 d, apparently the analogue of the one we previously identified in NGC 2516. We compare our period distribution to rotational isochrones in colour-period space and find that all considered models have certain shortcomings. Using more detailed spin-down models, we evolve the rotation periods of the younger NGC 2516 forward in time and find that the spindown of the models is too aggressive with respect to the slow rotators. In contrast, stars on the evolved fast rotator sequence are not spun down strongly enough by these models. Our observations suggest a shorter crossing time for the rotational gap, one we estimate to be ∼80 Myr for early-K dwarfs.

Full Table 2 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/652/A60

Based on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory under proposal 2008A-0476. Title: VizieR Online Data Catalog: Rotation periods for NGC 3532 (Fritzewski+, 2021) Authors: Fritzewski, D. J.; Barnes, S. A.; James, D. J.; Strassmeier, K. G. Bibcode: 2021yCat..36520060F Altcode: The table contains the rotation periods and photometric colours for 279 solar-like members of the open cluster NGC 3532. Each star is cross-matched to Gaia DR2. The possible binarity status (from photometry and astrometry) is given.

(1 data file). Title: Further Optical Spectroscopic Observations of V1674 Herculis Authors: Woodward, C. E.; Wagner, R. M.; Starrfield, S.; Kumar, V.; Srivastava, M.; Banerjee, D. P. K.; Joshi, V.; IIyin, I.; Strassmeier, K. G.; Evans, A. Bibcode: 2021ATel14723....1W Altcode: We report optical spectroscopic observations of the very fast nova V1674 Her (TCP J18573095+1653396) between 2021 June 13 to 15, obtained at R = 1700 using the Blue Channel spectrograph (Schmidt et al. 1989, PASP 101, 713) on the 6.5-m MMT, Mt. Hopkins, AZ, at high resolution (R = 220 000) using PEPSI (Strassmeier et al. 2015, Aston. Title: Betelgeuse: An Iconic and Surprising Red Supergiant Authors: Dupree, Andrea; Anugu, Narsireddy; Calderwood, Thomas; Cannon, Emily; Granzer, Thomas; Kervella, Pierre; Kravchenko, Kateryna; Matthews, Lynn D.; Montarges, Miguel; Quirrenbach, Andreas; Rau, Gioia; Richards, Anita; Strassmeier, Klaus G.; Thompson, William T.; Van Eck, Sophie; jorissen, alain Bibcode: 2021hst..prop16655D Altcode: Multiple ultraviolet spectra of the nearby red supergiant, Betelgeuse, using STIS will enable unique spatially resolved measures of photospheric and chromospheric structure and mass inflows and outflows. This follows the historic dimming of the star captured by HST/STIS in 2019-2020, and will probe the unusual atmospheric structure following the dimming event. An HST campaign of 2 cycles will be complemented by multi-frequency photometry, spectroscopy, interferometry and polarimetry at radio, infrared, and optical wavelengths in order to map surface structures and their variability, and the extended outer atmosphere over both the short (420-day) and long, secondary (2000-day) periods of this supergiant. These observations, coupled with detailed modeling and simulations. will probe the structure, dynamics, and mass loss from Betelgeuse to provide crucial insights into the atmospheric physics and wind-driving mechanisms of red supergiants. Title: A unicorn in monoceros: the 3 M⊙ dark companion to the bright, nearby red giant V723 Mon is a non-interacting, mass-gap black hole candidate Authors: Jayasinghe, T.; Stanek, K. Z.; Thompson, Todd A.; Kochanek, C. S.; Rowan, D. M.; Vallely, P. J.; Strassmeier, K. G.; Weber, M.; Hinkle, J. T.; Hambsch, F. -J.; Martin, D. V.; Prieto, J. L.; Pessi, T.; Huber, D.; Auchettl, K.; Lopez, L. A.; Ilyin, I.; Badenes, C.; Howard, A. W.; Isaacson, H.; Murphy, S. J. Bibcode: 2021MNRAS.504.2577J Altcode: 2021arXiv210102212J We report the discovery of the closest known black hole candidate as a binary companion to V723 Mon. V723 Mon is a nearby ($d\sim 460\, \rm pc$), bright (V ≃ 8.3 mag), evolved (Teff, giant ≃ 4440 K, and Lgiant ≃ 173 L⊙) red giant in a high mass function, f(M) = 1.72 ± 0.01 M⊙, nearly circular binary (P = 59.9 d, e ≃ 0). V723 Mon is a known variable star, previously classified as an eclipsing binary, but its All-Sky Automated Survey, Kilodegree Extremely Little Telescope, and Transiting Exoplanet Survey Satellite light curves are those of a nearly edge-on ellipsoidal variable. Detailed models of the light curves constrained by the period, radial velocities, and stellar temperature give an inclination of $87.0^{\circ ^{+1.7^\circ }}_{-1.4^\circ }$, a mass ratio of q ≃ 0.33 ± 0.02, a companion mass of Mcomp = 3.04 ± 0.06 M⊙, a stellar radius of Rgiant = 24.9 ± 0.7 R⊙, and a giant mass of Mgiant = 1.00 ± 0.07 M⊙. We identify a likely non-stellar, diffuse veiling component with contributions in the B and V band of ${\sim }63{{\ \rm per\ cent}}$ and ${\sim }24{{\ \rm per\ cent}}$, respectively. The SED and the absence of continuum eclipses imply that the companion mass must be dominated by a compact object. We do observe eclipses of the Balmer lines when the dark companion passes behind the giant, but their velocity spreads are low compared to observed accretion discs. The X-ray luminosity of the system is $L_{\rm X}\simeq 7.6\times 10^{29}~\rm ergs~s^{-1}$, corresponding to L/Ledd ~ 10-9. The simplest explanation for the massive companion is a single compact object, most likely a black hole in the 'mass gap'. Title: Space Photometry with Brite-Constellation Authors: Weiss, Werner W.; Zwintz, Konstanze; Kuschnig, Rainer; Handler, Gerald; Moffat, Anthony F. J.; Baade, Dietrich; Bowman, Dominic M.; Granzer, Thomas; Kallinger, Thomas; Koudelka, Otto F.; Lovekin, Catherine C.; Neiner, Coralie; Pablo, Herbert; Pigulski, Andrzej; Popowicz, Adam; Ramiaramanantsoa, Tahina; Rucinski, Slavek M.; Strassmeier, Klaus G.; Wade, Gregg A. Bibcode: 2021Univ....7..199W Altcode: 2021arXiv210612952W BRITE-Constellation is devoted to high-precision optical photometric monitoring of bright stars, distributed all over the Milky Way, in red and/or blue passbands. Photometry from space avoids the turbulent and absorbing terrestrial atmosphere and allows for very long and continuous observing runs with high time resolution and thus provides the data necessary for understanding various processes inside stars (e.g., asteroseismology) and in their immediate environment. While the first astronomical observations from space focused on the spectral regions not accessible from the ground it soon became obvious around 1970 that avoiding the turbulent terrestrial atmosphere significantly improved the accuracy of photometry and satellites explicitly dedicated to high-quality photometry were launched. A perfect example is BRITE-Constellation, which is the result of a very successful cooperation between Austria, Canada and Poland. Research highlights for targets distributed nearly over the entire HRD are presented, but focus primarily on massive and hot stars. Title: Letter from the Editor Authors: Strassmeier, Klaus G. Bibcode: 2021AN....342..606S Altcode: No abstract at ADS Title: The Curious Case of Betelgeuse Authors: Granzer, Thomas; Weber, Michael; Strassmeier, Klaus G.; Dupree, Andrea Bibcode: 2021csss.confE..41G Altcode: Since more than a decade, the AIP is monitoring (\alpha) Ori with its robotic spectroscopic facility STELLA/SES in Teide observatory, Tenerife along with its automated photoelectric telescope T7 in Fairborn observatory, Az. Additionally, we got access with exclusive two-band photometric data on Betelgeuse from the BRITE satellite consortium, covering the last seven seasons. In late 2019, Betelgeuse showed a rapid brightness decline, reaching an all-time low in Feb. 2020, followed by a quick re-brightening. This poster shows radial velocity data together with the photometry. The radial velocity follows the photometry in general, but sometimes shows a time-shift, which was particularly visible in the grand dimming event. Interesting is the time-frequency analysis of the different data set: All three show similar features at split-periods around the known P=420d. Title: Role of the impact parameter in exoplanet transmission spectroscopy Authors: Alexoudi, Xanthippi; Mallonn, Matthias; Keles, Engin; Poppenhäger, Katja; Strassmeier, Klaus Bibcode: 2021csss.confE...9A Altcode: Transmission spectroscopy is the widely used observational technique that exploits the planetary transit events with aim to characterize the exoplanetary atmospheres. While it already revealed atomic and molecular absorption, haze layers and thick clouds in about two dozen of objects, the literature presents some worthy mentioned discrepant results on individual targets. An example of controversial results in the literature is the case of HAT-P-12b, which I solved successfully during my studies. Intriguingly, two independent investigations from different groups, one with ground-based observations and one using the Hubble Space Telescope (HST), concluded to contradicting transmission spectra, interpreted from opaque clouds in the atmosphere to a Rayleigh scattering slope. The optical slope in this case is affected by the orbital parameters yielding to inconsistencies. I will present this degeneracy investigated for the entire parameter space with aim to ameliorate the quality of the scientific output. Title: Characterization of Chromospheric Activity Based on Sun-as-a-star Spectral and Disk-resolved Observations Authors: Dineva, Ekaterina; Pearson, Jeniveve; Verman, Meetu; Ilyin, Ilya; Strassmeier, Klaus G.; Denker, Carsten Bibcode: 2021csss.confE.130D Altcode: The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) is a state-of-the-art, thermally stabilized, fiber-fed, high-resolution spectrograph for the Large Binocular Telescope (LBT) at Mt. Graham, Arizona. It can be fed with sunlight from the Solar Disk-Integrated (SDI) telescope. Synoptic solar observations with PEPSI/SDI produce daily spectra with high signal-to-noise ratio, providing access to unprecedented, quasi-continuous, long-term, disk-integrated spectra of the Sun with high spectral and temporal resolution. The observed spectra contain a multitude of photospheric and chromospheric spectral lines in the wavelength range of 380 910 nm. Strong chromospheric absorption lines, such as the Ca II H & K lines, are powerful diagnostic tools for solar activity studies, since they trace the variations of the solar magnetic field. Derivation of activity indices, such as the Ca II H & K emission ratio S-index provides insight into the chromospheric magnetic field and its variability over the solar activity cycle. The well known relation between solar calcium indices and UV flux variations motivates us to compute an excess brightness indices from Ca II K full-disk images from of the Chromospheric Telescope (ChroTel) at the Observatory del Teide on Tenerife, Spain and UV data of the Solar Dynamics Observatory (SDO). We present a set of indices representing magnetic activity at various heights in the solar atmosphere. In the present work, we carefully compare the indices computed from various datasets and discuss the differences in terms of physical and observational properties. Title: HIRES, the High-resolution Spectrograph for the ELT Authors: Marconi, A.; Abreu, M.; Adibekyan, V.; Aliverti, M.; Allende Prieto, C.; Amado, P.; Amate, M.; Artigau, E.; Augusto, S.; Barros, S.; Becerril, S.; Benneke, B.; Bergin, E.; Berio, P.; Bezawada, N.; Boisse, I.; Bonfils, X.; Bouchy, F.; Broeg, C.; Cabral, A.; Calvo-Ortega, R.; Canto Martins, B. L.; Chazelas, B.; Chiavassa, A.; Christensen, L.; Cirami, R.; Coretti, I.; Covino, S.; Cresci, G.; Cristiani, S.; Cunha Parro, V.; Cupani, G.; de Castro Leão, I.; Renan de Medeiros, J.; Furlande Souza, M. A.; Di Marcantonio, P.; Di Varano, I.; D'Odorico, V.; Doyon, R.; Drass, H.; Figueira, P.; Belen Fragoso, A.; Uldall Fynbo, J. P.; Gallo, E.; Genoni, M.; González Hernández, J.; Haehnelt, M.; Hlavacek-Larrondo, J.; Hughes, I.; Huke, P.; Humphrey, A.; Kjeldsen, H.; Korn, A.; Kouach, D.; Landoni, M.; Liske, J.; Lovis, C.; Lunney, D.; Maiolino, R.; Malo, L.; Marquart, T.; Martins, C.; Mason, E.; Molaro, P.; Monnier, J.; Monteiro, M.; Mordasini, C.; Morris, T.; Mucciarelli, A.; Murray, G.; Niedzielski, A.; Nunes, N.; Oliva, E.; Origlia, L.; Pallé, E.; Pariani, G.; Parr-Burman, P.; Peñate, J.; Pepe, F.; Pinna, E.; Piskunov, N.; Rasilla Piñeiro, J. L.; Rebolo, R.; Rees, P.; Reiners, A.; Riva, M.; Romano, D.; Rousseau, S.; Sanna, N.; Santos, N.; Sarajlic, M.; Shen, T. -C.; Sortino, F.; Sosnowska, D.; Sousa, S.; Stempels, E.; Strassmeier, K.; Tenegi, F.; Tozzi, A.; Udry, S.; Valenziano, L.; Vanzi, L.; Weber, M.; Woche, M.; Xompero, M.; Zackrisson, E.; Zapatero Osorio, M. R. Bibcode: 2021Msngr.182...27M Altcode: 2020arXiv201112317M HIRES will be the high-resolution spectrograph at optical and near-infrared (NIR) wavelengths for ESO's Extremely Large Telescope (ELT). It will consist of three fibre-fed spectrographs providing a wavelength coverage of 0.4-1.8 µm (with a goal of 0.35-1.8 µm) at a spectral resolution of ~ 100 000. Fibre-feeding allows HIRES to have several interchangeable observing modes, including a single-conjugate adaptive optics (SCAO) module and a small diffraction-limited integral field unit in the NIR. It will therefore be able to operate in both seeing- and diffraction-limited modes. HIRES will address a wide range of science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Some of the top science cases will be the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars (Pop III), tests on the stability of Nature's fundamental couplings, and the direct detection of the cosmic acceleration. The HIRES consortium is composed of more than 30 institutes from 14 countries, forming a team of more than 200 scientists and engineers. Title: Time-resolved Rotational Velocities in the Upper Atmosphere of WASP-33 b Authors: Cauley, P. Wilson; Wang, Ji; Shkolnik, Evgenya L.; Ilyin, Ilya; Strassmeier, Klaus G.; Redfield, Seth; Jensen, Adam G. Bibcode: 2021AJ....161..152C Altcode: 2020arXiv201002118C While steady empirical progress has been made in understanding the structure and composition of hot-planet atmospheres, direct measurements of velocity signatures, including winds, rotation, and jets, have lagged behind. Quantifying atmospheric dynamics of hot planets is critical for a complete understanding of their atmospheres, and such measurements may even illuminate other planetary properties, such as magnetic field strengths. In this manuscript we present the first detection of the Balmer lines Hα and Hβ in the atmosphere of the ultra-hot Jupiter WASP-33 b. Using atmospheric models that include the effects of atmospheric dynamics, we show that the shape of the average Balmer line transmission spectrum is consistent with rotational velocities in the planet's thermosphere of ${v}_{\mathrm{rot}}={10.1}_{-1.0}^{+0.8}$ km s-1. We also measure a low-significance day- to nightside velocity shift of $-{4.6}_{-3.4}^{+3.4}$ km s-1 in the transmission spectrum, which is naturally explained by a global wind across the planet's terminator. In a separate analysis the time-resolved velocity centroids of individual transmission spectra show unambiguous evidence of rotation, with a best-fit velocity of ${10.0}_{-2.0}^{+2.4}$ km s-1, consistent with the value of vrot derived from the shape of the average Balmer line transmission spectrum. Our observations and analysis confirm the power of time-resolved transmission spectra with a high signal-to-noise ratio to measure the velocity structures in exoplanet atmospheres. The high rotational and wind velocities we measure highlight the need for more detailed 3D global climate simulations of the rarefied upper atmospheres of ultra-hot gas giants. * Based on data acquired with PEPSI using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are the University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Leibniz-Institute for Astrophysics Potsdam (AIP), and Heidelberg University; the Ohio State University; and the Research Corporation, on behalf of the University of Notre Dame, University of Minnesota and University of Virginia. Title: ELT-HIRES the High Resolution Spectrograph for the ELT: status of the polarization ray tracing tool for the polarimetric unit Authors: Di Varano, I.; Yuan, S.; Woche, M.; Strassmeier, K. G.; Weber, M. Bibcode: 2020SPIE11451E..4GD Altcode: ELT-HIRES (High Resolution Spectrograph for the Extremely Large Telescope) is a multifold fiber-fed spectrograph planned for the Nasmyth B focal station on ELT, covering a wavelength range between 0.4 and 1.8 μ. One of the most relevant science cases is represented by the detection of life signature in the extrasolar atmospheres for Earth-like planets. The polarimetric unit, feeding the UBVRI and the zYJH spectrograph modules, will consist of two subassemblies: the main one, aimed to be installed in the intermediate focus, will host the polarizer (a double Wollaston calcite prism) and the retarder plates splitting the optical beam into the four Stokes vector components; the other will be located in one of the four dedicated arms of the Front End on the Nasmyth platform, providing the atmospheric dispersion correction, field stabilization and selection of the operating modes before the fiber injection. At the conclusion of Phase A, we have presented this as the optimal design solution fulfilling the top level requirement of reaching a sensitivity of 10-5 S/I (S being equivalent to one of the Stokes vectors), a condition achievable only if the polarizers are installed in a rotationally symmetric focus. The current work, which can be considered a continuation of two preceding papers, illustrates new simulation results from the development of the polarization-ray-tracing tool. We have included also the crystal anisotropic properties of the polarizing components, analyzing the transmission loss that the light beam encounters propagating through the optical train before entering the fiber bundles in the different operating modes, bearing in mind the polarimetric aberrations induced by the active compensation of the primary mirror and the loads contributing as Zernike polynomials of different orders, namely the telescope cross-talk. Title: BRITE photometry and STELLA spectroscopy of bright stars in Auriga: Rotation, pulsation, orbits, and eclipses⋆ Authors: Strassmeier, K. G.; Granzer, T.; Weber, M.; Kuschnig, R.; Pigulski, A.; Popowicz, A.; Moffat, A. F. J.; Wade, G. A.; Zwintz, K.; Handler, G. Bibcode: 2020A&A...644A.104S Altcode: 2020arXiv201010092S Context. Knowing rotational and pulsational periods across the Hertzsprung-Russell diagram is of top priority for understanding stellar activity as a function of time.
Aims: We aim to determine periods for bright stars in the Auriga field that are otherwise not easily accessible for ground-based photometry.
Methods: Continuous photometry with up to three BRITE satellites was obtained for 12 targets and subjected to a period search. Contemporaneous high-resolution optical spectroscopy with STELLA was used to obtain radial velocities through cross correlation with template spectra as well as to determine astrophysical parameters through a comparison with model spectra.
Results: The Capella red light curve was found to be constant over 176 days with a root mean square of 1 mmag, but the blue light curve showed a period of 10.1 ± 0.6 d, which we interpret to be the rotation period of the G0 component. From STELLA we obtained an improved orbital solution based on 9600 spectra from the previous 12.9 yr. We derive masses precise to ≈0.3% but 1% smaller than previously published. The BRITE light curve of the F0 supergiant ɛ Aur suggests 152 d as its main pulsation period, while the STELLA radial velocities reveal a clear 68 d period. An ingress of an eclipse of the ζ Aur binary system was covered with BRITE and a precise timing for its eclipse onset derived. A possible 70 d period fits the proposed tidal-induced, nonradial pulsations of this ellipsoidal K4 supergiant. η Aur is identified as a slowly pulsating B (SPB) star with a main period of 1.29 d and is among the brightest SPB stars discovered so far. The rotation period of the magnetic Ap star θ Aur is detected from photometry and spectroscopy with a period of 3.6189 d and 3.6177 d, respectively, likely the same within the errors. The radial velocities of this star show a striking non-sinusoidal shape with a large amplitude of 7 km s-1. Photometric rotation periods are also confirmed for the magnetic Ap star IQ Aur of 2.463 d and for the solar-type star κ1 Cet of 9.065 d, and also for the B7 HgMn giant β Tau of 2.74 d. Revised orbital solutions are derived for the eclipsing SB2 binary β Aur, which replaces the initial orbit dating from 1948 for the 27-year eclipsing SB1 ɛ Aur, and for the RS CVn binary V711 Tau, for which a spot-corrected orbital solution was achieved. The two stars ν Aur and ι Aur are found to be long-term, low-amplitude RV and brightness variables, but provisional orbital elements based on a period of 20 yr and an eccentricity of 0.7 could only be extracted for ν Aur. The variations of ι Aur are due to oscillations with a period of ≈4 yr.

The data used in this paper 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/644/A104

Based on data obtained with the BRITE-Constellation satellite and the STELLA robotic telescope in Tenerife. BRITE (BRIght Target Explorer) Constellation was designed, built, launched, operated, and supported by the Austrian Research Promotion Agency (FFG), the University of Vienna, the Technical University of Graz, the University of Innsbruck, the Canadian Space Agency (CSA), the University of Toronto Institute for Aerospace Studies (UTIAS), the Foundation for Polish Science & Technology (FNiTP MNiSW), and National Science Centre (NCN). Title: Using raytracing to derive the expected performance of STELLA's SES-VIS spectrograph Authors: Weber, Michael; Strassmeier, Klaus G.; Woche, Manfred; Ilyin, Ilya; Järvinen, Arto Bibcode: 2020SPIE11450E..1CW Altcode: 2020arXiv201208218W The new visual STELLA echelle spectrograph (SES-VIS) is a new instrument for the STELLA-II telescope at the Iza~na observatory on Tenerife. Together with the original SES spectrograph - which will still be used in the near IR - and a new H&K-optimized spectrograph, which is currently in the design phase, it will change the focus of the spectroscopic observations at STELLA towards the follow up of planetary candidates detected by upcoming surveys focusing on bright targets (TESS, PLATO2). It is optimized for precise radial velocity determination and long term stability. We have developed a ZEMAX based software package to create simulated spectra, which are then extracted using our new reduction package, which is based on the PEPSI software package. The focus has been put on calibration spectra, and the full range of available calibration sources (at field, Th-Ar, and Fabry-Perot), which can be compared to actual commissioning data once they are available. Furthermore we tested for the effect of changes of the environmental parameters to the wavelength calibration precision. Title: On the binary orbit of Henry Draper one ( HD 1) Authors: Strassmeier, Klaus G.; Weber, Michael Bibcode: 2020AN....341..983S Altcode: 2020arXiv201113330S We present our final orbit for the late type spectroscopic binary Henry Draper one (HD 1). area total of 553 spectra from 13 years of observations are used with our robotic STELLA facility and its high resolution echelle spectrograph SES. Its long term radial velocity stability is ≈50 m s-1. A single radial velocity of HD 1 reached an rms residual of 63 m s-1, close to the expected precision. Spectral lines of HD 1 are rotationally broadened with a v sin i of 9.1 ± 0.1 km s-1. The overall spectrum appears single lined and yielded an orbit with an eccentricity of 0.5056 ± 0.0005 and a semiamplitude of 4.44 km s-1. We constrain and refine the orbital period based on the SES data alone to 2, 318.70 ± 0.32 days, compared to 2, 317.8 ± 1.1 days when including the older dataset published by DAO and Cambridge/Coravel. Owing to the higher precision of the SES data, we base the orbit calculation only on the STELLA/SES velocities so as to not degrade its solution. We redetermine astrophysical parameters for HD 1 from spectrum synthesis and, together with the new Gaia DR 2 parallax, suggest a higher luminosity than published previously. We conclude that HD 1 is a slightly metal deficient K0 III II giant 217 times more luminous than the Sun. The secondary remains invisible at optical wavelengths. We present evidence for the existence of a third component. Title: ELT-HIRES, the high resolution spectrograph for the ELT: the Phase A study and the path to construction Authors: Marconi, A.; Abreu, M.; Adibekyan, V.; Aliverti, M.; Allende Prieto, C.; Amado, P.; Amate, M.; Artigau, E.; Augusto, S.; Barros, S.; Becerril, S.; Benneke, B.; Bergin, E.; Berio, P.; Bezawada, N.; Boisse, I.; Bonfils, X.; Bouchy, F.; Broeg, C.; Cabral, A.; Calvo-Ortega, R.; Canto Martins, B. L.; Chazelas, B.; Chiavassa, A.; Christensen, L.; Cirami, R.; Coretti, I.; Covino, S.; Cresci, G.; Cristiani, S.; Cunha Parro, V.; Cupani, G.; D'Odorico, V.; de Castro Leão, I.; de Medeiros, J. R.; de Souza, M.; Di Marcantonio, P.; Di Varano, I.; Doyon, R.; Drass, H.; Figueira, P.; Fragoso, A.; Fynbo, J.; Gallo, E.; Genoni, M.; González Hernández, J.; Gratton, R.; Haehnelt, M.; Hansen, C.; Hlavacek-Larrondo, J.; Hughes, I.; Huke, P.; Humphrey, A.; Kjeldsen, H.; Korn, A.; Kouach, D.; Landoni, M.; Liske, J.; Lovis, C.; Lunney, D.; Maiolino, R.; Malo, L.; Marquart, T.; Martins, C. J. A. P.; Maslowski, P.; Mason, E.; Micela, G.; Molaro, P.; Monnier, J.; Monteiro, M.; Mordasini, C.; Morris, T.; Mucciarelli, A.; Murray, G.; Niedzielski, A.; Niemczura, E.; Nisini, B.; Nunes, N.; Oliva, E.; Origlia, L.; Pallé, E.; Pariani, G.; Parr-Burman, P.; Pasquini, L.; Peñate, J.; Pepe, F.; Pietrzynski, G.; Pinna, E.; Piskunov, N.; Pollo, A.; Rasilla, J.; Rebolo, R.; Rees, P.; Reiners, A.; Riva, M.; Romano, D.; Rousseau, S.; Sanna, N.; Sarajlic, M.; Shen, T. -C.; Sortino, F.; Sosnowska, D.; Sousa, S.; Stempels, E.; Strassmeier, K.; Tenegi, F.; Tozzi, A.; Udry, S.; Valenziano, L.; Vanzi, L.; Weber, M.; Woche, M.; Xompero, M.; Zackrisson, E.; Zapatero Osorio, M. R. Bibcode: 2020SPIE11447E..26M Altcode: HIRES is the high-resolution spectrograph of the European Extremely Large Telescope at optical and near-infrared wavelengths. It consists of three fibre-fed spectrographs providing a wavelength coverage of 0.4-1.8 µm (goal 0.35-2.4 µm) at a spectral resolution of 100,000. The fibre-feeding allows HIRES to have several, interchangeable observing modes including a SCAO module and a small diffraction-limited IFU in the NIR. Therefore, it will be able to operate both in seeing- and diffraction-limited modes. Its modularity will ensure that HIRES can be placed entirely on the Nasmyth platform, if enough mass and volume is available, or part on the Nasmyth and part in the Coud`e room. ELT-HIRES has a wide range of science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars (PopIII), tests on the stability of Nature's fundamental couplings, and the direct detection of the cosmic acceleration. The HIRES consortium is composed of more than 30 institutes from 14 countries, forming a team of more than 200 scientists and engineers. Title: Second generation spectroscopic instrumentation for the STELLA robotic observatory Authors: Weber, Michael; Woche, Manfred; Strassmeier, Klaus G.; Ilyin, Ilya; Järvinen, Arto Bibcode: 2020SPIE11449E..0JW Altcode: 2020arXiv201208210W The current STELLA Échelle spectrograph (SES), which records 390nm to 870nm in one shot at a spectral resolution of 55000, will be replaced by a suite of specialized spectrographs in three spectral bands. The UV will be covered by a newly designed H and K spectrograph covering 380nm to 470nm (SES-H and K), the visual band (470nm - 690 nm) will be covered by SES-VIS, which is a vacuum-stabilized spectrograph designed for high radial-velocity accuracy, and the NIR will be covered by the current SES spectrograph from 690nm to 1050 nm. In order to improve the UV transmission, and to accommodate three different fibre-feeds, the prime focus corrector of the telescope will be refurbished, leading to an optical system with the f/2 1200mm spherical primary, a 4-lens collimator with 2" aperture, atmospheric dispersion corrector (ADC), and two dichroic beam splitters, feeding 3 separate fibre feeds for the three bands. The newly designed H and K spectrograph will be an Échelle spectrograph, based on a R4-grating with 41.6 l/mm and 110mmx420mm, using a f/5 camera and the cross-disperser in double pass (as in TRAFICOS, MIKE, KPF), using 21 spectral orders. The spectral resolution of all three spectrographs will be comparable to the current SES's 55000. Title: Mono-enriched stars and Galactic chemical evolution. Possible biases in observations and theory Authors: Hansen, C. J.; Koch, A.; Mashonkina, L.; Magg, M.; Bergemann, M.; Sitnova, T.; Gallagher, A. J.; Ilyin, I.; Caffau, E.; Zhang, H. W.; Strassmeier, K. G.; Klessen, R. S. Bibcode: 2020A&A...643A..49H Altcode: 2020arXiv200911876H A long sought after goal using chemical abundance patterns derived from metal-poor stars is to understand the chemical evolution of the Galaxy and to pin down the nature of the first stars (Pop III). Metal-poor, old, unevolved stars are excellent tracers as they preserve the abundance pattern of the gas from which they were born, and hence they are frequently targeted in chemical tagging studies. Here, we use a sample of 14 metal-poor stars observed with the high-resolution spectrograph called the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) to derive abundances of 32 elements (34 including upper limits). We present well-sampled abundance patterns for all stars obtained using local thermodynamic equilibrium (LTE) radiative transfer codes and one-dimensional (1D) hydrostatic model atmospheres. However, it is currently well-known that the assumptions of 1D and LTE may hide several issues, thereby introducing biases in our interpretation as to the nature of the first stars and the chemical evolution of the Galaxy. Hence, we use non-LTE (NLTE) and correct the abundances using three-dimensional model atmospheres to present a physically more reliable pattern. In order to infer the nature of the first stars, we compare unevolved, cool stars, which have been enriched by a single event ("mono-enriched"), with a set of yield predictions to pin down the mass and energy of the Pop III progenitor. To date, only few bona fide second generation stars that are mono-enriched are known. A simple χ2-fit may bias our inferred mass and energy just as much as the simple 1D LTE abundance pattern, and we therefore carried out our study with an improved fitting technique considering dilution and mixing. Our sample presents Carbon Enhanced Metal-Poor (CEMP) stars, some of which are promising bona fide second generation (mono-enriched) stars. The unevolved, dwarf BD+09_2190 shows a mono-enriched signature which, combined with kinematical data, indicates that it moves in the outer halo and likely has been accreted onto the Milky Way early on. The Pop III progenitor was likely of 25.5 M⊙ and 0.6 foe (0.6 1051 erg) in LTE and 19.2 M⊙ and 1.5 foe in NLTE, respectively. Finally, we explore the predominant donor and formation site of the rapid and slow neutron-capture elements. In BD-10_3742, we find an almost clean r-process trace, as is represented in the star HD20, which is a "metal-poor Sun benchmark" for the r-process, while TYC5481-00786-1 is a promising CEMP-r/-s candidate that may be enriched by an asymptotic giant branch star of an intermediate mass and metallicity.

The line list is 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/643/A49

Based on data acquired with PEPSI using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. Title: VizieR Online Data Catalog: Auriga bright stars BRITE phot. and RV (Strassmeier+, 2020) Authors: Strassmeier, K. G.; Granzer, T.; Weber, M.; Kuschnig, R.; Pigulski, A.; Popowicz, A.; Moffat, A. F. J.; Wade, G. A.; Zwintz, K.; Handler, G. Bibcode: 2020yCat..36440104S Altcode: Continuous photometry with BRITE satellites BRITE-Toronto (BTr), BRITE-Heweliusz (BHr), and BRITE-Lem (BLb) of 12 very bright stars in BRITE fields 20-AurPer-I-2016 (9 stars), 21-CetEri-I-2016 (2 stars) and one star at the edge of fields 31-Tau-I-2017 and 48-OriTau-II-2019 are presented. Contemporaneous high-resolution optical spectroscopy (R=55000) with STELLA-SES was used to obtain radial velocities and to determine astrophysical parameters. BTr and BHr are red sensitive, filter passband comparable to Sloan r, while BLb is blue sensitive (Geneva B). The Aur-Per field was observed from JD 2457640 to 2457822 (9th Sept., 2016 to 9th March 2017) with BTr and BLb, from the latter only the first 35 days and the last 27 days were successful. In this field, the following stars were observed (names in parenthesis): HD 34029 (alpha Aur), HD 40183 (beta Aur), HD 31964 (epsilon Aur), HD 32069 (zeta Aur), HD 32630 (eta Aur), HD 40312 (theta Aur), HD 39003 (nu Aur, only BTr), HD 31398 (iota Aur), and HD 34452 (IQ Aur). The latter was observed only between JD 2457647 and 2457672. The Cet-Eri field was observed with BHr from JD 2457668 to 2457757 (6th Oct., 2016 to 3rd Jan., 2017) with BHr only. In this field, HD 20630 (kappa1 Cet) and HD 22468 (V711 Tau) were observed. Finally, HD 40183 (beta Tau) was observed in two fields, with BLb from JD 2458030 (3rd Oct., 2017) to 2458170 (20th Feb. 2018) and BTr from 2458155 (5th Feb., 2018) to 2458179 (1st March, 2018) in field Tau, and again with Blb from JD 2458749 (22nd Sept., 2019) to 2458871 (22nd Jan., 2020) in field Ori-Tau.

The BRITE data are obtained in different satellite configurations and are provided by the BRITE consortium comprising HJD, absolute magnitude plus ancillary data used for data decorrelation. For analysis of the individual stars, data within an orbit, consisting of up to 60 individual data points taken in immediate succession, were 3-sigma clipped and then zero-point adjusted, see paper for details. Provided in the data files are HJD and magnitude averages plus an error estimate which is the sample standard deviation divided by the square-root of the number of observations within an orbit (RMS). The STELLA-SES spectroscopic data were obtained contemporaneously to the BRITE data for nine stars, namely HD 34029, HD 31964, HD 40183, HD 32630, HD 40312, HD 39003, HD 31398, HD 20630, and HD 22468, usually on a daily basis. The first two stars have been observed in extended campaigns. Consequentially, for HD 34029, all observed epochs from JD 2454305 (24th July 2007) to 2458996 (26th May 2020) are listed, while HD 31964 data spans from 2457228 (25th July 2015) to 2458242 (3rd May 2018).

Barycentric radial velocities (RV) were determined from an order-by-order cross correlation with a synthetic template spectrum. 60 echelle orders were used, the RV in the files is the weighted average, the error is the RMS value.

(3 data files). Title: VizieR Online Data Catalog: Linelist (Hansen+, 2020) Authors: Hansen, C. J.; Koch, A.; Mashonkina, L.; Magg, M.; Bergemann, M.; Sitnova, T.; Gallagher, A. J.; Ilyin, I.; Caffau, E.; Zhang, H. W.; Strassmeier, K. G.; Klessen, R. S. Bibcode: 2020yCat..36430049H Altcode: Linelist containing wavelength, element and ionisation degree (0 = neutral, 1 = single ionised), excitation potential [eV], oscillator strength (loggf), number of stars in the study in which the line has been detected (limits indicated by <), and finally, hyperfine structure of oscillator strength indicated by HFS.

(1 data file). Title: Probing the atmosphere of HD189733b with the Na I and K I lines Authors: Keles, E.; Kitzmann, D.; Mallonn, M.; Alexoudi, X.; Fossati, L.; Pino, L.; Seidel, J. V.; Carroll, T. A.; Steffen, M.; Ilyin, I.; Poppenhäger, K.; Strassmeier, K. G.; von Essen, C.; Nascimbeni, V.; Turner, J. D. Bibcode: 2020MNRAS.498.1023K Altcode: 2020MNRAS.tmp.2443K; 2020arXiv200804044K High spectral resolution transmission spectroscopy is a powerful tool to characterize exoplanet atmospheres. Especially for hot Jupiters, this technique is highly relevant, due to their high-altitude absorption, e.g. from resonant sodium (Na I) and potassium (K I) lines. We resolve the atmospheric K I absorption on HD189733b with the aim to compare the resolved K I line and previously obtained high-resolution Na I-D line observations with synthetic transmission spectra. The line profiles suggest atmospheric processes leading to a line broadening of the order of ∼10 km/s for the Na I-D lines and only a few km/s for the K I line. The investigation hints that either the atmosphere of HD189733b lacks a significant amount of K I or the alkali lines probe different atmospheric regions with different temperature, which could explain the differences we see in the resolved absorption lines. Title: On the Chemical Abundance of HR 8799 and the Planet c Authors: Wang, Ji; Wang, Jason J.; Ma, Bo; Chilcote, Jeffrey; Ertel, Steve; Guyon, Olivier; Ilyin, Ilya; Jovanovic, Nemanja; Kalas, Paul; Lozi, Julien; Macintosh, Bruce; Strassmeier, Klaus G.; Stone, Jordan Bibcode: 2020AJ....160..150W Altcode: 2020arXiv200702810W Comparing chemical abundances of a planet and the host star reveals the origin and formation pathway of the planet. Stellar abundance is measured with high-resolution spectroscopy. Planet abundance, on the other hand, is usually inferred from low-resolution data. For directly imaged exoplanets, the data are available from a slew of high-contrast imaging/spectroscopy instruments. Here, we study the chemical abundance of HR 8799 and its planet c. We measure stellar abundance using LBT/PEPSI (R = 120,000) and archival HARPS data: stellar [C/H], [O/H], and C/O are 0.11 ± 0.12, 0.12 ± 0.14, and ${0.54}_{-0.09}^{+0.12}$ , all consistent with solar values. We conduct atmospheric retrieval using newly obtained Subaru/CHARIS data together with archival Gemini/GPI and Keck/OSIRIS data. We model the planet spectrum with petitRADTRANS and conduct retrieval using PyMultiNest. Retrieved planetary abundance can vary by ∼0.5 dex, from sub-stellar to stellar C and O abundances. The variation depends on whether strong priors are chosen to ensure a reasonable planet mass. Moreover, comparison with previous works also reveals inconsistency in abundance measurements. We discuss potential issues that can cause the inconsistency, e.g., systematics in individual data sets and different assumptions in the physics and chemistry in retrieval. We conclude that no robust retrieval can be obtained unless the issues are fully resolved. Title: The rotation period distribution of the rich Pleiades-age southern open cluster NGC 2516. Existence of a representative zero-age main sequence distribution Authors: Fritzewski, D. J.; Barnes, S. A.; James, D. J.; Strassmeier, K. G. Bibcode: 2020A&A...641A..51F Altcode: 2021arXiv211203299F
Aims: We wish to measure the cool star rotation period distribution for the Pleiades-age rich open cluster NGC 2516 and use it to determine whether cluster-to-cluster variations exist in otherwise identical open clusters.
Methods: We obtained 42 d-long time-series CCD photometry of NGC 2516 in the V and Ic filters using the Yale 1 m telescope at CTIO and performed a number of related analyses, including PSF-based time-series photometry. Our data are complemented with additional information from several photometric datasets, literature radial velocities, and Gaia DR2 astrometry. All available data are used to construct an integrated membership list for NGC 2516, containing 844 stars in our ≈1° field of view.
Results: We derived 308 rotation periods for late-F to mid-M cluster members from our photometry. We identified an additional 247 periodic M dwarf stars from a prior study as cluster members, and used these to construct a 555-star rotation period distribution for NGC 2516. The colour-period diagram (in multiple colours) has almost no outliers and exhibits the anticipated triangular shape, with a diagonal slow rotator sequence that is preferentially occupied by the warmer stars along with a flat fast rotator sequence that is preferentially populated by the cooler cluster members. We also find a group of extremely slowly rotating M dwarfs (10 d ≲ Prot ≲ 23 d), forming a branch in the colour-period diagram which we call the "extended slow rotator sequence". This, and other features of the rotational distribution can also be found in the Pleiades, making the colour-period diagrams of the two clusters nearly indistinguishable. A comparison with the well-studied (and similarly aged) open cluster M 35 indicates that the cluster's rotational distribution is also similarly indistinguishable from that of NGC 2516. Those for the open clusters M 50 and Blanco 1 are similar, but data issues for those clusters make the comparisons somewhat more ambiguous. Nevertheless, we demonstrate the existence of a representative zero-age main sequence rotational distribution and provide a simple colour-independent way to represent it. We perform a detailed comparison of the NGC 2516 rotation period data with a number of recent rotational evolution models. Using X-ray data from the literature, we also construct the first rotation-activity diagram for solar-type stars in NGC 2516, one that we find is essentially indistinguishable from those for the Pleiades and Blanco 1.
Conclusions: The two clusters NGC 2516 and Pleiades can be considered twins in terms of stellar rotation and related properties (and M 35, M 50, and Blanco 1 are similar), suggesting that otherwise identical open clusters also have intrinsically similar cool star rotation and activity distributions.

Full Tables 3 and 4 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/641/A51

Based on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory under proposal 2008A-0476. Title: Spatially Resolved Ultraviolet Spectroscopy of the Great Dimming of Betelgeuse Authors: Dupree, Andrea K.; Strassmeier, Klaus G.; Matthews, Lynn D.; Uitenbroek, Han; Calderwood, Thomas; Granzer, Thomas; Guinan, Edward F.; Leike, Reimar; Montargès, Miguel; Richards, Anita M. S.; Wasatonic, Richard; Weber, Michael Bibcode: 2020ApJ...899...68D Altcode: 2020arXiv200804945D The bright supergiant Betelgeuse (Alpha Orionis, HD 39801) experienced a visual dimming during 2019 December and the first quarter of 2020, reaching an historic minimum 2020 February 7-13. During 2019 September-November, prior to the optical dimming event, the photosphere was expanding. At the same time, spatially resolved ultraviolet spectra using the Hubble Space Telescope/Space Telescope Imaging Spectrograph revealed a substantial increase in the ultraviolet spectrum and Mg II line emission from the chromosphere over the southern hemisphere of the star. Moreover, the temperature and electron density inferred from the spectrum and C II diagnostics also increased in this hemisphere. These changes happened prior to the Great Dimming Event. Variations in the Mg II k-line profiles suggest material moved outwards in response to the passage of a pulse or acoustic shock from 2019 September through November. It appears that this extraordinary outflow of material from the star, likely initiated by convective photospheric elements, was enhanced by the coincidence with the outward motions in this phase of the ∼400 day pulsation cycle. These ultraviolet observations appear to provide the connecting link between the known large convective cells in the photosphere and the mass ejection event that cooled to form the dust cloud in the southern hemisphere imaged in 2019 December, and led to the exceptional optical dimming of Betelgeuse in 2020 February. Title: Role of the impact parameter in exoplanet transmission spectroscopy Authors: Alexoudi, X.; Mallonn, M.; Keles, E.; Poppenhäger, K.; von Essen, C.; Strassmeier, K. G. Bibcode: 2020A&A...640A.134A Altcode: 2020arXiv200707716A Context. Transmission spectroscopy is a promising tool for the atmospheric characterization of transiting exoplanets. Because the planetary signal is faint, discrepancies have been reported regarding individual targets.
Aims: We investigate the dependence of the estimated transmission spectrum on deviations of the orbital parameters of the star-planet system that are due to the limb-darkening effects of the host star. We describe how the uncertainty on the orbital parameters translates into an uncertainty on the planetary spectral slope.
Methods: We created synthetic transit light curves in seven different wavelength bands, from the near-ultraviolet to the near-infrared, and fit them with transit models parameterized by fixed deviating values of the impact parameter b. First, we performed a qualitative study to illustrate the effect by presenting the changes in the transmission spectrum slope with different deviations of b. Then, we quantified these variations by creating an error envelope (for centrally transiting, off-center, and grazing systems) based on a derived typical uncertainty on b from the literature. Finally, we compared the variations in the transmission spectra for different spectral types of host stars.
Results: Our simulations show a wavelength-dependent offset that is more pronounced at the blue wavelengths where the limb-darkening effect is stronger. This offset introduces a slope in the planetary transmission spectrum that becomes steeper with increasing b values. Variations of b by positive or negative values within its uncertainty interval introduce positive or negative slopes, thus the formation of an error envelope. The amplitude from blue optical to near-infrared wavelength for a typical uncertainty on b corresponds to one atmospheric pressure scale height and more. This impact parameter degeneracy is confirmed for different host types; K stars present prominently steeper slopes, while M stars indicate features at the blue wavelengths.
Conclusions: We demonstrate that transmission spectra can be hard to interpret, basically because of the limitations in defining a precise impact parameter value for a transiting exoplanet. This consequently limits a characterization of its atmosphere. Title: VizieR Online Data Catalog: NGC 2516 membership list (Fritzewski+, 2020) Authors: Fritzewski, D. J.; Barnes, S. A.; James, D. J.; Strassmeier, K. G. Bibcode: 2020yCat..36410051F Altcode: Table 2 lists radial velocity variable stars in NGC 2516 which can be considered radial velocity binaries. Their radial velocities were acquired from various sources in the literature (see references of Table 2).

Table 3 includes our members of NGC 2516 upon which we based the analysis of the rotation periods. The data are exclusively taken from the literature and the membership is based on photometry, radial velocities, parallax, and proper motions.

Table 4 includes rotation periods measured from our photometric time-series campaign between 19 February 2008 and 01 April 2008 at the CTIO Yale 1m telescope. This table lists additional periods by Irwin et al. (2007MNRAS.377..741I, Cat. J/MNRAS/377/741) and related activity properties.

(3 data files). Title: The STIX Aspect System (SAS): The Optical Aspect System of the Spectrometer/Telescope for Imaging X-Rays (STIX) on Solar Orbiter Authors: Warmuth, A.; Önel, H.; Mann, G.; Rendtel, J.; Strassmeier, K. G.; Denker, C.; Hurford, G. J.; Krucker, S.; Anderson, J.; Bauer, S. -M.; Bittner, W.; Dionies, F.; Paschke, J.; Plüschke, D.; Sablowski, D. P.; Schuller, F.; Senthamizh Pavai, V.; Woche, M.; Casadei, D.; Kögl, S.; Arnold, N. G.; Gröbelbauer, H. -P.; Schori, D.; Wiehl, H. J.; Csillaghy, A.; Grimm, O.; Orleanski, P.; Skup, K. R.; Bujwan, W.; Rutkowski, K.; Ber, K. Bibcode: 2020SoPh..295...90W Altcode: The Spectrometer/Telescope for Imaging X-rays (STIX) is a remote sensing instrument on Solar Orbiter that observes the hard X-ray bremsstrahlung emission of solar flares. This paper describes the STIX Aspect System (SAS), a subunit that measures the pointing of STIX relative to the Sun with a precision of ±4″, which is required to accurately localize the reconstructed X-ray images on the Sun. The operating principle of the SAS is based on an optical lens that images the Sun onto a plate that is perforated by small apertures arranged in a cross-shaped configuration of four radial arms. The light passing through the apertures of each arm is detected by a photodiode. Variations of spacecraft pointing and of distance from the Sun cause the solar image to move over different apertures, leading to a modulation of the measured lightcurves. These signals are used by ground analysis to calculate the locations of the solar limb, and hence the pointing of the telescope. Title: 16th Potsdam Thinkshop: The rotation periods of cool stars: Measurements, uses, connections and prospects Authors: Barnes, S. A.; Steffen, M.; Strassmeier, K. G. Bibcode: 2020AN....341..485B Altcode: No abstract at ADS Title: Improving spectroscopic lithium abundances. Fitting functions for 3D non-LTE corrections in FGK stars of different metallicity Authors: Mott, A.; Steffen, M.; Caffau, E.; Strassmeier, K. G. Bibcode: 2020A&A...638A..58M Altcode: 2020arXiv200410803M Context. Accurate spectroscopic lithium abundances are essential in addressing a variety of open questions, such as the origin of a uniform lithium content in the atmospheres of metal-poor stars (Spite plateau) or the existence of a correlation between the properties of extrasolar planetary systems and the lithium abundance in the atmosphere of their host stars.
Aims: We have developed a tool that allows the user to improve the accuracy of standard lithium abundance determinations based on 1D model atmospheres and the assumption of local thermodynamic equilibrium (LTE) by applying corrections that account for hydrodynamic (3D) and non-LTE (NLTE) effects in FGK stars of different metallicity.
Methods: Based on a grid of CO5BOLD 3D models and associated 1D hydrostatic atmospheres, we computed three libraries of synthetic spectra of the lithium λ 670.8 nm line for a wide range of lithium abundances, accounting for detailed line formation in 3D NLTE, 1D NLTE, and 1D LTE, respectively. The resulting curves-of-growth were then used to derive 3D NLTE and 1D NLTE lithium abundance corrections.
Results: For all metallicities, the largest corrections are found at the coolest effective temperature, Teff = 5000 K. They are mostly positive, up to + 0.2 dex, for the weakest lines (lithium abundance A(Li)1DLTE = 1.0), whereas they become more negative towards lower metallicities, where they can reach - 0.4 dex for the strongest lines (A(Li)1DLTE = 3.0) at [Fe/H] = - 2.0. We demonstrate that 3D and NLTE effects are small for metal-poor stars on the Spite plateau, leading to errors of at most ± 0.05 dex if ignored. We present analytical functions evaluating the 3D NLTE and 1D NLTE corrections as a function of Teff [5000…6500 K], log g [3.5…4.5], and LTE lithium abundance A(Li) [1.0…3.0] for a fixed grid of metallicities [Fe/H] [ - 3.0…0.0]. In addition, we also provide analytical fitting functions for directly converting a given lithium abundance into an equivalent width, or vice versa, a given equivalent width (EW) into a lithium abundance. For convenience, a Python script is made available that evaluates all fitting functions for given Teff, log g, [Fe/H], and A(Li) or EW.
Conclusions: By means of the fitting functions developed in this work, the results of complex 3D and NLTE calculations are made readily accessible and quickly applicable to large samples of stars across a wide range of metallicities. Improving the accuracy of spectroscopic lithium abundance determinations will contribute to a better understanding of the open questions related to the lithium content in metal-poor and solar-like stellar atmospheres. Title: Focus on Betelgeuse Authors: Dupree, Andrea; Chiavassa, Andrea; Freytag, Bernd; Harper, Graham M.; Kervella, Pierre; Lebre, Agnes; Montarges, Miguel; Ohnaka, Keiichi; Quirrenbach, Andreas; Richards, Anita; Schmitt, Henrique R.; Strassmeier, Klaus G.; Uitenbroek, Han; Wheeler, J. Craig; Wittkowski, Markus; Matthews, Lynn D. Bibcode: 2020hst..prop16216D Altcode: Multiple ultraviolet spectra of the nearby red supergiant, Betelgeuse, using STIS will enable spatially resolved measures of chromospheric structure and mass inflows and outflows. An HST campaign of 3 cycles will be complemented by multi-frequency photometry, spectroscopy, interferometry, and polarimetry at radio, infrared, and optical wavelengths in order to map surface structures and their variability, and the extended outer atmosphere over both the short (400-day) and long secondary (2000-day) periods of this supergiant. These observations, coupled with detailed modeling and simulations, will probe the structure, the dynamics, and the mass loss from Betelgeuse in unprecedented detail and provide crucial insights into the atmospheric physics and wind-driving mechanisms of red supergiants. Title: Lithium in T Coronae Borealis Authors: Woodward, C. E.; Pavlenko, Ya. V.; Evans, A.; Wagner, R. M.; IIyin, I.; Strassmeier, K. G.; Starrfield, S.; Munari, U. Bibcode: 2020AJ....159..231W Altcode: T Coronae Borealis is a recurrent, symbiotic nova system currently in quiescence between its periodic ≍80 yr cycle of eruptions. Observations during inter-outburst epochs provide an opportunity to study properties of the accretion disk and the M red giant. Here we present new irradiated (blackbody veiling) models, incorporating modern molecular opacities and line lists, of spectra derived from high-resolution (22,000 ≲ R ≲ 120,000) optical echelle observations obtained at two epochs, one prior to and one post the 2015 rebrightening event at similar spectroscopic system phase. We find a lithium abundance in the secondary at both epochs to be comparable. The non-irradiated (classical) model atmospheres yield a lithium abundance, A(Li) = 1.3 ± 0.1. The irradiated model (veiled) atmospheres, which are likely a better representation of the system in which the white dwarf and accretion disk illuminate the red giant, give A(Li) = 2.4 ± 0.1. Title: No Consistent Atmospheric Absorption Detected for the Ultra-hot Jupiter WASP-189 b Authors: Cauley, P. Wilson; Shkolnik, Evgenya L.; Ilyin, Ilya; Strassmeier, Klaus G.; Redfield, Seth; Jensen, Adam Bibcode: 2020RNAAS...4...53C Altcode: 2020arXiv200406859C We observed a partial transit of the ultra-hot Jupiter WASP-189 b with PEPSI on the LBT. We detect a highly variable transit signal in multiple atomic transitions, including H-alpha, Fe I, and Mg I. The signal is not consistent with a transiting planetary atmosphere. We suggest instead that the in-transit signal is due to an inhomogeneous stellar surface. Our observations demonstrate the lack of a highly extended atmosphere in common optical atomic tracers. Although WASP-189 is very bright, atmospheric characterization of the planet will be difficult due to the small transit depth and apparently compact atmosphere. Title: Monitoring solar activity with PEPSI Authors: Dineva, Ekaterina; Denker, Carsten; Strassmeier, Klaus G.; Ilyin, Ilya; Pevtsov, Alexei A. Bibcode: 2020IAUGA..30..351D Altcode: Synoptic Sun-as-a-star observations are carried out with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI), which receives light from the Solar Disk-Integration (SDI) telescope. Daily spectra are produced with a high signal-to-noise ratio, providing access to unprecedented quasi-continuous, long-term, disk-integrated spectra of the Sun with high spectral and temporal resolution. We developed tools to monitor and study solar activity on different time-scales ranging from daily changes, over periods related to solar rotation, to annual and decadal trends. Strong chromospheric absorption lines, such as the Ca ii H & K λ3934 & 3968 Å lines, are powerful diagnostic tools for solar activity studies, since they trace the variations of the solar magnetic field. Other lines, such as Hα λ6563 Å line and the near-infrared (NIR) Ca ii λ8542 Å line, provide additional information on the physical properties in this highly complex and dynamic atmospheric layer. Currently, we work on a data pipeline for extraction, calibration, and analysis of the PEPSI/SDI data. We compare the SDI data with daily spectra from the Integrated Sunlight Spectrometer (ISS), which is part of the Synoptic Long-Term Investigation of the Sun (SOLIS) facility operated by the U.S. National Solar Observatory (NSO). This facilitates cross-calibration and validation of the SDI data. Title: High-resolution spectroscopy and spectropolarimetry of the total lunar eclipse January 2019 Authors: Strassmeier, K. G.; Ilyin, I.; Keles, E.; Mallonn, M.; Järvinen, A.; Weber, M.; Mackebrandt, F.; Hill, J. M. Bibcode: 2020A&A...635A.156S Altcode: 2020arXiv200208690S Context. Observations of the Earthshine off the Moon allow for the unique opportunity to measure the large-scale Earth atmosphere. Another opportunity is realized during a total lunar eclipse which, if seen from the Moon, is like a transit of the Earth in front of the Sun.
Aims: We thus aim at transmission spectroscopy of an Earth transit by tracing the solar spectrum during the total lunar eclipse of January 21, 2019.
Methods: Time series spectra of the Tycho crater were taken with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope in its polarimetric mode in Stokes IQUV at a spectral resolution of 130 000 (0.06 Å). In particular, the spectra cover the red parts of the optical spectrum between 7419-9067 Å. The spectrograph's exposure meter was used to obtain a light curve of the lunar eclipse.
Results: The brightness of the Moon dimmed by 10.m75 during umbral eclipse. We found both branches of the O2 A-band almost completely saturated as well as a strong increase of H2O absorption during totality. A pseudo O2 emission feature remained at a wavelength of 7618 Å, but it is actually only a residual from different P-branch and R-branch absorptions. It nevertheless traces the eclipse. The deep penumbral spectra show significant excess absorption from the Na I 5890-Å doublet, the Ca II infrared triplet around 8600 Å, and the K I line at 7699 Å in addition to several hyper-fine-structure lines of Mn I and even from Ba II. The detections of the latter two elements are likely due to an untypical solar center-to-limb effect rather than Earth's atmosphere. The absorption in Ca II and K I remained visible throughout umbral eclipse. Our radial velocities trace a wavelength dependent Rossiter-McLaughlin effect of the Earth eclipsing the Sun as seen from the Tycho crater and thereby confirm earlier observations. A small continuum polarization of the O2 A-band of 0.12% during umbral eclipse was detected at 6.3σ. No line polarization of the O2 A-band, or any other spectral-line feature, is detected outside nor inside eclipse. It places an upper limit of ≈0.2% on the degree of line polarization during transmission through Earth's atmosphere and magnetosphere.

All 1D spectra 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/635/A156

Based on data acquired with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) using the Large Binocular Telescope (LBT) in Arizona. Title: VizieR Online Data Catalog: Total lunar eclipse January 2019 spectra (Strassmeier+, 2020) Authors: Strassmeier, K. G.; Ilyin, I.; Keles, E.; Mallonn, M.; Jaervinen, A.; Weber, M.; Mackebrandt, F.; Hill, J. M. Bibcode: 2020yCat..36350156S Altcode: All observations were obtained with PEPSI (Strassmeier et al., 2015AN....336..324S) at the 28.4m LBT (Hill et al., 2012, Proc. SPIE, 8444-1) in Arizona.

Observations of the Moon commenced between UT 3:25 and 7:41 on January 21, 2019. Maximum of the total eclipse was at UT 5:12.

(3 data files). Title: Sun-as-a-star observations of the 2017 August 21 solar eclipse Authors: Dineva, Ekaterina; Denker, Carsten; Verma, Meetu; Strassmeier, Klaus G.; Ilyin, Ilya; Milic, Ivan Bibcode: 2020IAUS..354..473D Altcode: The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) is a state-of-the-art, thermally stabilized, fiber-fed, high-resolution spectrograph for the Large Binocular Telescope (LBT) at Mt. Graham, Arizona. During daytime the instrument is fed with sunlight from the 10-millimeter aperture, fully automated, binocular Solar Disk-Integrated (SDI) telescope. The observed Sun-as-a-star spectra contain a multitude of photospheric and chromospheric spectral lines in the wavelength ranges 4200-4800 Å and 5300-6300 Å. One of the advantages of PEPSI is that solar spectra are recorded in the exactly same manner as nighttime targets. Thus, solar and stellar spectra can be directly compared. PEPSI/SDI recorded 116 Sun-as-a-star spectra during the 2017 August 21 solar eclipse. The observed maximum obscuration was 61.6%. The spectra were taken with a spectral resolution of ≈ 250000 and an exposure time of 0.3 s. The high-spectral resolution facilitates detecting subtle changes in the spectra while the Moon passes the solar disk. Sun-as-a-star spectra are affected by changing contributions due to limb darkening and solar differential rotation, and to a lesser extend by supergranular velocity pattern and the presence of active regions on the solar surface. The goal of this study is to investigate the temporal evolution of the chromospheric Na D doublet during the eclipse and to compare observations with synthetic line profiles computed with the state-of-the-art Bifrost code. Title: LBT/PEPSI Spectropolarimetry of a Magnetic Topology Shift in Old Solar-type Stars Authors: Metcalfe, T. S.; Kochukhov, O.; Ilyin, I.; Strassmeier, K.; Godoy Rivera, D.; Pinsonneault, M. Bibcode: 2020AAS...23513105M Altcode: Solar-type stars are born with relatively rapid rotation and strong magnetic fields. Through a process known as magnetic braking, the rotation slows over time as stellar winds gradually remove angular momentum from the system. The rate of angular momentum loss depends sensitively on the magnetic topology, with the dipole field exerting the largest torque on the star. Recent observations suggest that the efficiency of magnetic braking may decrease dramatically in stars near the middle of their main-sequence lifetimes. One hypothesis to explain this reduction in efficiency is a shift in magnetic topology from predominantly larger to smaller spatial scales. We aim to test this hypothesis with spectropolarimetric measurements of two stars that sample chromospheric activity levels above and below the proposed magnetic transition. As predicted, the more active star (HD 100180) exhibits a significant Stokes profile due to a non-axisymmetric large-scale magnetic field, while the less active star (HD 143761) shows no significant signal. We identify analogs of the two stars among a sample of well-characterized Kepler targets, and we predict that the asteroseismic age of HD 143761 from future TESS observations will substantially exceed the age expected from gyrochronology. We conclude that a shift in magnetic topology is likely to be responsible for the loss of magnetic braking in middle-aged stars, which appears to coincide with the shutdown of their global dynamos. Title: Cycle times of early M dwarf stars: mean field models versus observations Authors: Küker, Manfred; Rüdiger, Günther; Oláh, Katalin; Strassmeier, Klaus G. Bibcode: 2020IAUS..354..116K Altcode: 2019arXiv191113094K Observations of early-type M stars suggest that there are two characteristic cycle times, one of order one year for fast rotators (Prot < 1 day) and another of order four years for slower rotators. For a sample of fast-rotating stars, the equator-to-pole differences of the rotation rates up to 0.03 rad d-1 are also known from Kepler data. These findings are well-reproduced by mean field models. These models predict amplitudes of the meridional flow, from which the travel time from pole to equator at the base of the convection zone of early-type M stars can be calculated. As these travel times always exceed the observed cycle times, our findings do not support the flux transport dynamo. Title: Letter from the Editor Authors: Strassmeier, Klaus G. Bibcode: 2020AN....341....9S Altcode: No abstract at ADS Title: LBT/PEPSI Spectropolarimetry of a Magnetic Morphology Shift in Old Solar-type Stars Authors: Metcalfe, T. S.; Kochukhov, O.; Ilyin, I. V.; Strassmeier, K. G.; Godoy-Rivera, D.; Pinsonneault, M. H. Bibcode: 2019ApJ...887L..38M Altcode: 2019arXiv191201186M Solar-type stars are born with relatively rapid rotation and strong magnetic fields. Through a process known as magnetic braking, the rotation slows over time as stellar winds gradually remove angular momentum from the system. The rate of angular momentum loss depends sensitively on the magnetic morphology, with the dipole field exerting the largest torque on the star. Recent observations suggest that the efficiency of magnetic braking may decrease dramatically in stars near the middle of their main-sequence lifetimes. One hypothesis to explain this reduction in efficiency is a shift in magnetic morphology from predominantly larger to smaller spatial scales. We aim to test this hypothesis with spectropolarimetric measurements of two stars that sample chromospheric activity levels on opposite sides of the proposed magnetic transition. As predicted, the more active star (HD 100180) exhibits a significant circular polarization signature due to a nonaxisymmetric large-scale magnetic field, while the less active star (HD 143761) shows no significant signal. We identify analogs of the two stars among a sample of well-characterized Kepler targets, and we predict that the asteroseismic age of HD 143761 from future Transiting Exoplanet Survey Satellite observations will substantially exceed the age expected from gyrochronology. We conclude that a shift in magnetic morphology likely contributes to the loss of magnetic braking in middle-aged stars, which appears to coincide with the shutdown of their global dynamos.

The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, The Leibniz Institute for Astrophysics Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia. Title: The potassium absorption on HD189733b and HD209458b Authors: Keles, Engin; Mallonn, Matthias; von Essen, Carolina; Carroll, Thorsten A.; Alexoudi, Xanthippi; Pino, Lorenzo; Ilyin, Ilya; Poppenhäger, Katja; Kitzmann, Daniel; Nascimbeni, Valerio; Turner, Jake D.; Strassmeier, Klaus G. Bibcode: 2019MNRAS.489L..37K Altcode: 2019arXiv190904884K; 2019MNRAS.tmpL.124K In this work, we investigate the potassium excess absorption around 7699 Å of the exoplanets HD189733b and HD209458b. For this purpose, we used high-spectral resolution transit observations acquired with the 2 × 8.4 m Large Binocular Telescope (LBT) and the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI). For a bandwidth of 0.8 Å, we present a detection >7σ with an absorption level of 0.18 per cent for HD189733b. Applying the same analysis to HD209458b, we can set 3σ upper limit of 0.09 per cent, even though we do not detect a K-excess absorption. The investigation suggests that the K feature is less present in the atmosphere of HD209458b than in the one of HD189733b. This comparison confirms previous claims that the atmospheres of these two planets must have fundamentally different properties. Title: Antisolar differential rotation of slowly rotating cool stars Authors: Rüdiger, G.; Küker, M.; Käpylä, P. J.; Strassmeier, K. G. Bibcode: 2019A&A...630A.109R Altcode: 2019arXiv190204172R Rotating stellar convection transports angular momentum towards the equator, generating the characteristic equatorial acceleration of the solar rotation while the radial flux of angular momentum is always inwards. New numerical box simulations for the meridional cross-correlation ⟨uθuϕ⟩, however, reveal the angular momentum transport towards the poles for slow rotation and towards the equator for fast rotation. The explanation is that for slow rotation a negative radial gradient of the angular velocity always appears, which in combination with a so-far neglected rotation-induced off-diagonal eddy viscosity term ν⊥ provides "antisolar rotation" laws with a decelerated equator. Similarly, the simulations provided positive values for the rotation-induced correlation ⟨uruθ⟩, which is relevant for the resulting latitudinal temperature profiles (cool or warm poles) for slow rotation and negative values for fast rotation. Observations of the differential rotation of slowly rotating stars will therefore lead to a better understanding of the actual stress-strain relation, the heat transport, and the underlying model of the rotating convection. Title: Project BMK10k: Zeiss Ballistische Messkammer with a 10k × 10k CCD for ground-based PLATO support Authors: Strassmeier, Klaus G.; Granzer, Thomas; Weingrill, Jörg; Woche, Manfred; Bittner, Wilbert; Bauer, Svend-Marian; Paschke, Jens; Chini, Rolf Bibcode: 2019AN....340..712S Altcode: Ballistische Messkammer with 10k CCD's (BMK10k) central goal is supporting the upcoming PLAnetary Transits and Oscillation of stars (PLATO) mission by reducing its number of false positives (planet-compatible transit candidates but not planets at the end). For Kepler, the number of false positives had been estimated to still be about 10%. Understanding the PLATO false alarm rate is not as straightforward, and preparatory data from the ground will dramatically improve the target selection and minimize the number of false positives. We aim to identify the target contamination for every PLATO target and initially provide well-sampled light curves of all detectable contaminants in the long-duration southern PLATO field. Thereby, it will be possible to identify background eclipsing binaries and rotating spotted stars with periods between 1 hr and 100 days down to 17-18th mag. This will be achieved with a dedicated robotic telescope with one of the world's largest CCDs with the smallest pixels, enabling a field of view of 52.5 square degrees with a sampling of 2.5″/pix. Auxiliary science is also foreseen and will focus on the period-mass relation of Ptolemy's cluster (M7). In this paper, we describe the entire telescope system and show initial commissioning data. Title: Focus on Betelgeuse Authors: Dupree, Andrea; Chiavassa, Andrea; Freytag, Bernd; Harper, Graham M.; Kervella, Pierre; Lebre, Agnes; Montarges, Miguel; Ohnaka, Keiichi; Quirrenbach, Andreas; Richards, Anita; Schmitt, Henrique R.; Strassmeier, Klaus G.; Uitenbroek, Han; Wheeler, J. Craig; Wittkowski, Markus; Matthews, Lynn D. Bibcode: 2019hst..prop15873D Altcode: Multiple ultraviolet spectra of the nearby red supergiant, Betelgeuse, using STIS will enable spatially resolved measures of chromospheric structure and mass inflows and outflows. An HST campaign of 3 cycles will be complemented by multi-frequency photometry, spectroscopy, interferometry, and polarimetry at radio, infrared, and optical wavelengths in order to map surface structures and their variability, and the extended outer atmosphere over both the short (400-day) and long secondary (2000-day) periods of this supergiant. These observations, coupled with detailed modeling and simulations, will probe the structure, the dynamics, and the mass loss from Betelgeuse in unprecedented detail and provide crucial insights into the atmospheric physics and wind-driving mechanisms of red supergiants. Title: Warm and cool starspots with opposite polarities. A high-resolution Zeeman-Doppler-Imaging study of II Pegasi with PEPSI Authors: Strassmeier, K. G.; Carroll, T. A.; Ilyin, I. V. Bibcode: 2019A&A...625A..27S Altcode: 2019arXiv190211201S
Aims: We present a temperature and a magnetic-field surface map of the K2 subgiant of the active binary II Peg. Employed are high resolution Stokes IV spectra obtained with the new Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT).
Methods: Fourteen average line profiles are inverted using our iMap code. We have employed an iterative regularization scheme without the need of a penalty function and incorporate a physical 3D description of the surface field vector. The spectral resolution of our data is 130 000 which converts to 20 resolution elements across the disk of II Peg.
Results: Our main result is that the temperature features on II Peg closely correlate with its magnetic field topology. We find a warm spot (350 K warmer with respect to the effective temperature) of positive polarity and radial field density of 1.1 kG coexisting with a cool spot (780 K cooler) of negative polarity of 2 kG. Several other cool features are reconstructed containing both polarities and with (radial) field densities of up to 2 kG. The largest cool spot is reconstructed with a temperature contrast of 550 K, an area of almost 10% of the visible hemisphere, and with a multipolar magnetic morphology. A meridional and an azimuthal component of the field of up to ±500 G is detected in two surface regions between spots with strong radial fields but different polarities. A force-free magnetic-field extrapolation suggests that the different polarities of cool spots and the positive polarity of warm spots are physically related through a system of coronal loops of typical height of ≈2 R⋆. While the Hα line core and its red-side wing exhibit variations throughout all rotational phases, a major increase of blue-shifted Hα emission was seen for the phases when the warm spot is approaching the stellar central meridian indicating high-velocity mass motion within its loop.
Conclusions: Active stars such as II Peg can show coexisting cool and warm spots on the surface that we interpret resulting from two different formation mechanisms. We explain the warm spots due to photospheric heating by a shock front from a siphon-type flow between regions of different polarities while the majority of the cool spots is likely formed due to the expected convective suppression like on the Sun.

The reduced LBT spectra (FITS files) 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/625/A27Based on data acquired with PEPSI using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. Title: Spectropolarimetric Observations of an Arch Filament System with GREGOR Authors: Balthasar, H.; Gömöry, P.; González Manrique, S. J.; Kuckein, C.; Kučera, A.; Schwartz, P.; Berkefeld, T.; Collados, M.; Denker, C.; Feller, A.; Hofmann, A.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; von der Lühe, O. Bibcode: 2019ASPC..526..217B Altcode: 2018arXiv180401789B We observed an arch filament system (AFS) in a sunspot group with the GREGOR Infrared Spectrograph attached to the GREGOR solar telescope. The AFS was located between the leading sunspot of negative polarity and several pores of positive polarity forming the following part of the sunspot group. We recorded five spectro-polarimetric scans of this region. The spectral range included the spectral lines Si I 1082.7 nm, He I 1083.0 nm, and Ca I 1083.9 nm. In this work we concentrate on the silicon line which is formed in the upper photosphere. The line profiles are inverted with the code 'Stokes Inversion based on Response functions' to obtain the magnetic field vector. The line-of-sight velocities are determined independently with a Fourier phase method. Maximum velocities are found close to the ends of AFS fibrils. These maximum values amount to 2.4 km s-1 next to the pores and to 4 km s-1 at the sunspot side. Between the following pores, we encounter an area of negative polarity that is decreasing during the five scans. We interpret this by new emerging positive flux in this area canceling out the negative flux. In summary, our findings confirm the scenario that rising magnetic flux tubes cause the AFS. Title: Photospheric Magnetic Fields of the Trailing Sunspots in Active Region NOAA 12396 Authors: Verma, M.; Balthasar, H.; Denker, C.; Böhm, F.; Fischer, C. E.; Kuckein, C.; González Manrique, S. J.; Sobotka, M.; Bello González, N.; Diercke, A.; Berkefeld, T.; Collados, M.; Feller, A.; Hofmann, A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pastor Yabar, A.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K.; Volkmer, R.; von der Lühe, O.; Waldmann, T. Bibcode: 2019ASPC..526..291V Altcode: 2018arXiv180507752V The solar magnetic field is responsible for all aspects of solar activity. Sunspots are the main manifestation of the ensuing solar activity. Combining high-resolution and synoptic observations has the ambition to provide a comprehensive description of the sunspot growth and decay processes. Active region NOAA 12396 emerged on 2015 August 3 and was observed three days later with the 1.5-meter GREGOR solar telescope on 2015 August 6. High-resolution spectropolarimetric data from the GREGOR Infrared Spectrograph (GRIS) are obtained in the photospheric lines Si I λ1082.7 nm and Ca I λ1083.9 nm, together with the chromospheric He I λ1083.0 nm triplet. These near-infrared spectropolarimetric observations were complemented by synoptic line-of-sight magnetograms and continuum images of the Helioseismic and Magnetic Imager (HMI) and EUV images of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). Title: Stars and exoplanets in Stokes IQUV: a decadal opportunity for HIRES at the ELT Authors: Strassmeier, Klaus G. Bibcode: 2019arXiv190405075S Altcode: We proposed that the European ELT will be equipped with an ultra-high-precision polarimetric light feed as part of its high resolution optical and near-IR spectrograph HIRES. Such a feed is unique among the new ELTs and only possible in a rotationally symmetric focus of the telescope. The ELT's f/4.4 intermediate focus near M4 could provide such a capability with a polarimetric sensitivity of down to 10^(-5) for the brightest targets. Among the new science steps forward with HIRES-Pol at the 39m ELT would be the full characterization of solar-like stellar magnetospheres by means of Zeeman-Doppler Imaging. In particular for planet-hosting stars it could constrain the habitability of a planet based on its particle-emission geometry from the host star. Besides, any stellar linear-polarization spectrum is new territory for astrophysics and I refresh reasons why this can be also important for exoplanet atmospheres. Title: Surface magnetic activity of the fast-rotating G5 giant IN Comae, central star of the faint planetary nebula LoTr 5 Authors: Kővári, Zs.; Strassmeier, K. G.; Oláh, K.; Kriskovics, L.; Vida, K.; Carroll, T. A.; Granzer, T.; Ilyin, I.; Jurcsik, J.; Kővári, E.; Weber, M. Bibcode: 2019A&A...624A..83K Altcode: 2019arXiv190209460K Context. On the asymptotic giant branch, low to intermediate mass stars blow away their outer envelopes, forming planetary nebulae. Dynamic interaction between the planetary nebula and its central progenitor is poorly understood. The interaction is even more complex when the central object is a binary star with a magnetically active component, as is the case for the target in this paper.
Aims: We aim to quantify the stellar surface activity of the cool binary component of IN Com and aim to explain its origin. In general, we need a better understanding of how central binary stars in planetary nebulae evolve and how this evolution could develop such magnetically active stars as IN Com.
Methods: We present a time series of 13 consecutive Doppler images covering six months in 2017 that we used to measure the surface differential rotation with a cross-correlation method. Hitherto unpublished high-precision photometric data from 1989 to 2017 are presented. We applied Fourier-transformation-based frequency analysis to both photometry and spectra. Very high resolution (R ≈ 200 000) spectra were used to update IN Com's astrophysical parameters by means of spectral synthesis.
Results: Our time-series Doppler images show cool and warm spots coexisting with an average surface temperature contrast of -1000 K and +300 K with respect to the effective temperature. Approximately 8% of the stellar surface is covered with cool spots and ∼3% with warm spots. A consistent cool polar spot is seen in all images. The average lifetime of the cool spots is not much more than a few stellar rotations (one month), while the warm spots appear to live longer (three months) and are mostly confined to high latitudes. We found anti-solar surface differential rotation with a shear coefficient of α = -0.026 ± 0.005 suggesting an equatorial rotation period of 5.973 ± 0.008 d. We reconfirm the 5.9 day rotation period of the cool star from photometry, radial velocities, and Hα line-profile variations. A long-term V-brightness variation with a likely period of 7.2 yr is also found. It appears in phase with the orbital radial velocity of the binary system in the sense that it is brightest at highest velocity and faintest at lowest velocity, that is, at the two phases of quadrature. We redetermine [Ba/Fe], [Y/Fe], and [Sr/Fe] ratios and confirm the overabundance of these s-process elements in the atmosphere of IN Com.

Based on data obtained with the STELLA robotic observatory in Tenerife, an AIP facility jointly operated by AIP and the Instituto de Astrofisica de Canarias, and on data acquired with PEPSI using the Vatican Advanced Technology Telescope (VATT) jointly operated by AIP and the Vatican Observatory. Title: Low albedos of hot to ultra-hot Jupiters in the optical to near-infrared transition regime Authors: Mallonn, M.; Köhler, J.; Alexoudi, X.; von Essen, C.; Granzer, T.; Poppenhaeger, K.; Strassmeier, K. G. Bibcode: 2019A&A...624A..62M Altcode: 2019arXiv190207944M The depth of a secondary eclipse contains information of both the thermally emitted light component of a hot Jupiter and the reflected light component. If the day side atmosphere of the planet is assumed to be isothermal, it is possible to disentangle both. In this work, we analyzed 11 eclipse light curves of the hot Jupiter HAT-P-32 b obtained at 0.89 μm in the z' band. We obtained a null detection for the eclipse depth with state-of-the-art precision, -0.01 ± 0.10 ppt. We confirm previous studies showing that a non-inverted atmosphere model is in disagreement to the measured emission spectrum of HAT-P-32 b. We derive an upper limit on the reflected light component, and thus, on the planetary geometric albedo Ag. The 97.5% confidence upper limit is Ag < 0.2. This is the first albedo constraint for HAT-P-32 b, and the first z' band albedo value for any exoplanet. This finding disfavors the influence of large-sized silicate condensates on the planetary day side. We inferred z' band geometric albedo limits from published eclipse measurements also for the ultra-hot Jupiters WASP-12 b, WASP-19 b, WASP-103 b, and WASP-121 b, applying the same method. These values consistently point to a low reflectivity in the optical to near-infrared transition regime for hot to ultra-hot Jupiters.

Based on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated by AIP and IAC.Lightcurves 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/624/A62 Title: VizieR Online Data Catalog: II Pegasi spectra with PEPSI (Strassmeier+, 2019) Authors: Strassmeier, K. G.; Carroll, T. A.; Ilyin, I. V. Bibcode: 2019yCat..36250027S Altcode: The polarimetric observations in this paper were obtained with PEPSI at the 2x8.4m LBT in Arizona. We employed both polarimeters in the LBT's two symmetric straight-through Gregorian foci.

(2 data files). Title: Carbon 12C/13C isotope ratio of α Aurigae revised Authors: Sablowski, Daniel P.; Järvinen, Silva; Ilyin, Ilya; Strassmeier, Klaus G. Bibcode: 2019A&A...622L..11S Altcode: 2019arXiv190201133S Context. Capella (α Aur) is one of the few binaries in the sky with two cool giant stars. With spectral types of G8III and G0III, the two components appear at different but distinct stages in their evolution. The G0 secondary star is a Hertzsprung-gap giant, and the G8 primary star is thought to be a clump giant.
Aims: We present a new measure of the carbon 12C/13C isotope ratio of the primary component of Capella using high-resolution R ≈ 250 000 spectra obtained with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) with both the Vatican Advanced Technology Telescope (VATT) and the Large Binocular Telescope (LBT).
Methods: Signal-to-noise ratios of up to 2 700 were obtained by averaging nightly spectra. These average spectra were used to disentangle the two binary components. The isotope ratio was derived with the use of spectrum synthesis from the CN lines at 8004 Å.
Results: We found that the 12C/13C ratio of the primary component of Capella is 17.8 ± 1.9. Our measurement precision is now primarily limited by the spectral-line data and by the grid-step size of the model atmospheres rather than the data. The separated spectrum of the secondary component does not show distinguishable 12CN and 13CN lines because of its vsini and higher temperature.
Conclusions: Our new 12C/13C value is significantly lower than the previous value of 27 ± 4 but now agrees better with the recent model prediction of 18.8-20.7. Title: Flares in open clusters with K2 . I. M 45 (Pleiades), M 44 (Praesepe), and M 67 Authors: Ilin, Ekaterina; Schmidt, Sarah J.; Davenport, James R. A.; Strassmeier, Klaus G. Bibcode: 2019A&A...622A.133I Altcode: 2018arXiv181206725I Context. The presence and strength of a stellar magnetic field and activity is rooted in a star's fundamental parameters such as mass and age. Can flares serve as an accurate stellar "clock"?
Aims: To explore if we can quantify an activity-age relation in the form of a flaring-age relation, we measured trends in the flaring rates and energies for stars with different masses and ages.
Methods: We investigated the time-domain photometry provided by Kepler's follow-up mission K2 and searched for flares in three solar metallicity open clusters with well-known ages, M 45 (0.125 Gyr), M 44 (0.63 Gyr), and M 67 (4.3 Gyr). We updated and employed the automated flare finding and analysis pipeline Appaloosa, originally designed for Kepler. We introduced a synthetic flare injection and recovery sub-routine to ascribe detection and energy recovery rates for flares in a broad energy range for each light curve.
Results: We collect a sample of 1761 stars, mostly late-K to mid-M dwarfs and found 751 flare candidates with energies ranging from 4 × 1032 erg to 6 × 1034 erg, of which 596 belong to M 45, 155 to M 44, and none to M 67. We find that flaring activity depends both on Teff, and age. But all flare frequency distributions have similar slopes with α ≈ 2.0-2.4, supporting a universal flare generation process. We discuss implications for the physical conditions under which flares occur, and how the sample's metallicity and multiplicity affect our results.

The detected flare indices, the stellar parameters for M 44 and M 45, and a copy of Table 4 are 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/A133. We also published all flares we validated, and stellar parameters used for M 44 and M 45 in the same location. Title: Spectroscopic membership for the populous 300 Myr-old open cluster NGC 3532 Authors: Fritzewski, D. J.; Barnes, S. A.; James, D. J.; Geller, A. M.; Meibom, S.; Strassmeier, K. G. Bibcode: 2019A&A...622A.110F Altcode: 2019arXiv190104507F Context. NGC 3532 is an extremely rich open cluster embedded in the Galactic disc, hitherto lacking a comprehensive, documented membership list.
Aims: We provide membership probabilities from new radial velocity observations of solar-type and low-mass stars in NGC 3532, in part as a prelude to a subsequent study of stellar rotation in the cluster.
Methods: Using extant optical and infra-red photometry we constructed a preliminary photometric membership catalogue, consisting of 2230 dwarf and turn-off stars. We selected 1060 of these for observation with the AAOmega spectrograph at the 3.9 m-Anglo-Australian Telescope and 391 stars for observations with the Hydra-South spectrograph at the 4 m Victor Blanco Telescope, obtaining spectroscopic observations over a decade for 145 stars. We measured radial velocities for our targets through cross-correlation with model spectra and standard stars, and supplemented them with radial velocities for 433 additional stars from the literature. We also measured log g, Teff, and [Fe/H] from the AAOmega spectra.
Results: The radial velocity distribution emerging from the observations is centred at 5.43 ± 0.04 km s-1 and has a width (standard deviation) of 1.46 km s-1. Together with proper motions from Gaia DR2 we find 660 exclusive members, of which five are likely binary members. The members are distributed across the whole cluster sequence, from giant stars to M dwarfs, making NGC 3532 one of the richest Galactic open clusters known to date, on par with the Pleiades. From further spectroscopic analysis of 153 dwarf members we find the metallicity to be marginally sub-solar, with [Fe/H] = -0.07 ± 0.10. We confirm the extremely low reddening of the cluster, EB - V = 0.034 ± 0.012 mag, despite its location near the Galactic plane. Exploiting trigonometric parallax measurements from Gaia DR2 we find a distance of 48435-30 pc [(m - M)0 = 8.42 ± 0.14 mag]. Based on the membership we provide an empirical cluster sequence in multiple photometric passbands. A comparison of the photometry of the measured cluster members with several recent model isochrones enables us to confirm the 300 Myr cluster age. However, all of the models evince departures from the cluster sequence in particular regions, especially in the lower mass range.

Full Tables 1, 3 and 4 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/A110Based on data acquired through the Australian Astronomical Observatory, under program S/2017A/02.Based on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory under proposals 2008A-0476, 2008A-0512, 2008B-0248, 2010A-0281, 2010B-0492, and 2011B-0322. Title: VizieR Online Data Catalog: HAT-P-32b differential photometry time series (Mallonn+, 2019) Authors: Mallonn, M.; Koehler, J.; Alexoudi, X.; von Essen, C.; Granzer, T.; Poppenhaeger, K.; Strassmeier, K. G. Bibcode: 2019yCat..36240062M Altcode: 11 differential photometry time series of secondary eclipse events of the hot Jupiter extrasolar planet HAT-P-32b. Filter: Sloan z' band.

(1 data file). Title: Ephemeris refinement of 21 hot Jupiter exoplanets with high timing uncertainties Authors: Mallonn, M.; von Essen, C.; Herrero, E.; Alexoudi, X.; Granzer, T.; Sosa, M.; Strassmeier, K. G.; Bakos, G.; Bayliss, D.; Brahm, R.; Bretton, M.; Campos, F.; Carone, L.; Colón, K. D.; Dale, H. A.; Dragomir, D.; Espinoza, N.; Evans, P.; Garcia, F.; Gu, S. -H.; Guerra, P.; Jongen, Y.; Jordán, A.; Kang, W.; Keles, E.; Kim, T.; Lendl, M.; Molina, D.; Salisbury, M.; Scaggiante, F.; Shporer, A.; Siverd, R.; Sokov, E.; Sokova, I.; Wünsche, A. Bibcode: 2019A&A...622A..81M Altcode: 2018arXiv181205882M Transit events of extrasolar planets offer a wealth of information for planetary characterization. However, for many known targets, the uncertainty of their predicted transit windows prohibits an accurate scheduling of follow-up observations. In this work, we refine the ephemerides of 21 hot Jupiter exoplanets with the largest timing uncertainties. We collected 120 professional and amateur transit light curves of the targets of interest, observed with a range of telescopes of 0.3 m-2.2 m, and analyzed them along with the timing information of the planets discovery papers. In the case of WASP-117b, we measured a timing deviation compared to the known ephemeris of about 3.5 h, and for HAT-P-29b and HAT-P-31b the deviation amounted to about 2 h and more. For all targets, the new ephemeris predicts transit timings with uncertainties of less than 6 min in the year 2018 and less than 13 min until 2025. Thus, our results allow for an accurate scheduling of follow-up observations in the next decade.

Observational lightcurves 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/A81 Title: Cycle period, differential rotation, and meridional flow for early M dwarf stars Authors: Küker, M.; Rüdiger, G.; Olah, K.; Strassmeier, K. G. Bibcode: 2019A&A...622A..40K Altcode: 2018arXiv180402925K Recent observations suggest the existence of two characteristic cycle times for early-type M stars dependent on the rotation period. They are of order one year for fast rotators (Prot < 1 day) and of order four years for slower rotators. Additionally, the equator-to-pole differences of the rotation rates with δΩ up to 0.03 rad d-1 are known from Kepler data for the fast-rotating stars. These values are well-reproduced by the theory of large-scale flows in rotating convection zones on the basis of the Λ effect. The resulting amplitudes um of the bottom value of the meridional circulation allows for the calculation of the travel time from pole to equator at the base of the convection zone of early-type M stars. These travel times strongly increase with rotation period and they always exceed the observed cycle periods. Therefore, the operation of an advection-dominated dynamo in early M dwarfs, where the travel time must always be shorter than the cycle period, is not confirmed by our model nor the data.

Based partly on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC. Title: Atmospheric Dynamics and the Variable Transit of KELT-9 b Authors: Cauley, P. Wilson; Shkolnik, Evgenya L.; Ilyin, Ilya; Strassmeier, Klaus G.; Redfield, Seth; Jensen, Adam Bibcode: 2019AJ....157...69C Altcode: 2018arXiv181005776C We present a spectrally and temporally resolved detection of the optical Mg I triplet at 7.8σ in the extended atmosphere of the ultra-hot Jupiter KELT-9 b, adding to the list of detected metal species in the hottest gas giant currently known. Constraints are placed on the density and radial extent of the excited hydrogen envelope using simultaneous observations of Hα and Hβ under the assumption of a spherically symmetric atmosphere. We find that planetary rotational broadening of {v}rot}={8.2}-0.7+0.6 km s-1 is necessary to reproduce the Balmer line transmission profile shapes, where the model including rotation is strongly preferred over the non-rotating model using a Bayesian information criterion comparison. The time series of both metal line and hydrogen absorption show remarkable structure, suggesting that the atmosphere observed during this transit is dynamic rather than static. We detect a relative emission feature near the end of the transit which exhibits a P-Cygni-like shape, evidence of material moving at ≈50-100 km s-1 away from the planet. We hypothesize that the in-transit variability and subsequent P-Cygni-like profiles are due to a flaring event that caused the atmosphere to expand, resulting in unbound material being accelerated to high speeds by stellar radiation pressure. Further spectroscopic transit observations will help establish the frequency of such events.

Based on data acquired with PEPSI using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are the University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Leibniz-Institute for Astrophysics Potsdam (AIP), and Heidelberg University; the Ohio State University; and the Research Corporation, on behalf of the University of Notre Dame, University of Minnesota and University of Virginia. Title: VizieR Online Data Catalog: 15 hot Jupiter exoplanets light curves (Mallonn+, 2019) Authors: Mallonn, M.; von Essen, C.; Herrero, E.; Alexoudi, X.; Granzer, T.; Sosa, M.; Strassmeier, K. G.; Bakos, G.; Bayliss, D.; Brahm, R.; Bretton, M.; Campos, F.; Carone, L.; Colon, K. D.; Dale, H. A.; Dragomir, D.; Espinoza, N.; Evans, P.; Garcia, F.; Gu, S. -H.; Guerra, P.; Jongen, Y.; Jordan, A.; Kang, W.; Keles, E.; Kim, T.; Lendl, M.; Molina, D.; Salisbury, M.; Scaggiante, F.; Shporer, A.; Siverd, R.; Sokov, E.; Sokova, I.; Wuensche, A. Bibcode: 2019yCat..36220081M Altcode: We obtained 35 photometric time series of transit events and employed them together with 85 publically available data sets to refine the orbital ephemeris of 21 hot Jupiter exoplanets.

We present 35 differential photometry time series of transit events of different extrasolar planets.

(2 data files). Title: Mapping EK Draconis with PEPSI. Possible evidence for starspot penumbrae Authors: Järvinen, S. P.; Strassmeier, K. G.; Carroll, T. A.; Ilyin, I.; Weber, M. Bibcode: 2018A&A...620A.162J Altcode: 2018arXiv181203675J
Aims: We present the first temperature surface map of EK Dra from very-high-resolution spectra obtained with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope.
Methods: Changes in spectral line profiles are inverted to a stellar surface temperature map using our iMap code. The long-term photometric record is employed to compare our map with previously published maps.
Results: Four cool spots were reconstructed, but no polar spot was seen. The temperature difference to the photosphere of the spots is between 990 and 280 K. Two spots are reconstructed with a typical solar morphology with an umbra and a penumbra. For the one isolated and relatively round spot (spot A), we determine an umbral temperature of 990 K and a penumbral temperature of 180 K below photospheric temperature. The umbra to photosphere intensity ratio of EK Dra is approximately only half of that of a comparison sunspot. A test inversion from degraded line profiles showed that the higher spectral resolution of PEPSI reconstructs the surface with a temperature difference that is on average 10% higher than before and with smaller surface areas by 10-20%. PEPSI is therefore better suited to detecting and characterising temperature inhomogeneities. With ten more years of photometry, we also refine the spot cycle period of EK Dra to 8.9 ± 0.2 yr with a continuing long-term fading trend.
Conclusions: The temperature morphology of spot A so far appears to show the best evidence for the existence of a solar-like penumbra for a starspot. We emphasise that it is more the non-capture of the true umbral contrast rather than the detection of the weak penumbra that is the limiting factor. The relatively small line broadening of EK Dra, together with the only moderately high spectral resolutions previously available, appear to be the main contributors to the lower-than-expected spot contrasts when comparing to the Sun.

Based on data acquired with PEPSI using the Large Binocular Telescope (LBT). Title: Deciphering the atmosphere of HAT-P-12b: solving discrepant results Authors: Alexoudi, X.; Mallonn, M.; von Essen, C.; Turner, J. D.; Keles, E.; Southworth, J.; Mancini, L.; Ciceri, S.; Granzer, T.; Denker, C.; Dineva, E.; Strassmeier, K. G. Bibcode: 2018A&A...620A.142A Altcode: 2018arXiv181002172A Context. Two independent investigations of the atmosphere of the hot Jupiter HAT-P-12b by two different groups resulted in discrepant solutions. Using broad-band photometry from the ground, one study found a flat and featureless transmission spectrum that was interpreted as gray absorption by dense cloud coverage. The second study made use of Hubble Space Telescope (HST) observations and found Rayleigh scattering at optical wavelengths caused by haze.
Aims: The main purpose of this work is to determine the source of this inconsistency and provide feedback to prevent similar discrepancies in future analyses of other exoplanetary atmospheres.
Methods: We studied the observed discrepancy via two methods. With further broad-band observations in the optical wavelength regions, we strengthened the previous measurements in precision, and with a homogeneous reanalysis of the published data, we were able to assess the systematic errors and the independent analyses of the two different groups.
Results: Repeating the analysis steps of both works, we found that deviating values for the orbital parameters are the reason for the aforementioned discrepancy. Our work showed a degeneracy of the planetary spectral slope with these parameters. In a homogeneous reanalysis of all data, the two literature data sets and the new observations converge to a consistent transmission spectrum, showing a low-amplitude spectral slope and a tentative detection of potassium absorption.

The transit light curves of HAT-P-12b 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/620/A142 Title: VizieR Online Data Catalog: M45, M44 and M67 flare stars (Ilin+, 2019) Authors: Ilin, E.; Schmidt, S. J.; Davenport, J. R. A.; Strassmeier, K. G. Bibcode: 2018yCat..36220133I Altcode: Using K2SC de-trended Kepler/K2 LCs we investigated the flaring activity of three solar metallicity OCs, the ZAMS cluster M 45, intermediate age M 44 and solar age M 67, a total of more than 250 years of cumulative observation time at 30-min cadence from 1761 targets, mostly late-K and early- to mid-M dwarfs. Pan-STARRS and 2MASS multiband photometry yielded Teff and radii of individual stars, using solar metallicity standards (Pickles, 1998PASP..110..863P), computed by Covey et al. (2007, Cat. J/AJ/134/2398), and colour-temperature relations from Pecaut & Mamajek (2013, Cat. J/ApJS/208/9). From these we derived quiescent luminosities and the Kepler band energies of flares detected by the flare finding and analysis pipeline Appaloosa (Davenport 2016, Cat. J/ApJ/829/23).

(3 data files). Title: VizieR Online Data Catalog: Spectroscopic membership for NGC 3532 (Fritzewski+, 2019) Authors: Fritzewski, D. J.; Barnes, S. A.; James, D. J.; Geller, A. M.; Meibom, S.; Strassmeier, K. G. Bibcode: 2018yCat..36220110F Altcode: The radial velocities were measured from spectroscopic observations with the Hydra-South spectrograph at the Victor Blanco Telescope at CTIO and the AAOmega on the Anglo-Australian Telescope at AAO. The observations at CTIO were carried out from February 2008 to March 2010 on 15 nights and at AAO we observed on 10 and 11 March 2017.

(4 data files). Title: 3D non-LTE corrections for Li abundance and 6Li/7Li isotopic ratio in solar-type stars. I. Application to HD 207129 and HD 95456 Authors: Harutyunyan, G.; Steffen, M.; Mott, A.; Caffau, E.; Israelian, G.; González Hernández, J. I.; Strassmeier, K. G. Bibcode: 2018A&A...618A..16H Altcode: 2018arXiv180704089H Context. Convective motions in solar-type stellar atmospheres induce Doppler shifts that affect the strengths and shapes of spectral absorption lines and create slightly asymmetric line profiles. One-dimensional (1D) local thermodynamic equilibrium (LTE) studies of elemental abundances are not able to reproduce this phenomenon, which becomes particularly important when modeling the impact of isotopic fine structure, like the subtle depression created by the 6Li isotope on the red wing of the Li I resonance doublet line.
Aims: The purpose of this work is to provide corrections for the lithium abundance, A(Li), and the 6Li/7Li isotopic ratio that can easily be applied to correct 1D LTE lithium abundances in G and F dwarf stars of approximately solar mass and metallicity for three-dimensional (3D) and non-LTE (NLTE) effects.
Methods: The corrections for A(Li) and 6Li/7Li are computed using grids of 3D NLTE and 1D LTE synthetic lithium line profiles, generated from 3D hydro-dynamical CO5BOLD and 1D hydrostatic model atmospheres, respectively. For comparative purposes, all calculations are performed for three different line lists representing the Li I λ670.8 nm spectral region. The 3D NLTE corrections are then approximated by analytical expressions as a function of the stellar parameters (Teff, log ℊ, [Fe/H], ν sin i, A(Li), 6Li/7Li). These are applied to adjust the 1D LTE isotopic lithium abundances in two solar-type stars, HD 207129 and HD 95456, for which high-quality HARPS observations are available.
Results: The derived 3D NLTE corrections range between -0.01 and +0.11 dex for A(Li), and between -4.9 and -0.4% for 6Li/7Li, depending on the adopted stellar parameters. We confirm that the inferred 6Li abundance depends critically on the strength of the Si I 670.8025 nm line. Our findings show a general consistency with recent works on lithium abundance corrections. After the application of such corrections, we do not find a significant amount of 6Li in any of the two target stars.
Conclusions: In the case of 6Li/7Li, our corrections are always negative, showing that 1D LTE analysis can significantly overestimate the presence of 6Li (up to 4.9% points) in the atmospheres of solar-like dwarf stars. These results emphasize the importance of reliable 3D model atmospheres combined with NLTE line formation for deriving precise isotopic lithium abundances. Although 3D NLTE spectral synthesis implies an extensive computational effort, the results can be made accessible with parametric tools like the ones presented in this work.

The table with the 3D NLTE corrections is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/618/A16 Title: VizieR Online Data Catalog: HAT-P-12b 2016-2017 light curve (Alexoudi+, 2018) Authors: Alexoudi, X.; Mallonn, M.; von Essen, C.; Turner, J. D.; Keles, E.; Southworth, J.; Mancini, L.; Ciceri, S.; Granzer, T.; Denker, C.; Dineva, E.; Strassmeier, K. G. Bibcode: 2018yCat..36200142A Altcode: Photometric observations of the transiting exoplanet HAT-P-12b in 2016-2017 with different ground-based facilities. These observations made use of the 1.2m STELLA robotic telescope (5 transits at Sloan g'), the 3.5m Telescopio Nazionale Galileo (TNG) on Roque de los Muchachos Observatory (1 transit at Johnson B), the 1.23m (two transits at Johnson B) and 2.2m (1 transit at Johnson B) telescopes of Calar Alto Observatory and the 3.5m (1 transit at Johnson B) Astrophysics Research Consortium (ARC) telescope from the Apache Point Observatory.

(2 data files). Title: VizieR Online Data Catalog: A(Li) and 6Li/7Li 3D NLTE corrections (Harutyunyan+, 2018) Authors: Harutyunyan, G.; Steffen, M.; Mott, A.; Caffau, E.; Israelian, G.; Gonzalez Hernandez, J. I.; Strassmeier, K. G. Bibcode: 2018yCat..36180016H Altcode: A grid of 3D non-LTE (NLTE) corrections for the lithium abundance, A(Li), and the 6Li/7Li isotopic ratio are presented. These corrections can be easily applied to correct 1D LTE lithium abundances in G and F dwarf stars of approximately solar mass and metallicity for 3D and NLTE effects. The stellar parameters defining the grid are effective temperatures, Teff (5900, 6300 and 6500K), surface gravity, logg (4.0 and 4.5), metallicity, [Fe/H] (-1.0, -0.5, 0.0, +0.5), 1D LTE lithium abundance, A(Li) (1.5, 2.0, 2.5), 1D LTE 6Li/7Li isotopic ratio (0, 5 and 10%), as well as projected rotational velocity, vsini (0, 2, 4 and 6km/s). Based on this table, a web page calculator was created that allows to compute the 3D NLTE corrections of A(Li) and 6Li/7Li ratio for a given combination of stellar parameters (https://pages.aip.de/li67nlte3d/).

(1 data file). Title: Exploring flaring activity as an age indicator using open cluster data Authors: Ilin, Ekaterina; Schmidt, Sarah J.; Davenport, James R. A.; Strassmeier, Klaus G. Bibcode: 2018csss.confE...1I Altcode: The presence and strength of stellar magnetic activity is rooted in a star's fundamental parameters such as mass and age. Age-resolved investigations of chromospheric activity indicators, and large scale magnetic field observations suggest that one can access an individual star's age via its magnetic activity. Can flares, magnetically driven energetic outbursts of energy on the surfaces of stars, serve as an accurate stellar clock" then? For a star with given mass, the probability to encounter a flare scales as a power law with its total released energy. If there is an activity-age relation in the form of a flaring-age relation we expect the observed flaring rates and energies to vary significantly in these objects. Thus, the slope and intercept of the power law fit to the flare frequency distribution would be a function of both mass and age. The Kepler mission provides the means to test this hypothesis - high precision time domain photometry of thousands of stars in more than 10 open clusters spanning a wide range of ages. Using Kepler's K2 Campaigns 4 and 5 we explore the possibility to calibrate such a clock on the example of three open clusters: M67 (4.3 Gyr), M44 (0.63 Gyr) and the Pleiades (0.125 Gyr), and present first results. Title: GANS: a nighttime spectrograph for the GREGOR solar telescope Authors: Järvinen, Arto S.; Weber, M.; Strassmeier, K. G.; Granzer, T.; Woche, M.; Bauer, S. -M.; Bittner, W.; Weingrill, J.; Sablowski, D. P. Bibcode: 2018SPIE10702E..6LJ Altcode: GREGOR at night spectrograph (GANS) is a high-resolution thermally-stabilised vacuum-enclosed fixed-format fiber-fed Echelle spectrograph. GANS will be installed starting 2018 alongside the daytime instrumentation in the building of the 1,5m Gregor Solar Telescope at the Observatorio del Teide at Izan∼a, Tenerife. Specified resolving power is R 55k with wavelength coverage from 470 to 680 nm in single shot on 2k 2k CCD with 3", 50μm fiber on sky, and with space between orders for simultaneous calibration light in the form of a Fabry-Perot Etalon or a Laser-comb spectrum. The end-to-end simulated radial velocity precision performance estimate is 2 ms-1. The main observing project of GANS will be the ground-based follow-up survey of TESS and PLATO2.0 exoplanet candidates. GANS will observe its targets in autonomous operation without human intervention using the normally human-operated day-time observatory. Limited operations will begin in first half of 2019 with first science-light planned for summer 2019. Title: Want a PEPSI? Performance status of the recently commissioned high-resolution spectrograph and polarimeter for the 2x8.4m Large Binocular Telescope Authors: Strassmeier, Klaus G.; Ilyin, I.; Weber, M.; Järvinen, A.; Woche, M.; Järvinen, S.; Sablowski, D.; Mallonn, M.; Keles, E.; Carroll, T.; Johnson, M. C.; Bender, C.; Wagner, R. M.; Veillet, C. Bibcode: 2018SPIE10702E..12S Altcode: PEPSI is the new fiber-fed and stabilized "Potsdam Echelle Polarimetric and Spectroscopic Instrument" for the Large Binocular Telescope (LBT). It covers the entire optical wavelength range from 384 to 913 nm in three exposures at resolutions of either R=λ/▵λ=50,000, 130,000 or 250,000. The R=130,000 mode can also be used with two dual-beam Stokes IQUV polarimeters. The 50,000-mode with its 12-pix sampling per resolution element is our "bad seeing" or "faint-object" mode. A robotic solar-disk-integration (SDI) telescope feeds solar light to PEPSI during day time and a 450-m fiber feed from the 1.8m VATT can be used when the LBT is busy otherwise. CCD characterization and a removal procedure for the spatial fixed-pattern noise were the main tasks left from the commissioning phase. Several SDI spectral time series with up to 300 individual spectra per day recovered the well-known solar 5-minute oscillation at a peak of 3 mHz (5.5min) with a disk-integrated radial-velocity amplitude of only 47 cm/s. Spectral atlases for 50 bright benchmark stars including the Sun were recently released to the scientific community, among them the ancient planet- system host Kepler-444. These data combine PEPSI's high spectral resolution of R=250,000 with signal-to-noise ratio (S/N) of many hundreds to even thousands covering the entire optical to near-infrared wavelength range from 384 to 913 nm. Other early science cases were exoplanet transits including TRAPPIST-1, a spectrum of Boyajian's star that revealed strong and structured but stable ISM Na D lines, a spectrum of Oph allowing a redetermination of the ISM Li line doublet, and a first Doppler image of the young solar analog EK Dra that revealed starspots with solar-like penumbrae. Title: ELT-HIRES the high resolution spectrograph for the ELT: optical design studies for the polarimetric unit Authors: Woche, M.; Di Varano, I.; Strassmeier, K. G.; Weber, M.; Laux, U.; Riva, M. Bibcode: 2018SPIE10706E..53W Altcode: We present the optical design of the ELT polarimeter in the context of the Phase-A study for HIRES. It is well known that in order to reduce the instrumental polarization and cross-talk, the optimal position for a polarimeter along the optical path of a telescope is the rotationally symmetric focus. In the particular case of ELT this is represented by the intermediate focus (IF) below M4 which is not directly accessible and needs therefore a reimaging to a safety distance of at least 500 mm. The design of a transfer optics unit for such location is challenging due to the constraint of having an allowed vignetting area of maximum 5 arc min. We focus in our paper on two optical design solutions. The first one is deploying a double Cassegrain system to reimage the IF, which includes the polarization optics and feeds the other ELT mirrors, redirecting the ordinary and extraordinary beams to the front end module (FE) onto the Nasmyth focus. This module comprises components for sky derotation, atmospheric dispersion correction (ADC), wavelength splitting in two bands (UBVRI, zYJH), field stabilization and conversion to f/20, dispatching the light into two pairs of fiber bundles to feed the HIRES spectrograph. The other solution considers a fiber based compact IF module, using a Schwarzschild Collimator with Foster prism, ADC and beam splitters for the two spectral bands. The two polarized beams are sent by pupil imaging through four separate long fibers to the fiber link module of the spectrograph. There we convert the output fiber f ratio from f/2.5 to f/20. Title: ELT-HIRES the high resolution spectrograph for the ELT: phase-A design of its polarimetric unit Authors: Di Varano, I.; Woche, M.; Strassmeier, K. G.; Ilyin, I.; Weber, M.; Yuan, S.; Covino, S.; Di Marcantonio, P.; Landoni, M.; Genoni, M.; Riva, M.; Marconi, A. Bibcode: 2018SPIE10706E..1YD Altcode: The Phase A study for the high-resolution spectrograph for the Extremely Large Telescope (ELT-HIRES) has been concluded in late 2017. We present the main outcome for a polarimetric light feed from the intermediate focus (IF) and a Nasmyth focus of the telescope. We conclude that the use of the IF is mandatory for high-precision spectropolarimetry. Among the description of the product tree, we present phase-A level opto-mechanical designs of the subunits, describe the observational and calibration modes, the PSF error budget, and the preliminary FEM structural and earthquake analysis. An update on the development of a ray tracing polarimetric simulator to estimate the instrumental polarization including both the telescope mirrors and the optical elements of the polarimeter is reported. Trade-off strategies and ongoing solutions in view of the Phase B are outlined too. Title: Radial velocity accuracy prediction of the GREGOR at night spectrograph based on simulated spectra Authors: Weber, Michael; Strassmeier, Klaus G.; Woche, Manfred; Ilyin, Ilya; Järvinen, Arto Bibcode: 2018SPIE10705E..1EW Altcode: The Gregor At Night Spectrograph (GANS) is a new instrument currently being built for the GREGOR solar telescope at Iza na observatory on Tenerife. Its primary science case will be the follow up of planetary candidates detected by upcoming surveys focussing on bright targets (TESS, PLATO2). Therefore it will be optimised for precise radial velocity determination and long term stability. We have developed a ZEMAX based software package to create simulated spectra, which are reduced using standard IRAF tasks. We used a solar model spectrum to determine the influence of S/N ratio, wavelength coverage, pixel sampling and telluric lines on the extracted radial velocities. Furthermore we derived the effect of an asymmetric spectrograph illumination on the measured radial velocity. Title: ELT-HIRES, the high resolution spectrograph for the ELT: results from the Phase A study Authors: Marconi, A.; Allende Prieto, C.; Amado, P. J.; Amate, M.; Augusto, S. R.; Becerril, S.; Bezawada, N.; Boisse, I.; Bouchy, F.; Cabral, A.; Chazelas, B.; Cirami, R.; Coretti, I.; Cristiani, S.; Cupani, G.; de Castro Leão, I.; de Medeiros, J. R.; de Souza, M. A. F.; Di Marcantonio, P.; Di Varano, I.; D'Odorico, V.; Drass, H.; Figueira, P.; Fragoso, A. B.; Fynbo, J. P. U.; Genoni, M.; González Hernández, J. I.; Haehnelt, M.; Hughes, I.; Huke, P.; Kjeldsen, H.; Korn, A. J.; Landoni, M.; Liske, J.; Lovis, C.; Maiolino, R.; Marquart, T.; Martins, C. J. A. P.; Mason, E.; Monteiro, M. A.; Morris, T.; Murray, G.; Niedzielski, A.; Oliva, E.; Origlia, L.; Pallé, E.; Parr-Burman, P.; Parro, V. C.; Pepe, F.; Piskunov, N.; Rasilla, J. L.; Rees, P.; Rebolo, R.; Riva, M.; Rousseau, S.; Sanna, N.; Santos, N. C.; Shen, T. -C.; Sortino, F.; Sosnowska, D.; Sousa, S.; Stempels, E.; Strassmeier, K.; Tenegi, F.; Tozzi, A.; Udry, S.; Valenziano, L.; Vanzi, L.; Weber, M.; Woche, M.; Xompero, M.; Zackrisson, E. Bibcode: 2018SPIE10702E..1YM Altcode: We present the results from the phase A study of ELT-HIRES, an optical-infrared High Resolution Spectrograph for ELT, which has just been completed by a consortium of 30 institutes from 12 countries forming a team of about 200 scientists and engineers. The top science cases of ELT-HIRES will be the detection of life signatures from exoplanet atmospheres, tests on the stability of Nature's fundamental couplings, the direct detection of the cosmic acceleration. However, the science requirements of these science cases enable many other groundbreaking science cases. The baseline design, which allows to fulfil the top science cases, consists in a modular fiber- fed cross-dispersed echelle spectrograph with two ultra-stable spectral arms providing a simultaneous spectral range of 0.4-1.8 μm at a spectral resolution of 100,000. The fiber-feeding allows ELT-HIRES to have several, interchangeable observing modes including a SCAO module and a small diffraction-limited IFU. Title: A study of white pupil configurations for high-resolution échelle spectrographs Authors: Sablowski, D. P.; Woche, M.; Weber, M.; Järvinen, A.; Strassmeier, K. G. Bibcode: 2018SPIE10706E..6FS Altcode: White pupil arrangements using parabolic off-axis mirrors are commonly used by instrument designers of high-resolution spectrographs. Their advantage is a non-chromatic, spherical free collimation, an intermediate focus providing the possibility for stray light apertures, and the compression of the beam diameter using a second, a transfer, collimator. However, these arrangements suffer from off-axis aberrations in the field. Many configurations create the intermediate focus, after double-passing the primary collimator, in the vicinity of the spectrograph input. This makes it necessary to introduce small angles at the main collimator, further increasing off-axis aberrations. Furthermore, image curvature is high and requires toroidal surfaces to be added near the spectrograph focus in front of the CCD. In high-precision radial velocity measurements, it is of great importance to properly model the spectrographs transfer function in order to derive exact line positions. Therefore, clean and very well defined spots, even when working near the sampling limit, which can simply be represented by gaussians will benefit such measurements. This point is usually considered less by instrument designers. We have studied several possible off-axis mirror arrangements for white pupil spectrographs and discuss our results here. We focus on the image quality generated by the mirrors, on-axis as well as in the field. We come to the conclusion that a fairly uncommon arrangement provides best performance in the sense of image quality and focus accessibility. Title: GJ 1214: Rotation period, starspots, and uncertainty on the optical slope of the transmission spectrum Authors: Mallonn, M.; Herrero, E.; Juvan, I. G.; von Essen, C.; Rosich, A.; Ribas, I.; Granzer, T.; Alexoudi, X.; Strassmeier, K. G. Bibcode: 2018A&A...614A..35M Altcode: 2018arXiv180305677M
Aims: Brightness inhomogeneities in the stellar photosphere (dark spots or bright regions) affect the measurements of the planetary transmission spectrum. To investigate the star spots of the M dwarf GJ 1214, we conducted a multicolor photometric monitoring from 2012 to 2016.
Methods: The time-series photometry was analyzed with the light curve inversion tool StarSim. Using the derived stellar surface properties from the light curve inversion, we modeled the impact of the star spots when unocculted by the transiting planet. We compared the photometric variability of GJ 1214 to published results of mid- to late M dwarfs from the MEarth sample.
Results: The measured variability shows a periodicity of 125 ± 5 days, which we interpret as the signature of the stellar rotation period. This value overrules previous suggestions of a significantly shorter stellar rotation period. A light curve inversion of the monitoring data yields an estimation of the flux dimming of a permanent spot filling factor not contributing to the photometric variability, a temperature contrast of the spots of 370 K and persistent active longitudes. The derived surface maps over all five seasons were used to estimate the influence of the star spots on the transmission spectrum of the planet from 400 to 2000 nm. The monitoring data presented here do not support a recent interpretation of a measured transmission spectrum of GJ 1214b as to be caused by bright regions in the stellar photosphere. Instead, we list arguments as to why the effect of dark spots likely dominated over bright regions in the period of our monitoring. Furthermore, our photometry proves an increase in variability over at least four years, indicative for a cyclic activity behavior. The age of GJ 1214 is likely between 6 and 10 Gyr.
Conclusions: The long-term photometry allows for a correction of unocculted spots. For an active star such as GJ 1214, there remains a degeneracy between occulted spots and the transit parameters used to build the transmission spectrum. This degeneracy can only be broken by high-precision transit photometry resolving the spot crossing signature in the transit light curve.

Based on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated by AIP and IAC.The photometry tables are only 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/614/A35 Title: PEPSI deep spectra. III. Chemical analysis of the ancient planet-host star Kepler-444 Authors: Mack, C. E.; Strassmeier, K. G.; Ilyin, I.; Schuler, S. C.; Spada, F.; Barnes, S. A. Bibcode: 2018A&A...612A..46M Altcode: 2017arXiv171206986M Context. With the Large Binocular Telescope (LBT), we obtained a spectrum with PEPSI, its new optical high-resolution échelle spectrograph. The spectrum has very high resolution and a high signal-to-noise (S/N) and is of the K0V host Kepler-444, which is known to host five sub-Earth-sized rocky planets. The spectrum has a resolution of R ≈ 250 000, a continuous wavelength coverage from 4230 Å to 9120 Å, and an S/N between 150-550:1 (blue to red). Aim. We performed a detailed chemical analysis to determine the photospheric abundances of 18 chemical elements. These were used to place constraints on the bulk composition of the five rocky planets.
Methods: Our spectral analysis employs the equivalent-width method for most of our spectral lines, but we used spectral synthesis to fit a small number of lines that required special care. In both cases, we derived our abundances using the MOOG spectral analysis package and Kurucz model atmospheres.
Results: We find no correlation between elemental abundance and condensation temperature among the refractory elements (TC > 950 K). In addition, using our spectroscopic stellar parameters and isochrone fitting, we find an age of 10 ± 1.5 Gyr, which is consistent with the asteroseismic age of 11 ± 1 Gyr. Finally, from the photospheric abundances of Mg, Si, and Fe, we estimate that the typical Fe-core mass fraction for the rocky planets in the Kepler-444 system is approximately 24%.
Conclusions: If our estimate of the Fe-core mass fraction is confirmed by more detailed modeling of the disk chemistry and simulations of planet formation and evolution in the Kepler-444 system, then this would suggest that rocky planets in more metal-poor and α-enhanced systems may tend to be less dense than their counterparts of comparable size in more metal-rich systems.

Based on data acquired with PEPSI using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are the University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Leibniz-Institute for Astrophysics Potsdam (AIP), and Heidelberg University; the Ohio State University; and the Research Corporation, on behalf of the University of Notre Dame, University of Minnesota and University of Virginia. Title: PEPSI deep spectra. II. Gaia benchmark stars and other M-K standards Authors: Strassmeier, K. G.; Ilyin, I.; Weber, M. Bibcode: 2018A&A...612A..45S Altcode: 2017arXiv171206967S Context. High-resolution échelle spectra confine many essential stellar parameters once the data reach a quality appropriate to constrain the various physical processes that form these spectra. Aim. We provide a homogeneous library of high-resolution, high-S/N spectra for 48 bright AFGKM stars, some of them approaching the quality of solar-flux spectra. Our sample includes the northern Gaia benchmark stars, some solar analogs, and some other bright Morgan-Keenan (M-K) spectral standards.
Methods: Well-exposed deep spectra were created by average-combining individual exposures. The data-reduction process relies on adaptive selection of parameters by using statistical inference and robust estimators. We employed spectrum synthesis techniques and statistics tools in order to characterize the spectra and give a first quick look at some of the science cases possible.
Results: With an average spectral resolution of R ≈ 220 000 (1.36 km s-1), a continuous wavelength coverage from 383 nm to 912 nm, and S/N of between 70:1 for the faintest star in the extreme blue and 6000:1 for the brightest star in the red, these spectra are now made public for further data mining and analysis. Preliminary results include new stellar parameters for 70 Vir and α Tau, the detection of the rare-earth element dysprosium and the heavy elements uranium, thorium and neodymium in several RGB stars, and the use of the 12C to 13C isotope ratio for age-related determinations. We also found Arcturus to exhibit few-percent Ca II H&K and Hα residual profile changes with respect to the KPNO atlas taken in 1999.

Based on data acquired with PEPSI using the Large Binocular Telescope (LBT) and the Vatican Advanced Technology Telescope (VATT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are the University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Leibniz-Institute for Astrophysics Potsdam (AIP), and Heidelberg University; the Ohio State University; and the Research Corporation, on behalf of the University of Notre Dame, University of Minnesota and University of Virginia. Title: PEPSI deep spectra. I. The Sun-as-a-star Authors: Strassmeier, K. G.; Ilyin, I.; Steffen, M. Bibcode: 2018A&A...612A..44S Altcode: 2017arXiv171206960S Context. Full-disk solar flux spectra can be directly compared to stellar spectra and thereby serve as our most important reference source for, for example stellar chemical abundances, magnetic activity phenomena, radial-velocity signatures or global pulsations. Aim. As part of the first Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) key-science project, we aim to provide well-exposed and average-combined (viz. deep) high-resolution spectra of representative stellar targets. Such deep spectra contain an overwhelming amount of information, typically much more than what could be analyzed and discussed within a single publication. Therefore, these spectra will be made available in form of (electronic) atlases. The first star in this series of papers is our Sun. It also acts as a system-performance cornerstone.
Methods: The Sun was monitored with PEPSI at the Large Binocular Telescope (LBT). Instead of the LBT we used a small robotic solar disk integration (SDI) telescope. The deep spectra in this paper are the results of combining up to ≈100 consecutive exposures per wavelength setting and are compared with other solar flux atlases.
Results: Our software for the optimal data extraction and reduction of PEPSI spectra is described and verified with the solar data. Three deep solar flux spectra with a spectral resolution of up to 270 000, a continuous wavelength coverage from 383 nm to 914 nm, and a photon signal to noise ratio (S/N) of between 2000-8000:1 depending on wavelength are presented. Additionally, a time-series of 996 high-cadence spectra in one cross disperser is used to search for intrinsic solar modulations. The wavelength calibration based on Th-Ar exposures and simultaneous Fabry-Pérot combs enables an absolute wavelength solution within 10 m s-1 (rms) with respect to the HARPS laser-comb solar atlas and a relative rms of 1.2 m s-1 for one day. For science demonstration, we redetermined the disk-average solar Li abundance to 1.09 ± 0.04 dex on the basis of 3D NLTE model atmospheres. We detected disk-averaged p-mode RV oscillations with a full amplitude of 47 cm s-1 at 5.5 min.
Conclusions: Comparisons with two solar FTS atlases, as well as with the HARPS solar atlas, validate the PEPSI data product. Now, PEPSI/SDI solar-flux spectra are being taken with a sampling of one deep spectrum per day, and are supposed to continue a full magnetic cycle of the Sun.

Based on data acquired with PEPSI fed by the solar disk integration (SDI) telescope operated by AIP at the Large Binocular Telescope Observatory (LBTO). The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, The Leibniz Institute for Astrophysics Potsdam (AIP), and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia. Title: Tracking of an electron beam through the solar corona with LOFAR Authors: Mann, G.; Breitling, F.; Vocks, C.; Aurass, H.; Steinmetz, M.; Strassmeier, K. G.; Bisi, M. M.; Fallows, R. A.; Gallagher, P.; Kerdraon, A.; Mackinnon, A.; Magdalenic, J.; Rucker, H.; Anderson, J.; Asgekar, A.; Avruch, I. M.; Bell, M. E.; Bentum, M. J.; Bernardi, G.; Best, P.; Bîrzan, L.; Bonafede, A.; Broderick, J. W.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Corstanje, A.; de Gasperin, F.; de Geus, E.; Deller, A.; Duscha, S.; Eislöffel, J.; Engels, D.; Falcke, H.; Fender, R.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Grießmeier, J.; Gunst, A. W.; van Haarlem, M.; Hassall, T. E.; Heald, G.; Hessels, J. W. T.; Hoeft, M.; Hörandel, J.; Horneffer, A.; Juette, E.; Karastergiou, A.; Klijn, W. F. A.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; Maat, P.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; McKean, J. P.; Mulcahy, D. D.; Munk, H.; Nelles, A.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pandey, V. N.; Pizzo, R.; Polatidis, A. G.; Rafferty, D.; Reich, W.; Röttgering, H.; Scaife, A. M. M.; Schwarz, D. J.; Serylak, M.; Sluman, J.; Smirnov, O.; Stappers, B. W.; Tagger, M.; Tang, Y.; Tasse, C.; ter Veen, S.; Thoudam, S.; Toribio, M. C.; Vermeulen, R.; van Weeren, R. J.; Wise, M. W.; Wucknitz, O.; Yatawatta, S.; Zarka, P.; Zensus, J. A. Bibcode: 2018A&A...611A..57M Altcode: The Sun's activity leads to bursts of radio emission, among other phenomena. An example is type-III radio bursts. They occur frequently and appear as short-lived structures rapidly drifting from high to low frequencies in dynamic radio spectra. They are usually interpreted as signatures of beams of energetic electrons propagating along coronal magnetic field lines. Here we present novel interferometric LOFAR (LOw Frequency ARray) observations of three solar type-III radio bursts and their reverse bursts with high spectral, spatial, and temporal resolution. They are consistent with a propagation of the radio sources along the coronal magnetic field lines with nonuniform speed. Hence, the type-III radio bursts cannot be generated by a monoenergetic electron beam, but by an ensemble of energetic electrons with a spread distribution in velocity and energy. Additionally, the density profile along the propagation path is derived in the corona. It agrees well with three-fold coronal density model by (1961, ApJ, 133, 983). Title: VizieR Online Data Catalog: Differential photometry of GJ1214 (Mallonn+, 2018) Authors: Mallonn, M.; Herrero, E.; Juvan, I. G.; von Essen, C.; Rosich, A.; Ribas, I.; Granzer, T.; Alexoudi, X.; Strassmeier, K. G. Bibcode: 2018yCat..36140035M Altcode: The photometric monitoring data of GJ1214 have been observed with STELLA/WiFSIP over five observing seasons. In the first season 2012, the broad band filters V and I have been used. In the seasons 2013 to 2016, the filters B and V have been used.

(1 data file). Title: KELT-21b: A Hot Jupiter Transiting the Rapidly Rotating Metal-poor Late-A Primary of a Likely Hierarchical Triple System Authors: Johnson, Marshall C.; Rodriguez, Joseph E.; Zhou, George; Gonzales, Erica J.; Cargile, Phillip A.; Crepp, Justin R.; Penev, Kaloyan; Stassun, Keivan G.; Gaudi, B. Scott; Colón, Knicole D.; Stevens, Daniel J.; Strassmeier, Klaus G.; Ilyin, Ilya; Collins, Karen A.; Kielkopf, John F.; Oberst, Thomas E.; Maritch, Luke; Reed, Phillip A.; Gregorio, Joao; Bozza, Valerio; Calchi Novati, Sebastiano; D'Ago, Giuseppe; Scarpetta, Gaetano; Zambelli, Roberto; Latham, David W.; Bieryla, Allyson; Cochran, William D.; Endl, Michael; Tayar, Jamie; Serenelli, Aldo; Silva Aguirre, Victor; Clarke, Seth P.; Martinez, Maria; Spencer, Michelle; Trump, Jason; Joner, Michael D.; Bugg, Adam G.; Hintz, Eric G.; Stephens, Denise C.; Arredondo, Anicia; Benzaid, Anissa; Yazdi, Sormeh; McLeod, Kim K.; Jensen, Eric L. N.; Hancock, Daniel A.; Sorber, Rebecca L.; Kasper, David H.; Jang-Condell, Hannah; Beatty, Thomas G.; Carroll, Thorsten; Eastman, Jason; James, David; Kuhn, Rudolf B.; Labadie-Bartz, Jonathan; Lund, Michael B.; Mallonn, Matthias; Pepper, Joshua; Siverd, Robert J.; Yao, Xinyu; Cohen, David H.; Curtis, Ivan A.; DePoy, D. L.; Fulton, Benjamin J.; Penny, Matthew T.; Relles, Howard; Stockdale, Christopher; Tan, Thiam-Guan; Villanueva, Steven, Jr. Bibcode: 2018AJ....155..100J Altcode: 2017arXiv171203241J We present the discovery of KELT-21b, a hot Jupiter transiting the V = 10.5 A8V star HD 332124. The planet has an orbital period of P = 3.6127647 ± 0.0000033 days and a radius of {1.586}-0.040+0.039 {R}{{J}}. We set an upper limit on the planetary mass of {M}P< 3.91 {M}{{J}} at 3σ confidence. We confirmed the planetary nature of the transiting companion using this mass limit and Doppler tomographic observations to verify that the companion transits HD 332124. These data also demonstrate that the planetary orbit is well-aligned with the stellar spin, with a sky-projected spin-orbit misalignment of λ =-{5.6}-1.9+1.7\circ . The star has {T}{eff}={7598}-84+81 K, {M}* ={1.458}-0.028+0.029 {M}⊙ , {R}* =1.638 +/- 0.034 {R}⊙ , and v\sin {I}* =146 km s-1, the highest projected rotation velocity of any star known to host a transiting hot Jupiter. The star also appears to be somewhat metal poor and α-enhanced, with [{Fe}/{{H}}]=-{0.405}-0.033+0.032 and [α/Fe] = 0.145 ± 0.053 these abundances are unusual, but not extraordinary, for a young star with thin-disk kinematics like KELT-21. High-resolution imaging observations revealed the presence of a pair of stellar companions to KELT-21, located at a separation of 1.″2 and with a combined contrast of {{Δ }}{K}S=6.39+/- 0.06 with respect to the primary. Although these companions are most likely physically associated with KELT-21, we cannot confirm this with our current data. If associated, the candidate companions KELT-21 B and C would each have masses of ∼0.12 {M}⊙ , a projected mutual separation of ∼20 au, and a projected separation of ∼500 au from KELT-21. KELT-21b may be one of only a handful of known transiting planets in hierarchical triple stellar systems. Title: Letter from the Editor Authors: Strassmeier, Klaus G. Bibcode: 2018AN....339....9S Altcode: No abstract at ADS Title: The First Post-Kepler Brightness Dips of KIC 8462852 Authors: Boyajian, Tabetha. S.; Alonso, Roi; Ammerman, Alex; Armstrong, David; Asensio Ramos, A.; Barkaoui, K.; Beatty, Thomas G.; Benkhaldoun, Z.; Benni, Paul; Bentley, Rory O.; Berdyugin, Andrei; Berdyugina, Svetlana; Bergeron, Serge; Bieryla, Allyson; Blain, Michaela G.; Capetillo Blanco, Alicia; Bodman, Eva H. L.; Boucher, Anne; Bradley, Mark; Brincat, Stephen M.; Brink, Thomas G.; Briol, John; Brown, David J. A.; Budaj, J.; Burdanov, A.; Cale, B.; Aznar Carbo, Miguel; Castillo García, R.; Clark, Wendy J.; Clayton, Geoffrey C.; Clem, James L.; Coker, Phillip H.; Cook, Evan M.; Copperwheat, Chris M.; Curtis, J. L.; Cutri, R. M.; Cseh, B.; Cynamon, C. H.; Daniels, Alex J.; Davenport, James R. A.; Deeg, Hans J.; De Lorenzo, Roberto; de Jaeger, Thomas; Desrosiers, Jean-Bruno; Dolan, John; Dowhos, D. J.; Dubois, Franky; Durkee, R.; Dvorak, Shawn; Easley, Lynn; Edwards, N.; Ellis, Tyler G.; Erdelyi, Emery; Ertel, Steve; Farfán, Rafael. G.; Farihi, J.; Filippenko, Alexei V.; Foxell, Emma; Gandolfi, Davide; Garcia, Faustino; Giddens, F.; Gillon, M.; González-Carballo, Juan-Luis; González-Fernández, C.; González Hernández, J. I.; Graham, Keith A.; Greene, Kenton A.; Gregorio, J.; Hallakoun, Na'ama; Hanyecz, Ottó; Harp, G. R.; Henry, Gregory W.; Herrero, E.; Hildbold, Caleb F.; Hinzel, D.; Holgado, G.; Ignácz, Bernadett; Ilyin, Ilya; Ivanov, Valentin D.; Jehin, E.; Jermak, Helen E.; Johnston, Steve; Kafka, S.; Kalup, Csilla; Kardasis, Emmanuel; Kaspi, Shai; Kennedy, Grant M.; Kiefer, F.; Kielty, C. L.; Kessler, Dennis; Kiiskinen, H.; Killestein, T. L.; King, Ronald A.; Kollar, V.; Korhonen, H.; Kotnik, C.; Könyves-Tóth, Réka; Kriskovics, Levente; Krumm, Nathan; Krushinsky, Vadim; Kundra, E.; Lachapelle, Francois-Rene; LaCourse, D.; Lake, P.; Lam, Kristine; Lamb, Gavin P.; Lane, Dave; Lau, Marie Wingyee; Lewin, Pablo; Lintott, Chris; Lisse, Carey; Logie, Ludwig; Longeard, Nicolas; Lopez Villanueva, M.; Whit Ludington, E.; Mainzer, A.; Malo, Lison; Maloney, Chris; Mann, A.; Mantero, A.; Marengo, Massimo; Marchant, Jon; Martínez González, M. J.; Masiero, Joseph R.; Mauerhan, Jon C.; McCormac, James; McNeely, Aaron; Meng, Huan Y. A.; Miller, Mike; Molnar, Lawrence A.; Morales, J. C.; Morris, Brett M.; Muterspaugh, Matthew W.; Nespral, David; Nugent, C. R.; Nugent, Katherine M.; Odasso, A.; O'Keeffe, Derek; Oksanen, A.; O'Meara, John M.; Ordasi, András; Osborn, Hugh; Ott, John J.; Parks, J. R.; Rodriguez Perez, Diego; Petriew, Vance; Pickard, R.; Pál, András; Plavchan, P.; Pollacco, Don; Pozo Nuñez, F.; Pozuelos, F. J.; Rau, Steve; Redfield, Seth; Relles, Howard; Ribas, Ignasi; Richards, Jon; Saario, Joonas L. O.; Safron, Emily J.; Sallai, J. Martin; Sárneczky, Krisztián; Schaefer, Bradley E.; Schumer, Clea F.; Schwartzendruber, Madison; Siegel, Michael H.; Siemion, Andrew P. V.; Simmons, Brooke D.; Simon, Joshua D.; Simón-Díaz, S.; Sitko, Michael L.; Socas-Navarro, Hector; Sódor, Á.; Starkey, Donn; Steele, Iain A.; Stone, Geoff; Strassmeier, Klaus G.; Street, R. A.; Sullivan, Tricia; Suomela, J.; Swift, J. J.; Szabó, Gyula M.; Szabó, Róbert; Szakáts, Róbert; Szalai, Tamás; Tanner, Angelle M.; Toledo-Padrón, B.; Tordai, Tamás; Triaud, Amaury H. M. J.; Turner, Jake D.; Ulowetz, Joseph H.; Urbanik, Marian; Vanaverbeke, Siegfried; Vanderburg, Andrew; Vida, Krisztián; Vietje, Brad P.; Vinkó, József; von Braun, K.; Waagen, Elizabeth O.; Walsh, Dan; Watson, Christopher A.; Weir, R. C.; Wenzel, Klaus; Westendorp Plaza, C.; Williamson, Michael W.; Wright, Jason T.; Wyatt, M. C.; Zheng, WeiKang; Zsidi, Gabriella Bibcode: 2018ApJ...853L...8B Altcode: 2018arXiv180100732B We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the Kepler space mission in 2013 May. Our regular photometric surveillance started in 2015 October, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1%-2.5% dips, named “Elsie,” “Celeste,” “Skara Brae,” and “Angkor,” which persist on timescales from several days to weeks. Our main results so far are as follows: (i) there are no apparent changes of the stellar spectrum or polarization during the dips and (ii) the multiband photometry of the dips shows differential reddening favoring non-gray extinction. Therefore, our data are inconsistent with dip models that invoke optically thick material, but rather they are in-line with predictions for an occulter consisting primarily of ordinary dust, where much of the material must be optically thin with a size scale ≪1 μm, and may also be consistent with models invoking variations intrinsic to the stellar photosphere. Notably, our data do not place constraints on the color of the longer-term “secular” dimming, which may be caused by independent processes, or probe different regimes of a single process. Title: High Resolution Optical Spectroscopy of the Classical Nova V5668 Sgr Showing the Presence of Lithium Authors: Wagner, R. Mark; Woodward, Charles E.; Starrfield, Sumner; Ilyin, Ilya; Strassmeier, Klaus Bibcode: 2018AAS...23135810W Altcode: The classical nova (CN) V5668 Sgr was discovered on 2015 March 15.634 and initial optical spectra implied it was an Fe II-class CN. We obtained high resolution optical spectroscopy on 30 nights between 2015 April 3 and 2016 June 5 with the 2 x 8.4 m Large Binocular Telescope (LBT) and the 1.8 m Vatican Advanced Technology Telescope (VATT) using the Potsdam Echelle Polarimetric Spectroscopic Instrument (PEPSI). The spectra cover all or part of the 3830-9065 Å spectral region at a spectral resolution of up to 270,000 (1 km/s); the highest resolution currently available on any 8-10 m class telescope. The early spectra are dominated by emission lines of the Balmer and Paschen series of hydrogen, Fe II, Ca II, and Na I with P Cyg-type line profiles as well as emission lines of [O I]. Numerous interstellar lines and bands are readily apparent at high spectral resolution. The permitted line profiles show complex and dramatic variations in the multi-component P Cyg-type line profiles with time. We detect a weak blue-shifted absorption line at a velocity consistent with Li I 6708 Å when compared with the line profiles of Hβ, Fe II 5169 Å, and Na I D. This line is present in spectra obtained on 7 of 8 consecutive nights up to day 21 of the outburst; but absent on day 42 when it is evident that the ionization of the ejecta has significantly increased. The equivalent width of the line converted to a column density, and the resulting mass fraction, imply a significant enrichment of 7Li in the ejecta. 7Li is produced by the decay of unstable 7Be created during the thermonuclear runaway. The discovery of the resonance lines of 7Be II in the optical spectra of the recent CNe V339 Del, V2944 Oph, and V5668 Sgr by Tajitsu et al. (2016) and its subsequent decay to 7Li (half life of 53 days) suggests a significant enrichment of 7Li in the Galaxy from CNe is possible. Our observations of the Li I 6708 Å line in the early optical spectra of V5668 Sgr mark the second direct detection of Li in a CN following the detection of Li I in the early optical spectra of V1369 Cen by Izzo et al. (2015). SS acknowledges partial support from NSF and NASA grants to ASU. CEW acknowledges support from NASA. Title: Transmission spectroscopy of the hot Jupiter TrES-3 b: Disproof of an overly large Rayleigh-like feature Authors: Mackebrandt, F.; Mallonn, M.; Ohlert, J. M.; Granzer, T.; Lalitha, S.; García Muñoz, A.; Gibson, N. P.; Lee, J. W.; Sozzetti, A.; Turner, J. D.; Vaňko, M.; Strassmeier, K. G. Bibcode: 2017A&A...608A..26M Altcode: 2017arXiv170906124M Context. Transit events of extrasolar planets offer the opportunity to study the composition of their atmospheres. Previous work on transmission spectroscopy of the close-in gas giant (TrES)-3 b revealed an increase in absorption towards blue wavelengths of very large amplitude in terms of atmospheric pressure scale heights, too large to be explained by Rayleigh-scattering in the planetary atmosphere.
Aims: We present a follow-up study of the optical transmission spectrum of the hot Jupiter TrES-3 b to investigate the strong increase in opacity towards short wavelengths found by a previous study. Furthermore, we aim to estimate the effect of stellar spots on the transmission spectrum.
Methods: This work uses previously published long slit spectroscopy transit data of the Gran Telescopio Canarias (GTC) and published broad band observations as well as new observations in different bands from the near-UV to the near-IR, for a homogeneous transit light curve analysis. Additionally, a long-term photometric monitoring of the TrES-3 host star was performed.
Results: Our newly analysed GTC spectroscopic transit observations show a slope of much lower amplitude than previous studies. We conclude from our results the previously reported increasing signal towards short wavelengths is not intrinsic to the TrES-3 system. Furthermore, the broad band spectrum favours a flat spectrum. Long-term photometric monitoring rules out a significant modification of the transmission spectrum by unocculted star spots.

Based on (1) data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated by AIP and IAC, (2) observations collected at the German-Spanish Astronomical Center, Calar Alto, jointly operated by the Max-Planck-Institut für Astronomie Heidelberg and the Instituto de Astrofísica de Andalucía (CSIC) and (3) observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.Newly observed photometric data from Sects. 2.2 and 2.3 and tables of the lightcurves are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/608/A26 Title: Contemporaneous Imaging Comparisons of the Spotted Giant σ Geminorum Using Interferometric, Spectroscopic, and Photometric Data Authors: Roettenbacher, Rachael M.; Monnier, John D.; Korhonen, Heidi; Harmon, Robert O.; Baron, Fabien; Hackman, Thomas; Henry, Gregory W.; Schaefer, Gail H.; Strassmeier, Klaus G.; Weber, Michael; ten Brummelaar, Theo A. Bibcode: 2017ApJ...849..120R Altcode: 2017arXiv170910109R Nearby active stars with relatively rapid rotation and large starspot structures offer the opportunity to compare interferometric, spectroscopic, and photometric imaging techniques. In this paper, we image a spotted star with three different methods for the first time. The giant primary star of the RS Canum Venaticorum binary σ Geminorum (σ Gem) was imaged for two epochs of interferometric, high-resolution spectroscopic, and photometric observations. The light curves from the reconstructions show good agreement with the observed light curves, supported by the longitudinally consistent spot features on the different maps. However, there is strong disagreement in the spot latitudes across the methods. Title: Rotation-differential rotation relationships for late-type single and binary stars from Doppler imaging Authors: Kővári, Zs.; Oláh, K.; Kriskovics, L.; Vida, K.; Forgács-Dajka, E.; Strassmeier, K. G. Bibcode: 2017AN....338..903K Altcode: 2017arXiv170909001K From our sample of spotted late-type stars showing surface differential rotation, we find that the relationship between the rotation period and the surface shear coefficient α = ΔΩ/Ωeq is significantly different for single stars compared to members in close binaries. Single stars follow a general trend that α increases with the rotation period. However, differential rotation of stars in close binary systems shows much weaker dependence on the rotation, if any, suggesting that in such systems, tidal forces operate as a controlling mechanism of differential rotation. Title: 3D simulations of rising magnetic flux tubes in a compressible rotating interior: The effect of magnetic tension Authors: Fournier, Y.; Arlt, R.; Ziegler, U.; Strassmeier, K. G. Bibcode: 2017A&A...607A...1F Altcode: 2017arXiv170706781F Context. Long-term variability in solar cycles represents a challenging constraint for theoretical models. Mean-field Babcock-Leighton dynamos that consider non-instantaneous rising flux tubes have been shown to exhibit long-term variability in their magnetic cycle. However a relation that parameterizes the rise-time of non-axisymmetric magnetic flux tubes in terms of stellar parameters is still missing.
Aims: We aim to find a general parameterization of the rise-time of magnetic flux tubes for solar-like stars.
Methods: By considering the influence of magnetic tension on the rise of non-axisymmetric flux tubes, we predict the existence of a control parameter referred as Γα1α2. This parameter is a measure of the balance between rotational effects and magnetic effects (buoyancy and tension) acting on the magnetic flux tube. We carry out two series of numerical experiments (one for axisymmetric rise and one for non-axisymmetric rise) and demonstrate that Γα1α2 indeed controls the rise-time of magnetic flux tubes.
Results: We find that the rise-time follows a power law of Γα1α2 with an exponent that depends on the azimuthal wavenumber of the magnetic flux loop.
Conclusions: Compressibility does not impact the rise of magnetic flux tubes, while non-axisymmetry does. In the case of non-axisymmetric rise, the tension force modifies the force balance acting on the magnetic flux tube. We identified the three independent parameters required to predict the rise-time of magnetic flux tubes, that is, the stellar rotation rate, the magnetic flux density of the flux tube, and its azimuthal wavenumber. We combined these into one single relation that is valid for any solar-like star. We suggest using this generalized relation to constrain the rise-time of magnetic flux tubes in Babcock-Leighton dynamo models. Title: Antisolar differential rotation with surface lithium enrichment on the single K-giant V1192 Orionis Authors: Kővári, Zs.; Strassmeier, K. G.; Carroll, T. A.; Oláh, K.; Kriskovics, L.; Kővári, E.; Kovács, O.; Vida, K.; Granzer, T.; Weber, M. Bibcode: 2017A&A...606A..42K Altcode: 2017arXiv170801577K Context. Stars with about 1-2 solar masses at the red giant branch (RGB) represent an intriguing period of stellar evolution, I.e. when the convective envelope interacts with the fast-rotating core. During these mixing episodes freshly synthesized lithium can come up to the stellar surface along with high angular momentum material. This high angular momentum may alter the surface rotation pattern.
Aims: The single rapidly rotating K-giant V1192 Ori is revisited to determine its surface differential rotation, lithium abundance, and basic stellar properties such as a precise rotation period. The aim is to independently verify the antisolar differential rotation of the star and possibly find a connection to the surface lithium abundance.
Methods: We applied time-series Doppler imaging to a new multi-epoch data set. Altogether we reconstructed 11 Doppler images from spectroscopic data collected with the STELLA robotic telescope between 2007-2016. We used our inversion code iMap to reconstruct all stellar surface maps. We extracted the differential rotation from these images by tracing systematic spot migration as a function of stellar latitude from consecutive image cross-correlations.
Results: The position of V1192 Ori in the Hertzsprung-Russell diagram suggests that the star is in the helium core-burning phase just leaving the RGB bump. We measure A(Li)NLTE = 1.27, I.e. a value close to the anticipated transition value of 1.5 from Li-normal to Li-rich giants. Doppler images reveal extended dark areas arranged quasi-evenly along an equatorial belt. No cool polar spot is found during the investigated epoch. Spot displacements clearly suggest antisolar surface differential rotation with α = - 0.11 ± 0.02 shear coefficient.
Conclusions: The surface Li enrichment and the peculiar surface rotation pattern may indicate a common origin.

Based on data obtained with the STELLA robotic observatory in Tenerife, an AIP facility jointly operated by AIP and IAC. Title: Flows along arch filaments observed in the GRIS `very fast spectroscopic mode' Authors: González Manrique, S. J.; Denker, C.; Kuckein, C.; Pastor Yabar, A.; Collados, M.; Verma, M.; Balthasar, H.; Diercke, A.; Fischer, C. E.; Gömöry, P.; Bello González, N.; Schlichenmaier, R.; Cubas Armas, M.; Berkefeld, T.; Feller, A.; Hoch, S.; Hofmann, A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T. Bibcode: 2017IAUS..327...28G Altcode: 2017arXiv170102206G A new generation of solar instruments provides improved spectral, spatial, and temporal resolution, thus facilitating a better understanding of dynamic processes on the Sun. High-resolution observations often reveal multiple-component spectral line profiles, e.g., in the near-infrared He i 10830 Å triplet, which provides information about the chromospheric velocity and magnetic fine structure. We observed an emerging flux region, including two small pores and an arch filament system, on 2015 April 17 with the `very fast spectroscopic mode' of the GREGOR Infrared Spectrograph (GRIS) situated at the 1.5-meter GREGOR solar telescope at Observatorio del Teide, Tenerife, Spain. We discuss this method of obtaining fast (one per minute) spectral scans of the solar surface and its potential to follow dynamic processes on the Sun. We demonstrate the performance of the `very fast spectroscopic mode' by tracking chromospheric high-velocity features in the arch filament system. Title: VizieR Online Data Catalog: TrES-3b UBVIz' light curves (Mackebrandt+, 2017) Authors: Mackebrandt, F.; Mallonn, M.; Ohlert, J. M.; Granzer, T.; Lalitha, S.; Garcia Munoz, A.; Gibson, N. P.; Lee, J. W.; Sozzetti, A.; Turner, J. D.; Vanko, M.; Strassmeier, K. G. Bibcode: 2017yCat..36080026M Altcode: We observed transits of the hot Jupiter TrES-3b in Johnson U, B, V, I and Sloan z'. Telescopes are named according to the paper.

We monitored the exoplanet host star TrES-3 with STELLA/WiFSIP in 2016 over the course of four months from March 7 to July 10, 2016. We observed in two filters, Johnson B and Johnson V, in blocks of three exposures each.

(4 data files). Title: Lithium abundance and 6Li/7Li ratio in the active giant HD 123351. I. A comparative analysis of 3D and 1D NLTE line-profile fits Authors: Mott, A.; Steffen, M.; Caffau, E.; Spada, F.; Strassmeier, K. G. Bibcode: 2017A&A...604A..44M Altcode: 2017arXiv170406460M Context. Current three-dimensional (3D) hydrodynamical model atmospheres together with detailed spectrum synthesis, accounting for departures from local thermodynamic equilibrium (LTE), permit to derive reliable atomic and isotopic chemical abundances from high-resolution stellar spectra. Not much is known about the presence of the fragile 6Li isotope in evolved solar-metallicity red giant branch (RGB) stars, not to mention its production in magnetically active targets like HD 123351.
Aims: A detailed spectroscopic investigation of the lithium resonance doublet in HD 123351 in terms of both abundance and isotopic ratio is presented. From fits of the observed spectrum, taken at the Canada-France-Hawaii telescope, with synthetic line profiles based on 1D and 3D model atmospheres, we seek to estimate the abundance of the 6Li isotope and to place constraints on its origin.
Methods: We derive the lithium abundance A(Li) and the 6Li/7Li isotopic ratio by fitting different synthetic spectra to the Li-line region of a high-resolution CFHT spectrum (R = 120 000, S/N = 400). The synthetic spectra are computed with four different line lists, using in parallel 3D hydrodynamical CO5BOLD and 1D LHD model atmospheres and treating the line formation of the lithium components in non-LTE (NLTE). The fitting procedure is repeated with different assumptions and wavelength ranges to obtain a reasonable estimate of the involved uncertainties.
Results: We find A(Li) = 1.69 ± 0.11 dex and 6Li/7Li = 8.0 ± 4.4% in 3D-NLTE, using the line list of Meléndez et al. (2012, A&A, 543, A29), updated with new atomic data for V I, which results in the best fit of the lithium line profile of HD 123351. Two other line lists lead to similar results but with inferior fit qualities.
Conclusions: Our 2σ detection of the 6Li isotope is the result of a careful statistical analysis and the visual inspection of each achieved fit. Since the presence of a significant amount of 6Li in the atmosphere of a cool evolved star is not expected in the framework of standard stellar evolution theory, non-standard, external lithium production mechanisms, possibly related to stellar activity or a recent accretion of rocky material, need to be invoked to explain the detection of 6Li in HD 123351. 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: Surface magnetism of cool stars Authors: Kochukhov, O.; Petit, P.; Strassmeier, K. G.; Carroll, T. A.; Fares, R.; Folsom, C. P.; Jeffers, S. V.; Korhonen, H.; Monnier, J. D.; Morin, J.; Rosén, L.; Roettenbacher, R. M.; Shulyak, D. Bibcode: 2017AN....338..428K Altcode: 2016arXiv161203388K Magnetic fields are essential ingredients of many physical processes in the interiors and envelopes of cool stars. Yet their direct detection and characterization is notoriously difficult, requiring high-quality observations and advanced analysis techniques. Significant progress has been recently achieved by several types of direct magnetic field studies on the surfaces of cool, active stars. In particular, complementary techniques of field topology mapping with polarization data and total magnetic flux measurements from intensity spectra have been systematically applied to different classes of active stars, leading to interesting and occasionally controversial results. In this paper, we summarize the current status of direct magnetic field studies of cool stars and investigations of surface inhomogeneities caused by the field, based on the material presented at the Cool Stars 19 splinter session. Title: 3D non-LTE corrections for the 6Li/7Li isotopic ratio in solar-type stars Authors: Harutyunyan, G.; Steffen, M.; Mott, A.; Caffau, E.; Israelian, G.; González Hernández, J. I.; Strassmeier, K. G. Bibcode: 2017MmSAI..88...61H Altcode: Doppler shifts induced by convective motions in stellar atmospheres affect the shape of spectral absorption lines and create slightly asymmetric line profiles. It is important to take this effect into account in modeling the subtle depression created by the 6Li isotope which lies on the red wing of the Li I 670.8 nm resonance doublet line, since convective motions in stellar atmospheres can mimic a presence of 6Li when intrinsically symmetric theoretical line profiles are presumed for the analysis of the 7Li doublet \citep{cayrel2007}. Based on CO5BOLD hydrodynamical model atmospheres, we compute 3D non-local thermodynamic equilibrium (NLTE) corrections for the 6Li/7Li isotopic ratio by using a grid of 3D NLTE and 1D LTE synthetic spectra. These corrections must be added to the results of the 1D LTE analysis to correct them for the combined 3D non-LTE effects. As one would expect, the resulting corrections are always negative and they range between 0 and -5 %, depending on effective temperature, surface gravity, and metallicity. For each metallicity we derive an analytic expression approximating the 3D NLTE corrections as a function of effective temperature, surface gravity and projected rotational velocity. Title: Letter from the Editor Authors: Strassmeier, Klaus G. Bibcode: 2017AN....338....7S Altcode: No abstract at ADS Title: CoRoT photometry and STELLA spectroscopy of an eccentric, eclipsing, and spotted HgMn binary with sub-synchronized rotation Authors: Strassmeier, K. G.; Granzer, T.; Mallonn, M.; Weber, M.; Weingrill, J. Bibcode: 2017A&A...597A..55S Altcode: 2016A&A...597A..55S Context. We report the discovery and analysis of very narrow transits in the eccentric spectroscopic binary HSS 348 (IC 4756).
Aims: The aim is to characterize the full HSS 348 system.
Methods: We obtained high-precision CoRoT photometry over two long runs and multi-epoch high-resolution échelle spectroscopy and imaging with STELLA. Standard radial-velocity extraction, spectrum synthesis, Fourier analysis, and light-curve inversions are applied to the data.
Results: HSS 348 is found to be an eccentric (e = 0.18) double-lined spectroscopic binary with a period of 12.47 d in which at least the primary component is a peculiar B star of the HgMn class. The orbital elements are such that the system undergoes a grazing eclipse with the primary in front but no secondary eclipse. The out-of-eclipse light variations show four nearly equidistant but unequal minima stable in shape and amplitude throughout our observations. Their individual photometric periods are all harmonics of the same fundamental period which happens to agree with the transit period to within the errors. We interpret the fundamental period to be the rotation period of at least one if not both stars due to surface inhomogeneities. Due to the non-zero eccentricity of the orbit the two components are rotating sub-synchronously.
Conclusions: It appears that HSS 348 is not a member of the IC 4756 cluster but a background B8+B8.5 binary system. Its sharp eclipses every 12.47 days just mimic a small-body transit but are in reality the grazing eclipses of a B-star binary and thus a classical false positive. The system seems to be pre-main sequence with the primary possibly just arrived on the ZAMS. The light curve with four unequal minima can be explained with four cool spots of different size equidistantly positioned in longitude. Our data do not allow to uniquely assign the spots to either of the two stars.

The CoRoT space mission, launched on 2006 December 27, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain. Partly based on data obtained with the STELLA robotic observatory in Tenerife, an AIP facility jointly operated by AIP and IAC.The final data sets are only 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/597/A55 Title: Short-term evolution and coexistence of spots, plages and flare activity on LQ Hydrae Authors: Flores Soriano, M.; Strassmeier, K. G. Bibcode: 2017A&A...597A.101F Altcode: 2016arXiv161005067F
Aims: We aim to study the short-term evolution of the chromospheric and photospheric activity of the young, single K2 dwarf LQ Hya.
Methods: Four months of quasi-simultaneous spectroscopic and photometric observations were used to study the variations of the photometric light curve, the evolution of the chromospheric activity from the Hα and Hβ lines, and the distribution of cool spots from Doppler maps.
Results: During our observations one side of the star was more active than the other. The equivalent width of the Hα line from the least active hemisphere increased from ≈0.7 Å at the beginning of the observation to 1.0 Å at the end. The basal emission of the most active hemisphere remained roughly constant at EWHαt1.0 Å. Intense flare activity was observed during the first twenty days, where at least four different events were detected. The line asymmetries of the Hα line suggest that one of the flares could have produced a mass ejection with a maximum projected speed of 70kms-1. The rotational modulation of the V-band photometry showed clear anti-correlation with the chromospheric activity. The difference in brightness between the opposite hemispheres decreased from 0.m16 to 0.m09 in two months. Three spots gradually moving apart from each other are dominating the photospheric Doppler maps. The comparison between the maps and the Hα line as the star rotates reveals the spatial coexistence of chromospheric Hα emission and photospheric spots.
Conclusions: Our results indicate that the active regions of LQ Hya can live for at least four months. The detected changes in the photometric light curve and the spectroscopic Doppler images seem to be more a consequence of the spatial redistribution of the active regions rather than due to changes in their strength. Only one of the active regions shows significant changes in its chromospheric emission.

Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC, and the Vienna-Potsdam Automatic Photoelectric Telescopes at Fairborn Observatory in Arizona, operated by AIP. Title: Lithium in the active sub-giant HD123351. A quantitative analysis with 3D and 1D model atmospheres using different observed spectra Authors: Mott, A.; Steffen, M.; Caffau, E.; Strassmeier, K. G. Bibcode: 2017MmSAI..88...68M Altcode: Current 3D hydrodynamical model atmosphere simulations together with non-LTE spectrum synthesis calculations permit to determine reliable atomic and in particular isotopic chemical abundances. Although this approach is computationally time demanding, it became feasible in studying lithium in stellar spectra. In the literature not much is known about the presence of the more fragile {6Li} isotope in evolved metal-rich objects. In this case the analysis is complicated by the lack of a suitable list of atomic and molecular lines in the spectral region of the lithium resonance line at 670.8 nm.

Here we present a spectroscopic comparative analysis of the Li doublet region of HD 123351, an active sub-giant star of solar metallicity. We fit the Li profile in three observed spectra characterized by different qualities: two very-high resolution spectra (Gecko@CFHT, R=120 000, SNR=400 and PEPSI@LBT, R=150 000, SNR=663) and a high-resolution SOPHIE@OHP spectrum (R=40 000, SNR=300). We adopt a set of model atmospheres, both 3D and 1D, having different stellar parameters (T_{eff} and log g). The 3D models are taken from the CIFIST grid of COBOLD model atmospheres and departures from LTE are considered for the lithium components. For the blends other than the lithium in this wavelength region we adopt the linelist of \citet{melendez12}. We find consistent results for all three observations and an overall good fit with the selected list of atomic and molecular lines, indicating a high {6Li} content.

The presence of {6Li} is not expected in cool stellar atmospheres. Its detection is of crucial importance for understanding mixing processes in stars and external lithium production mechanisms, possibly related to stellar activity or planetray accretion of {6Li}-rich material. Title: Slipping reconnection in a solar flare observed in high resolution with the GREGOR solar telescope Authors: Sobotka, M.; Dudík, J.; Denker, C.; Balthasar, H.; Jurčák, J.; Liu, W.; Berkefeld, T.; Collados Vera, M.; Feller, A.; Hofmann, A.; Kneer, F.; Kuckein, C.; Lagg, A.; Louis, R. E.; von der Lühe, O.; Nicklas, H.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; Waldmann, T. Bibcode: 2016A&A...596A...1S Altcode: 2016arXiv160500464S A small flare ribbon above a sunspot umbra in active region 12205 was observed on November 7, 2014, at 12:00 UT in the blue imaging channel of the 1.5 m GREGOR telescope, using a 1 Å Ca II H interference filter. Context observations from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO), the Solar Optical Telescope (SOT) onboard Hinode, and the Interface Region Imaging Spectrograph (IRIS) show that this ribbon is part of a larger one that extends through the neighboring positive polarities and also participates in several other flares within the active region. We reconstructed a time series of 140 s of Ca II H images by means of the multiframe blind deconvolution method, which resulted in spatial and temporal resolutions of 0.1″ and 1 s. Light curves and horizontal velocities of small-scale bright knots in the observed flare ribbon were measured. Some knots are stationary, but three move along the ribbon with speeds of 7-11 km s-1. Two of them move in the opposite direction and exhibit highly correlated intensity changes, which provides evidence of a slipping reconnection at small spatial scales.

Movies associated to Figs. 1 and 2 are available at http://www.aanda.org Title: Broad-band spectrophotometry of HAT-P-32 b: search for a scattering signature in the planetary spectrum Authors: Mallonn, M.; Bernt, I.; Herrero, E.; Hoyer, S.; Kirk, J.; Wheatley, P. J.; Seeliger, M.; Mackebrandt, F.; von Essen, C.; Strassmeier, K. G.; Granzer, T.; Künstler, A.; Dhillon, V. S.; Marsh, T. R.; Gaitan, J. Bibcode: 2016MNRAS.463..604M Altcode: 2016arXiv160802346M; 2016MNRAS.tmp.1124M Multicolour broad-band transit observations offer the opportunity to characterize the atmosphere of an extrasolar planet with small- to medium-sized telescopes. One of the most favourable targets is the hot Jupiter HAT-P-32 b. We combined 21 new transit observations of this planet with 36 previously published light curves for a homogeneous analysis of the broad-band transmission spectrum from the Sloan u' band to the Sloan z' band. Our results rule out cloud-free planetary atmosphere models of solar metallicity. Furthermore, a discrepancy at reddest wavelengths to previously published results makes a recent tentative detection of a scattering feature less likely. Instead, the available spectral measurements of HAT-P-32 b favour a completely flat spectrum from the near-UV to the near-IR. A plausible interpretation is a thick cloud cover at high altitudes. Title: Deep probing of the photospheric sunspot penumbra: no evidence of field-free gaps Authors: Borrero, J. M.; Asensio Ramos, A.; Collados, M.; Schlichenmaier, R.; Balthasar, H.; Franz, M.; Rezaei, R.; Kiess, C.; Orozco Suárez, D.; Pastor Yabar, A.; Berkefeld, T.; von der Lühe, O.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Soltau, D.; Volkmer, R.; Waldmann, T.; Denker, C.; Hofmann, A.; Staude, J.; Strassmeier, K. G.; Feller, A.; Lagg, A.; Solanki, S. K.; Sobotka, M.; Nicklas, H. Bibcode: 2016A&A...596A...2B Altcode: 2016arXiv160708165B Context. Some models for the topology of the magnetic field in sunspot penumbrae predict regions free of magnetic fields or with only dynamically weak fields in the deep photosphere.
Aims: We aim to confirm or refute the existence of weak-field regions in the deepest photospheric layers of the penumbra.
Methods: We investigated the magnetic field at log τ5 = 0 is by inverting spectropolarimetric data of two different sunspots located very close to disk center with a spatial resolution of approximately 0.4-0.45''. The data have been recorded using the GRIS instrument attached to the 1.5-m solar telescope GREGOR at the El Teide observatory. The data include three Fe I lines around 1565 nm, whose sensitivity to the magnetic field peaks half a pressure scale height deeper than the sensitivity of the widely used Fe I spectral line pair at 630 nm. Before the inversion, the data were corrected for the effects of scattered light using a deconvolution method with several point spread functions.
Results: At log τ5 = 0 we find no evidence of regions with dynamically weak (B< 500 Gauss) magnetic fields in sunspot penumbrae. This result is much more reliable than previous investigations made on Fe I lines at 630 nm. Moreover, the result is independent of the number of nodes employed in the inversion, is independent of the point spread function used to deconvolve the data, and does not depend on the amount of stray light (I.e., wide-angle scattered light) considered. Title: Spectropolarimetric observations of an arch filament system with the GREGOR solar telescope Authors: Balthasar, H.; Gömöry, P.; González Manrique, S. J.; Kuckein, C.; Kavka, J.; Kučera, A.; Schwartz, P.; Vašková, R.; Berkefeld, T.; Collados Vera, M.; Denker, C.; Feller, A.; Hofmann, A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pastor Yabar, A.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T. Bibcode: 2016AN....337.1050B Altcode: 2016arXiv160901514B Arch filament systems occur in active sunspot groups, where a fibril structure connects areas of opposite magnetic polarity, in contrast to active region filaments that follow the polarity inversion line. We used the GREGOR Infrared Spectrograph (GRIS) to obtain the full Stokes vector in the spectral lines Si I λ1082.7 nm, He I λ1083.0 nm, and Ca I λ1083.9 nm. We focus on the near-infrared calcium line to investigate the photospheric magnetic field and velocities, and use the line core intensities and velocities of the helium line to study the chromospheric plasma. The individual fibrils of the arch filament system connect the sunspot with patches of magnetic polarity opposite to that of the spot. These patches do not necessarily coincide with pores, where the magnetic field is strongest. Instead, areas are preferred not far from the polarity inversion line. These areas exhibit photospheric downflows of moderate velocity, but significantly higher downflows of up to 30 km s-1 in the chromospheric helium line. Our findings can be explained with new emerging flux where the matter flows downward along the field lines of rising flux tubes, in agreement with earlier results. Title: Magnetic fields of opposite polarity in sunspot penumbrae Authors: Franz, M.; Collados, M.; Bethge, C.; Schlichenmaier, R.; Borrero, J. M.; Schmidt, W.; Lagg, A.; Solanki, S. K.; Berkefeld, T.; Kiess, C.; Rezaei, R.; Schmidt, D.; Sigwarth, M.; Soltau, D.; Volkmer, R.; von der Luhe, O.; Waldmann, T.; Orozco, D.; Pastor Yabar, A.; Denker, C.; Balthasar, H.; Staude, J.; Hofmann, A.; Strassmeier, K.; Feller, A.; Nicklas, H.; Kneer, F.; Sobotka, M. Bibcode: 2016A&A...596A...4F Altcode: 2016arXiv160800513F Context. A significant part of the penumbral magnetic field returns below the surface in the very deep photosphere. For lines in the visible, a large portion of this return field can only be detected indirectly by studying its imprints on strongly asymmetric and three-lobed Stokes V profiles. Infrared lines probe a narrow layer in the very deep photosphere, providing the possibility of directly measuring the orientation of magnetic fields close to the solar surface.
Aims: We study the topology of the penumbral magnetic field in the lower photosphere, focusing on regions where it returns below the surface.
Methods: We analyzed 71 spectropolarimetric datasets from Hinode and from the GREGOR infrared spectrograph. We inferred the quality and polarimetric accuracy of the infrared data after applying several reduction steps. Techniques of spectral inversion and forward synthesis were used to test the detection algorithm. We compared the morphology and the fractional penumbral area covered by reversed-polarity and three-lobed Stokes V profiles for sunspots at disk center. We determined the amount of reversed-polarity and three-lobed Stokes V profiles in visible and infrared data of sunspots at various heliocentric angles. From the results, we computed center-to-limb variation curves, which were interpreted in the context of existing penumbral models.
Results: Observations in visible and near-infrared spectral lines yield a significant difference in the penumbral area covered by magnetic fields of opposite polarity. In the infrared, the number of reversed-polarity Stokes V profiles is smaller by a factor of two than in the visible. For three-lobed Stokes V profiles the numbers differ by up to an order of magnitude. Title: Horizontal flow fields in and around a small active region. The transition period between flux emergence and decay Authors: Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; González Manrique, S. J.; Sobotka, M.; Bello González, N.; Hoch, S.; Diercke, A.; Kummerow, P.; Berkefeld, T.; Collados, M.; Feller, A.; Hofmann, A.; Kneer, F.; Lagg, A.; Löhner-Böttcher, J.; Nicklas, H.; Pastor Yabar, A.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Schubert, M.; Sigwarth, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T. Bibcode: 2016A&A...596A...3V Altcode: 2016arXiv160507462V Context. The solar magnetic field is responsible for all aspects of solar activity. Thus, emergence of magnetic flux at the surface is the first manifestation of the ensuing solar activity.
Aims: Combining high-resolution and synoptic observations aims to provide a comprehensive description of flux emergence at photospheric level and of the growth process that eventually leads to a mature active region.
Methods: The small active region NOAA 12118 emerged on 2014 July 17 and was observed one day later with the 1.5-m GREGOR solar telescope on 2014 July 18. High-resolution time-series of blue continuum and G-band images acquired in the blue imaging channel (BIC) of the GREGOR Fabry-Pérot Interferometer (GFPI) were complemented by synoptic line-of-sight magnetograms and continuum images obtained with the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). Horizontal proper motions and horizontal plasma velocities were computed with local correlation tracking (LCT) and the differential affine velocity estimator (DAVE), respectively. Morphological image processing was employed to measure the photometric and magnetic area, magnetic flux, and the separation profile of the emerging flux region during its evolution.
Results: The computed growth rates for photometric area, magnetic area, and magnetic flux are about twice as high as the respective decay rates. The space-time diagram using HMI magnetograms of five days provides a comprehensive view of growth and decay. It traces a leaf-like structure, which is determined by the initial separation of the two polarities, a rapid expansion phase, a time when the spread stalls, and a period when the region slowly shrinks again. The separation rate of 0.26 km s-1 is highest in the initial stage, and it decreases when the separation comes to a halt. Horizontal plasma velocities computed at four evolutionary stages indicate a changing pattern of inflows. In LCT maps we find persistent flow patterns such as outward motions in the outer part of the two major pores, a diverging feature near the trailing pore marking the site of upwelling plasma and flux emergence, and low velocities in the interior of dark pores. We detected many elongated rapidly expanding granules between the two major polarities, with dimensions twice as large as the normal granules. Title: Upper chromospheric magnetic field of a sunspot penumbra: observations of fine structure Authors: Joshi, J.; Lagg, A.; Solanki, S. K.; Feller, A.; Collados, M.; Orozco Suárez, D.; Schlichenmaier, R.; Franz, M.; Balthasar, H.; Denker, C.; Berkefeld, T.; Hofmann, A.; Kiess, C.; Nicklas, H.; Pastor Yabar, A.; Rezaei, R.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T. Bibcode: 2016A&A...596A...8J Altcode: 2016arXiv160801988J
Aims: The fine-structure of the magnetic field in a sunspot penumbra in the upper chromosphere is to be explored and compared to that in the photosphere.
Methods: Spectropolarimetric observations with high spatial resolution were recorded with the 1.5-m GREGOR telescope using the GREGOR Infrared Spectrograph (GRIS). The observed spectral domain includes the upper chromospheric Hei triplet at 10 830 Å and the photospheric Sii 10 827.1 Å and Cai 10 833.4 Å spectral lines. The upper chromospheric magnetic field is obtained by inverting the Hei triplet assuming a Milne-Eddington-type model atmosphere. A height-dependent inversion was applied to the Sii 10 827.1 Å and Cai 10 833.4 Å lines to obtain the photospheric magnetic field.
Results: We find that the inclination of the magnetic field varies in the azimuthal direction in the photosphere and in the upper chromosphere. The chromospheric variations coincide remarkably well with the variations in the inclination of the photospheric field and resemble the well-known spine and interspine structure in the photospheric layers of penumbrae. The typical peak-to-peak variations in the inclination of the magnetic field in the upper chromosphere are found to be 10°-15°, which is roughly half the variation in the photosphere. In contrast, the magnetic field strength of the observed penumbra does not vary on small spatial scales in the upper chromosphere.
Conclusions: Thanks to the high spatial resolution of the observations that is possible with the GREGOR telescope at 1.08 microns, we find that the prominent small-scale fluctuations in the magnetic field inclination, which are a salient part of the property of sunspot penumbral photospheres, also persist in the chromosphere, although at somewhat reduced amplitudes. Such a complex magnetic configuration may facilitate penumbral chromospheric dynamic phenomena, such as penumbral micro-jets or transient bright dots. Title: Active region fine structure observed at 0.08 arcsec resolution Authors: Schlichenmaier, R.; von der Lühe, O.; Hoch, S.; Soltau, D.; Berkefeld, T.; Schmidt, D.; Schmidt, W.; Denker, C.; Balthasar, H.; Hofmann, A.; Strassmeier, K. G.; Staude, J.; Feller, A.; Lagg, A.; Solanki, S. K.; Collados, M.; Sigwarth, M.; Volkmer, R.; Waldmann, T.; Kneer, F.; Nicklas, H.; Sobotka, M. Bibcode: 2016A&A...596A...7S Altcode: 2016arXiv160707094S Context. The various mechanisms of magneto-convective energy transport determine the structure of sunspots and active regions.
Aims: We characterise the appearance of light bridges and other fine-structure details and elaborate on their magneto-convective nature.
Methods: We present speckle-reconstructed images taken with the broad-band imager (BBI) at the 1.5 m GREGOR telescope in the 486 nm and 589 nm bands. We estimate the spatial resolution from the noise characteristics of the image bursts and obtain 0.08″ at 589 nm. We describe structure details in individual best images as well as the temporal evolution of selected features.
Results: We find branched dark lanes extending along thin (≈1″) light bridges in sunspots at various heliocentric angles. In thick (≳ 2″) light bridges the branches are disconnected from the central lane and have a Y shape with a bright grain toward the umbra. The images reveal that light bridges exist on varying intensity levels and that their small-scale features evolve on timescales of minutes. Faint light bridges show dark lanes outlined by the surrounding bright features. Dark lanes are very common and are also found in the boundary of pores. They have a characteristic width of 0.1″ or smaller. Intergranular dark lanes of that width are seen in active region granulation.
Conclusions: We interpret our images in the context of magneto-convective simulations and findings: while central dark lanes in thin light bridges are elevated and associated with a density increase above upflows, the dark lane branches correspond to locations of downflows and are depressed relative to the adjacent bright plasma. Thick light bridges with central dark lanes show no projection effect. They have a flat elevated plateau that falls off steeply at the umbral boundary. There, Y-shaped filaments form as they do in the inner penumbra. This indicates the presence of inclined magnetic fields, meaning that the umbral magnetic field is wrapped around the convective light bridge. Title: Probing deep photospheric layers of the quiet Sun with high magnetic sensitivity Authors: Lagg, A.; Solanki, S. K.; Doerr, H. -P.; Martínez González, M. J.; Riethmüller, T.; Collados Vera, M.; Schlichenmaier, R.; Orozco Suárez, D.; Franz, M.; Feller, A.; Kuckein, C.; Schmidt, W.; Asensio Ramos, A.; Pastor Yabar, A.; von der Lühe, O.; Denker, C.; Balthasar, H.; Volkmer, R.; Staude, J.; Hofmann, A.; Strassmeier, K.; Kneer, F.; Waldmann, T.; Borrero, J. M.; Sobotka, M.; Verma, M.; Louis, R. E.; Rezaei, R.; Soltau, D.; Berkefeld, T.; Sigwarth, M.; Schmidt, D.; Kiess, C.; Nicklas, H. Bibcode: 2016A&A...596A...6L Altcode: 2016arXiv160506324L Context. Investigations of the magnetism of the quiet Sun are hindered by extremely weak polarization signals in Fraunhofer spectral lines. Photon noise, straylight, and the systematically different sensitivity of the Zeeman effect to longitudinal and transversal magnetic fields result in controversial results in terms of the strength and angular distribution of the magnetic field vector.
Aims: The information content of Stokes measurements close to the diffraction limit of the 1.5 m GREGOR telescope is analyzed. We took the effects of spatial straylight and photon noise into account.
Methods: Highly sensitive full Stokes measurements of a quiet-Sun region at disk center in the deep photospheric Fe I lines in the 1.56 μm region were obtained with the infrared spectropolarimeter GRIS at the GREGOR telescope. Noise statistics and Stokes V asymmetries were analyzed and compared to a similar data set of the Hinode spectropolarimeter (SOT/SP). Simple diagnostics based directly on the shape and strength of the profiles were applied to the GRIS data. We made use of the magnetic line ratio technique, which was tested against realistic magneto-hydrodynamic simulations (MURaM).
Results: About 80% of the GRIS spectra of a very quiet solar region show polarimetric signals above a 3σ level. Area and amplitude asymmetries agree well with small-scale surface dynamo-magneto hydrodynamic simulations. The magnetic line ratio analysis reveals ubiquitous magnetic regions in the ten to hundred Gauss range with some concentrations of kilo-Gauss fields.
Conclusions: The GRIS spectropolarimetric data at a spatial resolution of ≈0.̋4 are so far unique in the combination of high spatial resolution scans and high magnetic field sensitivity. Nevertheless, the unavoidable effect of spatial straylight and the resulting dilution of the weak Stokes profiles means that inversion techniques still bear a high risk of misinterpretating the data. Title: Flow and magnetic field properties in the trailing sunspots of active region NOAA 12396 Authors: Verma, M.; Denker, C.; Böhm, F.; Balthasar, H.; Fischer, C. E.; Kuckein, C.; Bello González, N.; Berkefeld, T.; Collados, M.; Diercke, A.; Feller, A.; González Manrique, S. J.; Hofmann, A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pator Yabar, A.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T. Bibcode: 2016AN....337.1090V Altcode: Improved measurements of the photospheric and chromospheric three-dimensional magnetic and flow fields are crucial for a precise determination of the origin and evolution of active regions. We present an illustrative sample of multi-instrument data acquired during a two-week coordinated observing campaign in August 2015 involving, among others, the GREGOR solar telescope (imaging and near-infrared spectroscopy) and the space missions Solar Dynamics Observatory (SDO) and Interface Region Imaging Spectrograph (IRIS). The observations focused on the trailing part of active region NOAA 12396 with complex polarity inversion lines and strong intrusions of opposite polarity flux. The GREGOR Infrared Spectrograph (GRIS) provided Stokes IQUV spectral profiles in the photospheric Si I λ1082.7 nm line, the chromospheric He I λ1083.0 nm triplet, and the photospheric Ca I λ1083.9 nm line. Carefully calibrated GRIS scans of the active region provided maps of Doppler velocity and magnetic field at different atmospheric heights. We compare quick-look maps with those obtained with the ``Stokes Inversions based on Response functions'' (SIR) code, which furnishes deeper insight into the magnetic properties of the region. We find supporting evidence that newly emerging flux and intruding opposite polarity flux are hampering the formation of penumbrae, i.e., a penumbra fully surrounding a sunspot is only expected after cessation of flux emergence in proximity to the sunspots. Title: VizieR Online Data Catalog: Corot photometry of TYC 455-791-1 (Strassmeier+, 2017) Authors: Strassmeier, K. G.; Granzer, T.; Mallonn, M.; Weber, M.; Weingrill, J. Bibcode: 2016yCat..35970055S Altcode: From the original CoRoT white-light flux obtained on two consecutive runs, we filter out obvious outliers from the SAA (south Atlantic Anomaly). The third column are the remaining CoRoT data points. The two data set were merged using individual zero-points of 716386.54e- for the first data set and 721882.56e- for the second data set, respectively. The magnitudes thus calculates are in column four. The last column is the combined model of the transit plus a 12th order Fourier-series fit to the out-of-transit data.

(1 data file). Title: Three-dimensional structure of a sunspot light bridge Authors: Felipe, T.; Collados, M.; Khomenko, E.; Kuckein, C.; Asensio Ramos, A.; Balthasar, H.; Berkefeld, T.; Denker, C.; Feller, A.; Franz, M.; Hofmann, A.; Joshi, J.; Kiess, C.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pastor Yabar, A.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T. Bibcode: 2016A&A...596A..59F Altcode: 2016arXiv161104803F Context. Active regions are the most prominent manifestations of solar magnetic fields; their generation and dissipation are fundamental problems in solar physics. Light bridges are commonly present during sunspot decay, but a comprehensive picture of their role in the removal of the photospheric magnetic field is still lacking.
Aims: We study the three-dimensional configuration of a sunspot, and in particular, its light bridge, during one of the last stages of its decay.
Methods: We present the magnetic and thermodynamical stratification inferred from full Stokes inversions of the photospheric Si I 10 827 Å and Ca I 10 839 Å lines obtained with the GREGOR Infrared Spectrograph of the GREGOR telescope at the Observatorio del Teide, Tenerife, Spain. The analysis is complemented by a study of continuum images covering the disk passage of the active region, which are provided by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory.
Results: The sunspot shows a light bridge with penumbral continuum intensity that separates the central umbra from a smaller umbra. We find that in this region the magnetic field lines form a canopy with lower magnetic field strength in the inner part. The photospheric light bridge is dominated by gas pressure (high-β), as opposed to the surrounding umbra, where the magnetic pressure is higher. A convective flow is observed in the light bridge. This flow is able to bend the magnetic field lines and to produce field reversals. The field lines merge above the light bridge and become as vertical and strong as in the surrounding umbra. We conclude that this occurs because two highly magnetized regions approach each other during the sunspot evolution.

Movies associated to Figs. 2 and 13 are available at http://www.aanda.org Title: Inference of magnetic fields in the very quiet Sun Authors: Martínez González, M. J.; Pastor Yabar, A.; Lagg, A.; Asensio Ramos, A.; Collados, M.; Solanki, S. K.; Balthasar, H.; Berkefeld, T.; Denker, C.; Doerr, H. P.; Feller, A.; Franz, M.; González Manrique, S. J.; Hofmann, A.; Kneer, F.; Kuckein, C.; Louis, R.; von der Lühe, O.; Nicklas, H.; Orozco, D.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Verma, M.; Waldman, T.; Volkmer, R. Bibcode: 2016A&A...596A...5M Altcode: 2018arXiv180410089M Context. Over the past 20 yr, the quietest areas of the solar surface have revealed a weak but extremely dynamic magnetism occurring at small scales (<500 km), which may provide an important contribution to the dynamics and energetics of the outer layers of the atmosphere. Understanding this magnetism requires the inference of physical quantities from high-sensitivity spectro-polarimetric data with high spatio-temporal resolution.
Aims: We present high-precision spectro-polarimetric data with high spatial resolution (0.4'') of the very quiet Sun at 1.56 μm obtained with the GREGOR telescope to shed some light on this complex magnetism.
Methods: We used inversion techniques in two main approaches. First, we assumed that the observed profiles can be reproduced with a constant magnetic field atmosphere embedded in a field-free medium. Second, we assumed that the resolution element has a substructure with either two constant magnetic atmospheres or a single magnetic atmosphere with gradients of the physical quantities along the optical depth, both coexisting with a global stray-light component.
Results: Half of our observed quiet-Sun region is better explained by magnetic substructure within the resolution element. However, we cannot distinguish whether this substructure comes from gradients of the physical parameters along the line of sight or from horizontal gradients (across the surface). In these pixels, a model with two magnetic components is preferred, and we find two distinct magnetic field populations. The population with the larger filling factor has very weak ( 150 G) horizontal fields similar to those obtained in previous works. We demonstrate that the field vector of this population is not constrained by the observations, given the spatial resolution and polarimetric accuracy of our data. The topology of the other component with the smaller filling factor is constrained by the observations for field strengths above 250 G: we infer hG fields with inclinations and azimuth values compatible with an isotropic distribution. The filling factors are typically below 30%. We also find that the flux of the two polarities is not balanced. From the other half of the observed quiet-Sun area 50% are two-lobed Stokes V profiles, meaning that 23% of the field of view can be adequately explained with a single constant magnetic field embedded in a non-magnetic atmosphere. The magnetic field vector and filling factor are reliable inferred in only 50% based on the regular profiles. Therefore, 12% of the field of view harbour hG fields with filling factors typically below 30%. At our present spatial resolution, 70% of the pixels apparently are non-magnetised. Title: Fitting peculiar spectral profiles in He I 10830Å absorption features Authors: González Manrique, S. J.; Kuckein, C.; Pastor Yabar, A.; Collados, M.; Denker, C.; Fischer, C. E.; Gömöry, P.; Diercke, A.; Bello González, N.; Schlichenmaier, R.; Balthasar, H.; Berkefeld, T.; Feller, A.; Hoch, S.; Hofmann, A.; Kneer, F.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Verma, M.; Volkmer, R.; von der Lühe, O.; Waldmann, T. Bibcode: 2016AN....337.1057G Altcode: 2016arXiv160300679G The new generation of solar instruments provides better spectral, spatial, and temporal resolution for a better understanding of the physical processes that take place on the Sun. Multiple-component profiles are more commonly observed with these instruments. Particularly, the He I 10830 Å triplet presents such peculiar spectral profiles, which give information on the velocity and magnetic fine structure of the upper chromosphere. The purpose of this investigation is to describe a technique to efficiently fit the two blended components of the He I 10830 Å triplet, which are commonly observed when two atmospheric components are located within the same resolution element. The observations used in this study were taken on 2015 April 17 with the very fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS) attached to the 1.5-m GREGOR solar telescope, located at the Observatorio del Teide, Tenerife, Spain. We apply a double-Lorentzian fitting technique using Levenberg-Marquardt least-squares minimization. This technique is very simple and much faster than inversion codes. Line-of-sight Doppler velocities can be inferred for a whole map of pixels within just a few minutes. Our results show sub- and supersonic downflow velocities of up to 32 km s-1 for the fast component in the vicinity of footpoints of filamentary structures. The slow component presents velocities close to rest. Title: Time-series Doppler images and surface differential rotation of the effectively single, rapidly rotating K-giant KU Pegasi Authors: Kővári, Zs.; Künstler, A.; Strassmeier, K. G.; Carroll, T. A.; Weber, M.; Kriskovics, L.; Oláh, K.; Vida, K.; Granzer, T. Bibcode: 2016A&A...596A..53K Altcode: 2016arXiv160900196K Context. According to most stellar dynamo theories, differential rotation (DR) plays a crucial role in the generation of toroidal magnetic fields. Numerical models predict surface differential rotation to be anti-solar for rapidly rotating giant stars, I.e. their surface angular velocity could increase with stellar latitude. However, surface differential rotation has been derived only for a handful of individual giant stars to date.
Aims: The spotted surface of the K-giant KU Pegasi is investigated in order to detect its time evolution and to quantify the surface differential rotation.
Methods: We present 11 Doppler images from spectroscopic data collected with the robotic telescope STELLA between 2006 and 2011. All maps are obtained with the surface reconstruction code iMap. Differential rotation is extracted from these images by detecting systematic (latitude-dependent) spot displacements. We apply a cross-correlation technique to find the best differential rotation law.
Results: The surface of KU Peg shows cool spots at all latitudes and one persistent warm spot at high latitude. A small cool polar spot exists for most but not all of the epochs. Re-identification of spots in at least two consecutive maps is mostly possible only at middle and high latitudes and thus restricts the differential-rotation determination mainly to these latitudes. Our cross-correlation analysis reveals solar-like differential rotation with a surface shear of α = + 0.040 ± 0.006, I.e., approximately five times weaker than on the Sun. We also derive a more accurate and consistent set of stellar parameters for KU Peg including a small Li abundance of ten times less than solar.

Based on data obtained with the STELLA robotic observatory in Tenerife, an AIP facility jointly operated by AIP and IAC. Title: Time-series Doppler imaging of the red giant HD 208472. Active longitudes and differential rotation Authors: Özdarcan, O.; Carroll, T. A.; Künstler, A.; Strassmeier, K. G.; Evren, S.; Weber, M.; Granzer, T. Bibcode: 2016A&A...593A.123O Altcode: 2016arXiv160706841O Context. HD 208472 is among the most active RS CVn binaries with cool starspots. Decade-long photometry has shown that the spots seem to change their longitudinal appearance with a period of about six years, coherent with brightness variations.
Aims: Our aim is to spatially resolve the stellar surface of HD 208472 and relate the photometric results to the true longitudinal and latitudinal spot appearance. Furthermore, we investigate the surface differential rotation pattern of the star.
Methods: We employed three years of high-resolution spectroscopic data with a high signal-to-noise ratio (S/N) from the STELLA robotic observatory and determined new and more precise stellar physical parameters. Precalculated synthetic spectra were fit to each of these spectra, and we provide new spot-corrected orbital elements. A sample of 34 absorption lines per spectrum was used to calculate mean line profiles with a S/N of several hundred. A total of 13 temperature Doppler images were reconstructed from these line profiles with the inversion code iMap. Differential rotation was investigated by cross-correlating successive Doppler images in each observing season.
Results: Spots on HD 208472 are distributed preferably at high latitudes and less frequently around mid-to-low latitudes. No polar-cap like structure is seen at any epoch. We observed a flip-flop event between 2009 and 2010, manifested as a flip of the spot activity from phase 0.0 to phase 0.5, while the overall brightness of the star continued to increase and reached an all-time maximum in 2014. Cross-correlation of successive Doppler images suggests a solar-like differential rotation that is ≈15 times weaker than that of the Sun.

Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC, and the Potsdam Automatic Photoelectric Telescopes (APT) in Arizona, jointly operated by AIP and Fairborn Observatory.Radial velocity measurements 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/593/A123 Title: EELT-HIRES the high-resolution spectrograph for the E-ELT Authors: Marconi, A.; Di Marcantonio, P.; D'Odorico, V.; Cristiani, S.; Maiolino, R.; Oliva, E.; Origlia, L.; Riva, M.; Valenziano, L.; Zerbi, F. M.; Abreu, M.; Adibekyan, V.; Allende Prieto, C.; Amado, P. J.; Benz, W.; Boisse, I.; Bonfils, X.; Bouchy, F.; Buchhave, L.; Buscher, D.; Cabral, A.; Canto Martins, B. L.; Chiavassa, A.; Coelho, J.; Christensen, L. B.; Delgado-Mena, E.; de Medeiros, J. R.; Di Varano, I.; Figueira, P.; Fisher, M.; Fynbo, J. P. U.; Glasse, A. C. H.; Haehnelt, M.; Haniff, C.; Hansen, C. J.; Hatzes, A.; Huke, P.; Korn, A. J.; Leão, I. C.; Liske, J.; Lovis, C.; Maslowski, P.; Matute, I.; McCracken, R. A.; Martins, C. J. A. P.; Monteiro, M. J. P. F. G.; Morris, S.; Morris, T.; Nicklas, H.; Niedzielski, A.; Nunes, N. J.; Palle, E.; Parr-Burman, P. M.; Parro, V.; Parry, I.; Pepe, F.; Piskunov, N.; Queloz, D.; Quirrenbach, A.; Rebolo Lopez, R.; Reiners, A.; Reid, D. T.; Santos, N.; Seifert, W.; Sousa, S.; Stempels, H. C.; Strassmeier, K.; Sun, X.; Udry, S.; Vanzi, L.; Vestergaard, M.; Weber, M.; Zackrisson, E. Bibcode: 2016SPIE.9908E..23M Altcode: 2016arXiv160900497M The first generation of E-ELT instruments will include an optic-infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics. A 2-year long phase A study for EELT-HIRES has just started and will be performed by a consortium composed of institutes and organisations from Brazil, Chile, Denmark, France, Germany, Italy, Poland, Portugal, Spain, Sweden, Switzerland and United Kingdom. In this paper we describe the science goals and the preliminary technical concept for EELT-HIRES which will be developed during the phase A, as well as its planned development and consortium organisation during the study. Title: Anti-solar differential rotation on the active sub-giant HU Virginis Authors: Harutyunyan, G.; Strassmeier, K. G.; Künstler, A.; Carroll, T. A.; Weber, M. Bibcode: 2016A&A...592A.117H Altcode: 2016arXiv160605497H Context. Measuring surface differential rotation (DR) on different types of stars is important when characterizing the underlying stellar dynamo. It has been suggested that anti-solar DR laws can occur when strong meridional flows exist.
Aims: We aim to investigate the differential surface rotation on the primary star of the RS CVn binary, HU Vir, by tracking its starspot distribution as a function of time. We also aim to recompute and update the values for several system parameters of the triple system HU Vir (close and wide orbits).
Methods: Time-series high-resolution spectroscopy for four continuous months was obtained with the 1.2-m robotic STELLA telescope. Nine consecutive Doppler images were reconstructed from these data, using our line-profile inversion code iMap. An image cross-correlation method was applied to derive the surface differential-rotation law for HU Vir. New orbital elements for the close and the wide orbits were computed using our new STELLA radial velocities (RVs) combined with the RV data available in the literature. Photometric observations were performed with the Amadeus Automatic Photoelectric Telescope (APT), providing contemporaneous Johnson-Cousins V and I data for approximately 20 yrs. This data was used to determine the stellar rotation period and the active longitudes.
Results: We confirm anti-solar DR with a surface shear parameter α of -0.029 ± 0.005 and -0.026 ± 0.009, using single-term and double-term differential rotation laws, respectively. These values are in good agreement with previously claimed results. The best fit is achieved assuming a solar-like double-term law with a lap time of ≈400 d. Our orbital solutions result in a period of 10.387678 ± 0.000003 days for the close orbit and 2726 ± 7 d (≈7.5 yr) for the wide orbit. A Lomb-Scarge (L-S) periodogram of the pre-whitened V-band data reveals a strong single peak providing a rotation period of 10.391 ± 0.008 d, well synchronized to the short orbit.

Based on data obtained with the STELLA robotic observatory in Tenerife, an AIP facility jointly operated by AIP and IAC.The tables with the STELLA radial velocity data set and the APT photometric data set are available only in electronic form 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/592/A117 Title: Thermal control modeling approach for GRAPE (GRAntecan PolarimEter) Authors: Di Varano, I.; Woche, M.; Strassmeier, K. G. Bibcode: 2016SPIE.9911E..15D Altcode: GRAPE is the polarimeter planned to be installed on the main Cassegrain focus of GTC (Gran Telescopio Canarias), having an equivalent entrance pupil of 10.4 m, located at the Observatorio del Roque de los Muchachos (ORM) , in La Palma, Canary Islands. It's meant to deliver full Stokes (IQUV) polarimetry covering the spectral range 0.420-1.6 μ, in order to feed the HORS instrument (High Optical Resolution Spectrograph), mounted on the Nasmyth platform, which has a FWHM resolving power of about 25,000 (5 pixel) designed for the wavelength range of 380-800 nm. Two calcite blocks and a BK-7 prism arranged in a Foster configuration are splitting the Ø12.5mm collimated beam into the ordinary and extraordinary components. The entire subunit from the Foster prisms down to the input fibers is rotated by steps of 45 degrees in order to retrieve Q, U components. By inserting a quarter wave retarder plate before the entrance to the Foster unit circular polarization is measured too. The current paper consist of two main parts: at first CFD simulations are introduced, which have been run compliant to the specifications derived by the environmental conditions and the transient thermal gradients taking into account the presence of the electronic cabinets installed, which are triggering the boundary conditions for the outer structure of the instrument; then a thermal control model is proposed based on heat exchangers to stabilize the inner temperature when compensation via passive insulation is not enough. The tools that have been adopted to reach for such goal are Ansys Multiphysics, in particular CFX package and Python scripts. Title: HIRES the high-resolution spectrograph for the E-ELT: dynamics and control of the repositioning mechanism for the E-ELT HIRES polarimeter Authors: Di Varano, I.; Strassmeier, K. G.; Woche, M. Bibcode: 2016SPIE.9908E..9LD Altcode: A full Stokes dual channel polarimeter for the E-ELT HIRES spectrograph has been envisioned for the intermediate focus f/4.4, operating within a spectral range of 0.4-1.6 μ. It will feed the EELT- HIRES instrument located on the Nasmyth platform via two pairs of dedicated fibers: one fibre pair optimized for the BVRI, the other one optimized for the JH band or any other feasible combination. The instrument must be retractable within a workspace in fulfillment with the ESO requirements on the allocated volume and the dynamic response of the AO tower. For such purpose a swinging arm has been designed with a rotation provided by 5 revolute joints and a jackscrew. Moreover repeatability in repositioning has to be guaranteed by a parallel manipulator, performing an alignment procedure mainly along 5 axes. Dynamics and control criteria with a feed forward chain to compensate for vibration forces and feedback chain for tracking procedure are hereafter presented. Title: PEPSI-feed: linking PEPSI to the Vatican Advanced Technology Telescope using a 450m long fibre Authors: Sablowski, D. P.; Weber, M.; Woche, M.; Ilyin, I.; Järvinen, A.; Strassmeier, K. G.; Gabor, P. Bibcode: 2016SPIE.9912E..5HS Altcode: Limited observing time at large telescopes equipped with the most powerful spectrographs makes it almost impossible to gain long and well-sampled time-series observations. Ditto, high-time-resolution observations of bright targets with high signal-to-noise are rare. By pulling an optical fibre of 450m length from the Vatican Advanced Technology Telescope (VATT) to the Large Binocular Telescope (LBT) to connect the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) to the VATT, allows for ultra-high resolution time-series measurements of bright targets. This article presents the fibre-link in detail from the technical point-of-view, demonstrates its performance from first observations, and sketches current applications. Title: VizieR Online Data Catalog: STELLA-SES Radial Velocities of HD 208472 (Ozdarcan+, 2016) Authors: Ozdarcan, O.; Carroll, T. A.; Kunstler, A.; Strassmeier, K. G.; Evren, S.; Weber, M.; Granzer, T. Bibcode: 2016yCat..35930123O Altcode: Precise radial velocity measurement of HD 208472 based on 229 high resolution Stella Echelle Spectrograph (SES) spectra obtained at STELLA robotic observatory on Tenerife, Spain from March 22, 2009 to July 20, 2011 are presented. High precision radial velocities allow one to trace spot jitter effect on measured radial velocities via residuals from spectroscopic orbit solution. In case of HD 208472, removing spot jitter effect from measured velocities, precision on calculated orbital parameters were improved by factor of 4 without changing the actual value of parameters.

(1 data file). Title: VizieR Online Data Catalog: HU Vir radial velocities and VI light curves (Harutyunyan+, 2016) Authors: Harutyunyan, G.; Strassmeier, K. G.; Kuenstler, A.; Carroll, T. A.; Weber, M. Bibcode: 2016yCat..35920117H Altcode: We present two tables with the new STELLA radial velocity data set and the APT Johnson-Cousins V and I photometric data set for HU Virginis. RVs from STELLA-SES spectra were derived from an order-by-order cross correlation with a synthetic template spectrum and then averaged. The photometric measurements were always made differentially with respect to HD 106270 and HD 106332 as a comparison and check star, respectively.

(2 data files). Title: An integrated thermo-structural model to design a polarimeter for the GTC Authors: Di Varano, I.; Strassmeier, K. G.; Woche, M.; Laux, U. Bibcode: 2016SPIE10012E..08D Altcode: The GTC (Gran Telescopio Canarias), with an equivalent aperture of 10.4 m, effective focal length of 169.9 m, located at the Observatorio del Roque de los Muchachos , in La Palma, Canary Islands, will host on its Cassegrain focus the GRAPE polarimeter (GRAntecan PolarimEter). At such focus the plate scale is 1.21 arcsec/mm and the unvignetted FOV 8 arcmin. The instrument will provide full Stokes polarimetry in the spectral range 380-1500 nm, feeding simultaneously up to two spectrographs. At the moment an interface to HORS (High Optical Resolution Spectrograph) is being defined, located on the Nasmyth platform, it has a FWHM resolving power of about 25,000 (5 pixel) within a spectral range of 400-680 nm. The rotator and instrumental flanges for the Cassegrain focus are currently under definition. Hereafter I present the state of art of the mechanical design of the polarimeter, whose strategy is based on an integrated model of Zemax design into ANSYS FEM static and dynamic analyses with thermal loads applied, in order to retrieve tip-tilt, decentering errors and other significant parameters to be looped back to the Zemax model. In such a way it is possible to compare and refine the results achieved through the tolerance analysis. Title: Multi-resolution waveguide image slicer for the PEPSI instrument Authors: Beckert, Erik; Strassmeier, Klaus G.; Woche, Manfred; Harnisch, Gerd; Hornaff, Marcel; Weber, Michael; Barnes, Stuart Bibcode: 2016SPIE.9912E..5OB Altcode: A waveguide image slicer with resolutions up to 270.000 (planned: 300.000) for the fiber fed PEPSI echelle spectrograph at the LBT and single waveguide thicknesses of down to 70 μm has been manufactured and tested. The waveguides were macroscopically prepared, stacked up to an order of seven and thinned back to square stack cross sections. A high filling ratio was achieved by realizing homogenous adhesive gaps of 3.6 μm, using index matching adhesives for TIR within the waveguides. The image slicer stacks are used in immersion mode and are miniaturized to enable implementation in a set of 2x8. The overall efficiency is between 92 % and 96 %. Title: STELLA: 10 years of robotic observations on Tenerife Authors: Weber, Michael; Granzer, Thomas; Strassmeier, Klaus G. Bibcode: 2016SPIE.9910E..0NW Altcode: STELLA is a robotic observatory on Tenerife housing two 1.2m robotic telescopes. One telescope is fibre-feeding a high-resolution (R=55,000) échelle spectrograph (SES), while the other telescope is equipped with a visible wide- field (FOV=22' x 22') imaging instrument (WiFSIP). Robotic observations started mid 2006, and the primary scientific driver is monitoring of stellar-activity related phenomena. The STELLA Control System (SCS) software package was originally tailored to the STELLA roll-off style building and high-resolution spectroscopy, but was extended over the years to support the wide-field imager, an off-axis guider for the imager, separate acquisition telescopes, classical domes, and targets-of-opportunity. The SCS allows for unattended, off-line operation of the observatory, targets can be uploaded at any time and are selected based on merit-functions in real-time (dispatch scheduling). We report on the current status of the observatory and the current capabilities of the SCS. Title: STELLA Meets RAVE: Calibrating Low-Resolution Ca II IRT Fluxes Authors: Järvinen, Silva P.; Kordopatis, Georges; Strassmeier, Klaus G.; Steinmetz, Matthias Bibcode: 2016csss.confE..65J Altcode: Within the RAVE (the Radial Velocity Experument) survey in total 574,630low-resolution spectra of 483,330 stars covering the Ca II IRT has beenobtained. With our selection criteria, out of those stars about 10% arelate-type dwarfs. We have selected these dwarfs from the database,converted the measured 1-Åcore equivalent widths into the fluxes, andobtained follow up high-resolution spectra of selected targets as well asspectra of MK standard stars using SES (STELLA échelle spectrograph) atSTELLA (STELLar Activity) telescope. With a single exposure, we cover allwavelengths from Ca H&K to IRT and can therefore relate IRT fluxes withthose of other activity indicators, such as Hα. Furthermore, we canplace these fluxes in relation to observable astrophysical parameters,such as global metallicity and temperature. Title: Rotation Periods for Cool Stars in the 4 Gyr old Open Cluster M67, The Solar-Stellar Connection, and the Applicability of Gyrochronology to at least Solar Age Authors: Barnes, Sydney A.; Weingrill, Joerg; Fritzewski, Dario; Strassmeier, Klaus G.; Platais, Imants Bibcode: 2016ApJ...823...16B Altcode: 2016arXiv160309179B We report rotation periods for 20 cool (FGK) main sequence member stars of the 4 Gyr-old open cluster M67 (=NGC 2682), obtained by analyzing data from Campaign 5 of the K2 mission with the Kepler Space Telescope. The rotation periods delineate a sequence in the color-period diagram (CPD) of increasing period with redder color. This sequence represents a cross-section at the cluster age of the surface P = P(t, M), suggested in prior work to extend to at least solar age. The current Sun is located marginally (approximately 1σ) above M67 in the CPD, as its relative age leads us to expect, and lies on the P = P(t, M) surface to within measurement precision. We therefore conclude that the solar rotation rate is normal as compared with cluster stars, a fact that strengthens the solar-stellar connection. The agreement between the M67 rotation period measurements and prior predictions further implies that rotation periods, especially when coupled with appropriate supporting work such as spectroscopy, can provide reliable ages via gyrochronology for other similar FGK dwarfs from the early main sequence to solar age and likely until the main sequence turnoff. The M67 rotators have a rotational age of 4.2 Gyr with a standard deviation of 0.7 Gyr, implying that similar field stars can be age-dated to precisions of ∼17%. The rotational age of the M67 cluster as a whole is therefore 4.2 Gyr, but with a lower (averaged) uncertainty of 0.2 Gyr. Title: Transmission spectroscopy of HAT-P-32b with the LBT: confirmation of clouds/hazes in the planetary atmosphere Authors: Mallonn, M.; Strassmeier, K. G. Bibcode: 2016A&A...590A.100M Altcode: 2016arXiv160309136M
Aims: Spectroscopic observations of a transit event of an extrasolar planet offer the opportunity to study the composition of the planetary atmosphere. This can be done with comparably little telescope time using a low-resolution multi-object spectrograph at a large aperture telescope. We observed a transit of the inflated hot Jupiter HAT-P-32b with the Multi-Object Double Spectrograph at the Large Binocular Telescope to characterize its atmosphere from 3300 to 10 000 Å.
Methods: A time series of target and reference star spectra was binned in two broad-band wavelength channels, from which differential transit light curves were constructed. These broad-band light curves were used to confirm previous transit parameter determinations. To derive the planetary transmission spectrum with a resolution of R ~ 60, we created a chromatic set of 62 narrow-band light curves. The spectrum was corrected for the third light of a nearby M star. Additionally, we undertook a photometric monitoring campaign of the host star to correct for the influence of starspots.
Results: The transmission spectrum of HAT-P-32b shows no pressure-broadened absorption features from Na and K, which is interpreted by the presence of clouds or hazes in the planetary atmosphere. This result is in agreement with previous studies on the same planet. The presence of TiO in gas phase could be ruled out. We find a 2.8σ indication of increased absorption in the line core of potassium (K I 7699 Å). No narrow absorption features of Na and Hα were detected. Furthermore, tentative indications were found for a slope of increasing opacity toward blue wavelengths from the near-IR to the near-UV with an amplitude of two scale heights. If confirmed by follow-up observations, it can be explained by aerosols either causing Mie scattering or causing Rayleigh scattering with an aerosol - gas scale height ratio below unity. The host star was found to be photometrically stable within the measurement precision.

Based on observations made with the Large Binocular Telescope (LBT) and the STELLA robotic telescopes. The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: LBT Beteiligungsgesellschaft, Germany, representing the Leibniz Institute for Astrophysics Potsdam (AIP), the Max-Planck Society, and Heidelberg University; The University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia. STELLA is an AIP facility jointly operated by AIP and Instituto de Astrofísica de Canarias (IAC).Tables of the lightcurves are only 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/590/A100 Title: VizieR Online Data Catalog: Transmission spectroscopy of HAT-P-32b (Mallonn+, 2016) Authors: Mallonn, M.; Strassmeier, K. G. Bibcode: 2016yCat..35900100M Altcode: A set of 62 simultaneous photometric light curves from 3300 to 10000Å of a transit event of HAT-P-32b. The wavelength range of each light curve is ~100Å in average. The light curves cover about one hour pre-transit, the transit event, and about 1 hour post-transit. Observations have been taken with MODS at LBT in multi-object mode. Light curves are given in differential magnitudes.

(2 data files). Title: Flows in and around Active Region NOAA12118 Observed with the GREGOR Solar Telescope and SDO/HMI Authors: Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; González Manrique, S. J.; Sobotka, M.; Bello González, N.; Hoch, S.; Diercke, A.; Kummerow, P.; Berkefeld, T.; Collados, M.; Feller, A.; Hofmann, A.; Kneer, F.; Lagg, A.; Löhner-Böttcher, J.; Nicklas, H.; Pastor Yabar, A.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Schubert, M.; Sigwarth, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K.; Volkmer, R.; von der Lühe, O.; Waldmann, T. Bibcode: 2016ASPC..504...29V Altcode: 2016arXiv160301109V Accurate measurements of magnetic and velocity fields in and around solar active regions are key to unlocking the mysteries of the formation and the decay of sunspots. High spatial resolution images and spectral sequences with a high cadence obtained with the GREGOR solar telescope give us an opportunity to scrutinize 3-D flow fields with local correlation tracking and imaging spectroscopy. We present GREGOR early science data acquired in 2014 July - August with the GREGOR Fabry-Pérot Interferometer and the Blue Imaging Channel. Time-series of blue continuum (λ 450.6 nm) images of the small active region NOAA 12118 were restored with the speckle masking technique to derive horizontal proper motions and to track the evolution of morphological changes. In addition, high-resolution observations are discussed in the context of synoptic data from the Solar Dynamics Observatory. Title: Triennial Report (2012-2015): the Legacy Issue Authors: Pollard, Karen; Jeffery, Simon; Handler, Gerald; Catelan, Márcio; Eyer, Laurent; Hekker, Saskia; Kolenberg, Katrien; Mkrtichian, David; Kepler, S. O.; Stello, Dennis; Strassmeier, Klaus; Uytterhoeven, Katrien Bibcode: 2016IAUTA..29..413P Altcode: The study of variable stars has played a central role in astronomy for over 400 years, and more so in the present than at any time in history. Stars, especially variable stars, are astrophysical laboratories for understanding physical processes in the universe. Stars represent the fundamental components of stellar systems, galaxies and the universe. Title: Comparing modal noise and FRD of circular and non-circular cross-section fibres Authors: Sablowski, D. P.; Plüschke, D.; Weber, M.; Strassmeier, K. G.; Järvinen, A. Bibcode: 2016AN....337..216S Altcode: 2015arXiv151109281S Modal noise is a common source of noise introduced to the measurements by optical fibres and is particularly important for fibre-fed spectroscopic instruments, especially for high-resolution measurements. This noise source can limit the signal-to-noise ratio and jeopardize photon-noise limited data. The subject of the present work is to compare measurements of modal noise and focal-ratio degradation (FRD) for several commonly used fibres. We study the influence of a simple mechanical scrambling method (excenter) on both FRD and modal noise. Measurements are performed with circular and octagonal fibres from Polymicro Technology (FBP-Series) with diameters of 100, 200, and 300 μm and for square and rectangular fibres from CeramOptec, among others. FRD measurements for the same sample of fibres are performed as a function of wavelength. Furthermore, we replaced the circular fibre of the STELLA-échelle-spectrograph (SES) in Tenerife with an octagonal and found a SNR increase by a factor of 1.6 at 678 nm. It is shown in the laboratory that an excenter with a large amplitude and low frequency will not influence the FRD but will reduce modal noise rather effectively by up to 180%. Title: FK Comae Berenices, King of Spin: The COCOA-PUFS Project Authors: Ayres, Thomas R.; Kashyap, V.; Saar, S.; Huenemoerder, D.; Korhonen, H.; Drake, J. J.; Testa, P.; Cohen, O.; Garraffo, C.; Granzer, T.; Strassmeier, K. Bibcode: 2016ApJS..223....5A Altcode: 2016arXiv160103305A COCOA-PUFS is an energy-diverse, time-domain study of the ultra-fast spinning, heavily spotted, yellow giant FK Comae Berenices (FK Com: HD117555; G4 III). This single star is thought to be a recent binary merger, and is exceptionally active by measure of its intense ultraviolet (UV) and X-ray emissions, and proclivity to flare. COCOA-PUFS was carried out with the Hubble Space Telescope in the UV (1200-3000 Å), using mainly its high-performance Cosmic Origins Spectrograph, but also high precision Space Telescope Imaging Spectrograph; Chandra X-ray Observatory in the soft X-rays (0.5-10 keV), utilizing its High-Energy Transmission Grating Spectrometer; together with supporting photometry and spectropolarimetry in the visible from the ground. This is an introductory report on the project. FK Com displayed variability on a wide range of timescales over all wavelengths during the week-long main campaign, including a large X-ray flare; “super-rotational broadening” of the far-ultraviolet “hot lines” (e.g., Si IV 1393 Å 8 × 104 K) together with chromospheric Mg II 2800 Å and C II 1335 Å (1-3 × 104 K); large Doppler swings suggestive of bright regions alternately on advancing and retreating limbs of the star; and substantial redshifts of the epoch-average emission profiles. These behaviors paint a picture of a highly extended, dynamic, hot (∼10 MK) coronal magnetosphere around the star, threaded by cooler structures perhaps analogous to solar prominences and replenished continually by surface activity and flares. Suppression of angular momentum loss by the confining magnetosphere could temporarily postpone the inevitable stellar spindown, thereby lengthening this highly volatile stage of coronal evolution.

COordinated Campaign of Observations and Analysis, Photosphere to Upper Atmosphere, of a Fast-rotating Star. Title: The LEECH Exoplanet Imaging Survey: Orbit and Component Masses of the Intermediate-Age, Late-Type Binary NO UMa Authors: Schlieder, Joshua E.; Skemer, Andrew J.; Maire, Anne-Lise; Desidera, Silvano; Hinz, Philip; Skrutskie, Michael F.; Leisenring, Jarron; Bailey, Vanessa; Defrère, Denis; Esposito, Simone; Strassmeier, Klaus G.; Weber, Michael; Biller, Beth A.; Bonnefoy, Mickaël; Buenzli, Esther; Close, Laird M.; Crepp, Justin R.; Eisner, Josh A.; Hofmann, Karl-Heinz; Henning, Thomas; Morzinski, Katie M.; Schertl, Dieter; Weigelt, Gerd; Woodward, Charles E. Bibcode: 2016ApJ...818....1S Altcode: 2015arXiv151003813S We present high-resolution Large Binocular Telescope LBTI/LMIRcam images of the spectroscopic and astrometric binary NO UMa obtained as part of the LBT Interferometer Exozodi Exoplanet Common Hunt exoplanet imaging survey. Our H-, Ks-, and L‧-band observations resolve the system at angular separations <0.″09. The components exhibit significant orbital motion over a span of ∼7 months. We combine our imaging data with archival images, published speckle interferometry measurements, and existing spectroscopic velocity data to solve the full orbital solution and estimate component masses. The masses of the K2.0 ± 0.5 primary and K6.5 ± 0.5 secondary are 0.83 ± 0.02 M⊙ and 0.64 ± 0.02 M⊙, respectively. We also derive a system distance of d = 25.87 ± 0.02 pc and revise the Galactic kinematics of NO UMa. Our revised Galactic kinematics confirm NO UMa as a nuclear member of the ∼500 Myr old Ursa Major moving group, and it is thus a mass and age benchmark. We compare the masses of the NO UMa binary components to those predicted by five sets of stellar evolution models at the age of the Ursa Major group. We find excellent agreement between our measured masses and model predictions with little systematic scatter between the models. NO UMa joins the short list of nearby, bright, late-type binaries having known ages and fully characterized orbits.

Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC. Title: Optical Spectroscopy of the Classical Novae V339 Del (2013) and V5668 Sgr (2015 No. 2) Authors: Wagner, R. Mark; Woodward, Charles E.; Starrfield, Sumner; Ilyin, Ilya; Strassmeier, Klaus G.; Page, Kim; Osborne, Julian P.; Beardmore, Andrew P. Bibcode: 2016AAS...22723910W Altcode: We report the results of optical spectroscopy of the gamma-ray classical novae V339 Del (2013) and V5668 Sgr (PNV J18365700-2855420/Nova Sgr 2015 No. 2) supplemented by UV and X-ray observations obtained with Swift. Our spectra were obtained with the Steward Observatory Bok 2.3 m telescope (+B&C), the MDM 2.4 m Hiltner telescope (+OSMOS), the 6.5 m MMT (+BlueChannel), and the 2 x 8.4 m Large Binocular Telescope (+MODS1 and PEPSI) between 2013 August and 2015 September. The PEPSI spectra cover all or part of the 384-907 nm spectral region at a resolution of up to 270,000 (1 km/s). This is the highest resolution available on any 8-10 m class telescope. V339 Del was discovered on 2015 August 14.58 by Itagaki at V about 6.8. This nova reached a peak magnitude of about 4.3 making it one of the brightest novae of this century. Because of its exceptional brightness it has been observed at a variety of wavelengths and by a host of observatories both on the ground and in space. V5668 Sgr was discovered on 2015 March 15.634 by Seach at a magnitude of 6.0. It subsequently reached a maximum brightness of about 4.0 in late March. High resolution PEPSI spectra obtained in early April show dramatic variations in the multi-component P Cygni-type line profiles. V5668 Sgr was observed to form dust in June thereafter fading to about 13th magnitude. Our recent observations show that it has now evolved into the nebular phase. SS acknowledges partial support from NSF and NASA grants to ASU. CEW acknowledges support from NASA. Title: Scientific problems addressed by the Spektr-UV space project (world space Observatory—Ultraviolet) Authors: Boyarchuk, A. A.; Shustov, B. M.; Savanov, I. S.; Sachkov, M. E.; Bisikalo, D. V.; Mashonkina, L. I.; Wiebe, D. Z.; Shematovich, V. I.; Shchekinov, Yu. A.; Ryabchikova, T. A.; Chugai, N. N.; Ivanov, P. B.; Voshchinnikov, N. V.; Gomez de Castro, A. I.; Lamzin, S. A.; Piskunov, N.; Ayres, T.; Strassmeier, K. G.; Jeffrey, S.; Zwintz, S. K.; Shulyak, D.; Gérard, J. -C.; Hubert, B.; Fossati, L.; Lammer, H.; Werner, K.; Zhilkin, A. G.; Kaigorodov, P. V.; Sichevskii, S. G.; Ustamuich, S.; Kanev, E. N.; Kil'pio, E. Yu. Bibcode: 2016ARep...60....1B Altcode: The article presents a review of scientific problems and methods of ultraviolet astronomy, focusing on perspective scientific problems (directions) whose solution requires UV space observatories. These include reionization and the history of star formation in the Universe, searches for dark baryonic matter, physical and chemical processes in the interstellar medium and protoplanetary disks, the physics of accretion and outflows in astrophysical objects, from Active Galactic Nuclei to close binary stars, stellar activity (for both low-mass and high-mass stars), and processes occurring in the atmospheres of both planets in the solar system and exoplanets. Technological progress in UV astronomy achieved in recent years is also considered. The well advanced, international, Russian-led Spektr-UV (World Space Observatory—Ultraviolet) project is described in more detail. This project is directed at creating a major space observatory operational in the ultraviolet (115-310 nm). This observatory will provide an effective, and possibly the only, powerful means of observing in this spectral range over the next ten years, and will be an powerful tool for resolving many topical scientific problems. Title: A temperature inversion in WASP-33b? Large Binocular Telescope occultation data confirm significant thermal flux at short wavelengths Authors: von Essen, C.; Mallonn, M.; Albrecht, S.; Antoci, V.; Smith, A. M. S.; Dreizler, S.; Strassmeier, K. G. Bibcode: 2015A&A...584A..75V Altcode: 2015arXiv150705963V We observed a secondary eclipse of WASP-33 b quasi-simultaneously in the optical (~0.55 μm) and the near-infrared (~1.05 μm) using the 2×8.4 m Large Binocular Telescope. WASP-33 is a δ Scuti star pulsating with periods comparable to the eclipse duration, making the determination of the eclipse depth challenging. We use previously determined oscillation frequencies to model and remove the pulsation signal from the light curves, isolating the secondary eclipse. The determined eclipse depth is ΔF = 1.03 ± 0.34 parts per thousand, corresponding to a brightness temperature of TB = 3398 ± 302 K. Combining previously published data with our new measurement we find the equilibrium temperature of WASP-33 b to be TB = 3358 ± 165 K. We compare all existing eclipse data to a blackbody spectrum, to a carbon-rich non-inverted model and to a solar composition model with an inverted temperature structure. We find that current available data on WASP-33 b's atmosphere can be best represented by a simple blackbody emission, without the need for more sophisticated atmospheric models with temperature inversions. Although our data cannot rule out models with or without a temperature inversion, they do confirm a high brightness temperature for the planet at short wavelengths. WASP-33 b is one of the hottest exoplanets known till date, and its equilibrium temperature is consistent with rapid reradiation of the absorbed stellar light and a low albedo.

The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona university system; Instituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Leibniz-Institute for Astrophysics Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia.Appendix A is available in electronic form at http://www.aanda.org Title: Chemical composition of a sample of bright solar-metallicity stars Authors: Caffau, E.; Mott, A.; Steffen, M.; Bonifacio, P.; Strassmeier, K. G.; Gallagher, A.; Faraggiana, R.; Sbordone, L. Bibcode: 2015AN....336..968C Altcode: 2015arXiv151004269C We present a detailed analysis of seven young stars observed with the spectrograph SOPHIE at the Observatoire de Haute-Provence for which the chemical composition was incomplete or absent in the literature. For five stars, we derived the stellar parameters and chemical compositions using our automatic pipeline optimized for F, G, and K stars, while for the other two stars with high rotational velocity, we derived the stellar parameters by using other information (parallax), and performed a line-by-line analysis. Chromospheric emission-line fluxes from Ca II are obtained for all targets. The stellar parameters we derive are generally in good agreement with what is available in the literature. We provide a chemical analysis of two of the stars for the first time. The star HIP 80124 shows a strong Li feature at 670.8 nm implying a high lithium abundance. Its chemical pattern is not consistent with it being a solar sibling, as has been suggested.

Data obtained at Observatoire de Haute Provence, with the SOPHIE spectrograph. Title: The LOFAR Solar Imaging Pipeline and the LOFAR Solar Data Center Authors: Breitling, F.; Mann, G.; Vocks, C.; Steinmetz, M.; Strassmeier, K. G. Bibcode: 2015A&C....13...99B Altcode: 2016arXiv160305990B LOFAR is a new and sensitive radio interferometer that can be used for dynamic high-resolution imaging spectroscopy at low radio frequencies from 10 to 90 and 110 to 250 MHz. Here we describe its usage for observations of the Sun and in particular of solar radio bursts. We also describe the processing, archiving and accessing of solar LOFAR data, which is accomplished via the LOFAR Solar Imaging Pipeline and the LOFAR Solar Data Center. Title: A color-period diagram for the open cluster M 48 (NGC 2548), and its rotational age Authors: Barnes, Sydney A.; Weingrill, Joerg; Granzer, Thomas; Spada, Federico; Strassmeier, Klaus G. Bibcode: 2015A&A...583A..73B Altcode: 2015arXiv151100554B Rotation periods are increasingly being used to derive ages for cool single field stars. Such ages are based on an empirical understanding of how cool stars spin down, acquired by constructing color-period diagrams (CPDs) for a series of open clusters. Our main aims here are to construct a CPD for M 48, to compare this with other clusters of similar age to check for consistency, and to derive a rotational age for M 48 using gyrochronology. We monitored M 48 photometrically for over 2 months with AIP's STELLA I 1.2 m telescope and the WiFSIP 4K imager in Tenerife. Light curves with 3 mmag precision for bright (V ~ 14 mag) stars were produced and then analysed to provide rotation periods. A cluster CPD has then been constructed. We report 62 rotation periods for cool stars in M 48. The CPD displays a clear slow/I-sequence of rotating stars, similar to those seen in the 625 Myr-old Hyades and 590 Myr-old Praesepe clusters, and below both, confirming that M 48 is younger. A similar comparison with the 250 Myr-old M 34 cluster shows that M 48 is older and does not possess any fast/C-sequence G or early K stars like those in M 34, although relatively fast rotators do seem to be present among the late-K and M stars. A more detailed comparison of the CPD with rotational evolution models shows that the cluster stars have a mean age of 450 Myr, and its (rotating) stars can be individually dated to ± 117 Myr (26%). Much of this uncertainty stems from intrinsic astrophysical spread in initial periods, and almost all stars are consistent with a single age of 450 Myr. The gyro-age of M 48 as a whole is 450 ± 50 Myr, in agreement with the previously determined isochrone age of 400 ± 100 Myr.

Based on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated by AIP and IAC; this paper presents results for the STELLA Open Cluster Survey (SOCS).Appendices A and B are available in electronic form at http://www.aanda.orgThe cluster photometry table is 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/583/A73 Title: Broad-band spectrophotometry of the hot Jupiter HAT-P-12b from the near-UV to the near-IR Authors: Mallonn, M.; Nascimbeni, V.; Weingrill, J.; von Essen, C.; Strassmeier, K. G.; Piotto, G.; Pagano, I.; Scandariato, G.; Csizmadia, Sz.; Herrero, E.; Sada, P. V.; Dhillon, V. S.; Marsh, T. R.; Künstler, A.; Bernt, I.; Granzer, T. Bibcode: 2015A&A...583A.138M Altcode: 2015arXiv150905272M Context. The detection of trends or gradients in the transmission spectrum of extrasolar planets is possible with observations at very low spectral resolution. Transit measurements of sufficient accuracy using selected broad-band filters allow for an initial characterization of the atmosphere of the planet.
Aims: We want to investigate the atmosphere of the hot Jupiter HAT-P-12b for an increased absorption at the very blue wavelength regions caused by scattering. Furthermore, we aim for a refinement of the transit parameters and the orbital ephemeris.
Methods: We obtained time series photometry of 20 transit events and analyzed them homogeneously, along with eight light curves obtained from the literature. In total, the light curves span a range from 0.35 to 1.25 microns. During two observing seasons over four months each, we monitored the host star to constrain the potential influence of starspots on the derived transit parameters.
Results: We rule out the presence of a Rayleigh slope extending over the entire optical wavelength range, a flat spectrum is favored for HAT-P-12b with respect to a cloud-free atmosphere model spectrum. A potential cause of such gray absorption is the presence of a cloud layer at the probed latitudes. Furthermore, in this work we refine the transit parameters, the ephemeris and perform a TTV analysis in which we found no indication for an unseen companion. The host star showed a mild non-periodic variability of up to 1%. However, no stellar rotation period could be detected to high confidence. Title: Line Profile Variations of Solar Analog Stars: Chromospheric Indexes vs. Li Abundance. The Host Star Search. Authors: Amazo-Gómez, E. M.; Harutyunyan, G.; Alvarado-Gómez, J. D.; Strassmeier, K. G.; Weber, M.; Carroll, T. A. Bibcode: 2015IAUS..305..340A Altcode: PolarBase contains stellar spectropolarimetric data collected with the NARVAL & ESPaDOnS instruments (Petit et al. 2014). Their respective spectral resolutions are 65 000 and 68 000, in spectropolarimetric mode. As the first part of this work, we use the NARVAL spectropolarimetric repositories. We selected spectra from a sample of cool stars with effective Temperature (T eff) ranging between 4900 to 6000 K. This sample contains stellar systems with and without reported exoplanets. We exploit the full wavelength range from 380 to 900 nm in order to obtain chromospheric indexes such as the Ca ii H&K S-Index, and a Ca ii IRT and Hα index. We calibrated our measurements using the Mount Wilson S-Index values. Furthermore, we employ lithium (Li) abundance measurements from the literature (Gonzalez et al. 2010; Delgado Mena et al. 2014; Israelian et al. 2004), investigating in this way a possible correlation between the chromospheric activity measurements and the Li abundance in 32 selected cool stars. Title: VizieR Online Data Catalog: BR light curves of GJ1214b (Nascimbeni+, 2015) Authors: Nascimbeni, V.; Mallonn, M.; Scandariato, G.; Pagano, I.; Piotto, G.; Micela, G.; Messina, S.; Leto, G.; Strassmeier, K. G.; Bisogni, S.; Speziali, R. Bibcode: 2015yCat..35790113N Altcode: We observed two complete transits of GJ1214b during the nights of March 29 and May 17, 2012 with the LBC camera mounted at the double 8.4m Large Binocular Telescope (LBT). We mounted a Bessel B and Bessel R filter on the blue and red channel, respectively.

(4 data files). Title: Antisolar-type surface differential rotation of the K1-giant sigma Geminorum Authors: Kovari, Zsolt; Künstler, Andreas; Vida, Krisztián; Kriskovics, Levente; Carroll, Thorsten; Strassmeier, Klaus Bibcode: 2015IAUGA..2242132K Altcode: Spot migration pattern is analysed to derive surface differential rotation on the active K1-giant component of the long-period RS CVn-type binary system σ Gem. From a set of high-resolution spectra taken with STELLA-I SES in 2006/07, three subsequent Doppler images were obtained using our advanced surface reconstruction code iMap. The time-evolution of the spotted surface suggests antisolar-type differential rotation with α of -0.04 shear parameter, in quite an agreement with preceding results. Title: Transmission spectroscopy of the inflated exo-Saturn HAT-P-19b Authors: Mallonn, M.; von Essen, C.; Weingrill, J.; Strassmeier, K. G.; Ribas, I.; Carroll, T. A.; Herrero, E.; Granzer, T.; Claret, A.; Schwope, A. Bibcode: 2015A&A...580A..60M Altcode: 2015arXiv150605685M Context. Transiting highly inflated giant planets offer the possibility of characterizing their atmospheres. A fraction of the starlight passes through the high-altitude layers of the planetary atmosphere during transit. The resulting absorption is expected to be wavelength dependent for cloud-free atmospheres with an amplitude of up to 10-3 of the stellar flux, while a high-altitude cloud deck would cause a gray opacity.
Aims: We observed the Saturn-mass and Jupiter-sized exoplanet HAT-P-19b to refine its transit parameters and ephemeris as well as to shed first light on its transmission spectrum. We monitored the host star over one year to quantify its flux variability and to correct the transmission spectrum for a slope caused by starspots.
Methods: A transit of HAT-P-19b was observed spectroscopically with OSIRIS at the Gran Telescopio Canarias in January 2012. The spectra of the target and the comparison star covered the wavelength range from 5600 to 7600 Å. One high-precision differential light curve was created by integrating the entire spectral flux. This white-light curve was used to derive absolute transit parameters. Furthermore, a set of light curves over wavelength was formed by a flux integration in 41 wavelength channels of 50 Å width. We analyzed these spectral light curves for chromatic variations of transit depth.
Results: The transit fit of the combined white-light curve yields a refined value of the planet-to-star radius ratio of 0.1390 ± 0.0012 and an inclination of 88.89 ± 0.32 deg. After a re-analysis of published data, we refine the orbital period to 4.0087844 ± 0.0000015 days. We obtain a flat transmission spectrum without significant additional absorption at any wavelength or any slope. However, our accuracy is not sufficient to significantly rule out the presence of a pressure-broadened sodium feature. Our photometric monitoring campaign allowed for an estimate of the stellar rotation period of 35.5 ± 2.5 days and an improved age estimate of 5.5+ 1.8-1.3 Gyr by gyrochronology. The calculated correction of the transit depth for unocculted spots on the visible hemisphere was found to be well within the derived 1σ uncertainty of the white-light curve and the spectral data points of the transmission spectrum.

Based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, in the island of La Palma, as well as on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC.Tables 1 and 3 are available in electronic form at http://www.aanda.org Title: Stellar rotation, binarity, and lithium in the open cluster IC 4756 Authors: Strassmeier, K. G.; Weingrill, J.; Granzer, T.; Bihain, G.; Weber, M.; Barnes, S. A. Bibcode: 2015A&A...580A..66S Altcode: 2015arXiv150305676S Context. An important aspect in the evolutionary scenario of cool stars is their rotation and the rotationally induced magnetic activity and interior mixing. Stars in open clusters are particularly useful tracers for these aspects because of their known ages.
Aims: We aim to characterize the open cluster IC 4756 and measure stellar rotation periods and surface differential rotation for a sample of its member stars.
Methods: Thirty-seven cluster stars were observed continuously with the CoRoT satellite for 78 days in 2010. Follow-up high-resolution spectroscopy of the CoRoT targets and deep Strömgren uvbyβ and Hα photometry of the entire cluster were obtained with our robotic STELLA facility and its echelle spectrograph and wide-field imager, respectively.
Results: We determined high-precision photometric periods for 27 of the 37 CoRoT targets and found values between 0.155 and 11.4 days. Twenty of these are rotation periods. Twelve targets are spectroscopic binaries of which 11 were previously unknown; orbits are given for six of them. Six targets were found that show evidence of differential rotation with ΔΩ/Ω in the range 0.04-0.15. Five stars are non-radially pulsating stars with fundamental periods of below 1 d, two stars are semi-contact binaries, and one target is a micro-flaring star that also shows rotational modulation. Nine stars in total were not considered members because of much redder color(s) and deviant radial velocities with respect to the cluster mean. Hα photometry indicates that the cluster ensemble does not contain magnetically over-active stars. The cluster average metallicity is -0.08 ± 0.06 (rms) and its logarithmic lithium abundance for 12 G-dwarf stars is 2.39 ± 0.17 (rms).
Conclusions: The cluster is 890 ± 70 Myrs old with an average turn-off mass of 1.8 M⊙ and a solar or slightly subsolar metallicity. The distance modulus is 8m.02 and the average reddening E(b - y) = 0m.16.. The cluster is masked by a very inhomogeneous foreground and background dust distribution and our survey covered 38% of the cluster. The average lithium abundance and the rotation periods in the range 1.7 to 11.4 d are consistent with the cluster age.

The CoRoT space mission has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain. Partly based on data obtained with the STELLA robotic observatory in Tenerife, an AIP facility jointly operated by AIP and IAC.Appendices are available in electronic form at http://www.aanda.org Title: Large Binocular Telescope view of the atmosphere of GJ1214b Authors: Nascimbeni, V.; Mallonn, M.; Scandariato, G.; Pagano, I.; Piotto, G.; Micela, G.; Messina, S.; Leto, G.; Strassmeier, K. G.; Bisogni, S.; Speziali, R. Bibcode: 2015A&A...579A.113N Altcode: 2015arXiv150501488N The atmospheric composition and vertical structure of the super-Earth GJ1214b has been a subject of debate since its discovery in 2009. Recent studies have indicated that high-altitude clouds might mask the lower layers. However, some data points that were gathered at different times and facilities do not fit this picture, probably because of a combination of stellar activity and systematic errors. We observed two transits of GJ1214b with the Large Binocular Camera, the dual-channel camera at the Large Binocular Telescope. For the first time, we simultaneously measured the relative planetary radius k = Rp/R⋆ at blue and red optical wavelengths (B + R), thus constraining the Rayleigh scattering on GJ1214b after correcting for stellar activity effects. To the same purpose, a long-term photometric follow-up of the host star was carried out with WiFSIP at STELLA, revealing a rotational period that is significantly longer than previously reported. Our new unbiased estimates of k yield a flat transmission spectrum extending to shorter wavelengths, thus confirming the cloudy atmosphere scenario for GJ1214b.

Based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are the University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; the Ohio State University; and the Research Corporation, on behalf of the University of Notre Dame, University of Minnesota and University of Virginia. Partly based on STELLA WiFSIP data (Strassmeier et al. 2004).The data of the light curves 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/579/A113 Title: Spot evolution on the red giant star XX Triangulum. A starspot-decay analysis based on time-series Doppler imaging Authors: Künstler, A.; Carroll, T. A.; Strassmeier, K. G. Bibcode: 2015A&A...578A.101K Altcode: 2015arXiv150402270K Context. Solar spots appear to decay linearly proportional to their size. The decay rate of solar spots is directly related to magnetic diffusivity, which itself is a key quantity for the length of a magnetic-activity cycle. Is a linear spot decay also seen on other stars, and is this in agreement with the large range of solar and stellar activity cycle lengths?
Aims: We investigate the evolution of starspots on the rapidly-rotating (Prot≈24 d) K0 giant XX Tri, using consecutive time-series Doppler images. Our aim is to obtain a well-sampled movie of the stellar surface over many years, and thereby detect and quantify a starspot decay law for further comparison with the Sun.
Methods: We obtained continuous high-resolution and phase-resolved spectroscopy with the 1.2-m robotic STELLA telescope on Tenerife over six years, and these observations are ongoing. For each observing season, we obtained between 5 to 7 independent Doppler images, one per stellar rotation, making up a total of 36 maps. All images were reconstructed with our line-profile inversion code iMap. A wavelet analysis was implemented for denoising the line profiles. To quantify starspot area decay and growth, we match the observed images with simplified spot models based on a Monte Carlo approach.
Results: It is shown that the surface of XX Tri is covered with large high-latitude and even polar spots and with occasional small equatorial spots. Just over the course of six years, we see a systematically changing spot distribution with various timescales and morphology, such as spot fragmentation and spot merging as well as spot decay and formation. An average linear decay of D = -0.022 ± 0.002 SH/day is inferred. We found evidence of an active longitude in phase toward the (unseen) companion star. Furthermore, we detect a weak solar-like differential rotation with a surface shear of α = 0.016 ± 0.003. From the decay rate, we determine a turbulent diffusivity of ηT = (6.3 ± 0.5) × 1014 cm2/s and predict a magnetic activity cycle of ≈26 ± 6 yr. Finally, we present a short movie of the spatially resolved surface of XX Tri.

Based on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated with IAC.Appendices and the movie are available in electronic form at http://www.aanda.org Title: PEPSI: The high-resolution échelle spectrograph and polarimeter for the Large Binocular Telescope Authors: Strassmeier, K. G.; Ilyin, I.; Järvinen, A.; Weber, M.; Woche, M.; Barnes, S. I.; Bauer, S. -M.; Beckert, E.; Bittner, W.; Bredthauer, R.; Carroll, T. A.; Denker, C.; Dionies, F.; DiVarano, I.; Döscher, D.; Fechner, T.; Feuerstein, D.; Granzer, T.; Hahn, T.; Harnisch, G.; Hofmann, A.; Lesser, M.; Paschke, J.; Pankratow, S.; Plank, V.; Plüschke, D.; Popow, E.; Sablowski, D. Bibcode: 2015AN....336..324S Altcode: 2015arXiv150506492S PEPSI is the bench-mounted, two-arm, fibre-fed and stabilized Potsdam Echelle Polarimetric and Spectroscopic Instrument for the 2×8.4 m Large Binocular Telescope (LBT). Three spectral resolutions of either 43 000, 120 000 or 270 000 can cover the entire optical/red wavelength range from 383 to 907 nm in three exposures. Two 10.3k×10.3k CCDs with 9-μm pixels and peak quantum efficiencies of 94-96 % record a total of 92 échelle orders. We introduce a new variant of a wave-guide image slicer with 3, 5, and 7 slices and peak efficiencies between 92-96 %. A total of six cross dispersers cover the six wavelength settings of the spectrograph, two of them always simultaneously. These are made of a VPH-grating sandwiched by two prisms. The peak efficiency of the system, including the telescope, is 15 % at 650 nm, and still 11 % and 10 % at 390 nm and 900 nm, respectively. In combination with the 110 m2 light-collecting capability of the LBT, we expect a limiting magnitude of ≈ 20th mag in V in the low-resolution mode. The R = 120 000 mode can also be used with two, dual-beam Stokes IQUV polarimeters. The 270 000-mode is made possible with the 7-slice image slicer and a 100-μm fibre through a projected sky aperture of 0.74 arcsec, comparable to the median seeing of the LBT site. The 43 000-mode with 12-pixel sampling per resolution element is our bad seeing or faint-object mode. Any of the three resolution modes can either be used with sky fibers for simultaneous sky exposures or with light from a stabilized Fabry-Pérot étalon for ultra-precise radial velocities. CCD-image processing is performed with the dedicated data-reduction and analysis package PEPSI-S4S. Its full error propagation through all image-processing steps allows an adaptive selection of parameters by using statistical inferences and robust estimators. A solar feed makes use of PEPSI during day time and a 500-m feed from the 1.8 m VATT can be used when the LBT is busy otherwise. In this paper, we present the basic instrument design, its realization, and its characteristics. Some pre-commissioning first-light spectra shall demonstrate the basic functionality. Title: Magnetic field measurements of ɛ Eridani from Zeeman broadening Authors: Lehmann, L. T.; Künstler, A.; Carroll, T. A.; Strassmeier, K. G. Bibcode: 2015AN....336..258L Altcode: 2015arXiv150306662L We present new magnetic field measurements of the K2 main-sequence star ɛ Eri based on principal components analysis (PCA) line-profile reconstructions. The aim of this paper is to quantify the surface-averaged magnetic field and search for possible variations. A total of 338 optical échelle spectra from our robotic telescope facility STELLA with a spectral resolution of 55 000 were available for analysis. This time-series was used to search for the small line-profile variations due to a surface magnetic field with the help of a PCA. Evidence for a spatial and temporal inhomogeneous magnetic field distribution is presented. The mean, surface averaged, magnetic field strength was found to be < B > = 186 ± 47 G in good agreement with previous Zeeman-broadening measurements. Clear short-term variations of the surface averaged magnetic field of up to few tens Gauss were detected together with evidence for a three-year cycle in the surface-averaged magnetic field of ɛ Eri.

Based on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated with IAC. Title: Chromospheric activity and lithium line variations in the spectra of the spotted star LQ Hydrae Authors: Flores Soriano, M.; Strassmeier, K. G.; Weber, M. Bibcode: 2015A&A...575A..57F Altcode: Context. Although the relationship between lithium abundance in stars and their magnetic activity is commonly accepted, it is still unclear how the different phenomena related to it can increase the amount of Li, reduce its depletion, or be a source of bias for the measurements.
Aims: We study the rotational modulation of chromospheric and photospheric parameters of the young, active, single K2 dwarf LQ Hya and their connection with the variability of the Li i 6708 Å line.
Methods: A total of 199 high-resolution STELLA spectra and quasi-simultaneous photometry were used to compute effective temperature, gravity, and chromospheric activity indicators such as Hα and Hβ emission, Balmer decrement, and chromospheric electron density, as a function of the rotational phase. The variation of the Li i 6708 Å line was characterized in terms of equivalent width, abundance, and of 6Li/7Li isotopic ratio in the form of line shifts.
Results: Photospheric and chromospheric parameters show clear rotational modulation. Effective temperatures and continuum variations reveal a higher concentration of cool spots on the side of the star on which we also detect stronger chromospheric activity. Increased electron densities and the modulation of the He i D3 line suggest that the source of this activity can be a combination of plages and repeated low-intensity flares. The Li line and other temperature-sensitive lines are clearly enhanced by the spots located on the most active side of the star. Li abundances calculated taking into account the temperature variations simultaneously show, although with high dispersion, a small overabundance of this element that correlates well with the surface magnetic activity. In addition, the Li line center is more intensely redshifted than in the other hemisphere, which might be interpreted as a weak enrichment of 6Li.

Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC, and the Vienna-Potsdam Automatic Photoelectric Telescopes at Fairborn Observatory in Arizona, operated by AIP.The numerical results of the spectral analysis 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/575/A57 Title: Driving magnetic activity: differential rotation, flow structures, and surface patterns Authors: Strassmeier, Klaus G. Bibcode: 2015HiA....16...94S Altcode: The interplay between stellar rotation and turbulent flows is a major ingredient for vertical angular momentum transport in stellar convection zone. Combined with the centrifugal force and the buoyancy force due to pole-equator temperature gradients one can expect a large-scale flow structure that is usually referred to as differential rotation and meridional flows. I review such observations for stars other than the Sun, mostly for stars significantly more active, and ask the question whether such observations can constrain the dynamo process. Title: Evidence for enhanced mixing on the super-meteoritic Li-rich red giant HD 233517 Authors: Strassmeier, K. G.; Carroll, T. A.; Weber, M.; Granzer, T. Bibcode: 2015A&A...574A..31S Altcode: Context. HD 233517 is among the most Li-rich stars in the sky. It is a rapidly rotating, single K giant thought to be on its first ascent on the red giant branch. The star has also the highest known infrared excess among any of the known first-ascent giants.
Aims: We revisit the physical parameters of the system and aim to map its surface temperature distribution.
Methods: New time-series photometry and high-resolution spectroscopy were obtained with our robotic facilities STELLA and Amadeus Automatic Photoelectric Telescope (APT) in 2007-2011. Inverse line-profile modelling is performed on a total of 167 échelle spectra and six Doppler images are presented.
Results: Light and radial-velocity variations suggest a stellar rotation period of 47.6±0.3 d. The atmospheric parameters agree with previous studies and verify a super-meteoritic log 7Li abundance of 4.29±0.10 with undetected 6Li, while the metals are generally deficient by -0.4 dex with respect to the Sun. We determine a lower than normal isotopic carbon ratio of 12C/13C = 9+4-2. Our Doppler images indicate warm and cool spots with an average temperature contrast of just ±65 K with respect to the effective temperature. Doppler maps from Li i 670.78 reveal practically identical surface morphology, with a higher average contrast of ±160 K and errors that are five times larger. Reconstructions with simultaneously 1617 and 3007 spectral lines showed both a signal degradation with respect to our 56-line final image. An error analysis indicates an average temperature error per surface pixel of just ±4 K.
Conclusions: HD 233517 appears to be an old (≈10-Gyr) single 0.95-M⊙ giant currently undergoing mild mass loss in the form of a wind. The cool and warm photospheric features are interpreted to be merely locations of suppressed and enhanced convection, respectively, probably intermingled by a yet undetected weak magnetic field. The low carbon-isotope ratio is indicative of extra mixing rather than of an engulfing event. We tentatively conclude that HD 233517 operates an enhanced non-axisymmetric mixing process that leads to an inhomogeneous super-granulation pattern on the surface in form of large cool and warm features.

Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC, and the Vienna-Potsdam Automatic Photoelectric Telescopes at Fairborn Observatory in Arizona, operated by AIP. Title: Doppler images and the underlying dynamo. The case of AF Leporis Authors: Järvinen, S. P.; Arlt, R.; Hackman, T.; Marsden, S. C.; Küker, M.; Ilyin, I. V.; Berdyugina, S. V.; Strassmeier, K. G.; Waite, I. A. Bibcode: 2015A&A...574A..25J Altcode: 2014arXiv1412.2892J Context. The (Zeeman-)Doppler imaging studies of solar-type stars very often reveal large high-latitude spots. This also includes F stars that possess relatively shallow convection zones, indicating that the dynamo operating in these stars differs from the solar dynamo.
Aims: We aim to determine whether mean-field dynamo models of late-F type dwarf stars can reproduce the surface features recovered in Doppler maps. In particular, we wish to test whether the models can reproduce the high-latitude spots observed on some F dwarfs.
Methods: The photometric inversions and the surface temperature maps of AF Lep were obtained using the Occamian-approach inversion technique. Low signal-to-noise spectroscopic data were improved by applying the least-squares deconvolution method. The locations of strong magnetic flux in the stellar tachocline as well as the surface fields obtained from mean-field dynamo solutions were compared with the observed surface temperature maps.
Results: The photometric record of AF Lep reveals both long- and short-term variability. However, the current data set is too short for cycle-length estimates. From the photometry, we have determined the rotation period of the star to be 0.9660 ± 0.0023 days. The surface temperature maps show a dominant, but evolving, high-latitude (around +65°) spot. Detailed study of the photometry reveals that sometimes the spot coverage varies only marginally over a long time, and at other times it varies rapidly. Of a suite of dynamo models, the model with a radiative interior rotating as fast as the convection zone at the equator delivered the highest compatibility with the obtained Doppler images.

Partially 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.Based partly on STELLA SES data.Tables 1-3 and Figs. 7-14 are available in electronic form at http://www.aanda.org Title: Editorial Authors: Strassmeier, Klaus G. Bibcode: 2015AN....336....4S Altcode: Not Available. Title: VizieR Online Data Catalog: LQ Hya activity and Li variations (Flores Soriano+, 2015) Authors: Flores Soriano, M.; Strassmeier, K. G.; Weber, M. Bibcode: 2015yCat..35750057F Altcode: 2015yCat..35759057F We preset in these two tables the observing log and the numerical results of the spectral analysis of LQ Hya. They are a tabular version of the results shown in the figures of the paper.

(2 data files). Title: Antisolar differential rotation of the K1-giant σ Geminorum revisited Authors: Kővári, Zs.; Kriskovics, L.; Künstler, A.; Carroll, T. A.; Strassmeier, K. G.; Vida, K.; Oláh, K.; Bartus, J.; Weber, M. Bibcode: 2015A&A...573A..98K Altcode: 2014arXiv1411.1774K Context. Surface differential rotation and other global surface flows on magnetically active stars are among the observable manifestations of the underlying stellar dynamo. Therefore, these types of observations are important for stellar dynamo theory and useful constraints for solar dynamo studies as well.
Aims: We revisit the active K1-giant component of the long-period RS CVn-type binary system σ Gem and its global surface flow pattern.
Methods: We refine the differential rotation law from recovering the spot migration pattern. We apply a detailed cross-correlation technique to a unique set of 34 time-series Doppler images recovered using data from 1996-97. By increasing the number of the available cross-correlation function maps, we expect a more robust determination of the differential surface rotation law. In addition, we present a new time-series Doppler imaging study of σ Gem using our advanced surface reconstruction code iMap for a data set collected in 2006-07.
Results: Results from the reprocessed cross-correlation study confirm that the star performs antisolar-type differential rotation with a surface shear α of - 0.04 ± 0.01, i.e., almost a factor of two larger compared to the previously claimed value. We also confirm the evidence of a global poleward spot migration, with an average velocity of 0.21 ± 0.03 km s-1, in accordance with theoretical predictions. From the new observations, we obtain three subsequent Doppler images. The time evolution of these images confirms the antisolar-type differential rotation of the same amount. Title: Magnitude-range brightness variations of overactive K giants Authors: Oláh, K.; Moór, A.; Kővári, Zs.; Granzer, T.; Strassmeier, K. G.; Kriskovics, L.; Vida, K. Bibcode: 2014A&A...572A..94O Altcode: 2014arXiv1409.6515O Context. Decades-long, phase-resolved photometry of overactive spotted cool stars has revealed that their long-term peak-to-peak light variations can be as large as one magnitude. Such brightness variations are too large to be solely explained by rotational modulation and/or a cyclic, or pseudo-cyclic, waxing and waning of surface spots and faculae as we see in the Sun.
Aims: We study three representative, overactive spotted K giants (IL Hya, XX Tri, and DM UMa) known to exhibit V-band light variations between 0.m65-1.m05. Our aim is to find the origin of their large brightness variation.
Methods: We employ long-term phase-resolved multicolor photometry, mostly from automatic telescopes, covering 42 yr for IL Hya, 28 yr for XX Tri, and 34 yr for DM UMa. For one target, IL Hya, we present a new Doppler image from NSO data taken in late 1996. Effective temperatures for our targets are determined from all well-sampled observing epochs and are based on a V - IC color-index calibration.
Results: The effective temperature change between the extrema of the rotational modulation for IL Hya and XX Tri is in the range 50-200 K. The bolometric flux during maximum of the rotational modulation, i.e., the least spotted states, varied by up to 39% in IL Hya and up to 54% in XX Tri over the course of our observations. We emphasize that for IL Hya it is just about half of the total luminosity variation that can be explained by the photospheric temperature (spots/faculae) changes, while for XX Tri it is even about one third. The long-term, 0.m6 V-band variation of DM UMa is more difficult to explain because little or no B - V color index change is observed on the same timescale. Placing the three stars with their light and color variations into H-R diagrams, we find that their overall luminosities are generally too low compared to predictions from current evolutionary tracks.
Conclusions: A change in the stellar radius due to strong and variable magnetic fields during activity cycles likely plays a role in explaining the anomalous brightness and luminosity of our three targets. At least for IL Hya, a radius change of about 9% is suggested from mbol and Teff, and is supported by independent v sin i measurements.

Appendix A is available in electronic form at http://www.aanda.org 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: Time-series high-resolution spectroscopy and photometry of ɛ Aurigae from 2006-2013: Another brick in the wall Authors: Strassmeier, K. G.; Weber, M.; Granzer, T.; Schanne, L.; Bartus, J.; Ilyin, I. Bibcode: 2014AN....335..904S Altcode: We present continuous and time-resolved R = 55 000 optical échelle spectroscopy of ɛ Aurigae from 2006-2013. Data were taken with the STELLA Echelle Spectrograph of the robotic STELLA facility at the Observatorio del Teide in Tenerife. Contemporaneous photometry with the Automatic Photoelectric Telescopes at Fairborn Observatory in Arizona is presented for the years 1996-2013. Spectroscopic observations started three years prior to the photometric eclipse and are still ongoing. A total of 474 high-resolution échelle spectra are analyzed and made available in this paper. We identify 368 absorption lines of which 161 lines show the characteristic sharp disk lines during eclipse. Another 207 spectral lines appeared nearly unaffected by the eclipse. From spectrum synthesis, we obtained the supergiant atmospheric parameters T_eff = 7395±70 K, log g≈ 1, and [Fe/H] = +0.02±0.2 with ξ_t = 9 km s-1 , ζ_RT = 13 km s-1 , and v sin i = 28±3 km s-1 . The residual average line broadening expressed in km s-1 varies with a period of 62.6±0.7 d, in particular at egress and after the eclipse. Two-dimensional line-profile periodograms show several periods, the strongest with ≈110 d evident in optically thin lines as well as in the Balmer lines. Center-of-intensity weighted radial velocities of individual spectral lines also show the 110-d period but, again, additional shorter and longer periods are evident and are different in the Balmer lines. The two main spectroscopic Hα periods, ≈ 116 d from the line core and ≈ 150 d from the center-of-intensity radial velocities, appear at 102 d and 139 d in the photometry. The Hβ and Johnson VI photometry on the other hand shows two well-defined and phase-coherent periods of 77 d and 132 d. We conclude that Hα is contaminated by changes in the circumstellar environment while the Hβ and VI photometry stems predominantly from the non radial pulsations of the F0 supergiant. We isolate the disk-rotation profile from 61 absorption lines and found that low disk eccentricity generally relates to low disk rotational velocity (but not always) while high disk eccentricity always relates to high velocity. There is also the general trend that the disk-absorption in spectral lines with higher excitation potential comes from disk regions with higher eccentricity and thus also with higher rotational velocity. The dependency on transition probability is more complex and shows a bi-modal trend. The outskirts of the disk is distributed asymmetrically around the disk and appears to have been built up mostly in a tail along the orbit behind the secondary. Our data show that this tail continues to eclipse the F0 Iab primary star even two years after the end of the photometric eclipse. High-resolution spectra were also taken of the other, bona-fide, visual-binary components of ɛ Aur (ADS 3605BCDE). Only the C-component, a K3-4-giant, appears at the same distance than ɛ Aur but its radial velocity is in disagreement with a bound orbit. The other components are a nearby (≈ 7 pc) cool DA white dwarf, a G8 dwarf, and a B9 supergiant, and not related to ɛ Aur. The cool white dwarf shows strong DIB lines that suggest the existence of a debris disk around this star.

Based on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated with IAC, and the Automatic Photoelectric Telescopes in Arizona, jointly operated with Fairborn Observatory. Title: HIRES: the high resolution spectrograph for the E-ELT Authors: Zerbi, F. M.; Bouchy, F.; Fynbo, J.; Maiolino, R.; Piskunov, N.; Rebolo Lopez, R.; Santos, N.; Strassmeier, K.; Udry, S.; Vanzi, L.; Riva, M.; Basden, A.; Boisse, I.; Bonfils, X.; Buscher, D.; Cabral, A.; Dimarcantonio, P.; Di Varano, I.; Henry, D.; Monteiro, M.; Morris, T.; Murray, G.; Oliva, Ernesto; Parry, I.; Pepe, F.; Quirrenbach, A.; Rasilla, J. L.; Rees, P.; Stempels, E.; Valenziano, L.; Wells, M.; Wildi, F.; Origlia, L.; Allende Prieto, C.; Chiavassa, A.; Cristiani, S.; Figueira, P.; Gustafsson, B.; Hatzes, A.; Haehnelt, M.; Heng, K.; Israelian, G.; Kochukhov, O.; Lovis, C.; Marconi, A.; Martins, C. J. A. P.; Noterdaeme, P.; Petitjean, P.; Puzia, T.; Queloz, D.; Reiners, A.; Zoccali, M. Bibcode: 2014SPIE.9147E..23Z Altcode: The current instrumentation plan for the E-ELT foresees a High Resolution Spectrograph conventionally indicated as HIRES. Shaped on the study of extra-solar planet atmospheres, Pop-III stars and fundamental physical constants, HIRES is intended to embed observing modes at high-resolution (up to R=150000) and large spectral range (from the blue limit to the K band) useful for a large suite of science cases that can exclusively be tackled by the E-ELT. We present in this paper the solution for HIRES envisaged by the "HIRES initiative", the international collaboration established in 2013 to pursue a HIRES on E-ELT. Title: Surface differential rotation of IL Hya from time-series Doppler images Authors: Kővári, Zsolt; Kriskovics, Levente; Oláh, Katalin; Vida, Krisztián; Bartus, János; Strassmeier, Klaus G.; Weber, Michael Bibcode: 2014IAUS..302..379K Altcode: 2013arXiv1309.1378K We present a time-series Doppler imaging study of the K-subgiant component in the RS CVn-type binary system IL Hya (P orb=12.905 d). From re-processing the unique long-term spectroscopic dataset of 70 days taken in 1996/97, we perform a thorough cross-correlation analysis to derive surface differential rotation. As a result we get solar-type differential rotation with a shear value α of 0.05, in agreement with preliminary suggestions from previous attempts. A possible surface pattern of meridional circulation is also detected. Title: Biosignatures from circular spectropolarimetry: key science for ELTs? Authors: Strassmeier, K. G.; Carroll, T. A.; Mallonn, M. Bibcode: 2014ebi..conf..4.7S Altcode: Vegetation has a fivefold higher reflectivity in the NIR than in the optical domain. The steep gradient at around 700 nm, the Vegetation Red Edge (VRE), can in principle be used to discriminate exo-planets with and without vegetation. Transiting exo-planets pose the possibility to isolate their (absorption-line) spectrum from that of its host star without the need for spatially resolving the planet. While the expected difference of the Stokes-I amplitude between a Super- Earth with and without an atmosphere in front of a G2V star would be just ≈3×10-5, its differential Stokes-V signal could be larger by up to an order of magnitude. Thus, a possible way out is to observe in polarized light and use the known albedo-polarization relation for planetary surfaces and/or atmospheres. Polarization degrees of up to 20% are expected from planets in short-period orbits. Already the isolation of the VRE from a transmission spectrum is beyond current instrumentation, the aim to detect a differential circular polarization (CP) signal from wavelengths blueward-minus-redward of the VRE in transmission spectra of exoplanets is clearly left to the Extremely Large Telescopes (ELT). While it is tempting to interpret such a simple CP detection as a sign of chirality in the atmosphere of the exoplanet, e.g. due to chlorophyll, its signal will be deeply buried in the photon noise and systematics, even for ELTs. We present our current status of signal-reconstruction algorithms used for magnetic- field mapping of stellar surfaces and how these could be employed for the isolation of biosignatures. We also present the current spectro-polarimetric instrumentation for the LBT and the ESO E-ELT. Title: Detecting and quantifying stellar magnetic fields. Sparse Stokes profile approximation using orthogonal matching pursuit Authors: Carroll, T. A.; Strassmeier, K. G. Bibcode: 2014A&A...563A..56C Altcode: 2014arXiv1401.5749C Context. In recent years, we have seen a rapidly growing number of stellar magnetic field detections for various types of stars. Many of these magnetic fields are estimated from spectropolarimetric observations (Stokes V) by using the so-called center-of-gravity (COG) method. Unfortunately, the accuracy of this method rapidly deteriorates with increasing noise and thus calls for a more robust procedure that combines signal detection and field estimation.
Aims: We introduce an estimation method that provides not only the effective or mean longitudinal magnetic field from an observed Stokes V profile but also uses the net absolute polarization of the profile to obtain an estimate of the apparent (i.e., velocity resolved) absolute longitudinal magnetic field.
Methods: By combining the COG method with an orthogonal-matching-pursuit (OMP) approach, we were able to decompose observed Stokes profiles with an overcomplete dictionary of wavelet-basis functions to reliably reconstruct the observed Stokes profiles in the presence of noise. The elementary wave functions of the sparse reconstruction process were utilized to estimate the effective longitudinal magnetic field and the apparent absolute longitudinal magnetic field. A multiresolution analysis complements the OMP algorithm to provide a robust detection and estimation method.
Results: An extensive Monte-Carlo simulation confirms the reliability and accuracy of the magnetic OMP approach where a mean error of under 2% is found. Its full potential is obtained for heavily noise-corrupted Stokes profiles with signal-to-noise variance ratios down to unity. In this case a conventional COG method yields a mean error for the effective longitudinal magnetic field of up to 50%, whereas the OMP method gives a maximum error of 18%. It is, moreover, shown that even in the case of very small residual noise on a level between 10-3 and 10-5, a regime reached by current multiline reconstruction techniques, the conventional COG method incorrectly interprets a large portion of the residual noise as a magnetic field, with values of up to 100 G. The magnetic OMP method, on the other hand, remains largely unaffected by the noise, regardless of the noise level the maximum error is no greater than 0.7 G. Title: Chromospherically Active Stars in the RAVE Survey Authors: Žerjal, M.; Zwitter, T.; Matijevič, G.; Strassmeier, K. G. Bibcode: 2014IAUS..298..298Z Altcode: We present a qualitative characterization of activity levels of a large database of ~44,000 candidate RAVE stars (unbiased, magnitude limited medium resolution survey) that show chromospheric emission in the Ca II infrared triplet and this vastly enlarges previously known samples. Our main motivation to study these stars is the anti-correlation of chromospheric activity and stellar ages that could be calibrated using stellar clusters with known ages. Locally linear embedding used for a morphological classification of spectra revealed 53,347 cases with a suggested emission component in the calcium lines. We analyzed a subsample of ~44,000 stars with S/N>20 using a spectral subtraction technique where observed reference spectra of inactive stars were used as templates instead of synthetic ones. Both the equivalent width of the excess emission for each calcium line and their sum is derived for all candidate active stars with no respect to the origin of their emission flux. ~17,800 spectra show a detectable chromospheric flux with at least 2 σ confidence level. The overall distribution of activity levels shows a bimodal shape, with the first peak coinciding with inactive stars and the second with the pre-main-sequence cases. Title: Pulsation analysis and its impact on primary transit modeling in WASP-33 Authors: von Essen, C.; Czesla, S.; Wolter, U.; Breger, M.; Herrero, E.; Mallonn, M.; Ribas, I.; Strassmeier, K. G.; Morales, J. C. Bibcode: 2014A&A...561A..48V Altcode: 2013arXiv1311.3614V
Aims: To date, WASP-33 is the only δ Scuti star known to be orbited by a hot Jupiter. The pronounced stellar pulsations, showing periods comparable to the primary transit duration, interfere with the transit modeling. Therefore our main goal is to study the pulsation spectrum of the host star to redetermine the orbital parameters of the system by means of pulsation-cleaned primary transit light curves.
Methods: Between August 2010 and October 2012 we obtained 457 h of photometry of WASP-33 using small and middle-class telescopes located mostly in Spain and in Germany. Our observations comprise the wavelength range between the blue and the red, and provide full phase coverage of the planetary orbit. After a careful detrend, we focus our pulsation studies in the high frequency regime, where the pulsations that mostly deform the primary transit exist.
Results: The data allow us to identify, for the first time in the system, eight significant pulsation frequencies. The pulsations are likely associated with low-order p-modes. Furthermore, we find that pulsation phases evolve in time. We use our knowledge of the pulsations to clean the primary transit light curves and carry out an improved transit modeling. Surprisingly, taking into account the pulsations in the modeling has little influence on the derived orbital parameters. However, the uncertainties in the best-fit parameters decrease. Additionally, we find indications for a possible dependence between wavelength and transit depth, but only with marginal significance. A clear pulsation solution, in combination with an accurate orbital period, allows us to extend our studies and search for star-planet interactions (SPI). Although we find no conclusive evidence of SPI, we believe that the pulsation nature of the host star and the proximity between members make WASP-33 a promising system for further SPI studies.

Tables 1 and 10 and Fig. 8 are available in electronic form at http://www.aanda.orgPhotometry is 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/561/A48 Title: Multiperiodicity, modulations and flip-flops in variable star light curves. II. Analysis of II Pegasus photometry during 1979-2010 Authors: Lindborg, M.; Mantere, M. J.; Olspert, N.; Pelt, J.; Hackman, T.; Henry, G. W.; Jetsu, L.; Strassmeier, K. G. Bibcode: 2013A&A...559A..97L Altcode: 2013arXiv1304.4144L
Aims: According to previously published Doppler images of the magnetically active primary giant component of the RS CVn binary II Peg, the surface of the star was dominated by one single active longitude that was clearly drifting in the rotational frame of the binary system during 1994-2002; later imaging for 2004-2010, however, showed decreased and chaotic spot activity, with no signs of the drift pattern. Here we set out to investigate from a more extensive photometric dataset whether this drift is a persistent phenomenon, in which case it could be caused either by an azimuthal dynamo wave or be an indication that the binary system's orbital synchronization is still incomplete. On a differentially rotating stellar surface, spot structures preferentially on a certain latitude band could also cause such a drift, the disruption of which could arise from the change of the preferred spot latitude.
Methods: We analyzed the datasets using the carrier fit (CF) method, which is especially suitable for analyzing time series in which a fast clocking frequency (such as the rotation of the star) is modulated with a slower process (such as the stellar activity cycle).
Results: We combined all collected photometric data into one single data set and analyzed it with the CF method. We confirm the previously published results that the spot activity has been dominated by one primary spotted region almost through the entire data set and also confirm a persistent, nearly linear drift. Disruptions of the linear trend and complicated phase behavior are also seen, but the period analysis reveals a rather stable periodicity with Pspot = 6.71054d ± 0.00005d. After removing the linear trend from the data, we identified several abrupt phase jumps, three of which are analyzed in more detail with the CF method. These phase jumps closely resemble what is called a flip-flop event, but the new spot configurations do not persist for longer than a few months in most cases.
Conclusions: There is some evidence that the regular drift without phase jumps is related to the high state, while the complex phase behavior and disrupted drift pattern are related to the low state of magnetic activity. The most natural explanation of the drift is weak anti-solar (pole rotating faster than the equator) differential rotation with a coefficient k ≈ 0.002 combined with the preferred latitude of the spot structure.

The full predicted light curve over the whole data span (Table 3) is 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/559/A97 Title: Robotic observations of the most eccentric spectroscopic binary in the sky Authors: Strassmeier, K. G.; Weber, M.; Granzer, T. Bibcode: 2013A&A...559A..17S Altcode: 2013arXiv1310.2107S Context. The visual A component of the Gliese 586AB system is a double-lined spectroscopic binary consisting of two cool stars with the exceptional orbital eccentricity of 0.976. Such an extremely eccentric system may be important for our understanding of low-mass binary formation.
Aims: Precise stellar masses, ages, orbital elements, and rotational periods are a prerequisite for comparing stellar observations to angular-momentum evolution models.
Methods: We present a total of 598 high-resolution échelle spectra from our robotic facility STELLA from 2006-2012, which we used to compute orbital elements of unprecedented accuracy. New Johnson VI photometry for the two visual components is also presented.
Results: Our double-lined orbital solution for the A system has average velocity residuals for a measure of unit weight of 41 m s-1 for the G9V primary and 258 m s-1 for the M0V secondary, better by a factor ≈10 than the discovery orbit. The orbit constrains the eccentricity to 0.97608 ± 0.00004 and the orbital period to 889.8195 ± 0.0003 d. The masses of the two components are 0.87 ± 0.05 M⊙ and 0.58 ± 0.03 M⊙ if the inclination is 55 ± 1.5° as determined from adaptive-optics images, that is good to only 6% due to the error of the inclination, although the minimum masses reached a precision of 0.3%. The flux ratio Aa:Ab in the optical is between 30:1 in Johnson-B and 11:1 in I. Radial velocities of the visual B-component (K0-1V) appear constant to within 130 m s-1 over six years. Sinusoidal modulations of Teff of Aa with an amplitude of ≈55 K are seen with the orbital period. Component Aa appears warmest at periastron and coolest at apastron, indicating atmospheric changes induced by the high orbital eccentricity. No light variations larger than approximately 4 mmag are detected for A, while a photometric period of 8.5 ± 0.2 d with an amplitude of 7 mmag is discovered for the active star B, which we interpret to be its rotation period. We estimate an orbital period of ≈50 000 yr for the AB system. The most likely age of the AB system is ≥2 Gyr, while the activity of the B component, if it were a single star, would imply 0.5 Gyr. Both Aa and B are matched with single-star evolutionary tracks of their respective mass.

Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC, as well as on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 75.C-0733(A) and 60.A-9800(J).Full Table 1 is 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/559/A17 Title: VizieR Online Data Catalog: II Pegasus photometry during 1979-2010 (Lindborg+, 2013) Authors: Lindborg, M.; Mantere, M. J.; Olspert, N.; Pelt, J.; Hackman, T.; Henry, G. W.; Jetsu, L.; Strassmeier, K. G. Bibcode: 2013yCat..35590097L Altcode: 2013yCat..35599097L We combine all collected photometric data into one single data set, and analyze it with the Carrier Fit (CF) method.

The first data set (hereafter DATA1), published and analyzed by Rodono et al. (2000A&A...358..624R), covers the years 1973-1998. The second data set (hereafter DATA2) was published by Messina (2008A&A...480..495M) covering the years 1992-2004, therefore partly overlapping with DATA1. The third data set (hereafter DATA3) consists of unpublished observations with the Wolfgang-Amadeus, the university of Potsdam/Vienna twin automatic photoelectric telescope (APT), covering the years 1996-2009, again partially overlapping with the previous datasets. The fourth dataset (hereafter DATA4) was obtained with the Tennessee State University T3 0.4-m Automated Photometric Telescope at Fairborn Observatory in Arizona, covering the time span of 1987-2010 (see also Roettenbacher et al. 2011AJ....141..138R, for another analysis of the same dataset).

(1 data file). Title: A Community Science Case for E-ELT HIRES Authors: Maiolino, R.; Haehnelt, M.; Murphy, M. T.; Queloz, D.; Origlia, L.; Alcala, J.; Alibert, Y.; Amado, P. J.; Allende Prieto, C.; Ammler-von Eiff, M.; Asplund, M.; Barstow, M.; Becker, G.; Bonfils, X.; Bouchy, F.; Bragaglia, A.; Burleigh, M. R.; Chiavassa, A.; Cimatti, D. A.; Cirasuolo, M.; Cristiani, S.; D'Odorico, V.; Dravins, D.; Emsellem, E.; Farihi, J.; Figueira, P.; Fynbo, J.; Gansicke, B. T.; Gillon, M.; Gustafsson, B.; Hill, V.; Israelyan, G.; Korn, A.; Larsen, S.; De Laverny, P.; Liske, J.; Lovis, C.; Marconi, A.; Martins, C.; Molaro, P.; Nisini, B.; Oliva, E.; Petitjean, P.; Pettini, M.; Recio Blanco, A.; Rebolo, R.; Reiners, A.; Rodriguez-Lopez, C.; Ryde, N.; Santos, N. C.; Savaglio, S.; Snellen, I.; Strassmeier, K.; Tanvir, N.; Testi, L.; Tolstoy, E.; Triaud, A.; Vanzi, L.; Viel, M.; Volonteri, M. Bibcode: 2013arXiv1310.3163M Altcode: Building on the experience of the high-resolution community with the suite of VLT high-resolution spectrographs, which has been tremendously successful, we outline here the (science) case for a high-fidelity, high-resolution spectrograph with wide wavelength coverage at the E-ELT. Flagship science drivers include: the study of exo-planetary atmospheres with the prospect of the detection of signatures of life on rocky planets; the chemical composition of planetary debris on the surface of white dwarfs; the spectroscopic study of protoplanetary and proto-stellar disks; the extension of Galactic archaeology to the Local Group and beyond; spectroscopic studies of the evolution of galaxies with samples that, unlike now, are no longer restricted to strongly star forming and/or very massive galaxies; the unraveling of the complex roles of stellar and AGN feedback; the study of the chemical signatures imprinted by population III stars on the IGM during the epoch of reionization; the exciting possibility of paradigm-changing contributions to fundamental physics. The requirements of these science cases can be met by a stable instrument with a spectral resolution of R~100,000 and broad, simultaneous spectral coverage extending from 370nm to 2500nm. Most science cases do not require spatially resolved information, and can be pursued in seeing-limited mode, although some of them would benefit by the E-ELT diffraction limited resolution. Some multiplexing would also be beneficial for some of the science cases. (Abridged) Title: Chromospherically Active Stars in the RAdial Velocity Experiment (RAVE) Survey. I. The Catalog Authors: Žerjal, M.; Zwitter, T.; Matijevič, G.; Strassmeier, K. G.; Bienaymé, O.; Bland-Hawthorn, J.; Boeche, C.; Freeman, K. C.; Grebel, E. K.; Kordopatis, G.; Munari, U.; Navarro, J. F.; Parker, Q. A.; Reid, W.; Seabroke, G.; Siviero, A.; Steinmetz, M.; Wyse, R. F. G. Bibcode: 2013ApJ...776..127Z Altcode: 2013arXiv1309.4274Z RAVE, the unbiased magnitude limited survey of southern sky stars, contained 456,676 medium-resolution spectra at the time of our analysis. Spectra cover the Ca II infrared triplet (IRT) range, which is a known indicator of chromospheric activity. Our previous work classified all spectra using locally linear embedding. It identified 53,347 cases with a suggested emission component in calcium lines. Here, we use a spectral subtraction technique to measure the properties of this emission. Synthetic templates are replaced by the observed spectra of non-active stars to bypass the difficult computations of non-local thermal equilibrium profiles of the line cores and stellar parameter dependence. We derive both the equivalent width of the excess emission for each calcium line on a 5 Å wide interval and their sum EWIRT for ~44,000 candidate active dwarf stars with signal-to-noise ratio >20, with no cuts on the basis of the source of their emission flux. From these, ~14,000 show a detectable chromospheric flux with at least a 2σ confidence level. Our set of active stars vastly enlarges previously known samples. Atmospheric parameters and, in some cases, radial velocities of active stars derived from automatic pipelines suffer from systematic shifts due to their shallower calcium lines. We re-estimate the effective temperature, metallicity, and radial velocities for candidate active stars. The overall distribution of activity levels shows a bimodal shape, with the first peak coinciding with non-active stars and the second with the pre-main-sequence cases. The catalog will be made publicly available with the next RAVE public data releases. Title: Detection and initial characterisation of an exoplanet atmosphere with small aperture telescopes Authors: Bernt, I.; Müller, M.; Strassmeier, K. G.; Granzer, T. Bibcode: 2013EPSC....8...14B Altcode: In the recent years atmospheres of exoplanets have been studied with space-based telescopes like the HST or large aperture ground-based telescopes like the Gran Telescopio Canarias. But as the number of suitable exoplanets is rising, comparative studies of atmospheres with a statistically meaningful amount of targets will follow, for which the observational time with large telescopes is limited and expensive. Our aim is to investigate whether it is possible to detect and initially characterise the atmosphere of an exoplanet with small aperture telescopes using chromatic variations in transit depths. We collected multi-color transits in the years 2011 to 2013 using the robotic 1.2m-telescope STELLA on Tenerife as well as the Nordic Optical Telescope and the 70cm-telescope at the Leibniz Institute for Astrophysics Potsdam. The highly inflated Hot Jupiter HAT-P-32 b was chosen as target for our pilot study for its favorable large atmospheric scale height and therefore enhanced atmospheric detectability. Models of the atmospheric spectra of HAT-P-32 b indicate that the STELLA-data can be used to distinguish between a dusty and a cloud-free atmosphere using the gradient in transit depth of the observations in the blue band and in the visible band. Here we want to present our project together with the first results of the transit depth analysis. Title: VizieR Online Data Catalog: Barycentric radial velocities of Gl 586A (Strassmeier+, 2013) Authors: Strassmeier, K. G.; Weber, M.; Granzer, T. Bibcode: 2013yCat..35590017S Altcode: 2013yCat..35599017S Barycentric radial velocities of Gl 586A. Data from the STELLA echelle spectrograph (SES), from the ELODIE archive (ELODIE), from the SOPHIE archive (SOPHIE) and from Duquennoy et al. 1992 (CORAVEL). All velocities are in the STELLA radial velocity system (see paper). Secondary velocities are set to -999.99 where they are not available or not used in the paper (SOPHIE and CORAVEL).

(1 data file). Title: Radial velocity membership for the open cluster IC4756 Authors: Weingrill, Joerg; Geller, Aaron; Strassmeier, Klaus; Barnes, Sydney; Meibom, Soeren; Granzer, Thomas; Spada, Federico Bibcode: 2013noao.prop...44W Altcode: IC 4756 is an ~800 Myr-old nearby (500 pc) open cluster that conveniently splits the difference in age between the well-studied Hyades (625 Myr) and NGC 6811 (1 Gyr) clusters. As a result, measuring IC 4756 rotation periods offers us the chance to test the universality of the intermediate-age rotational evolution of stars independent of any theoretical models. Therefore we have performed precision time-series photometry of the IC 4756 field with the CoRoT satellite, and derived 111 main sequence rotation periods in the cluster region. We have also acquired new multicolor Stromgren photometry of the cluster. However, heavy differential reddening and imprecise membership information do not yet allow a satisfactory determination of the cluster parameters and membership, far less interpretation of the rotation periods. We propose here to use WIYN+Hydra to securely identify the cluster members, determine the cluster parameters, and to fully interpret the corresponding color-period diagram. This work will provide a new benchmark open cluster for the community, and help to develop the associated study of stellar rotation and gyrochronology. Title: Long-term photometry of three active red giants in close binary systems: V2253 Oph, IT Com and IS Vir Authors: Oláh, K.; Moór, A.; Strassmeier, K. G.; Borkovits, T.; Granzer, T. Bibcode: 2013AN....334..625O Altcode: 2013arXiv1301.3435O We present and analyze long-term optical photometric measurements of the three active stars V2253 Oph, IT Com and IS Vir. All three systems are single-lined spectroscopic binaries with an early K giant as primary component but in different stages of orbital-rotational synchronization. Our photometry is supplemented by 2MASS and WISE near-IR and mid-IR magnitudes and then used to obtain more accurate effective temperatures and extinctions. For V2253 Oph and IT Com, we found their spectral energy distributions consistent with pure photospheric emission. For IS Vir, we detect a marginal mid-IR excess which hints towards a dust disk. The orbital and rotational planes of IT Com appear to be coplanar, contrary to previous findings in the literature. We apply a multiple frequency analysis technique to determine photometric periods, and possibly changes of periods, ranging from days to decades. New rotational periods of 21.55±0.03 d, 65.1±0.3 d, and 23.50±0.04 d were determined for V2253 Oph, IT Com, and IS Vir, respectively. Splitting of these periods led to tentative detections of differential surface rotations of δ P/P≈0.02 for V2253 Oph and 0.07 for IT Com. Using a time-frequency technique based on short-term Fourier transforms we present evidence of cyclic light variations of length ≈ 10 yr for V2253 Oph and 5-6 yr for IS Vir. A single flip-flop event has been observed for IT Com of duration 2-3 yr. Its exchange of the dominant active longitude had happened close to a time of periastron passage, suggesting some response of the magnetic activity from the orbital dynamics. The 21.55-d rotational modulation of V2253 Oph showed phase coherence also with the orbital period, which is 15 times longer than the rotational period, thus also indicating a tidal feedback with the stellar magnetic activity. Title: Observational methods for stellar magnetism: from detection to cartography Authors: Strassmeier, Klaus G.; Carroll, Thorsten A.; Ilyin, Ilya; Järvinen, Silva Bibcode: 2013IAUS..294..447S Altcode: We review some of the currently used techniques to detect stellar magnetic fields on cool stars. Emphasis is put on spectropolarimetry with high-resolution spectrographs and its related data de-noising techniques and multi-line inverse modeling. Detections and results from Zeeman splittings and broadenings are briefly mentioned. We discuss some of our most recent Zeeman Doppler Imaging (ZDI) results and present a comparison of ZDI maps of the K-type WTTS V410 Tauri and the planet-hosting F8 star HD 179949 with results from other groups. Title: The STELLA Robotic Observatory on Tenerife Authors: Weber, M.; Strassmeier, K. G.; Granzer, T. Bibcode: 2013POBeo..92...21W Altcode: The STELLA project is made up of two 1.2 m robotic telescopes to simultaneously monitor stellar activity using a high-resolution spectrograph on one telescope, and an imaging instrument on the other telescope. The STELLA Échelle spectrograph (SES) along with the building has been in operation successfully since 2006, and is producing spectra covering the visual wavelength range between 390 and 870 nm at a spectral resolution of 55~000. The stability of the spectrograph over the entire two year span, measured by monitoring 15 radial velocity standard stars, is 30 to 150 m/s rms. The Wide-field stellar imager and photometer (WIFSIP) was put into operation in 2010, when the SES-lightfeed was physically moved to the second telescope. We will give an overview of the main scientific topics of the bulk of the observing programs. Title: Flip-flops of FK Comae Berenices Authors: Hackman, T.; Pelt, J.; Mantere, M. J.; Jetsu, L.; Korhonen, H.; Granzer, T.; Kajatkari, P.; Lehtinen, J.; Strassmeier, K. G. Bibcode: 2013A&A...553A..40H Altcode: 2012arXiv1211.0914H Context.FK Comae Berenices is a rapidly rotating magnetically active star, the light curve of which is modulated by cool spots on its surface. It was the first star where the "flip-flop" phenomenon was discovered. Since then, flip-flops in the spot activity have been reported in many other stars. Follow-up studies with increasing length have shown, however, that the phenomenon is more complex than was thought right after its discovery.
Aims: Therefore, it is of interest to perform a more thorough study of the evolution of the spot activity in FK Com. In this study, we analyse 15 years of photometric observations with two different time series analysis methods, with a special emphasis on detecting flip-flop type events from the data.
Methods: We apply the continuous period search and carrier fit methods on long-term standard Johnson-Cousins V-observations from the years 1995-2010. The observations were carried out with two automated photometric telescopes, Phoenix-10 and Amadeus T7 located in Arizona.
Results: We identify complex phase behaviour in 6 of the 15 analysed data segments. We identify five flip-flop events and two cases of phase jumps, where the phase shift is Δφ < 0.4. In addition we see two mergers of spot regions and two cases where the apparent phase shifts are caused by spot regions drifting with respect to each other. Furthermore we detect variations in the rotation period corresponding to a differential rotation coefficient of |k| > 0.031.
Conclusions: The flip-flop cannot be interpreted as a single phenomenon, where the main activity jumps from one active longitude to another. In some of our cases the phase shifts can be explained by differential rotation: two spot regions move with different angular velocity and even pass each other. Comparison between the methods show that the carrier fit utility is better in retrieving slow evolution especially from a low amplitude light curve, while the continuous period search is more sensitive in case of rapid changes.

Based on data obtained with the Amadeus T7 Automatic Photoelectric Telescope (APT) at Fairborn Observatory, jointly operated by the University of Vienna and AIP, the Phoenix-10 APT at Mt. Hopkins, Arizona, and the Nordic Optical Telescope, Observatorio Roque de los Muchachos, La Palma, Canary Islands.The photometric observations are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/553/A40 Title: VizieR Online Data Catalog: UBVI light curves of FK Com (Hackman+, 2013) Authors: Hackman, T.; Pelt, J.; Mantere, M. J.; Jetsu, L.; Korhonen, H.; Granzer, T.; Kajatkari, P.; Lehtinen, J.; Strassmeier, K. G. Bibcode: 2013yCat..35530040H Altcode: 2013yCat..35539040H Differential Johnson V- and B-photometry of the star FK Comae (HD 117555) from automated photometric telescopes are presented. HD 117567 was used as the comparison star. Missing observations are denoted as "99.0000".

(2 data files). Title: The spectroscopic orbit of the K-giant binary γ Canis Minoris Authors: Fekel, F. C.; Williamson, M. H.; Weber, M.; Strassmeier, K. G.; Pourbaix, D. Bibcode: 2013AN....334..223F Altcode: We have determined an improved orbit for the bright, evolved, double lined binary γ Canis Minoris. The system has an orbital period of 389.31 days and an eccentricity of 0.2586. We have revised the secondary to primary mass ratio to 0.987. The spectral types of the primary and secondary are K4 III and K1: III, respectively, and the components have a V magnitude difference of 2.2. Orbital fits to the Hipparcos astrometry are not definitive, but they suggest an orbital inclination of ∼ 66o, which produces masses of 1.88 and 1.85 M⊙ for the components. A comparison with evolutionary tracks results in an age of 1.3 Gyr. STELLA very low amplitude radial velocity residuals of the secondary indicate a period of 278 days. We interpret this as the rotation period of the secondary, detectable because of star spots rotating in and out of view. This period is nearly identical to the pseudosynchronous rotation period of the star. The primary is rotating more slowly than its pseudosynchronous rate.

Based partly on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated with IAC. Title: Doppler imaging of stellar surface structure. XXIV. The lithium-rich single K-giants DP Canum Venaticorum and DI Piscium Authors: Kővári, Zs.; Korhonen, H.; Strassmeier, K. G.; Weber, M.; Kriskovics, L.; Savanov, I. Bibcode: 2013A&A...551A...2K Altcode: 2013arXiv1301.0445K
Aims: We present the first Doppler imaging study of the two rapidly rotating, single K-giants DP CVn and DI Psc in order to study the surface spot configuration and to pinpoint their stellar evolutionary status.
Methods: Optical spectroscopy and photometry were used to determine the fundamental astrophysical properties. Doppler imaging was applied to recover the surface temperature distribution for both stars, while photometric light-curve inversions were carried out for studying the long-term changes of the surface activity of DP CVn. Surface differential rotation of DP CVn was estimated from cross-correlating the available subsequent Doppler reconstructions separated by roughly one rotation period.
Results: Both stars appear to have higher than normal lithium abundance, LTE log n of 2.28 (DP CVn) and 2.20 (DI Psc), and are supposed to be located at the end of the first Li dredge-up on the RGB. Photometric observations reveal rotational modulation with a period of 14.010 d (DP CVn) and 18.066 d (DI Psc). Doppler reconstructions from the available mapping lines well agree in the revealed spot patterns, recovering rather low latitude spots for both stars with temperature contrasts of ΔT ≈ 600-800 K below the unspotted photospheric background. Spots at higher latitudes are also found but either with less contrast (DP CVn) or with smaller extent (DI Psc). A preliminary antisolar-type differential rotation with α = -0.035 is found for DP CVn from cross-correlating the subsequent Doppler images. Long-term photometric analysis supports the existence of active longitudes, as well as the differential rotation.

Based on observations obtained at the Kitt Peak National Observatory, USA, and at the Canada-France-Hawaii Telescope, USA.Tables 1 and 2 are only available in electronic form at http://www.aanda.orgPhotometric data summarized in Table 2 are available in electronic form 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/551/A2 Title: Editors' note: Cool Stars, Stellar Systems, and the Sun 17 Authors: López-Morales, Mercedes; Strassmeier, Klaus G. Bibcode: 2013AN....334....3L Altcode: 2013csss...17....3L No abstract at ADS Title: Stellar differential rotation in theory and observation Authors: Czesla, S.; Arlt, R.; Bonanno, A.; Strassmeier, K. G.; Huber, K. F. Bibcode: 2013AN....334...89C Altcode: 2013csss...17...89C Stellar differential rotation is intimately related to the stellar magnetic dynamo and, thus, to stellar activity. In recent years, significant progress in the measurement of differential rotation on the basis of Doppler imaging techniques and the availability of space-based long-term photometry has been achieved. Similarly, simulations incorporate ever more details of the complexity of convective zones. While some aspects of solar and stellar differential rotation can be explained now, several important questions remain open or controversial. In this splinter session, we discussed the latest observational and theoretical progress in the field of differential rotation. Title: VizieR Online Data Catalog: Light curves of DP CVn and DI Psc (Kovari+, 2013) Authors: Kovari, Zs.; Korhonen, H.; Strassmeier, K. G.; Weber, M.; Kriskovics, L.; Savanov, I. Bibcode: 2013yCat..35510002K Altcode: 2013yCat..35519002K Differential photometric magnitudes of DP CVn and DI Psc obtained with 'Wolfgang' (in Stroemgren b, y) and 'Amadeus' (in Johnson-Cousins V, Ic), the two automated photoelectric telescopes owned by the Leibniz-Institute for Astrophysics Potsdam (formerly of University of Vienna), located at Fairborn Observatory in Arizona, USA. Comparison stars were HD1095129 (for DP CVn) and HD217019 (for DI Psc).

(8 data files). Title: Strange Active Giants in Close Binary Systems Authors: Oláh, K.; Moór, A.; Granzer, T.; Strassmeier, K. G. Bibcode: 2013CEAB...37..235O Altcode: We selected six, well-observed close binary systems, all with evolved, K-giant active primaries. The stars have similar spectral types but different ages, orbits and secondary components. Some of the systems show evidence for connection between the magnetic activity and binary motion. Examples of huge long-term light variation which is hard to explain, mid-infrared excess caused by circumstellar dust in the system, multiple activity cycles and asynchron (both super- and subsynchron) rotations are found among these strange binaries. Title: The GREGOR Solar Telescope on Tenerife Authors: Schmidt, W.; von der Lühe, O.; Volkmer, R.; Denker, C.; Solanki, S. K.; Balthasar, H.; Bello González, N.; Berkefeld, T.; Collados Vera, M.; Hofmann, A.; Kneer, F.; Lagg, A.; Puschmann, K. G.; Schmidt, D.; Sobotka, M.; Soltau, D.; Strassmeier, K. G. Bibcode: 2012ASPC..463..365S Altcode: 2012arXiv1202.4289S 2011 was a successful year for the GREGOR project. The telescope was finally completed in May with the installation of the 1.5-meter primary mirror. The installation of the first-light focal plane instruments was completed by the end of the year. At the same time, the preparations for the installation of the high-order adaptive optics were finished, its integration to the telescope is scheduled for early 2012. This paper describes the telescope and its instrumentation in their present first-light configuration, and provides a brief overview of the science goals of GREGOR. Title: The GREGOR Solar Telescope Authors: Denker, C.; Lagg, A.; Puschmann, K. G.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Soltau, D.; Strassmeier, K. G.; Volkmer, R.; von der Luehe, O.; Solanki, S. K.; Balthasar, H.; Bello Gonzalez, N.; Berkefeld, T.; Collados Vera, M.; Hofmann, A.; Kneer, F. Bibcode: 2012IAUSS...6E.203D Altcode: The 1.5-meter GREGOR solar telescope is a new facility for high-resolution observations of the Sun. The telescope is located at the Spanish Observatorio del Teide on Tenerife. The telescope incorporates advanced designs for a foldable-tent dome, an open steel-truss telescope structure, and active and passive means to minimize telescope and mirror seeing. Solar fine structure can be observed with a dedicated suite of instruments: a broad-band imaging system, the "GREGOR Fabry-Perot Interferometer", and the "Grating Infrared Spectrograph". All post-focus instruments benefit from a high-order (multi-conjugate) adaptive optics system, which enables observations close to the diffraction limit of the telescope. The inclusion of a spectrograph for stellar activity studies and the search for solar twins expands the scientific usage of the GREGOR to the nighttime domain. We report on the successful commissioning of the telescope until the end of 2011 and the first steps towards science verification in 2012. Title: The magnetic field topology of the weak-lined T Tauri star V410 Tauri. New strategies for Zeeman-Doppler imaging Authors: Carroll, T. A.; Strassmeier, K. G.; Rice, J. B.; Künstler, A. Bibcode: 2012A&A...548A..95C Altcode: 2012arXiv1211.2720C
Aims: In a follow-up investigation we present Zeeman-Doppler maps of the weak-lined T Tauri star (WTTS) V410 Tau. As a rapid rotating star and a typical WTTS the stellar surface of V410 Tau is accessible to surface imaging techniques and allows us to detect and reconstruct the major magnetic surface features on this pre-main sequence star.
Methods: The polarized signals we are measuring are on the order of 10-4 to 10-3 and are hidden well below the noise level of a single observation. A new line profile reconstruction technique based on a singular value decomposition (SVD) allows us to extract the weak polarized line profiles (Stokes V) as well as the intensity profiles (Stokes I). One of the key features of the line profile reconstruction is that the SVD line profiles are amenable to radiative transfer modeling within our Zeeman-Doppler Imaging code iMap. The code also utilizes a new iterative regularization scheme which is independent of any additional surface constraints. To provide more stability a vital part of our inversion strategy is to invert both Stokes I and Stokes V profiles to simultaneously reconstruct the temperature and magnetic field surface distribution of V410 Tau. A new image-shear analysis is also implemented to allow the search for image and line profile distortions induced by a differential rotation of the star.
Results: The magnetic field structure we obtain for V410 Tau shows a good spatial correlation with the surface temperature and is dominated by a strong field within the cool polar spot. The Zeeman-Doppler maps exhibit a large-scale organization of both polarities around the polar cap in the form of a twisted bipolar structure. The magnetic field reaches a value of almost 2 kG within the polar region but smaller fields are also present down to lower latitudes. The pronounced non-axisymmetric field structure and the non-detection of a differential rotation for V410 Tau supports the idea of an underlying α2-type dynamo, which is predicted for WTTS.

Appendices are available in electronic form at http://www.aanda.org Title: Gregor@night: The future high-resolution stellar spectrograph for the GREGOR solar telescope Authors: Strassmeier, K. G.; Ilyin, I. V.; Woche, M.; Granzer, T.; Weber, M.; Weingrill, J.; Bauer, S. -M.; Popow, E.; Denker, C.; Schmidt, W.; von der Lühe, O.; Berdyugina, S.; Collados, M.; Koubsky, P.; Hackman, T.; Mantere, M. J. Bibcode: 2012AN....333..901S Altcode: We describe the future night-time spectrograph for the GREGOR solar telescope and present its science core projects. The spectrograph provides a 3-pixel resolution of up to R=87 000 in 45 échelle orders covering the wavelength range 390-900 nm with three grating settings. An iodine cell can be used for high-precision radial velocity work in the 500-630 nm range. The operation of the spectrograph and the telescope will be fully automated without the presence of humans during night-time and will be based on the successful STELLA control system. Future upgrades include a second optical camera for even higher spectral resolution, a Stokes-V polarimeter and a link to the laser-frequency comb at the Vacuum Tower Telescope. The night-time core projects are a study of the angular-momentum evolution of ``The Sun in Time'' and a continuation of our long-term Doppler imaging of active stars. Title: A retrospective of the GREGOR solar telescope in scientific literature Authors: Denker, C.; von der Lühe, O.; Feller, A.; Arlt, K.; Balthasar, H.; Bauer, S. -M.; Bello González, N.; Berkefeld, Th.; Caligari, P.; Collados, M.; Fischer, A.; Granzer, T.; Hahn, T.; Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Kentischer, T.; Klva{ňa, M.; Kneer, F.; Lagg, A.; Nicklas, H.; Popow, E.; Puschmann, K. G.; Rendtel, J.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; Waldmann, T.; Wiehr, E.; Wittmann, A. D.; Woche, M. Bibcode: 2012AN....333..810D Altcode: 2012arXiv1210.3167D In this review, we look back upon the literature, which had the GREGOR solar telescope project as its subject including science cases, telescope subsystems, and post-focus instruments. The articles date back to the year 2000, when the initial concepts for a new solar telescope on Tenerife were first presented at scientific meetings. This comprehensive bibliography contains literature until the year 2012, i.e., the final stages of commissioning and science verification. Taking stock of the various publications in peer-reviewed journals and conference proceedings also provides the ``historical'' context for the reference articles in this special issue of Astronomische Nachrichten/Astronomical Notes. Title: The 1.5 meter solar telescope GREGOR Authors: Schmidt, W.; von der Lühe, O.; Volkmer, R.; Denker, C.; Solanki, S. K.; Balthasar, H.; Bello Gonzalez, N.; Berkefeld, Th.; Collados, M.; Fischer, A.; Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Kneer, F.; Lagg, A.; Nicklas, H.; Popow, E.; Puschmann, K. G.; Schmidt, D.; Sigwarth, M.; Sobotka, M.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Waldmann , T. A. Bibcode: 2012AN....333..796S Altcode: The 1.5 m telescope GREGOR opens a new window to the understanding of solar small-scale magnetism. The first light instrumentation includes the Gregor Fabry Pérot Interferometer (GFPI), a filter spectro-polarimeter for the visible wavelength range, the GRating Infrared Spectro-polarimeter (GRIS) and the Broad-Band Imager (BBI). The excellent performance of the first two instruments has already been demonstrated at the Vacuum Tower Telescope. GREGOR is Europe's largest solar telescope and number 3 in the world. Its all-reflective Gregory design provides a large wavelength coverage from the near UV up to at least 5 microns. The field of view has a diameter of 150 arcsec. GREGOR is equipped with a high-order adaptive optics system, with a subaperture size of 10 cm, and a deformable mirror with 256 actuators. The science goals are focused on, but not limited to, solar magnetism. GREGOR allows us to measure the emergence and disappearance of magnetic flux at the solar surface at spatial scales well below 100 km. Thanks to its spectro-polarimetric capabilities, GREGOR will measure the interaction between the plasma flows, different kinds of waves, and the magnetic field. This will foster our understanding of the processes that heat the chromosphere and the outer layers of the solar atmosphere. Observations of the surface magnetic field at very small spatial scales will shed light on the variability of the solar brightness. Title: GRIS: The GREGOR Infrared Spectrograph Authors: Collados, M.; López, R.; Páez, E.; Hernández, E.; Reyes, M.; Calcines, A.; Ballesteros, E.; Díaz, J. J.; Denker, C.; Lagg, A.; Schlichenmaier, R.; Schmidt, W.; Solanki, S. K.; Strassmeier, K. G.; von der Lühe, O.; Volkmer, R. Bibcode: 2012AN....333..872C Altcode: This paper describes the main characteristics of GRIS (GREGOR Infrared Spectrograph), the grating spectrograph installed in the recently inaugurated (May 2012) 1.5-meter GREGOR telescope located at the Observatorio del Teide in Tenerife. The spectrograph has a standard Czerny-Turner configuration with parabolic collimator and camera mirrors that belong to the same conic surface. Although nothing prevents its use at visible wavelengths, the spectrograph will be initially used in combination with the infrared detector of the Tenerife Infrared Polarimeter (TIP-II) in standard spectroscopic mode as well as for spectropolarimetric measurements. Title: Rotation, activity, and lithium abundance in cool binary stars Authors: Strassmeier, K. G.; Weber, M.; Granzer, T.; Järvinen, S. Bibcode: 2012AN....333..663S Altcode: 2012arXiv1208.3741S We have used two robotic telescopes to obtain time-series high-resolution optical echelle spectroscopy and V I and/or by photometry for a sample of 60 active stars, mostly binaries. Orbital solutions are presented for 26 double-lined systems and for 19 single-lined systems, seven of them for the first time but all of them with unprecedented phase coverage and accuracy. Eighteen systems turned out to be single stars. The total of 6609 {R=55 000} échelle spectra are also used to systematically determine effective temperatures, gravities, metallicities, rotational velocities, lithium abundances and absolute Hα-core fluxes as a function of time. The photometry is used to infer unspotted brightness, {V-I} and/or b-y colors, spot-induced brightness amplitudes and precise rotation periods. An extra 22 radial-velocity standard stars were monitored throughout the science observations and yield a new barycentric zero point for our STELLA/SES robotic system. Our data are complemented by literature data and are used to determine rotation-temperature-activity relations for active binary components. We also relate lithium abundance to rotation and surface temperature. We find that 74 % of all known rapidly-rotating active binary stars are synchronized and in circular orbits but 26 % (61 systems) are rotating asynchronously of which half have {P_rot>P_orb} and {e>0}. Because rotational synchronization is predicted to occur before orbital circularization active binaries should undergo an extra spin-down besides tidal dissipation. We suspect this to be due to a magnetically channeled wind with its subsequent braking torque. We find a steep increase of rotation period with decreasing effective temperature for active stars, P_rot ∝ T_eff-7, for both single and binaries, main sequence and evolved. For inactive, single giants with {P_rot>100} d, the relation is much weaker, {P_rot ∝ T_eff-1.12}. Our data also indicate a period-activity relation for Hα of the form {R_Hα ∝ P_rot-0.24} for binaries and {R_Hα ∝ P_rot-0.14} for singles. Its power-law difference is possibly significant. Lithium abundances in our (field-star) sample generally increase with effective temperature and are paralleled with an increase of the dispersion. The dispersion for binaries can be 1-2 orders of magnitude larger than for singles, peaking at an absolute spread of 3 orders of magnitude near T_eff≈ 5000 K. On average, binaries of comparable effective temperature appear to exhibit 0.25 dex less surface lithium than singles, as expected if the depletion mechanism is rotation dependent. We also find a trend of increased Li abundance with rotational period of form log n (Li) ∝ -0.6 log P_rot but again with a dispersion of as large as 3-4 orders of magnitude.

Based on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated with IAC, and the Automatic Photoelectric Telescopes in Arizona, jointly operated with Fairborn Observatory. Title: All-sky mid-infrared imagery to characterize sky conditions and improve STELLA's observational performance Authors: Weber, Michael; Klebe, Dimitri; Strassmeier, Klaus; Granzer, Thomas; Blatherwick, Ronald D.; Müller, Matthias Bibcode: 2012SPIE.8448E..1HW Altcode: The All Sky Infrared Visible Analyzer (ASIVA) is an instrument principally designed to characterize sky con- ditions for purposes of improving ground-based astronomical observational performance. The ASIVA's primary functionality is to provide radiometrically calibrated imagery across the entire sky over the mid-infrared (IR) spectrum (8-13 μm). Calibration procedures have been developed for purposes of quantifying the photometric quality of the sky. These data products are used to provide the STELLA scheduler with real-time measured conditions of the sky/clouds, including thin cirrus to better optimize observing strategy. We describe how this can be used in the denition of the observing programs to make best use of the telescope time. Additional research is underway to correlate infrared spectral radiance with visible-spectrum extinction. Title: A spectropolarimetric focal station for the ESO E-ELT Authors: Strassmeier, Klaus G.; DiVarano, Igor; Ilyin, Ilya; Woche, Manfred; Laux, Uwe Bibcode: 2012SPIE.8444E..35S Altcode: We present a conceptual design for a spectropolarimetric focal station for ESO's European Extremely Large Telescope (E-ELT). It uses the intermediate f/4.4 focus, the only symmetric focus of the telescope. A dual channel, full Stokesvector polarimeter provides on-axis light for the wavelength range 380-1600nm to up to two spectrographs simultaneously via two pairs of fibers. With such spectropolarimetric capability and a proper spectrograph for the optical and the near infrared wavelengths, the E-ELT would be able to provide the full parameter space of an incoming wavefront. Because of the on-axis entrance location of the polarimeter collimator and an entrance aperture of just 1.3 arcsec, the expected poor image quality of the intermediate telescope focus is not directly relevant. Title: The STELLA robotic observatory on Tenerife Authors: Weber, Michael; Granzer, Thomas; Strassmeier, Klaus G. Bibcode: 2012SPIE.8451E..0KW Altcode: The STELLA project is made up of two 1.2m robotic telescopes to simultaneously monitor stellar activity using a high-resolution spectrograph on one telescope, and an imaging instrument on the other telescope. The STELLA Echelle spectrograph (SES) along with the building has been in operation successfully since 2006, and is producing spectra covering the visual wavelength range between 390 and 900 nm at a resolution of 55 000. The stability of the spectrograph over the entire two year span, measured by monitoring 15 radial velocity standard stars, is 30 to 150 m/s rms. The Wide-field stellar imager and photometer (WIFSIP) was put into operation in 2010, when the SES-lightfeed was physically moved to the second telescope. We describe the final instrument conguration in use now, and on the efficiency of the robotic scheduling in use at the observatory. Title: Critical Fields and Growth Rates of the Tayler Instability as Probed by a Columnar Gallium Experiment Authors: Rüdiger, Günther; Gellert, Marcus; Schultz, Manfred; Strassmeier, Klaus G.; Stefani, Frank; Gundrum, Thomas; Seilmayer, Martin; Gerbeth, Gunter Bibcode: 2012ApJ...755..181R Altcode: 2012arXiv1201.2318R Many astrophysical phenomena (such as the slow rotation of neutron stars or the rigid rotation of the solar core) can be explained by the action of the Tayler instability of toroidal magnetic fields in the radiative zones of stars. In order to place the theory of this instability on a safe fundament, it has been realized in a laboratory experiment measuring the critical field strength, the growth rates, as well as the shape of the supercritical modes. A strong electrical current flows through a liquid metal confined in a resting columnar container with an insulating outer cylinder. As the very small magnetic Prandtl number of the gallium-indium-tin alloy does not influence the critical Hartmann number of the field amplitudes, the electric currents for marginal instability can also be computed with direct numerical simulations. The results of this theoretical concept are confirmed by the experiment. Also the predicted growth rates on the order of minutes for the nonaxisymmetric perturbations are certified by the measurements. That they do not directly depend on the size of the experiment is shown as a consequence of the weakness of the applied fields and the absence of rotation. Title: Modulated stellar and solar cycles: parallels and differences Authors: Oláh, K.; van Driel-Gesztelyi, L.; Strassmeier, K. G. Bibcode: 2012IAUS..286..279O Altcode: We present examples of activity cycle timescales on different types of stars from lowmass dwarfs to more massive giants, with wide-ranging rotation rates, and compare the observed cyclicities to the irradiance based solar cycle and its modulations. Using annual spectral solar irradiance in wavelength bands typical for stellar observations reconstructed by Shapiro et al. (2011), a direct comparison can be made between cycle timescales and amplitudes derived for the Sun and the stars. We show that cycles on multiple timescales, known to be present in solar activity, also show up on stars when the dataset is long enough to allow recognition. The cycle lengths are not fixed, but evolve - gradually during some periods but there are also changes on short timescales. In case the activity is dominated by spots, i.e., by cooler surface features, the star is redder when fainter, whereas other type of activity make the stars bluer when the activity is higher. We found the Sun to be a member of the former group, based on reconstructed spectral irradiance data by Shapiro et al. (2011). Title: Magnetic Activity of Two Similar Subgiants in Binaries with Very Different Mass Ratios: EI Eri and V711 Tau Authors: Oláh, Katalin; Kővári, Zsolt; Vida, Krisztián; Strassmeier, Klaus G. Bibcode: 2012IAUS..282..478O Altcode: We use more than three decades-long photometry to study the activity patterns on the two fast-rotating subgiant components in EI Eri (G5IV) and V711 Tau (K1IV). From yearly mean rotational periods from the light curves, we find that EI Eri, with well-measured solar-type differential rotation, always has spots from the equator to high latitudes. The measured differential rotation of V711 Tau is controversial, and in any case is very small. The spots on the K1IV star in V711 Tau seem to be tidally locked. The physical parameters of the two systems are similar, with one remarkable difference: EI Eri has a low mass M4-5 dwarf companion, whereas V711 Tau has a G5V star in the system, thus their mass centers are in very different positions. This may modify the whole internal structure of the active stars, causing marked differences in their surface features. Title: Differential Rotation in Two RS CVn Systems: σ Gem and ζ And Authors: Kővári, Zsolt; Bartus, János; Kriskovics, Levente; Oláh, Katalin; Vida, Krisztián; Ribárik, Orsolya; Strassmeier, Klaus G. Bibcode: 2012IAUS..282..197K Altcode: The differentially rotating convective envelope is an indispensable element of the magnetic dynamo working in RS CVn-systems. Tidal coupling is responsible for maintaining fast rotation, and also the observed high level of magnetic activity. In this work, we compare the physical properties of two well known RS CVn-type binaries, that is the long-period system σ Gem and the ellipsoidal variable ζ And. For the comparison, we use the results obtained from processing time-series Doppler images. We also aim at understanding how differential rotation could be affected by tidal forces in such close binaries. Title: Determining the Cepheid Period-Luminosity Relation Using Distances to Individual Cepheids from the Near-infrared Surface Brightness Method Authors: Storm, J.; Gieren, W.; Fouqué, P.; Barnes, T. G.; Granzer, T.; Nardetto, N.; Pietrzyński, G.; Queloz, D.; Soszyński, I.; Strassmeier, K. G.; Weber, M. Bibcode: 2012Msngr.147...14S Altcode: The near-infrared surface brightness method has been applied to 111 Cepheids in the Milky Way, the Large Magellanic Cloud and the Small Magellanic Cloud, and distances and luminosities to the individual stars have thus been determined. As the Cepheid populations in these galaxies have significantly different metallicities, the effect of metallicity on the Cepheid Period-Luminosity (PL) relation can be directly determined. We show that the K-band PL relation is very insensitive to abundance and argue that it is the best Cepheid PL relation for distance determination. Title: The STELLA échelle spectrograph, five years of robotic high-resolution spectroscopy Authors: Weber, M.; Strassmeier, K. G.; Granzer, T. Bibcode: 2012ASInC...7..165W Altcode: The STELLA robotic observatory is made up of two 1.2m telescopes. One is feeding an échelle spectrograph with a spectral resolution of 55,000 since 2006, the other is equipped with an imaging instrument with a field of view of 22'. Data are collected during every clear night, calibration data are also taken during bad weather periods to assure the functionality of the system. All CCD frames are stored locally and immediately queued for transfer to the AIP. All environmental data together with meta-data about the scientific observations are stored in a SQL database, which is replicated to our data center in Potsdam. Data reduction is started after each observing night, results of the post-reduction analysis, like radial velocity and stellar parameters, along with the reduced spectra are inserted into the database. This database, with information spanning from how often a target is picked, when it has been successfully acquired, how big were the guiding errors, all the way to radial velocities measurements is an essential tool for both data analysis and quality control. Title: The STELLA control system Authors: Granzer, T.; Weber, M.; Strassmeier, K. G. Bibcode: 2012ASInC...7..247G Altcode: The STELLA autonomous observatory comprises two different telescopes with different instrumentation, explicitly an imaging-photometer and a high-resolution spectrograph. This different instrumentation also demanded for different control software, which led to the decision to design a generic solution to robotic observing strategies, which not only can handle the existing hardware, but could also incorporate new hardware or observing strategies at relative ease. This article is about our solution. Title: Letter from the Editor Authors: Strassmeier, Klaus G. Bibcode: 2012AN....333....3S Altcode: No abstract at ADS Title: The STELLA Open Cluster Survey - Rotational Evolution of Low-mass Stars: a Status Report Authors: Fügner, D.; Granzer, T.; Strassmeier, K. G. Bibcode: 2011ASPC..448..863F Altcode: 2011csss...16..863F Our study targets on measuring the rotational periods and absolute parameters of a well-selected sample of cool cluster stars. If an empirical law between rotational period, stellar age, and mass could be established it would provide valuable boundary conditions for evolutionary models. Current models predict a measurable difference of the rotational period between a solidly rotating and a differentially rotating star, and this could be tested. Our time-series observations are made in the Sloan r bandpass. Using image-stacking, we intend to boost the S/N to more than 500:1 even for the (early) M dwarfs in the fields. For calculations of stellar properties, like age, metallicity, gravity and surface temperature, we use the Strömgren system with few very deep exposures. In this paper, we present the survey outline, the instruments and the first steps already undertaken. Title: Oscillations and Magnetic Fields in the G8 Star EK Eridani Authors: Dall, T. H.; Cunha, M.; Strassmeier, K. G.; Stello, D.; Bruntt, H. Bibcode: 2011ASPC..448.1091D Altcode: 2011csss...16.1091D; 2010arXiv1012.1152D Asteroseismology can provide information that is otherwise not easily accessible, like the stellar mass and the evolutionary stage. Strong magnetic fields are usually accompanied by rapid rotation, which makes asteroseismology difficult due to spectral line broadening. We have found what may turn out to be the Rosetta Stone of the stars: A slowly rotating solar-like star with a strong magnetic field. We have recently detected solar-like oscillations in this active sub-giant, but with amplitudes much lower than expected. We suggest that the large-scale magnetic field alters the pulsations, which become magnetoacoustic in nature. Here we present our results and discuss possible implications and how this may open up a new frontier in the studies of magnetic fields and stellar evolution. Title: Binary-induced magnetic activity?. Time-series echelle spectroscopy and photometry of HD 123351 = CZ CVn Authors: Strassmeier, K. G.; Carroll, T. A.; Weber, M.; Granzer, T.; Bartus, J.; Oláh, K.; Rice, J. B. Bibcode: 2011A&A...535A..98S Altcode: 2011arXiv1108.4673S Context. Multi-wavelength time-series observations with high cadence and long duration are needed to resolve and understand the many variations of magnetically active late-type stars, which is an approach often used to observe the Sun.
Aims: We present a first and detailed study of the bright and active K0IV-III star HD 123351.
Methods: We acquired a total of 955 high-resolution STELLA echelle spectra during the years 2006-2010 and a total of 2260 photometric VIC data points during 1998-2010. These data are complemented by some spectra from CFHT and KPNO.
Results: The star is found to be a single-lined spectroscopic binary with a period of 147.8919 ± 0.0003 days and a large eccentricity of e = 0.8086 ± 0.0001. The rms of the orbital solution is just 47 m s-1, making it the most precise orbit ever obtained for an active binary system. The rotation period is constrained from long-term photometry to be 58.32 ± 0.01 days. It shows that HD 123351 is a very asynchronous rotator, rotating five times slower than the expected pseudo-synchronous value. Two spotted regions persisted throughout the 12 years of our observations. We interpret them as active longitudes on a differentially rotating surface with a ΔP/P of 0.076. Four years of Hα, Ca ii H&K and He i D3 monitoring identifies the same main periodicity as the photometry but dynamic spectra also indicate that there is an intermittent dependence on the orbital period, in particular for Ca ii H&K in 2008. Line-profile inversions of a pair of Zeeman sensitive/insensitive iron lines yield an average surface magnetic-flux density of 542 ± 72 G. The time series for 2008 is modulated by the stellar rotation as well as the orbital motion, such that the magnetic flux is generally weaker during times of periastron and that the chromospheric emissions vary in anti-phase with the magnetic flux. We also identify a broad and asymmetric lithium line profile and measure an abundance of log n(Li) = 1.70 ± 0.05. The star's position in the H-R diagram indicates a mass of 1.2 ± 0.1 M⊙ and an age of 6-7 Gyr.
Conclusions: We interpret the anti-phase relation of the magnetic flux with the chromospheric emissions as evidence that there are two magnetic fields present at the same time, a localized surface magnetic field associated with spots and a global field that is oriented towards the (low-mass) secondary component. We suggest that the inter-binary field is responsible for the magnetic-flux dilution at periastron. It is also likely to be responsible for the unexpected slow and asynchronous rotation of the primary star.

Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC, and the Potsdam Automatic Photoelectric Telescopes (APT) in Arizona, jointly operated by AIP and Fairborn Observatory. Title: Calibrating the Cepheid period-luminosity relation from the infrared surface brightness technique. I. The p-factor, the Milky Way relations, and a universal K-band relation Authors: Storm, J.; Gieren, W.; Fouqué, P.; Barnes, T. G.; Pietrzyński, G.; Nardetto, N.; Weber, M.; Granzer, T.; Strassmeier, K. G. Bibcode: 2011A&A...534A..94S Altcode: 2011arXiv1109.2017S
Aims: We determine period-luminosity relations for Milky Way Cepheids in the optical and near-IR bands. These relations can be used directly as reference for extra-galactic distance determination to Cepheid populations with solar metallicity, and they form the basis for a direct comparison with relations obtained in exactly the same manner for stars in the Magellanic Clouds, presented in an accompanying paper. In that paper we show that the metallicity effect is very small and consistent with a null effect, particularly in the near-IR bands, and we combine here all 111 Cepheids from the Milky Way, the LMC and SMC to form a best relation.
Methods: We employ the near-IR surface brightness (IRSB) method to determine direct distances to the individual Cepheids after we have recalibrated the projection factor using the recent parallax measurements to ten Galactic Cepheids and the constraint that Cepheid distances to the LMC should be independent of pulsation period.
Results: We confirm our earlier finding that the projection factor for converting radial velocity to pulsational velocity depends quite steeply on pulsation period, p = 1.550 - 0.186log (P) in disagrement with recent theoretical predictions. We find PL relations based on 70 Milky Way fundamental mode Cepheids of MK = -3.33( ± 0.09)(log (P) - 1.0) - 5.66( ± 0.03), WVI = -3.26( ± 0.11)(log (P) - 1.0) - 5.96(±0.04). Combining the 70 Cepheids presented here with the results for 41 Magellanic Cloud Cepheids which are presented in an accompanying paper, we find MK = -3.30( ± 0.06)(log (P) - 1.0) - 5.65( ± 0.02), WVI = -3.32( ± 0.08)(log (P) - 1.0) - 5.92( ± 0.03).
Conclusions: We delineate the Cepheid PL relation using 111 Cepheids with direct distances from the IRSB analysis. The relations are by construction in agreement with the recent HST parallax distances to Cepheids and slopes are in excellent agreement with the slopes of apparent magnitudes versus period observed in the LMC.

Full Table 3 is 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/534/A94 Title: On the design of the PEPSI spectropolarimeter for the LBT Authors: Ilyin, I.; Strassmeier, K. G.; Woche, M.; Dionies, F.; Di Varano, I. Bibcode: 2011AN....332..753I Altcode: We present the design concept of the spectropolarimeter for the high-resolution echelle spectrograph PEPSI to be installed at the 2×8.4 m Large Binocular Telescope (LBT) in Arizona. We discuss the optical key elements, the principles of operations of the instrument and its instrumental polarization effects. Title: VizieR Online Data Catalog: Milky Way Cepheids radial velocities (Storm+, 2011) Authors: Storm, J.; Gieren, W.; Fouque, P.; Barnes, T. G.; Pietrzynski, G.; Nardetto, N.; Weber, M.; Granzer, T.; Strassmeier, K. G. Bibcode: 2011yCat..35340094S Altcode: 2011yCat..35349094S Repeated high precision radial velocity measurements for 14 galactic Cepheids obtained with the STELLA telescope and echelle spectrograph are presented together with the associated time stamps. From these data radial velocity curves with good phase coverage can be established. The Cepheids observed are: V496 Aql, TT Aql, VZ Cyg, {zeta} Gem, X Pup, AQ Pup, BN Pup, LS Pup, VZ Pup, X Sgr, Y Sgr, BB Sgr, XX Sgr, YZ Sgr.

(2 data files). Title: Integration of a thermo-structural analysis with an optical model for PEPSI polarimeter Authors: Di Varano, Igor; Strassmeier, Klaus G.; Ilyin, Ilya; Woche, Manfred; Kaercher, Hans J. Bibcode: 2011SPIE.8336E..0WD Altcode: 2011SPIE.8336E..31D The two spectropolarimeters for PEPSI (Potsdam Echelle Polarimetric and Spectroscopic Instrument) have been de¬signed in order to reconstruct the full Stokes vector measuring linear and circular polarization simultaneously with a re¬solving power of 120,000. The polarimeters will be attached to the Gregorian focus of the so far largest LBT 2x8.4m telescope and will feed together with permanent focus stations the spectrograph via 44m long fibers connection. The spectrograph will be located in a pressure-temperature controlled chamber within the telescope pier. We present hereafter the last results from combined structural and CFD analyses in order to fulfill the optical requirements. Title: Physics of Sun and Star Spots (IAU S273) Authors: Prasad Choudhary, Debi; Strassmeier, Klaus G. Bibcode: 2011IAUS..273.....P Altcode: Preface; 1. Formation and decay of sunspots; 2. Solar magnetism; 3. Origin of solar activity; 4. Formation and evolution of starspots; 5. Stellar magnetism; 6. Starspots and stellar activity; 7. Observational techniques; 8. Unified approach in understanding sun and starspots; Author index; Subject index. Title: The zoo of starspots Authors: Strassmeier, Klaus G. Bibcode: 2011IAUS..273..174S Altcode: Starspots are being observed with many different techniques but not always with coherent results. In particular not if model-dependent data analysis must be employed, e.g. through two-dimensional spot modelling of one-dimensional photometric light curves. I review the zoo of currently available physical spot parameters, i.e. their size, temperature and variability time scales, and also compare results from different techniques. Most of the current values come from Doppler imaging and multi-color photometry. I also list a few cases where starspot detections turned out to be very different to the solar analog. Title: The spectroscopic orbit of Capella revisited Authors: Weber, M.; Strassmeier, K. G. Bibcode: 2011A&A...531A..89W Altcode: 2011arXiv1104.0342W Context. Capella is among the few binary stars with two evolved giant components. The hotter component is a chromospherically active star within the Hertzsprung gap, while the cooler star is possibly helium-core burning.
Aims: The known inclination of the orbital plane from astrometry in combination with precise radial velocities will allow very accurate masses to be determined for the individual Capella stars. This will constrain their evolutionary stage and possibly the role of the active star's magnetic field on the dynamical evolution of the binary system.
Methods: We obtained a total of 438 high-resolution échelle spectra during the years 2007-2010 and used the measured velocities to recompute the orbital elements. Our double-lined orbital solution yields average residuals of 64 m s-1 for the cool component and 297 m s-1 for the more rapidly rotating hotter component.
Results: The semi-amplitude of the cool component is smaller by 0.045 km s-1 than the orbit determination of Torres et al. from data taken during 1996-1999 but more precise by a factor of 5.5, while for the hotter component it is larger by 0.580 km s-1 and more precise by a factor of 3.6. This corresponds to masses of 2.573 ± 0.009 M⊙ and 2.488 ± 0.008 M⊙ for the cool and hot component, respectively. Their relative errors of 0.34% and 0.30% are about half of the values given in Torres et al. for a combined literature-data solution but with absolute values different by 4% and 2% for the two components, respectively. The mass ratio of the system is therefore q = MA/MB = 0.9673 ± 0.0020.
Conclusions: Our orbit is the most precise and also likely to be the most accurate ever obtained for Capella.

Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC.Full Table 1 is 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/531/A89 Title: Towards observational MHD. Advances in spectropolarimetry and the prospects for the E-ELT Authors: Strassmeier, Klaus G. Bibcode: 2011IAUS..274..274S Altcode: Polarization and wavelength are the bits of information attached to every photon that reveal the most about its formation and subsequent history. The E-ELT will, for the foreseeable future, be the most powerful optical light-collecting machine ever built. The strength of its combination, spectropolarimetry with the E-ELT, is the anchorage in physics of astronomical observations. I present a strawman design of a spectropolarimeter for its intermediate focus. Title: The Surface of V410 Tauri Authors: Rice, J. B.; Strassmeier, K. G.; Kopf, M. Bibcode: 2011ApJ...728...69R Altcode: We present Doppler images of the weak-lined T Tauri star V410 Tau obtained with two different Doppler-imaging codes. The images are consistent and show a cool extended spot, symmetric about the pole, at a temperature approximately 750 K below the average photospheric value. Smaller cool spots are found fairly uniformly distributed at latitudes below the polar cap with temperatures about 450 K below the average photospheric temperature. Resolution on the stellar surface is limited to about 7° of arc, so structure within these spots is not visible. Also at lower latitudes are hotter features with temperatures up to 1000 K above the photosphere. A trial Doppler image using a TiO molecular feature reproduced the cool polar cap at a temperature about 100 K below the value from the atomic line images. The equatorial features, however, were not properly reproduced since Doppler imaging relies on information in the wings of lines for reconstructing equatorial features, and for V410 Tau these molecular band lines overlap. In 1993, V410 Tau had a large photometric amplitude resulting from the concentration of cool spots on the hemisphere of the star visible at phase 0°, a phenomenon known as preferred longitude. In contrast, the small photometric amplitude observed currently is due to a strong symmetric polar spot and the uniform distribution in longitude of equatorial cool and warm spots. This redistribution of surface features may be the beginning of a slow "flip-flop" for V410 Tau where spot locations alternate between preferred longitudes. Flare events linked to two of the hotter spots in the Doppler image were observed. Title: VizieR Online Data Catalog: Spectroscopic orbit of Capella (Weber+, 2011) Authors: Weber, M.; Strassmeier, K. G. Bibcode: 2011yCat..35310089W Altcode: 2011yCat..35319089W Barycentric STELLA radial velocities of Capella.

(1 data file). Title: The First HELAS Local Helioseismology Workshop: Roadmap for European local helioseismology Authors: Strassmeier, Klaus G. Bibcode: 2011AN....332....3S Altcode: No abstract at ADS Title: Modeling the Subsurface Structure of Sunspots Authors: Moradi, H.; Baldner, C.; Birch, A. C.; Braun, D. C.; Cameron, R. H.; Duvall, T. L.; Gizon, L.; Haber, D.; Hanasoge, S. M.; Hindman, B. W.; Jackiewicz, J.; Khomenko, E.; Komm, R.; Rajaguru, P.; Rempel, M.; Roth, M.; Schlichenmaier, R.; Schunker, H.; Spruit, H. C.; Strassmeier, K. G.; Thompson, M. J.; Zharkov, S. Bibcode: 2010SoPh..267....1M Altcode: 2009arXiv0912.4982M; 2010SoPh..tmp..171M While sunspots are easily observed at the solar surface, determining their subsurface structure is not trivial. There are two main hypotheses for the subsurface structure of sunspots: the monolithic model and the cluster model. Local helioseismology is the only means by which we can investigate subphotospheric structure. However, as current linear inversion techniques do not yet allow helioseismology to probe the internal structure with sufficient confidence to distinguish between the monolith and cluster models, the development of physically realistic sunspot models are a priority for helioseismologists. This is because they are not only important indicators of the variety of physical effects that may influence helioseismic inferences in active regions, but they also enable detailed assessments of the validity of helioseismic interpretations through numerical forward modeling. In this article, we provide a critical review of the existing sunspot models and an overview of numerical methods employed to model wave propagation through model sunspots. We then carry out a helioseismic analysis of the sunspot in Active Region 9787 and address the serious inconsistencies uncovered by Gizon et al. (2009a, 2009b). We find that this sunspot is most probably associated with a shallow, positive wave-speed perturbation (unlike the traditional two-layer model) and that travel-time measurements are consistent with a horizontal outflow in the surrounding moat. 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: The magnetic field and the evolution of element spots on the surface of the HgMn eclipsing binary ARAur Authors: Hubrig, S.; Savanov, I.; Ilyin, I.; González, J. F.; Korhonen, H.; Lehmann, H.; Schöller, M.; Granzer, T.; Weber, M.; Strassmeier, K. G.; Hartmann, M.; Tkachenko, A. Bibcode: 2010MNRAS.408L..61H Altcode: 2010MNRAS.tmpL.125H The system ARAur is a young late B-type double-lined eclipsing binary with a primary star of HgMn peculiarity. We applied the Doppler imaging method to reconstruct the distribution of Fe and Y over the surface of the primary using spectroscopic time series obtained in 2005 and from 2008 October to 2009 February. The results show a remarkable evolution of the element distribution and overabundances. Measurements of the magnetic field with the moment technique using several elements reveal the presence of a longitudinal magnetic field of the order of a few hundred gauss in both stellar components and a quadratic field of the order of 8kG on the surface of the primary star.

Based on observations obtained at the 2.56-m Nordic Optical Telescope on La Palma, the Karl-Schwarzschild-Observatorium in Tautenburg and the STELLA robotic telescope on Tenerife.

E-mail: shubrig@aip.de Title: Rotation and magnetic activity of the Hertzsprung-gap giant 31 Comae Authors: Strassmeier, K. G.; Granzer, T.; Kopf, M.; Weber, M.; Küker, M.; Reegen, P.; Rice, J. B.; Matthews, J. M.; Kuschnig, R.; Rowe, J. F.; Guenther, D. B.; Moffat, A. F. J.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W. Bibcode: 2010A&A...520A..52S Altcode: Context. The single rapidly-rotating G0 giant 31 Comae has been a puzzle because of the absence of photometric variability despite its strong chromospheric and coronal emissions. As a Hertzsprung-gap giant, it is expected to be at the stage of rearranging its moment of inertia, hence likely also its dynamo action, which could possibly be linked with its missing photospheric activity.
Aims: Our aim is to detect photospheric activity, obtain the rotation period, and use it for a first Doppler image of the star's surface. Its morphology could be related to the evolutionary status.
Methods: We carried out high-precision, white-light photometry with the MOST satellite, ground-based Strömgren photometry with automated telescopes, and high-resolution optical echelle spectroscopy with the new STELLA robotic facility.
Results: The MOST data reveal, for the first time, light variations with a full amplitude of 5 mmag and an average photometric period of 6.80 ± 0.06 days. Radial-velocity variations with a full amplitude of 270 m s-1 and a period of 6.76 ± 0.02 days were detected from our STELLA spectra, which we also interpret as due to stellar rotation. The two-year constancy of the average radial velocity of +0.10 ± 0.33 km s-1 confirms the star's single status, as well as the membership in the cluster Melotte 111. A spectrum synthesis gives Teff = 5660 ± 42 K, log g = 3.51 ± 0.09, and [Fe/H] = -0.15 ± 0.03, which together with the revised Hipparcos distance, suggests a mass of 2.6 ± 0.1 M_⊙ and an age of ≈540 Myr. The surface lithium abundance is measured to be nearly primordial. A detection of a strong He i absorption line indicates nonradiative heating processes in the atmosphere. Our Doppler images show a large, asymmetric polar spot, cooler than Teff by ≈1600 K, and several small low-to-mid latitude features that are warmer by ≈300-400 K and are possibly of chromospheric origin. We computed the convective turnover time for 31 Com as a function of depth and found on average τC ≈ 5 days.
Conclusions: 31 Com appears to be just at the onset of rapid magnetic braking and Li dilution because its age almost exactly coincides with the predicted onset of envelope convection. That we recover a big polar starspot despite the Rossby number being larger than unity, and thus no efficient (envelope) dynamo is expected, leads us to conclude that 31 Com still harbors a fossil predominantly poloidal magnetic field. However, the increasing convective envelope may have just started an interface dynamo that now is the source of the warm surface features and the corresponding UV and X-ray emission.

Based on data obtained with the MOST satellite, a Canadian Space Agency mission, operated jointly by Dynacon, Inc., and the Universities of Toronto and British Columbia, with assistance from the University of Vienna; the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC, and the Vienna Automatic Photoelectric Telescopes in Arizona, jointly operated by the University of Vienna and AIP.Full Tables 2 and 3 are only available in electronic form 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/520/A52 Title: Discovery of cyclic spot activity on the G8 giant HD 208472 Authors: Özdarcan, O.; Evren, S.; Strassmeier, K. G.; Granzer, T.; Henry, G. W. Bibcode: 2010AN....331..794O Altcode: % We present and analyze 17 consecutive years of U BV RI time-series photometry of the spotted giant component of the RS CVn binary HD 208472. Our aim is to determine the morphology and the evolution of its starspots by using period-search techniques and two-spot light-curve modelling. Spots on HD208472 always occur on hemispheres facing the observer during orbital quadrature and flip their location to the opposite hemisphere every approximately six years. The times when the spots change their preferential hemisphere correspond to times when the light curve amplitudes are the smallest and when abrupt changes of the photometric periods are observed. During these times the star is also close to a relative maximum brightness, suggesting a vanishing overall spottedness at each end of the previous cycle and the start of a new one. We find evidence for a 6.28±0.06-yr brightness cycle, which we interpret to be a stellar analog of the solar 11-year sunspot cycle. We also present clear evidence for a brightening trend, approximated with a 21.5±0.5-yr period, possibly due to a stellar analog of the solar Gleissberg cycle. From the two-spot modelling we also determine an upper limit for the differential-rotation coefficient of α=Δ P/P of 0.004±0.010, which would be fifty times weaker than on the Sun.

Based on data obtained with the Amadeus T7 Automatic Photoelectric Telescope at Fairborn Observatory, jointly operated by the University of Vienna and AIP, the Tennessee State University T3 0.4 m APT at Fairborn Observatory, operated by Tennessee State University, and the telescopes of the Ege University Observatory in Izmir. Title: VizieR Online Data Catalog: 31 Com radial velocities (Strassmeier+, 2010) Authors: Strassmeier, K. G.; Granzer, T.; Kopf, M.; Weber, M.; Kueker, M.; Reegen, P.; Rice, J. B.; Matthews, J. M.; Kuschnig, R.; Rowe, J. F.; Guenther, D. B.; Moffat, A. F. J.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W. Bibcode: 2010yCat..35200052S Altcode: 2010yCat..35209052S We carried out high-precision, white-light photometry with the MOST satellite, ground-based Stroemgren photometry with automated telescopes, and high-resolution optical echelle spectroscopy with the new STELLA robotic facility.

(2 data files). Title: GREGOR telescope: start of commissioning Authors: Volkmer, R.; von der Lühe, O.; Denker, C.; Solanki, S.; Balthasar, H.; Berkefeld, T.; Caligari, P.; Collados, M.; Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Klvana, M.; Kneer, F.; Lagg, A.; Popow, E.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Soltau, D.; Strassmeier, K. Bibcode: 2010SPIE.7733E..0KV Altcode: 2010SPIE.7733E..18V With the integration of a 1-meter Cesic primary mirror the GREGOR telescope pre-commissioning started. This is the first time, that the entire light path has seen sunlight. The pre-commissioning period includes testing of the main optics, adaptive optics, cooling system, and pointing system. This time was also used to install a near-infrared grating spectro-polarimeter and a 2D-spectropolarimeter for the visible range as first-light science instruments. As soon as the final 1.5 meter primary mirror is installed, commissioning will be completed, and an extended phase of science verification will follow. In the near future, GREGOR will be equipped with a multi-conjugate adaptive optics system that is presently under development at KIS. Title: The Opto-mechanical design of the Antarctic Telescope ICE-T Authors: Strassmeier, Klaus G.; Divarano, Igor; Woche, Manfred; Kaercher, Hans J.; Eisenträger, Peter Bibcode: 2010SPIE.7733E..4US Altcode: 2010SPIE.7733E.152S The International Concordia Explorer Telescope (ICE-T) is two 60cm wide-field robotic Schmidt telescopes optimized for high-precision CCD photometry in two separate bandpasses. The project is under final design by an international consortium led by the Astrophysical Institute Potsdam, Germany, and was foreseen to be placed at the French-Italian Concordia Station on Dome C in Antarctica. Its core scientific objective would be to detect and investigate the combined effects of extra-solar planets, stellar magnetic activity and non-radial pulsations on the structure and evolution of stars. We present the optical, the mechanical, and the electronic design of the telescope and lay out the operational constraints for its search for extrasolar planets and magnetic stellar activity. Title: Thermal design and de-icing system for the Antarctic Telescope ICE-T Authors: Strassmeier, Klaus G.; Kärcher, Hans J.; Kühn, Jürgen; Divarano, Igor Bibcode: 2010SPIE.7733E..1WS Altcode: 2010SPIE.7733E..58S ICE-T, the International Concordia Explorer Telescope, is under final design by an international consortium led by the Astrophysical Institute Potsdam AIP, Germany, and is intended to be placed at the French-Italian Concordia Station on Dome C in Antarctica. Experience with smaller telescopes at Concordia has shown that under the weather conditions at this site - with mean outside temperatures of -60° to -80° C and temperature changes of 20° in short time intervals - the ice-accumulation on the optical components during observation is a major problem. Also, energy consumption at this site should be minimized because fuel transport to the site is very costly. The paper describes the thermal concept for the telescope where the waste energy of the instrument electronics is used for heating the front surfaces of the Schmidt optics. All other parts of the telescope are protected by an insulated smooth cladding against the harsh outside environment. The effectiveness of the thermal concept is verified by CFD (Computer Fluid Dynamics) calculations. Title: Ellipsoidal primary of the RS CVn binary ζ Andromedae . Investigation using high-resolution spectroscopy and optical interferometry Authors: Korhonen, H.; Wittkowski, M.; Kovári, Zs.; Granzer, Th.; Hackman, T.; Strassmeier, K. G. Bibcode: 2010A&A...515A..14K Altcode: 2010arXiv1002.4201K
Aims: We have obtained high-resolution spectroscopy, optical interferometry, and long-term broad band photometry of the ellipsoidal primary of the RS CVn-type binary system ζ And. These observations are used to obtain fundamental stellar parameters and to study surface structures and their temporal evolution.
Methods: Temperature maps of the stellar surface were obtained from high-resolution spectra with Doppler imaging techniques. These spectra were also used to investigate the chromospheric activity using the Hα line and to correlate it with the photospheric activity. The possible cyclicity in the spot activity was investigated from the long-term broad band photometry. Optical interferometry was obtained during the same time period as the high-resolution spectra. These observations were used to derive the size and fundamental parameters of ζ And.
Results: Based on the optical interferometry the apparent limb darkened diameter of ζ And is 2.55 ± 0.09 mas using a uniform disk fit. The expected ~4% maximum difference between the long and short axes of the ellipsoidal stellar surface cannot be confirmed from the current data which have 4% errors. The Hipparcos distance and the limb-darkened diameter obtained with a uniform disk fit give stellar radius of 15.9 ± 0.8 R⊙, and combined with bolometric luminosity, it implies an effective temperature of 4665 ± 140 K. The temperature maps obtained from Doppler imaging show a strong belt of equatorial spots and hints of a cool polar cap. The equatorial spots show a concentration around the phase 0.75, i.e., 0.25 in phase from the secondary, and another concentration spans the phases 0.0-0.4. This spot configuration is reminiscent of the one seen in the earlier published temperature maps of ζ And. Investigation of the Hα line reveals both prominences and cool clouds in the chromosphere. These features do not seem to have a clearly preferred location in the binary reference frame, nor are they strongly associated with the cool photospheric spots. The investigation of the long-term photometry spanning 12 years shows hints of a spot activity cycle, which is also implied by the Doppler images, but the cycle length cannot be reliably determined from the current data.

Based on observations collected at the European Southern Observatory, Chile (Prg. 081.D-0216(AB)); and with the Vienna automatic photometric telescopes Wolfgang and Amadeus, Arizona, USA. Title: GREGOR solar telescope: Design and status Authors: Volkmer, R.; von der Lühe, O.; Denker, C.; Solanki, S. K.; Balthasar, H.; Berkefeld, T.; Caligari, P.; Collados, M.; Fischer, A.; Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Klvaňa, M.; Kneer, F.; Lagg, A.; Popow, E.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Soltau, D.; Strassmeier, K. G. Bibcode: 2010AN....331..624V Altcode: The integration and verification phase of the GREGOR telescope reached an important milestone with the installation of the interim 1 m SolarLite primary mirror. This was the first time that the entire light path had seen sunlight. Since then extensive testing of the telescope and its subsystems has been carried out. The integration and verification phase will culminate with the delivery and installation of the final 1.5 m Zerodur primary mirror in the summer of 2010. Observatory level tests and science verification will commence in the second half of 2010 and in 2011. This phase includes testing of the main optics, adaptive optics, cooling and pointing systems. In addition, assuming the viewpoint of a typical user, various observational modes of the GREGOR Fabry-Pérot Interferometer (GFPI), the Grating Infrared Spectrograph (GRIS), and high-speed camera systems will be tested to evaluate if they match the expectations and science requirements. This ensures that GREGOR will provide high-quality observations with its combination of (multi-conjugate) adaptive optics and advanced post-focus instruments. Routine observations are expected for 2012. Title: Solar-like oscillations and magnetic activity of the slow rotator EK Eridani Authors: Dall, T. H.; Bruntt, H.; Stello, D.; Strassmeier, K. G. Bibcode: 2010A&A...514A..25D Altcode: 2010arXiv1003.0433D
Aims: We aim to understand the interplay between non-radial oscillations and stellar magnetic activity and test the feasibility of doing asteroseismology of magnetically active stars. We investigate the active slow rotator EK Eri which is the likely descendant of an Ap star.
Methods: We analyze 30 years of photometric time-series data, 3 years of HARPS radial velocity monitoring, and 3 nights of high-cadence HARPS asteroseismic data. We construct a high-S/N HARPS spectrum that we use to determine atmospheric parameters and chemical composition. Spectra observed at different rotation phases are analyzed to search for signs of temperature or abundance variations. An upper limit on the projected rotational velocity is derived from very high-resolution CES spectra.
Results: We detect oscillations in EK Eri with a frequency of the maximum power of ν_max = 320 ± 32 μHz, and we derive a peak amplitude per radial mode of ≈0.15 m s-1, which is a factor of ≈3 lower than expected. We suggest that the magnetic field may act to suppress low-degree modes. Individual frequencies can not be extracted from the available data. We derive accurate atmospheric parameters, refining our previous analysis, finding T_eff = 5135 ± 80 K, log g = 3.39 ± 0.12, and metallicity [M/H] = + 0.02 ± 0.04. Mass and radius estimates from the seismic analysis are not accurate enough to constrain the position in the HR diagram and the evolutionary state. We confirm that the main light variation is due to cool spots, but that other contributions may need to be taken into account. We tentatively suggest that the rotation period is twice the photometric period, i.e., P_rot = 2P_phot = 617.6 d, and that the star is a dipole-dominated oblique rotator viewed close to equator-on. We conclude from our derived parameters that v sin i < 0.40 km s-1 and we show that the value is too low to be reliably measured. We also link the time series of direct magnetic field measurements available in the literature to our newly derived photometric ephemeris.

Based on data from the HARPS spectrograph at the La Silla Observatory, European Southern Observatory, obtained under programs IDs 77.C-0080 and 78.C-0233, and on data from the CES spectrograph obtained from the ESO Science Archive Facility. Title: HD 1: The number-one star in the sky Authors: Strassmeier, K. G.; Weber, M.; Granzer, T.; Dall, T. H. Bibcode: 2010AN....331..368S Altcode: We present the first ever study of the bright star HD 1. The star was chosen arbitrarily just because of its outstanding Henry Draper number. Surprisingly, almost nothing is known about this bright 7.4 m star. Our observations were performed as part of the commissioning of the robotic telescope facility STELLA and its fiber-fed high-resolution optical echelle spectrograph SES in the years 2007-2010. We found long-term radial velocity variations with a full amplitude of 9 km s-1 with an average velocity of -29.8 km s-1 and suggest the star to be a hitherto unknown single-lined spectroscopic binary. A preliminary orbit with a period of 6.2 years (2279±69 days) and an eccentricity of 0.50±0.01 is given. Its rms uncertainty is just 73 m s-1 . HD 1 appears to be a G9-K0 giant of luminosity class IIIa with T_eff = 4850±100 K, log g = 2.0±0.2, L≈ 155 L_⊙, a mass of 3.0±0.3 M⊙, a radius of 17.7 R⊙, and an age of ≈350 Myr. A relative abundance analysis led to a metallicity of [Fe/H] =-0.12±0.09. The α-element silicon may indicate an overabundance of +0.13 though. The low strengths of some s-process lines and a lower limit for the 12C/13C isotope ratio of ≥16 indicate that HD 1 is on the first ascend of the RGB. The absorption spectral lines appear rotationally broadened with a v sin i of 5.5±1.2 km s-1 but no chromospheric activity is evident. We also present photometric monitoring BV(RI)_C data taken in parallel with STELLA. The star is likely a small-amplitude (<10 mmag) photometric variable although no periodicity was found.

Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC, and the Vienna Automatic Photoelectric Telescopes in Arizona, jointly operated by the University of Vienna and AIP. Title: RS CVn binary IM Peg - investigation of stellar activity and surface flows Authors: Korhonen, Heidi; Weber, Michael; Wittkowski, Markus; Granzer, Thomas; Strassmeier, Klaus G. Bibcode: 2010IAUS..264..267K Altcode: We have obtained high resolution, high S/N spectra of the RS CVn binary IM Peg using UVES spectrograph at Kueyen 8.2m telescope of ESO VLT. We use Doppler imaging techniques to obtain stellar surface temperature maps from the UVES data. The TempMap code allows us to use surface differential rotation as an input parameter and thus to try to construct the rotation pattern on the stellar surface as part of the inversion process. The UVES observations are combined with spectroscopic observations from another time period obtained at the STELLA observatory. We obtain stellar surface temperature maps also from these spectra. These Doppler images are used to study the magnetic activity and surface differential rotation on IM Peg. Title: Development of the opto-mechanical design for ICE-T Authors: di Varano, I.; Strassmeier, K. G.; Granzer, T.; Woche, M. Bibcode: 2010EAS....40..375D Altcode: 2009arXiv0909.4407D ICE-T (International Concordia Explorer Telescope) is a double 60 cm f/1.1 photometric robotic telescope, on a parallactic mount, which will operate at Dome C, in the long Antarctic night, aiming to investigate exoplanets and activity of the hosting stars. Antarctic Plateau site is well known to be one of the best in the world for observations because of sky transparency in all wavelengths and low scintillation noise. Due to the extremely harsh environmental conditions (the lowest average temperature is -80°C) the criteria adopted for an optimal design are really challenging. Here we present the strategies we have adopted so far to fulfill the mechanical and optical requirements. Title: Three Years of Experience with the STELLA Robotic Observatory Authors: Granzer, Thomas; Weber, Michael; Strassmeier, Klaus G. Bibcode: 2010AdAst2010E..79G Altcode: 2010arXiv1010.3523G Since May 2006, the two STELLA robotic telescopes at the Izana observatory in Tenerife, Spain, delivered an almost uninterrupted stream of scientific data. To achieve such a high level of autonomous operation, the replacement of all troubleshooting skills of a regular observer in software was required. Care must be taken on error handling issues and on robustness of the algorithms used. In the current paper, we summarize the approaches we followed in the STELLA observatory. Title: The STELLA Robotic Observatory on Tenerife Authors: Strassmeier, Klaus G.; Granzer, Thomas; Weber, Michael; Woche, Manfred; Popow, Emil; Järvinen, Arto; Bartus, Janos; Bauer, Svend-Marian; Dionies, Frank; Fechner, Thomas; Bittner, Wilbert; Paschke, Jens Bibcode: 2010AdAst2010E..19S Altcode: No abstract at ADS Title: VizieR Online Data Catalog: Starspots. Authors: Strassmeier, K. G. Bibcode: 2010yCatp039001701S Altcode: No abstract at ADS Title: Letter from the Editor Authors: Strassmeier, K. G. Bibcode: 2010AN....331....3S Altcode: No abstract at ADS Title: The Application of FORS1 Spectropolarimetry to the Investigation of Cool Solar-like Stars Authors: Korhonen, H.; Hubrig, S.; Kővári, Zs.; Weber, M.; Strassmeier, K.; Hackman, T.; Wittkowski, M. Bibcode: 2009Msngr.138...15K Altcode: The low resolution spectropolarimetric observations obtained with FORS1 at the VLT have often been used for investigating magnetic fields in hot stars. Here we describe the first investigation of the magnetic field over the stellar rotation in a cool late-type star, FK Com, based on FORS1 spectropolarimetry. We measure the mean longitudinal magnetic field from nine circularly polarised spectra, and study its behaviour over the stellar rotation. The magnetic field measurements are compared to a simultaneous stellar surface temperature map obtained with Doppler imaging techniques. These observations reveal two cool spots on the surface, and indicate that the main cool region coincides with the maximum value of the mean longitudinal magnetic field. Additionally, only 0.25 in phase apart from the main spot, the secondary spot is located at a similar phase to the field minimum. The observations can be interpreted as two spots having different magnetic field polarities, implying that the starspot configuration on FK Com is similar to that observed in the Sun. Title: On the differential rotation of CoRoT-2a Authors: Fröhlich, H. -E.; Küker, M.; Hatzes, A. P.; Strassmeier, K. G. Bibcode: 2009A&A...506..263F Altcode: We apply a robust spot model to fit the light curve of CoRoT-2a. The spots are assumed to be long-living and each has its own rotation period. A model with three circular spots reproduces the basic features of the longitude-time spot coverage map. One of the spots exhibits a noticeably lower rotational frequency than the other two. From the rotational frequencies of the three dark features we infer a differential rotation of above 0.11 rad/d, in rough agreement with theoretical models. Mean field models of angular momentum transport by convection and meridional flow lead to an equatorial rotational frequency that exceeds that of the poles by 0.09 rad/d. The spot decay corresponds to a turbulent magnetic diffusivity of (1.2± 0.1)× 1013 cm^2/s.

Based on observations obtained with CoRoT. The CoRoT space mission, launched on December 27th 2006, has been developed by CNES, with the contribution of Austria, Belgium, Brazil, ESA, Germany and Spain. Title: Starspots Authors: Strassmeier, Klaus G. Bibcode: 2009A&ARv..17..251S Altcode: 2009A&ARv.tmp....6S; 2009A&ARv.tmp....8S Starspots are created by local magnetic fields on the surfaces of stars, just as sunspots. Their fields are strong enough to suppress the overturning convective motion and thus block or redirect the flow of energy from the stellar interior outwards to the surface and consequently appear as locally cool and therefore dark regions against an otherwise bright photosphere (Biermann in Astronomische Nachrichten 264:361, 1938; Z Astrophysik 25:135, 1948). As such, starspots are observable tracers of the yet unknown internal dynamo activity and allow a glimpse into the complex internal stellar magnetic field structure. Starspots also enable the precise measurement of stellar rotation which is among the key ingredients for the expected internal magnetic topology. But whether starspots are just blown-up sunspot analogs, we do not know yet. This article is an attempt to review our current knowledge of starspots. A comparison of a white-light image of the Sun (G2V, 5 Gyr) with a Doppler image of a young solar-like star (EK Draconis; G1.5V, age 100 Myr, rotation 10 × Ω Sun) and with a mean-field dynamo simulation suggests that starspots can be of significantly different appearance and cannot be explained with a scaling of the solar model, even for a star of same mass and effective temperature. Starspots, their surface location and migration pattern, and their link with the stellar dynamo and its internal energy transport, may have far reaching impact also for our understanding of low-mass stellar evolution and formation. Emphasis is given in this review to their importance as activity tracers in particular in the light of more and more precise exoplanet detections around solar-like, and therefore likely spotted, host stars. Title: Spot evolution and active longitudes on FK Com: more than a decade of detailed surface mapping Authors: Korhonen, H.; Berdyugina, S. V.; Ilyin, I. V.; Strassmeier, K. G.; Hackman, T. Bibcode: 2009RMxAC..36..323K Altcode: Stellar surface maps can be obtained from high resolution, high signal-to-noise spectra using Doppler imaging techniques. In this work we present new surface temperature maps of the giant FK Com for 2004-2007, and combine them with our earlier maps. The detailed images of the stellar surface span now almost 15 years. Together with the photometric observations this unique time series is used to study the spot evolution, spot life times, and possible permanent active longitudes on FK Com. Title: Multiple and changing cycles of active stars. II. Results Authors: Oláh, K.; Kolláth, Z.; Granzer, T.; Strassmeier, K. G.; Lanza, A. F.; Järvinen, S.; Korhonen, H.; Baliunas, S. L.; Soon, W.; Messina, S.; Cutispoto, G. Bibcode: 2009A&A...501..703O Altcode: 2009arXiv0904.1747O Aims: We study the time variations in the cycles of 20 active stars based on decade-long photometric or spectroscopic observations.
Methods: A method of time-frequency analysis, as discussed in a companion paper, is applied to the data.
Results: Fifteen stars definitely show multiple cycles, but the records of the rest are too short to verify a timescale for a second cycle. The cycles typically show systematic changes. For three stars, we found two cycles in each of them that are not harmonics and vary in parallel, indicating a common physical mechanism arising from a dynamo construct. The positive relation between the rotational and cycle periods is confirmed for the inhomogeneous set of active stars.
Conclusions: Stellar activity cycles are generally multiple and variable. Title: From Gauß to Biermann: Highlights from the first 117 years of publications in Astronomische Nachrichten/Astronomical Notes Authors: von Berlepsch, R.; Strassmeier, K. G. Bibcode: 2009AN....330..589V Altcode: We present facsimiles of some of the scientifically and historically most relevant papers published in Astronomische Nachrichten/Astronomical Notes (AN) between 1821 and 1938. Almost all of these papers were written and printed in German and it is sometimes not completely straightforward to find these original works and then to cite the historically correct version, e.g. in case of a series of articles or editorial letters. It was common during the early years that many contributions were made in form of letters to the editor. We present a summary for these original works with an English translation of their titles. Among the highlights are the originals of the discovery of stellar parallaxes by Friedrich Wilhelm Bessel, the discovery of the solar cycle by Heinrich Schwabe, the discovery of the planet Neptune by Johann Gottfried Galle, the first ever measured stellar radial velocity by Hermann Vogel, the discovery of radio emission from the Sun by Wilsing and Scheiner, the first ever conducted photoelectric photometry of stars by Paul Guthnick and up to the pioneering work by Karl Schwarzschild, Ejnar Hertzsprung, Erwin Finlay Freundlich and others. As a particular gimmick we present the still world record holding shortest paper ever published; by Johannes Hartmann in AN 226, 63 (1926) on Nova Pictoris. Our focus is on contributions in the early years and published until 1938 near the verge of the second world war. Title: Cosmic Magnetic Fields (IAU S259) Authors: Strassmeier, Klaus G.; Kosovichev, Alexander G.; Beckman, John E. Bibcode: 2009IAUS..259.....S Altcode: Preface K. G. Strassmeier, A. G. Kosovichev and J. E. Beckman; Organising committee; Conference photograph; Conference participants; Session 1. Interstellar magnetic fields, star-forming regions and the Death Valley Takahiro Kudoh and Elisabeta de Gouveia Dal Pino; Session 2. Multi-scale magnetic fields of the Sun; their generation in the interior, and magnetic energy release Nigel O. Weiss; Session 3. Planetary magnetic fields and the formation and evolution of planetary systems and planets; exoplanets Karl-Heinz Glassmeier; Session 4. Stellar magnetic fields: cool and hot stars Swetlana Hubrig; Session 5. From stars to galaxies and the intergalactic space Dimitry Sokoloff and Bryan Gaensler; Session 6. Advances in methods and instrumentation for measuring magnetic fields across all wavelengths and targets Tom Landecker and Klaus G. Strassmeier; Author index; Object index; Subject index. Title: A Fast Stokes Profile Synthesis Authors: Kopf, M.; Carroll, T. A.; Strassmeier, K. G. Bibcode: 2009ASPC..405..535K Altcode: The disk integration process in Doppler imaging and Zeeman-Doppler imaging requires excessive calculations of local Stokes profiles and thus has high computational demands. We present a novel approximation method for the polarized radiative transfer calculation, base on a Principal Component Analysis and Artificial Neural Networks. A set of local line profiles is decomposed into their respective eigenspectra and Artificial Neural Networks are trained, to approximate the non-linear mapping between atmospheric parameters and principal components. In test calculations we demonstrate the reliability and precision of this fast radiative transfer approximation method. Title: A New Zeeman-Doppler Imaging Code for Active Late Type-stars. An Application to II Peg Authors: Kopf, M.; Carroll, T. A.; Ilyin, I.; Strassmeier, K. G.; Tuominen, I. Bibcode: 2009ASPC..405..517K Altcode: The fact, that late-type stars exhibit complex and small scale surface magnetic fields, imposes special requirements on their observation as well as on their modeling and reconstruction. Our new Zeeman-Doppler imaging code iMap, which we present here, was particularly designed for the application to late type stars. It does full radiative transfer calculations and utilizes a regularization scheme which is based on local maximum entropy. Furthermore a new multi-line cross-correlation technique by means of a Principal Component Analysis is used to enhance the quality of individual observed polarized line profiles.

In a first application we present Zeeman-Doppler images of II Pegasi, which reveal a surprisingly large scale surface structure with one predominant magnetic longitude, containing a mainly radially oriented field. Title: Cosmic Magnetic Fields (IAU S259) Authors: Strassmeier, Klaus G.; Kosovichev, Alexander G.; Beckman, John E. Bibcode: 2009cmf..book.....S Altcode: Preface K. G. Strassmeier, A. G. Kosovichev and J. E. Beckman; Organising committee; Conference photograph; Conference participants; Session 1. Interstellar magnetic fields, star-forming regions and the Death Valley Takahiro Kudoh and Elisabeta de Gouveia Dal Pino; Session 2. Multi-scale magnetic fields of the Sun; their generation in the interior, and magnetic energy release Nigel O. Weiss; Session 3. Planetary magnetic fields and the formation and evolution of planetary systems and planets; exoplanets Karl-Heinz Glassmeier; Session 4. Stellar magnetic fields: cool and hot stars Swetlana Hubrig; Session 5. From stars to galaxies and the intergalactic space Dimitry Sokoloff and Bryan Gaensler; Session 6. Advances in methods and instrumentation for measuring magnetic fields across all wavelengths and targets Tom Landecker and Klaus G. Strassmeier; Author index; Object index; Subject index. Title: First measurement of the magnetic field on FK Com and its relation to the contemporaneous star-spot locations Authors: Korhonen, H.; Hubrig, S.; Berdyugina, S. V.; Granzer, Th.; Hackman, T.; Schöller, M.; Strassmeier, K. G.; Weber, M. Bibcode: 2009MNRAS.395..282K Altcode: 2008arXiv0812.0603K; 2009MNRAS.tmp..407K In this study, we present simultaneous low-resolution longitudinal magnetic field measurements and high-resolution spectroscopic observations of the cool single giant FK Com. The variation of the magnetic field over the rotational period of 2.4d is compared with the star-spot location obtained using Doppler imaging techniques, V-band photometry and V - I colours. The chromospheric activity is studied simultaneously with the photospheric activity using high-resolution observations of the Hα, Hβ and Hγ line profiles. Both the maximum (272 +/- 24G) and minimum (60 +/- 17G) in the mean longitudinal magnetic field, <Bz>, are detected close to the phases where cool spots appear on the stellar surface. A possible explanation for such a behaviour is that the active regions at the two longitudes separated by 0.2 in phase have opposite polarities. *

Based on the observations collected at the European Southern Observatory, Chile (Prg. 280.D-5075); at the automatic STELLar Activity (STELLA) observatory at Tenerife, Spain; and with the Vienna automatic photometric telescopes Wolfgang and Amadeus, Arizona, USA.

E-mail: hkorhonen@eso.org Title: The isolated neutron star RBS1774 revisited. Revised XMM-Newton X-ray parameters and an optical counterpart from deep LBT-observations Authors: Schwope, A. D.; Erben, T.; Kohnert, J.; Lamer, G.; Steinmetz, M.; Strassmeier, K.; Zinnecker, H.; Bechtold, J.; Diolaiti, E.; Fontana, A.; Gallozzi, S.; Giallongo, E.; Ragazzoni, R.; de Santis, C.; Testa, V. Bibcode: 2009A&A...499..267S Altcode: 2009arXiv0902.4110S We report optical B-band observations with the Large Binocular Telescope (LBT) of the isolated neutron star RBS1774. The stacked image with a total exposure of 2fh5 reveals a candidate optical counterpart at mB = 26.96 ± 0.20 at position α (2000) = 21^h43^m03fs40, δ(2000) = +06degr54^prime17farcs5, within the joint Chandra and XMM-Newton error circles. We analyse archival XMM-Newton observations and derive revised spectral and positional parameters. The predicted optical flux from the extrapolated X-ray spectrum is likely twice as high as reported before. The measured optical flux exceeds the extrapolated X-ray spectral flux by a factor ∼40 (15-60 at 1σ confidence). We interpret our detection and the spectral energy distribution as further evidence of a temperature structure over the neutron star's surface and present a pure thermal model reflecting both the SED and the pulsed fraction of the light curve.

Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.

Based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the US, Italy, and Germany. LBT Corporation partners are the University of Arizona, on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; Ohio State University; and the Research Corporation, on behalf of the University of Notre Dame, the University of Minnesota, and the University of Virginia. Title: Zeeman-Doppler imaging: old problems and new methods Authors: Carroll, Thorsten A.; Kopf, Markus; Strassmeier, Klaus G.; Ilyin, Ilya Bibcode: 2009IAUS..259..633C Altcode: 2009arXiv0903.1008C Zeeman-Doppler Imaging (ZDI) is a powerful inversion method to reconstruct stellar magnetic surface fields. The reconstruction process is usually solved by translating the inverse problem into a regularized least-square or optimization problem. In this contribution we will emphasize that ZDI is an inherent non-linear problem and the corresponding regularized optimization is, like many non-linear problems, potentially prone to local minima. We show how this problem will be exacerbated by using an inadequate forward model. To facilitate a more consistent full radiative transfer driven approach to ZDI we describe a two-stage strategy that consist of a principal component analysis (PCA) based line profile reconstruction and a fast approximate polarized radiative transfer method to synthesize local Stokes profiles. Moreover, we introduce a novel statistical inversion method based on artificial neural networks (ANN) which provide a fast calculation of a first guess model and allows to incorporate better physical constraints into the inversion process. Title: Spectropolarimetry with PEPSI at the LBT: accuracy vs. precision in magnetic field measurements Authors: Ilyin, Ilya; Strassmeier, Klaus G.; Woche, Manfred; Hofmann, Axel Bibcode: 2009IAUS..259..663I Altcode: We present the design of the new PEPSI spectropolarimeter to be installed at the Large Binocular Telescope (LBT) in Arizona to measure the full set of Stokes parameters in spectral lines and outline its precision and the accuracy limiting factors. Title: The chromospherically active binary star EI Eridani: II. Long-term Doppler imaging Authors: Washuettl, A.; Strassmeier, K. G.; Weber, M. Bibcode: 2009AN....330..366W Altcode: 2008arXiv0811.3221W Data from 11 years of continuous spectroscopic observations of the active RS CVn-type binary star EI Eridani - gained at NSO/McMath-Pierce, KPNO/Coudé Feed and during the MUSICOS 98 campaign - were used to obtain 34 Doppler maps in three spectroscopic lines for 32 epochs, 28 of which are independent of each other. Various parameters are extracted from our Doppler maps: average temperature, fractional spottedness, and longitudinal and latitudinal spot-occurrence functions. We find that none of these parameters show a distinct variation nor a correlation with the proposed activity cycle as seen from photometric long-term observations. This suggests that the photometric brightness cycle may not necessarily be due to just a cool spot cycle. The general morphology of the spot pattern remains persistent over the whole period of 11 years. A large cap-like polar spot was recovered from all our images. A high degree of variable activity was noticed near latitudes of ≈60-70° where the appendages of the polar spot emerged and dissolved. Title: Zeeman-Doppler imaging of II Peg Authors: Carroll, Thorsten A.; Kopf, Markus; Strassmeier, Klaus G.; Ilyin, Ilya; Tuominen, Ilkka Bibcode: 2009IAUS..259..437C Altcode: We present Zeeman-Doppler images of the active K2 star II Peg for the years 2004 and 2007. The surface magnetic field was reconstructed with our new ZDI code iMap which provides a full polarized radiative transfer driven inversion to simultaneously reconstruct the surface temperature and magnetic vector field distribution. II Peg shows a remarkable large scale magnetic field structure for both years. The magnetic field is predominantly located at high latitudes and is arranged in active longitudes. A dramatic evolution in the magnetic field structure is visible for the two years, where a dominant and largely unipolar field in 2004 has changed into two distinct and large scale bipolar structures in 2007. Title: Field optimization and CCD data simulation for the antarctic International Concordia Explorer Telescope (ICE-T) Authors: Fügner, D.; Fuhrmann, C.; Strassmeier, K. G. Bibcode: 2009AN....330..330F Altcode: We performed extensive data simulations for the planned ultra-wide-field, high-precision photometric telescope ICE-T (International Concordia Explorer Telescope). ICE-T consists of two 60 cm-aperture Schmidt telescopes with a joint field of view simultaneously in two photometric bandpasses. Two CCD cameras, each with a single 10.3k×10.3k thinned back-illuminated device, would image a sky field of 65 square degrees. Given a location of the telescope at Dome C on the East Antarctic Plateau, we searched for the star fields that best exploit the technical capabilities of the instrument and the site. We considered the effects of diurnal air mass and refraction variations, solar and lunar interference, interstellar absorption, overexposing of bright stars and ghosts, crowding by background stars, and the ratio of dwarf to giant stars in the field. Using NOMAD, SSA, Tycho-2 and 2MASS-based stellar positions and BVIJH magnitudes for these fields, we simulated the effects of the telescope's point-spread-function, the integration, and the co-addition times. Simulations of transit light curves are presented for the selected star fields and convolved with the expected instrumental characteristics. For the brightest stars, we showed that ICE-T should be capable of detecting a 2 R_Earth Super Earth around a G2 solar-type star, as well as an Earth around an M0-star - if these targets were as abundant as hot Jupiters. Simultaneously, the telescope would monitor the host star's surface activity in an astrophysically interpretable manner. Title: Starspots: signatures of stellar magnetic activity Authors: Strassmeier, Klaus G. Bibcode: 2009IAUS..259..363S Altcode: Starspots, just as Sunspots, are among the most obvious tracers and signatures of stellar surface magnetic activity. Emphasized already several decades ago as the origin for the rotationally modulated brightness of cool late-type stars, it is just now that we start to trace individual surface features in great enough detail to understand their magnetic behavior and interaction. Starspots also became the most important “noise” for detecting extra-solar planets and could possibly be decisive when it comes to detect another Earth. Since this is not a review, and because indirect imaging techniques are covered in other papers in this volume, I focus in this paper on some specific detections of starspots and introduce four new facilities particularly suited for starspot research in the near future. Title: Time series Doppler imaging using STELLA Authors: Weber, Michael; Strassmeier, Klaus G.; Granzer, Thomas Bibcode: 2009IAUS..259..427W Altcode: One of the core programs of the STELLA robotic observatory is to monitor the stellar activity on a sample of stars using Doppler imaging. We present first preliminary results of the rapidly rotating, single giant star HD 31993 from the first two years of operation. We confirm the presence and orientation of differential rotation on the stellar surface. Title: Zeeman-Doppler Imaging of II Peg - Magnetic field restructuring from 2004 to 2007 Authors: Carroll, T. A.; Kopf, M.; Strassmeier, K. G.; Ilyin, I.; Tuominen, I. Bibcode: 2009arXiv0903.1016C Altcode: We present Zeeman-Doppler images of the active K2 star II Peg for the years 2004 and 2007. The surface magnetic field was reconstructed with our new ZDI code "iMap" which provides a full polarized radiative transfer driven inversion to simultaneously reconstruct the surface temperature and magnetic vector field distribution. II Peg shows a remarkable large scale magnetic field structure for both years. The magnetic field is predominantly located at high latitudes and is arranged in active longitudes. A dramatic evolution in the magnetic field structure is visible for the two years, where a dominant and largely unipolar field in 2004 has developed into two distinct and large scale bipolar structures in 2007. Title: The chromospherically active binary star EI Eridani: I. Absolute dimensions Authors: Washuettl, A.; Strassmeier, K. G.; Granzer, T.; Weber, M.; Oláh, K. Bibcode: 2009AN....330...27W Altcode: We present a detailed determination of the astrophysical parameters of the chromospherically active binary star EI Eridani. Our new radial velocities allow to improve the set of orbital elements and reveal long-term variations of the barycentric velocity. A possible third-body orbit with a period of {≈ 19} years is presented. Absolute parameters are determined in combination with the {Hipparcos} parallax. EI Eri's inclination angle of the rotational axis is confined to 56.0 ° ± 4.5 °, its luminosity class {IV} is confirmed by its radius of {2.37 ± 0.12} R_{⊙}. A comparison to theoretical stellar evolutionary tracks suggests a mass of 1.09 ± 0.05 M_{⊙} and an age of ≈ 6.15 Gyr. The present investigation is the basis of our long-term Doppler imaging study of its stellar surface. Title: The Small IRAIT telescope. Photometric time-series during the polar night Authors: Briguglio, R.; Tosti, G.; Strassmeier, K. G.; Bruntt, H.; Nesci, R.; Sabbatini, L. Bibcode: 2009MmSAI..80..147B Altcode: The Small IRAIT is a 25 cm telescope which was deployed and installed at Dome C, on the high antarctic plateau, in 2007. During the polar night an intensive photometric program was carried out: despite the harshness of the polar winter, the telescope worked in a semi-robotic way giving us a large amount of photometric data and precious informations about technology and procedures for polar missions. Title: The E-ELT: A Chance to Measure Cosmic Magnetic Fields Authors: Strassmeier, K. G.; Ilyin, I. V. Bibcode: 2009ASSP....9..255S Altcode: 2009svlt.conf..255S Magnetic fields affect the evolution of structure in the Universe and drive solar and stellar activity which is a key to life's origin and survival. However, our understanding of how cosmic magnetic fields form and evolve is currently very limited. Our close-up look at the Sun has enabled the creation of approximate dynamo models (which took us 100 years), but none yet predict the level of magnetic activity of the Sun or any other star. Therefore, major progress requires the understanding of solar, stellar and galactic magnetism in general and that in turn requires a population study. These population studies are now being thought about or some attempts are underway. The current 4-12 m class telescopes eventually provide the targets for future ELT magnetic-field observations of more complex and distant objects, even of the early Universe, and of more exotic objects like habitable extraterrestrial planets. Title: Letter from the Editor Authors: Strassmeier, Klaus G. Bibcode: 2009AN....330....3S Altcode: As of 2007, Astronomische Nachrichten -- Astronomical Notes has reached its all-time high regarding the ISI journal impact factor, with an impressive increase of 60% compared to 2005. We now rank at 1,461, as shown in the statistics below. This is solely due to the increased quality of the published articles: In 2006, Astronomische Nachrichten -- Astronomical Notes published 208 research papers and received 1,033 citations -- five citations per paper on average. In 2007, we have published 177 research papers with roughly the same number of citations. In co-operation with Wiley InterScience we have achieved an average online publication time of just 4.5 months. We hope that the year 2008 will be comparably prosperous. As in the past, publication in Astronomische Nachrichten -- Astronomical Notes continues to be free of charge. Also, all articles of the first issue of each volume can be downloaded free of charge, as can all articles labelled ``Editor's Choice'', which are additionally featured with a color image on the front cover. 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: Monitoring mass motions of Betelgeuse's photosphere using robotic telescopes . Authors: Weber, M.; Carroll, T.; Granzer, T.; Steffen, M.; Strassmeier, K. G. Bibcode: 2009MmSAI..80..743W Altcode: We started monitoring Betelgeuse using STELLA/SES, the STELLA échelle spectrograph fed by a robotic 1.2 m telescope on Tenerife, and the automatic photometric telescope (APT) T7 in Arizona in fall 2008. In this first observing season, we have collected 67 high resolution spectra from 390 to 900 nm at a resolution of 50,000 and a S/N between 100 and 300, and a comparable number of photometric observations in the Halpha filter. In this presentation, we report on the initial findings based on this first data set: Radial velocities, effective temperature (along with surface gravity and metallicity) are automatically computed by the STELLA/SES data reduction & analysis pipeline. We compare these global measurements and the photometric brightness with velocities and temperature indicators derived from individual spectral lines, to bring these values in line with recently published observations. Furthermore we compute synthetic line profiles from state-of-the-art 3D stellar convection models, and compare the line-profiles, their shapes and positions to our observations. The final aim of the observing program is to find out if the spectral line variations can be explained using these non-magnetic convection models. Title: First time-series optical photometry from Antarctica. sIRAIT monitoring of the RS CVn binary V841 Centauri and the δ-Scuti star V1034 Centauri Authors: Strassmeier, K. G.; Briguglio, R.; Granzer, T.; Tosti, G.; Divarano, I.; Savanov, I.; Bagaglia, M.; Castellini, S.; Mancini, A.; Nucciarelli, G.; Straniero, O.; Distefano, E.; Messina, S.; Cutispoto, G. Bibcode: 2008A&A...490..287S Altcode: Context: Eradicating the problems associated with the Earth's day-night cycle is mandatory for long and continuous time-series photometry and had been achieved with either large ground-based networks of observatories at different geographic longitudes or when conducted from space. A third possibility is offered by a polar location with astronomically-qualified site characteristics.
Aims: We present the first scientific stellar time-series optical photometry from Dome C in Antarctica and analyze approximately 13 000 CCD frames acquired in July 2007.
Methods: The optical pilot telescope of the “International Robotic Antarctic Infrared Telescope”, named “small IRAIT” (sIRAIT), and its UBVRI CCD photometer were used in BVR for a continuous 243 h (10.15 days) with a duty cycle of 98% and a cadence of 155 s. The prime targets were the chromospherically active, spotted binary star V841 Cen and the non-radially pulsating δ-Scuti star V1034 Cen.
Results: We confirmed the known 0.2-day fundamental period of V1034 Cen and detected a total of 23 further periods between 2.2 h and 3.5 days. In July 2007, V841 Cen's V amplitude due to spots appeared to be at a record high of 0.4 m in V. We completed a spot-model analysis with a light-curve inversion technique and discovered the star with a spot filling factor of 44% of the visible hemisphere, among the highest ever measured values for active stars, and a temperature-difference photosphere minus spot of 750 ± 100 K. Its odd-numbered (for a single site) rotation period was determined with a higher precision than before (5.8854 ± 0.0026 days), despite our comparably short data set. The rms scatter from a 2.4-h data subset was 3 mmag in V and 4.2 mmag in R. The differential data quality is 3-4 times higher than with the 25 cm Fairborn Automatic Photoelectric Telescope in southern Arizona and is probably due to the exceptionally low scintillation noise at Dome C.
Conclusions: We conclude that high-precision CCD photometry with exceptional time coverage and cadence can be acquired at Dome C in Antarctica and be successfully used to complete time-series astrophysics. Title: Magnetic activity on V889 Herculis. Combining photometry and spectroscopy Authors: Järvinen, S. P.; Korhonen, H.; Berdyugina, S. V.; Ilyin, I.; Strassmeier, K. G.; Weber, M.; Savanov, I.; Tuominen, I. Bibcode: 2008A&A...488.1047J Altcode: Aims: In this paper we analyse photometric and spectroscopic observations of the young active dwarf V889 Her. We present new surface temperature maps, and compare them to earlier published Doppler maps, as well as to the results obtained from long-term photometry.
Methods: The light curve inversions and surface temperature maps were obtained using the Occamian approach inversion technique.
Results: The 12 years of photometric records on V889 Her suggest a possible photometric cycle of approximately 9 years. Variability on this time scale is detected in the maximum, minimum, and mean photometric magnitudes. The spots prefer to concentrate on two active longitudes that are approximately 180° apart. Furthermore, one flip-flop event, i.e., a sudden change of the dominant active longitude by 180°, is detected at the time of the global maximum activity. The wings of the Ca II 8662 Å indicate that the quiet photosphere of the V889 Her is similar to the one of the present Sun supporting earlier determined atmospheric parameters, while the chromosphere of V889 Her shows signs of much stronger activity. The temperature maps reveal that the polar regions are covered by spots, which are about 1500 K cooler than the quiet photosphere. The mean spot latitude varies slightly with time. It appears that the spot latitudes from our Doppler images and the spot migration rates revealed by photometry indicate a weaker differential rotation than reported earlier, but in the same (solar-like) direction.

Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Table [see full textsee full textsee full text] and Figs. [see full textsee full textsee full text]-[see full textsee full textsee full text] are only available in electronic form at http://www.aanda.org Title: The chromospherically active binary star EI Eridani I. Absolute dimensions Authors: Washuettl, A.; Strassmeier, K. G.; Granzer, T.; Weber, M.; Oláh, K. Bibcode: 2008arXiv0809.0782W Altcode: We present a detailed determination of the astrophysical parameters of the chromospherically active binary star EI Eridani. Our new radial velocities allow to improve the set of orbital elements and reveal long-term variations of the barycentric velocity. A possible third-body orbit with a period of approximately 19 years is presented. Absolute parameters are determined in combination with the Hipparcos parallax. EI Eri's inclination angle of the rotational axis is confined to 56.0 plus/minus 4.5 degrees, its luminosity class IV is confirmed by its radius of 2.37 plus/minus 0.12 R_Sun. A comparison to theoretical stellar evolutionary tracks suggests a mass of 1.09 plus/minus 0.05 M_Sun and an age of approximately 6.15 Gyr. The present investigation is the basis of our long-term Doppler imaging study of its stellar surface. Title: A fast method for Stokes profile synthesis. Radiative transfer modeling for ZDI and Stokes profile inversion Authors: Carroll, T. A.; Kopf, M.; Strassmeier, K. G. Bibcode: 2008A&A...488..781C Altcode: 2008arXiv0807.3850C Context: The major challenges for a fully polarized radiative transfer driven approach to Zeeman-Doppler imaging are still the enormous computational requirements. In every cycle of the iterative interplay between the forward process (spectral synthesis) and the inverse process (derivative based optimization) the Stokes profile synthesis requires several thousand evaluations of the polarized radiative transfer equation for a given stellar surface model.
Aims: To cope with these computational demands and to allow for the incorporation of a full Stokes profile synthesis into Doppler- and Zeeman-Doppler imaging applications as well as into large scale solar Stokes profile inversions, we present a novel fast and accurate synthesis method for calculating local Stokes profiles.
Methods: Our approach is based on artificial neural network models, which we use to approximate the complex non-linear mapping between the most important atmospheric parameters and the corresponding Stokes profiles. A number of specialized artificial neural networks, are used to model the functional relation between the model atmosphere, magnetic field strength, field inclination, and field azimuth, on one hand and the individual components (I,Q,U,V) of the Stokes profiles, on the other hand.
Results: We performed an extensive statistical evaluation and show that our new approach yields accurate local as well as disk-integrated Stokes profiles over a wide range of atmospheric conditions. The mean rms errors for the Stokes I and V profiles are well below 0.2% compared to the exact numerical solution. Errors for Stokes Q and U are in the range of 1%. Our approach does not only offer an accurate approximation to the LTE polarized radiative transfer it, moreover, accelerates the synthesis by a factor of more than 1000. Title: The STELLA robotic observatory: first two years of high-resolution spectroscopy Authors: Weber, Michael; Granzer, Thomas; Strassmeier, Klaus G.; Woche, Manfred Bibcode: 2008SPIE.7019E..0LW Altcode: 2008SPIE.7019E..19W The STELLA project consists of two robotic 1.2m telescopes to simultaneously monitor stellar activity with a high resolution echelle spectrograph on one telescope, and a photometric imaging instrument on the other telescope. The STELLA observatory is located at the Observatorio del Teide on the Canary island of Tenerife. The STELLA Echelle spectrograph (SES) has been operated in robotic mode for two years now, and produced approximately 10,000 spectra of the entire optical range between 390 and 900 nm at a spectral resolution of 55,000 with a peak shutter-open time of 93%. Although we do not use an iodine cell nor an actively stabilized chamber, its average radial velocity precision over the past two years was 60 to 150m/s rms, depending on target. The Wide-Field STELLA Imaging Photometer (WIFSIP) is currently being tested and will enter operation early 2009. In this paper, we present an update report on the first two years of operation. Title: Waveguide image-slicers for ultrahigh resolution spectroscopy Authors: Beckert, Erik; Strassmeier, Klaus G.; Woche, Manfred; Eberhardt, Ramona; Tünnermann, Andreas; Andersen, Michael Bibcode: 2008SPIE.7018E..2JB Altcode: 2008SPIE.7018E..82B Waveguide image-slicer prototypes with resolutions up to 310.000 for the fiber fed PEPSI echelle spectrograph at the LBT and single waveguide thicknesses of down to 30 μm have been manufactured. The waveguides were macroscopically prepared, stacked up to an order of 7 and thinned back to square stack cross sections. A high filling ratio was achieved by realizing homogenous adhesive gaps of 4.6 μm, using index matching adhesives for TIR within the waveguides. The image-slicer stacks can be used in immersion mode and are miniaturized to be implemented in a set of four, measurements indicate an overall efficiency of above 80% for them. Title: Small IRAIT: telescope operations during the polar night Authors: Briguglio, R.; Tosti, G.; Busso, M.; Bagaglia, M.; Nucciarelli, G.; Mancini, A.; Castellini, S.; Strassmeier, K. G.; Straniero, O.; Sabbatini, L. Bibcode: 2008SPIE.7016E..0HB Altcode: Small IRAIT is a 25 cm Cassegrain telescope, installed at Dome C, on the high Antarctic plateau, during 2007 winter campaign. It performed a first test of multiband (UBVRI) photometry from Dome C, taking advantage of its remote control system that allowed a 10 days, 98% duty cycle run on a chromospherically active, spotted star in Cen (V841); it also tested multiband acquisition on open clusters, AGB stars, blazars (PKS2155), eclipsing binaries. In situ optimization made the telescope able to operate in the cold, harsh Antarctic environment. Title: The chromospherically active, triple, ellipsoidal, and eclipsing binary HD 6286 = BE Piscium: a laboratory for binary evolution Authors: Strassmeier, K. G.; Bartus, J.; Fekel, F. C.; Henry, G. W. Bibcode: 2008A&A...485..233S Altcode: Aims: We present a detailed analysis of the star HD 6286 = BE Psc from 16 years of spectroscopic observations and 18 seasons of photometric ones. The star is an evolved, chromospherically active, eclipsing binary, consisting of a K1 giant plus an F6 dwarf/subgiant in a circular orbit with a period of 35.671 days. A faint, close visual companion of spectral type ≈G0 makes the system triple. The orbital inclination of the eclipsing pair is 81.8deg.
Methods: We have obtained simultaneous solutions with our extensive set of radial velocities and BVI light curves that include the star spot variability of the K giant, the ellipticity of the K giant, and the eclipses of the spectroscopic binary system.
Results: Our spot solutions suggest persistent polar spots, one in each hemisphere, that are cooler than the surrounding photosphere by 810±150 K over the timespan of our observations. The K giant and the F6 dwarf/subgiant have masses of 1.56 M⊙ and 1.31 M⊙ and mean radii of 12.0 and 1.9 R⊙, respectively. The masses have uncertainties of just ≈1.5%. No irradiation effect was detected. We compared our results to theoretical evolutionary tracks that suggest an age for the system of ≈2.7 Gyr. The modest logarithmic lithium abundance of the primary of 1.30 (upper limit) indicates that the star may have already experienced its first dredge up. The rotation period of the primary is 35.49 ± 0.01 days and appears to be synchronized with the orbital period of the eclipsing pair to within 0.5%. Our data are inconclusive as to whether the secondary is synchronized.
Conclusions: Circularization of the orbit has taken place, and we conclude that the rapid increase in the size of the K giant, as it evolved across the Hertzsprung gap and up the base of the giant branch, likely caused the orbit to become circular. Title: PEPSI: the Potsdam Echelle Polarimetric and Spectroscopic Instrument for the LBT Authors: Strassmeier, K. G.; Woche, M.; Ilyin, I.; Popow, E.; Bauer, S. -M.; Dionies, F.; Fechner, T.; Weber, M.; Hofmann, A.; Storm, J.; Materne, R.; Bittner, W.; Bartus, J.; Granzer, T.; Denker, C.; Carroll, T.; Kopf, M.; DiVarano, I.; Beckert, E.; Lesser, M. Bibcode: 2008SPIE.7014E..0NS Altcode: 2008SPIE.7014E..21S We present the status of PEPSI, the bench-mounted fibre-fed and stabilized "Potsdam Echelle Polarimetric and Spectroscopic Instrument" for the 2×8.4m Large Binocular Telescope in southern Arizona. PEPSI is under construction at AIP and is scheduled for first light in 2009/10. Its ultra-high-resolution mode will deliver an unprecedented spectral resolution of approximately R=310,000 at high efficiency throughout the entire optical/red wavelength range 390-1050nm without the need for adaptive optics. Besides its polarimetric Stokes IQUV mode, the capability to cover the entire optical range in three exposures at resolutions of 40,000, 130,000 and 310,000 will surpass all existing facilities in terms of light-gathering-power times spectral-coverage product. A solar feed will make use of the spectrograph also during day time. As such, we hope that PEPSI will be the most powerful spectrometer of its kind for the years to come. Title: Light-curve inversions with truncated least-squares principal components: Tests and application to HD 291095 = V1355 Orionis Authors: Savanov, I. S.; Strassmeier, K. G. Bibcode: 2008AN....329..364S Altcode: We present a new inversion code that reconstructs the stellar surface spot configuration from the light curve of a rotating star. Our code employs a method that uses the truncated least-squares estimation of the inverse problem's objects principal components. We use spot filling factors as the unknown objects. Various test cases that represent a rapidly-rotating K subgiant are used for the forward problem. Tests are then performed to recover the artificial input map and include data errors and input-parameter errors. We demonstrate the robustness of the solution to false input parameters like photospheric temperature, spot temperature, gravity, inclination, unspotted brightness and different spot distributions and we also demonstrate the insensitivity of the solution to spot latitude. Tests with spots peppered over the entire stellar surface or with phase gaps do not produce fake active longitudes. The code is then applied to ten years of V and I-band light curve data of the spotted sub-giant HD 291095. A total of 22 light curves is presented. We find that for most of the time its spots were grouped around two active longitudes separated on average by 180°. Switches of the dominant active region between these two longitudes likely occurred about every 3.15±0.23 years while the amplitude modulation of the brightness occurred with a possible period of 3.0±0.15 years. For the first time, we found evidence that the times of the activity flips coincide with times of minimum light as well as minimum photometric amplitude, i.e. maximum spottedness. From a comparison with simultaneous Doppler images we conclude that the activity flips likely take place near the rotational pole of the star. Title: Chromospheric features of LQ Hydrae from Hα line profiles Authors: Frasca, A.; Kovári, Zs.; Strassmeier, K. G.; Biazzo, K. Bibcode: 2008A&A...481..229F Altcode: 2008arXiv0801.3898F We analyze the Hα spectral variability of the rapidly-rotating K1-dwarf LQ Hya using high-resolution Hα spectra recorded during April-May 2000. Chromospheric parameters were computed from the Hα profile as a function of rotational phase. We find that all these parameters vary in phase, with a higher chromospheric electron density coinciding with the maximum Hα emission. We find a clear rotational modulation of the Hα emission that is better emphasized by subtracting a reference photospheric template built up with a spectrum of a non-active star of the same spectral type. A geometrical plage model applied to the Hα variation curve allows us to derive the location of the active regions that come out to be close in longitude to the most pronounced photospheric spots found with Doppler imaging applied to the photospheric lines in the same spectra. Our analysis suggests that the Hα features observed in LQ Hya in 2000 are a scaled-up version of the solar plages as regards dimensions and/or flux contrast. No clear indication of chromospheric mass motions emerges. Title: Letter from the Editor Authors: Strassmeier, Klaus G. Bibcode: 2008AN....329....3S Altcode: As of 2006, Astronomische Nachrichten -- Astronomical Notes has reached its all-time high regarding the ISI journal impact factor, with an impressive increase of 60% compared to 2005. We now rank at position 1,399, as shown in the statistics below. This is solely due to the increased number and quality of published articles: In 2006, Astronomische Nachrichten -- Astronomical Notes published 208 research papers and received 1,033 citations -- five citations per paper on average. In 2007, we have published 177 research papers, and one may be curious to see how their factor will develop. In co-operation with Wiley InterScience we have achieved an average o nline publication time of just 4.5 months. As in the past, publication in Astronomische Nachrichten -- Astronomical Notes} continues to be free of charge. Also, all articles of the first issue of each volume can be downloaded free of charge, as can all articles labelled ``Editor's Choice'', which are additionally featured with a color image on the front cover. Title: Solar Physics and the Solar-Stellar Connection at Dome C Authors: Denker, C.; Strassmeier, K. G. Bibcode: 2008EAS....33...97D Altcode: 2007arXiv0712.1471D Solar magnetic fields evolve on many time-scales, e.g., the generation, migration, and dissipation of magnetic flux during the 22-year magnetic cycle of the Sun. Active regions develop and decay over periods of weeks. The build-up of magnetic shear in active regions can occur within less than a day. At the shortest time-scales, the magnetic field topology can change rapidly within a few minutes as the result of eruptive events such as flares, filament eruptions, and coronal mass ejections. The unique daytime seeing characteristics at Dome C, i.e., continuous periods of very good to excellent seeing during almost the entire Antarctic summer, allow us to address many of the top science cases related to the evolution of solar magnetic fields. We introduce the Advanced Solar Photometric Imager and Radiation Experiment and present the science cases for synoptic solar observations at Dome C. Furthermore, common science cases concerning the solar-stellar connection are discussed in the context of the proposed International Concordia Explorer Telescope. Title: Stellar Activity with BRITE: the ``Aurigae'' field Authors: Strassmeier, K. G. Bibcode: 2008CoAst.152..124S Altcode: Photometric time series of active stars can pin down some of the ingredients that govern the stellar magnetic field, itself being the driver of all non-thermal stellar emissions. Among the most important -- and least understood -- astrophysical ingredients is stellar rotation and its subtle latitudinal dependence called differential rotation. Rotation switches on and maintains the internal dynamo, itself a phenomenon from the interaction of turbulent plasma motions and large-scale shearing forces in the deep stellar interior. I propose to observe the active binary Capella, made up of two giants in exposed locations in the HR-diagram. Along with Capella (α Aur), another eight stars brighter than 4th magnitude would be in the field-of-view of BRITE, among them such benchmark variables as ζ Aur or θ Aur. Title: First time-series optical photometry from Dome C Authors: Strassmeier, K. G.; Granzer, T.; Briguglio, R.; Tosti, G.; Bagaglia, M.; Castellini, S.; Mancini, A.; Nucciarelli, G.; Straniero, O. Bibcode: 2008EAS....33..267S Altcode: 2008arXiv0807.2970S First time-series observations with the 25-cm sIRAIT Antarctic pilot telescope from May 2007 are presented and show that the site is well suited for time-series high-precision photometry. Our target stars were one spotted 5.998-day rotating variable and one short-period δ-Scuti star. A total of 13 000 BVR CCD frames covered a time series of 243 consecutive hours. Title: Main tasks for IRAIT installation at Dome C Authors: di Varano, I.; Nucciarelli, G.; Tosti, G.; Busso, M.; Strassmeier, K. G. Bibcode: 2008EAS....33..279D Altcode: IRAIT (International Robotic Antarctic Infrared Telescope) is a telescope with an 80 cm aperture, ready for installation at Dome C. Equipped with AMICA (Antarctic Multiband Infrared CAmera), the main focal plane instrument, it will observe in near (1 5 μ) and mid infrared regions (5 28 μ), benefiting from the exceptional site characteristics. The installation will start in December 2007. An overview of interfacing devices and the integration of various IRAIT subsystems are here presented. Title: Science with ICE-T: Exoplanets and stellar/solar activity Authors: Strassmeier, K. G.; Granzer, T.; Denker, C.; Fuhrmann, C.; Fügner, D.; Woche, M.; Divarano, I.; Cutispoto, G.; Herber, A.; Horne, K.; Rafanelli, P.; Bortoletto, F.; Ribas, I.; Tosti, G. Bibcode: 2008EAS....33..199S Altcode: We present the science case for ICE-T, the International Concordia Explorer Telescope, a double telescope optimized for ultra-high and ultra wide field optical time-series photometry from Dome C. ICE-T consists of two 60 cm 8^circ×8°-FOV Schmidt telescopes for Sloan g and i photometry and one independent 25 cm, solar, full-disk, Ca ii-K imaging telescope on a single mount. ICE-T is therefore operable during night and day. A 28 cm narrow-field Maksutov spectrophotometric telescope for night-time aerosol measurements (TAVERN-SP) will be provided by AWI early on and operated in parallel with IRAIT and later with ICE-T. The low scintillation noise and the long continuous darkness are among the unique properties for high precision optical time-series photometry. Title: Zeeman-Doppler imaging of late-type stars: The surface magnetic field of II Peg Authors: Carroll, T. A.; Kopf, M.; Ilyin, I.; Strassmeier, K. G. Bibcode: 2007AN....328.1043C Altcode: 2007arXiv0712.3769C Late-type stars in general possess complicated magnetic surface fields which makes their detection and in particular their modeling and reconstruction challenging. In this work we present a new Zeeman-Doppler imaging code which is especially designed for the application to late-type stars. This code uses a new multi-line cross-correlation technique by means of a principal component analysis to extract and enhance the quality of individual polarized line profiles. It implements the full polarized radiative transfer equation and uses an inversion strategy that can incorporate prior knowledge based on solar analogies. Moreover, our code utilizes a new regularization scheme which is based on local maximum entropy to allow a more appropriate reproduction of complex surface fields as those expected for late-type stars. In a first application we present Zeeman-Doppler images of II Pegasi which reveal a surprisingly large scale surface structure with one predominant (unipolar) magnetic longitude which is mainly radially oriented . Title: Changing stellar activity cycles Authors: Oláh, K.; Strassmeier, K. G.; Granzer, T.; Soon, W.; Baliunas, S. L. Bibcode: 2007AN....328.1072O Altcode: We investigated continuous long-term photometric datasets of thirteen active stars, Ca II variability of one single main-sequence star, and 10.7cm radio data of the Sun, with simple Fourier- and time-frequency analysis. The data reflect the strength of the activity manifested in magnetic spots. All studied stars show multiple (2 to 4) cycles of different lengths. The time-frequency analysis reveals, that in several cases of the sample one or two of the cycles exhibit continuous changes (increase or decrease). For four stars (V711 Tau, IL Hya, HK Lac, HD 100180) and for the Sun we find that the cycle length changes are strong, amounting to 10-50% during the observed time intervals. The cycle lengths are generally longer for stars with longer rotational periods. Title: Surface velocity network with anti-solar differential rotation on the active K-giant σ Geminorum Authors: Kovári, Zs.; Bartus, J.; Švanda, M.; Vida, K.; Strassmeier, K. G.; Oláh, K.; Forgács-Dajka, E. Bibcode: 2007AN....328.1081K Altcode: 2007arXiv0711.0771K We demonstrate the power of the local correlation tracking technique on stellar data for the first time. We recover the spot migration pattern of the long-period RS CVn-type binary σ Gem from a set of six Doppler images from 3.6 consecutive rotation cycles. The resulting surface flow map suggests a weak anti-solar differential rotation with {α≈-0.0022±0.0016}, and a coherent poleward spot migration with an average velocity of 220±10 m s-1. This result agrees with our recent findings from another study and could also be confirmed theoretically. Title: Anti-solar differential rotation and surface flow pattern on UZ Libræ Authors: Vida, K.; Kovári, Zs.; Švanda, M.; Oláh, K.; Strassmeier, K. G.; Bartus, J. Bibcode: 2007AN....328.1078V Altcode: 2007arXiv0711.1187V We re-investigate UZ Libræ spectra obtained at KPNO in 1998 and 2000. From the 1998 data we compose 11 consecutive Doppler images using the Ca I-6439, Fe I-6393 and Fe I-6411 lines. Applying the method of average cross-correlation of contiguous Doppler images we find anti-solar differential rotation with a surface shear of α≈-0.03. The pilot application of the local correlation tracking technique for the same data qualitatively confirms this result and indicates complex flow pattern on the stellar surface. From the cross-correlation of the two available Doppler images in 2000 we also get anti-solar differential rotation but with a much weaker shear of α≈-0.004. Title: Study of FK Comae Berenices. V. Spot evolution and detection of surface differential rotation Authors: Korhonen, H.; Berdyugina, S. V.; Hackman, T.; Ilyin, I. V.; Strassmeier, K. G.; Tuominen, I. Bibcode: 2007A&A...476..881K Altcode: Aims:We investigate the spot evolution and the surface differential rotation of the single late-type giant FK Com.
Methods: A total of 18 new surface temperature maps of FK Com are calculated with the Doppler imaging technique for the years 1993-2003. Photometric observations from 2002-2004 are also given. The new and previously published spectroscopic and photometric observations are used to study the spot locations and lifetimes, and to estimate the value of the surface differential rotation.
Results: The phases of the active regions determined from the Doppler images follow closely the active longitudes determined earlier from the long-term photometric observations. One active longitude can remain active for several years, but the exact spot configuration within the active longitude changes on much shorter time scales, indicating that the spot lifetime is months instead of years. There are periods during which the spot configuration changes even within days. Measurements using spot latitudes from the Doppler images and spot rotation periods from the photometric observations yield a surface differential rotation law of Ω=(151.30°/day ± 0.09°/day)-(1.78°/day ± 0.12°/{day})sin2ψ and the relative differential rotation coefficient α=0.012± 0.002 for FK Comae.

Based on observations obtained at the Nordic Optical Telescope, Observatorio Roque de los Muchachos, La Palma, Canary Islands, Spain; the Kitt Peak National Observatory, USA; the National Astronomical Observatory, Rozhen, Bulgaria; Automatic Photometric Telescopes Phoenix 10, Wolfgang and Amadeus, Arizona, USA. Tables 2a-c are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/476/881 Figures 2 and 3 are only available in electronic form at http://www.aanda.org Title: VizieR Online Data Catalog: Differential photometry of FK Com (Korhonen+, 2007) Authors: Korhonen, H.; Berdyugina, S. V.; Hackman, T.; Ilyin, I. V.; Strassmeier, K. G.; Tuominen, I. Bibcode: 2007yCat..34760881K Altcode: In the present work we publish new photometric observations of the very active single giant, FK Com for the time period between the 1st of January 2002 and the 8th of July 2004. The observations have been carried out with three different automatic photometric telescopes: Phoenix 10, Wolfgang and Amadeus, all located in Arizona, USA. Observations contain measurements at the following bands: Johnson U, B and V, Cousins I and Stroemgren b and y. The observations are differential photometry in respect to the primary comparison star HD 117567.

(3 data files). Title: Anti-solar differential rotation on the active K-giant σ Geminorum Authors: Kovári, Zs.; Bartus, J.; Strassmeier, K. G.; Vida, K.; Švanda, M.; Oláh, K. Bibcode: 2007A&A...474..165K Altcode: The active K1 giant σ Gem and its differential surface rotation is revisited. We refine our previous inconclusive result by recovering the spot migration pattern of this long-period RS CVn-type binary through application of the technique of “average cross-correlation of contiguous Doppler images” to a set of six Doppler images from 3.6 consecutive rotation cycles. We find an anti-solar differential rotation law with a shear of α≈ -0.022±0.006. We also find evidence of a poleward migration trend of spots with an average velocity of ≈300 m s-1. Title: PEPSI: The Potsdam Echelle Polarimetric and Spectroscopic Instrument for the Large Binocular Telescope Authors: Strassmeier, K. G.; Woche, M.; Andersen, M.; Ilyin, I. Bibcode: 2007AN....328..627S Altcode: No abstract at ADS Title: The PEPSI "deep spectrum" project Authors: Steffen, Matthias; Strassmeier, Klaus G. Bibcode: 2007AN....328..632S Altcode: No abstract at ADS Title: Doppler Imaging of Stars with Roche-Geometry Authors: Kővári, Zs.; Bartus, J.; Oláh, K.; Strassmeier, K. G.; Rice, J. B.; Weber, M.; Forgács-Dajka, E. Bibcode: 2007IAUS..240..587K Altcode: 2007IAUS..240Q.212K Tests are carried out on retrieving Doppler maps from distorted stars in close binaries to estimate how Doppler imaging may be aliased by ellipticity. Maps obtained for the distorted shape are compared with the results of the simple spherical approximation, using real data of the RS CVn-type close binary star ζ Andromedae. Title: Doppler Imaging of Close Binaries Authors: Strassmeier, Klaus G. Bibcode: 2007IAUS..240..170S Altcode: 2006IAUS..240E..15S Many of the interesting spotted stars are in close binaries, where one can find almost any rotational period due to the rotational synchronization with the orbital motion. Binaries are thus good laboratories to study the impact of particular astrophysical parameters that nature usually does not make easily observable. On rapidly-rotating stars, we may indirectly resolve the surface by a tomographic imaging technique and map the surface temperature distribution as a proxy of the (predominantly radial) magnetic field. Binaries are not as straightforward to map as single stars and I will show some examples where it was successful and some where it failed. Eclipses help to further constrain the solution from line-profile variations and may give some clues on the amount of unresolved features in the images. I present one case of a bright giant of 100 solar luminosities in a close binary with even a deformed surface geometry but otherwise solar-type behavior. One of the basic goals is to learn about the impact of inter-binary magnetic fields on the evolution of binaries and stars in general and to provide conclusive constraints for numerical MHD models. Title: Future facilities for solar and stellar activity research Authors: Strassmeier, Klaus G. Bibcode: 2007HiA....14..297S Altcode: I try to list the currently ongoing instrumental activities for solar and stellar activity research. Only projects that lead to operational ground-based facilities no later than 2013 and to operational space-based observatories no later than 2016 are considered. Any facility already in operation or any instrument under construction but with a very wide range of usage is excluded from this listing (like e.g. ALMA, Herschel or SOFIA). No details on science programs are given. The text is organized according to space, radio, and optical/IR projects. Title: Joint Discussion 8 Solar and stellar activity cycles Authors: Kosovichev, Alexander G.; Strassmeier, Klaus G. Bibcode: 2007HiA....14..271K Altcode: The solar magnetic field and its associated atmospheric activity exhibits periodic variations on a number of time scales. The 11-year sunspot cycle and its underlying 22-year magnetic cycle are, besides the 5-minute oscillation, the most widely known. Amplitudes and periods range from a few parts per million (ppm) and 2 3 minutes for p-modes in sunspots, a few 10 ppm and 10 minutes for the granulation turn around, a few 100 ppm and weeks for the lifetime of plages and faculae, 1000 ppm and 27 days for the rotational signal from spots, to the long-term cycles of 90 yr (Gleissberg cycle), 200 - 300 yr (Wolf, Spörer, Maunder minima), 2,400 yr from 14C tree-ring data, and possibly in excess of 100,000 yr. Title: The International Concordia Explorer Telescope (ICE-T): an Ultimate Transit-Search Experiment for Dome C Authors: Strassmeier, K. G.; Andersen, M. I.; Granzer, T.; Korhonen, H.; Herber, A.; Cutispoto, G.; Rafanelli, P.; Horne, K. Bibcode: 2007ASPC..366..332S Altcode: ICE-T is a fully robotic telescope for astrophysics and atmospheric research for the Antarctic station Concordia at Dome C. ICE-T consists of two 60cm optical ultra-wide-field Schmidt telescopes and one 18cm narrow-field Maksutov spectrophotometric telescope on a single mount. The dual 60cm will be mainly used for a transit search due to extrasolar planets while the 18-cm will be used for measuring aerosol optical depths. ICE-T is a team effort of the German Alfred-Wegener-Institute for Polar Research, the Italian Universities of Padova and Perugia, the INAF Observatory Catania, and the Catalonian IEEC in Barcelona, Spain, and the AIP with collaboration from the University of New South Wales, Australia and the University of St Andrews, U.K.. Title: WIFSIP: Wide-field Imager for the Robotic Observatory STELLA Authors: Korhonen, H.; Strassmeier, K. G.; Granzer, T.; Weber, M.; Staude, A.; Schwope, A. D.; Andersen, M. I.; Järvinen, A. S. Bibcode: 2007ASPC..366...93K Altcode: STELLA is an observatory on the Spanish island of Tenerife, hosting two robotic 1.2 meter telescopes (STELLA-I and STELLA-II) that operate in fully unattended mode (see Fig. ref{stella}). From mid 2007 onwards STELLA-I will host the Wide Field Stella Imaging Photometer (WIFSIP). One of the core science projects for WIFSIP is the time series study of open clusters of different ages. This study is mainly intended for investigating the stellar properties and magnetic activity in open clusters of different ages up to 2 Gyr, but the long photometric time series obtained are also suited for finding planet transits. Title: Telescope and instrument robotization at Dome C Authors: Strassmeier, K. G.; Agabi, K.; Agnoletto, L.; Allan, A.; Andersen, M. I.; Ansorge, W.; Bortoletto, F.; Briguglio, R.; Buey, J. -T.; Castellini, S.; Coudé du Foresto, V.; Damé, L.; Deeg, H. J.; Eiroa, C.; Durand, G.; Fappani, D.; Frezzotti, M.; Granzer, T.; Gröschke, A.; Kärcher, H. J.; Lenzen, R.; Mancini, A.; Montanari, C.; Mora, A.; Pierre, A.; Pirnay, O.; Roncella, F.; Schmider, F. -X.; Steele, I.; Storey, J. W. V.; Tothill, N. F. H.; Travouillon, T.; Vittuari, L. Bibcode: 2007AN....328..451S Altcode: 2004astro.ph..8233Z This article reviews the situation for robotization of telescopes and instruments at the Antarctic station Concordia on Dome C. A brain-storming meeting was held in Tenerife in March 2007 from which this review emerged. We describe and summarize the challenges for night-time operations of various astronomical experiments at conditions ``between Earth and Space'' and conclude that robotization is likely a prerequisite for continuous astronomical data taking during the 2000-hour night at Dome C. Title: Small IRAIT Telescope: photometry and asteroseismology at Dome C Authors: Tosti, G.; Nucciarelli, G.; Bagaglia, M.; Mancini, A.; Castellini, S.; Straniero, O.; Briguglio, R.; Strassmeier, K. G.; Stello, D.; IRAIT Collaboration Bibcode: 2007CoAst.150..315T Altcode: Small IRAIT is a 25 cm telescope planned to be installed at Dome C during February 2007. It will be equipped with a CCD, a filter wheel, two photomultipliers and a liquid crystal tunable filter. Small IRAIT is intended to: test astronomical measurements from Dome C; provide site qualification and suitability for asteroseismology by taking advantage of the low scintillation level and the possibility for long uninterrupted observations. Small IRAIT will be the forerunner of the IRAIT telescope that will be installed during the Antarctic Summer 2007-2008. Title: GREGOR: the New German Solar Telescope Authors: Balthasar, H.; von der Lühe, O.; Kneer, F.; Staude, J.; Volkmer, R.; Berkefeld, T.; Caligari, P.; Collados, M.; Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Klvaňa, M.; Nicklas, H.; Popow, E.; Puschmann, K.; Schmidt, W.; Sobotka, M.; Soltau, D.; Strassmeier, K.; Wittmann, A. Bibcode: 2007ASPC..368..605B Altcode: 2007arXiv0704.2693B GREGOR is a new open solar telescope with an aperture of 1.5 m. It replaces the former 45-cm Gregory Coudé telescope on the Canary island Tenerife. The optical concept is that of a double Gregory system. The main and the elliptical mirrors are made from a silicon-carbide material with high thermal conductivity. This is important to keep the mirrors on the ambient temperature avoiding local turbulence. GREGOR will be equipped with an adaptive optics system. The new telescope will be ready for operation in 2008. Post-focus instruments in the first stage will be a spectrograph for polarimetry in the near infrared and a 2-dimensional spectrometer based on Fabry-Pérot interferometers for the visible. Title: Doppler imaging of stellar surface structure. XXIII. The ellipsoidal K giant binary ζ Andromedae Authors: Kővári, Zs.; Bartus, J.; Strassmeier, K. G.; Oláh, K.; Weber, M.; Rice, J. B.; Washuettl, A. Bibcode: 2007A&A...463.1071K Altcode: Aims:We present the first Doppler images of the bright RS CVn-type binary ζ And. The star is a magnetically active K1 giant with its rotation synchronized to the 17.8-day orbital period. Our revised lithium abundance of log n=1.2 places ζ And in the vicinity of Li-rich RGB stars but it is nevertheless a Li-normal chromospherically active binary star. The star seems to undergo its first standard dredge-up dilution.
Methods: Four consecutive Doppler images were obtained from a continuous 67-night observing run at NSO-McMath in 1996/97. An additional single image was obtained from a continuous 19-night run at KPNO in 1997/98. These unique data allow to compute a small time series of the evolution of the star's surface structure. All line-profile inversions are done with a modified TempMap version that takes into account the non-spherical shape of the star. Representative test reconstructions are performed and demonstrate the code's reliability and robustness.
Results: High and low-latitude spot activity was recovered together with an asymmetric polar cap-like feature. The latter dominated the first half of the two-month time series in 1996/97. The second half showed mostly medium-to-high latitude activity and only a fainter polar spot. The coolest areas were restored with a temperature contrast of about 1000±200 K. Some weaker features at equatorial latitudes were also recovered but these could be partially spurious and appear blurred due to imperfect phase coverage. We use our line profiles to reconstruct an average non-sphericity of R_pole/R_point=0.96 which would, if not taken into account, mimic a temperature difference pole-to-equator of ≈220 K, especially at the phases of quadrature. Finally, we apply two different methods for restoring surface differential rotation and found a weak solar-type rotation law with a shear ΔΩ≈0.95°/day (α=ΔΩ/Ω_eq=+0.049±0.003), i.e. roughly a factor of four weaker at a rotation rate roughly 1.5 times faster than the Sun's.

Figures A.1-A.3 and Table A.1 are only available in electronic form at http://www.aanda.org Title: ARCO: a program for Automatic Reduction of CCD Observations Authors: Distefano, E.; Messina, S.; Cutispoto, G.; Parihar, P. S.; Comparato, M.; Busá, I.; Lanza, A. F.; Lanzafame, A. C.; Pagano, I.; Strassmeier, K. G. Bibcode: 2007EAS....25..165D Altcode: The huge amount of CCD photometric data collected by robotic telescopes (as for instance the ICE-T telescope to be installed at Dome-C) requires a fully automated approach to the reduction and analysis procedures. To this end, we are developing a pipeline, making use of IRAF, DAOPHOTII and tasks build up by us, which will enable to automatically extract differential magnitude time series. Both aperture and PSF photometry methods are used to build a proper sample of comparison stars, with the best method between the two being automatically selected. Finally, the search of rotational periods is performed. To test our package, we present results obtained using a 4-year dataset of a field in the Orion Nebula Cluster (ONC) containing about 350 stars (150 of which turned out to be periodic variables). Title: Gregor@Night Authors: Strassmeier, K. G.; Woche, M.; Granzer, T.; Andersen, M. I.; Schmidt, W.; Koubsky, P. Bibcode: 2007msfa.conf...51S Altcode: Gregor@Night is the concept for a fiber-fed double echelle spectrograph for the night-time use of GREGOR. Its design specifications are driven by a science case based on the solar-stellar connection, ranging from the search and characterization of solar analogs, the characterization of late-type stars with exoplanets, asteroseismology with high time resolution and cadence, stellar cycle analogs and many other related topics. The spectrographs are based on a white-pupil design with a 110 mm beam and are optimized for the wavelength ranges 360-490 nm and 510-870 nm, respectively and achieve a two-pixel resolution of 100,000 for an entrance aperture of 3" at 20% throughput. The instrument would be fully automated and no on-site night observer required. Title: Ultra-High Precision, Ultra-Wide-Field Optical Photometry Authors: Strassmeier, K. G. Bibcode: 2007EAS....25..233S Altcode: The low scintillation noise and the long continuous darkness are among the unique properties of the Dome-C site on the east Antarctic plateau. Ultra-high precision optical photometry is therefore among the techniques best suited for this particular site. We propose a telescope (ICE-T) optimized for ultra-high and ultra wide field photometry for Dome C. It consists of two 60cm optical ultra-wide-field Wynne-Schmidt telescopes and one 18cm narrow-field Maksutov spectrophotometric telescope on a single mount. ICE-T is currently a team effort of the German Alfred-Wegener-Institute for Polar Research, the Italian Universities of Padova and Perugia, the INAF Observatory Catania, and the Catalonian IEEC in Barcelona, Spain, and the AIP, with collaboration from the University of New South Wales, Australia and the University of St. Andrews, UK. In this paper, I discuss some of the many problems associated with sub-milli-mag photometry. Title: Solar-Like Activity and Planetary Transits Authors: Lanza, A. F.; Bonomo, A. S.; Cutispoto, G.; Busã, I.; Lanzafame, A. C.; Messina, S.; Pagano, I.; Strassmeier, K. G. Bibcode: 2007EAS....25..161L Altcode: Late-type MS stars display optical variability on different time scales due to the presence of photospheric brightness inhomogeneities produced by surface magnetic fields, analogous to cool spots and bright faculae observed in the Sun. We are developing methods to model the optical variability of main-sequence late-type stars to understand the impact of solar-like activity on the detection of planetary transits and to significantly improve the detection efficiency. Our techniques will also allow to map the longitude distribution of active regions on stars that harbor planets and to look for a possible connection between stellar activity and the presence of planets around a star. Title: Resolving stellar surface spots Authors: Strassmeier, K. G.; Carroll, T.; Rice, J. B.; Savanov, I. S. Bibcode: 2007MmSAI..78..278S Altcode: Doppler imaging of stellar surfaces is a novel technique with similarities to medical brain tomography (instead of a fixed brain and a rotating scanner, astronomers have a fixed spectrograph and a rotating brain, star of course). The number of free (internal) parameters is of the order of the number of surface grid points and only constrained by the number of input data points. This obviously ill-posed situation requires modern inversion algorithms with penalty functions of the form of maximum entropy or Tikhonov etc.. We present a brief status review of our Doppler imaging codes at AIP that span from temperature and spot-filling-factor mapping to full Stokes-based magnetic field mapping. Title: New high resolution solar telescope GREGOR Authors: Volkmer, R.; von der Lühe, O.; Kneer, F.; Staude, J.; Balthasar, H.; Berkefeld, T.; Caligari, P.; Collados, M.; Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Klvaña, M.; Sobotka, M.; Nicklas, H.; Popow, E.; Puschmann, K. G.; Schmidt, W.; Soltau, D.; Strassmeier, K.; Wittmann, A. D. Bibcode: 2007msfa.conf...39V Altcode: The 1.5m solar telescope GREGOR is being constructed at Tenerife, Spain. Its purpose is to observe with high spatial and spectral resolution small-scale dynamic magnetic features on the Sun. The telescope is completely open with retractable dome and actively cooled primary mirror made of silicon carbide to minimize thermal effects on the image quality. After completion it will be one of the most powerful solar telescopes. This paper presents a general overview of the telescope characteristics and the current status. Title: First Doppler images of the very young K2-dwarf PW Andromedae = HD 1405 Authors: Strassmeier, K. G.; Rice, J. B. Bibcode: 2006A&A...460..751S Altcode: Aims.We present the first Doppler images of the single pre-main-sequence star PW And. Its position in the HR-diagram suggests it to be in the rapid-braking phase just prior to arrival on the ZAMS.
Methods: .Images are obtained from seven individual spectral lines as well as from 5-nm wide chunks of spectrum that invert a total of 58 line profiles simultaneously.
Results: .Cool spots with temperature differences with respect to the stellar photosphere of up to 1200 K are detected. Spot occurrence is mostly within an equatorial band up to ±40° of the stellar equator and thus contradicts magnetic-flux tube emergence models based on young K-star properties that predict an emerging latitude in two distinct bands of +45-55°. This confirms previous suggestions that current magnetic-flux tube models predict emergence latitudes too low for G-dwarfs and too high for K-dwarfs, which may be caused by the fact that the G-dwarf models heavily rely on comparisons with the Sun. We also redetermine the absolute parameters of PW And in the light of a missing Hipparcos parallax and revise its age to be more near 20 Myr, in agreement with its logarithmic lithium abundance of 2.87±0.05. A precise rotational period of 1.76159d±0.00006 was found from our photometric data in 2004.
Title: STELLA Robotic Observatory for Stellar Activity Research Authors: Bartus, J.; Kõvári, Zs.; Oláh, K.; Granzer, T.; Strassmeier, K. G.; Weber, M. Bibcode: 2006PADEU..17..101B Altcode: The STELLA Robotic Observatory (abbreviation for STELLar Activity) is a long-term project for observing and monitoring activity tracers on cool stars with two robotic telescopes: STELLA-I equipped with a high resolution echelle spectrograph, a large-format CCD imager and photometer, and STELLA-II also equipped with an optical CCD imager and photometer. After listing the most important technical details we focus on some of the scientific programs planned for routine observations of active stars by STELLA. Title: Spot Modelling of ζ Andromedae Authors: Kővári, Zsolt; Oláh, Katalin; Bartus, János; Strassmeier, Klaus G.; Granzer, Thomas Bibcode: 2006Ap&SS.304...55K Altcode: 2006Ap&SS.tmp...90K The photometric light modulation of ζ Andromedae originates from the distorted geometry of the primary, and additionally, from spots of which parameters (temperature, size, location) are variable in time. We present spot modelling results for six two-colour light curves which show that spots preferably appear on the stellar surface towards the companion star and opposite to it, where the distortion also causes dimming. Therefore, simple fitting of the measured data for the ellipticity effect does not yield correct result. Instead, ellipticity calculated from exact stellar parameters should be removed from the data to get reliable spotted light curves. Title: STELLA: Two New Robotic Telescopes for Binary-Star Research Authors: Strassmeier, Klaus G. Bibcode: 2006Ap&SS.304..397S Altcode: 2006Ap&SS.tmp...34S Several new robotic telescopes had or will see first light in 2005/2006 and are designed for either wide-field imaging, high-precision photometry or even for high-resolution echelle spectroscopy. These telescopes are in the 1 2 m class and therefore will focus on very specific tasks. Here, I present an update of the robotic STELLA facility currently under construction in Tenerife and emphasize its science capabilities for binary-star research. Among the many science applications of STELLA is the monitoring of magnetic activity in single and binary stars and their relation to age, rotation rate, metallicity and binarity per se. Title: The International Concordia Explorer Telescope: a joint telescope for atmospheric and astrophysical applications at Dome C Authors: Strassmeier, K. G.; Herber, A.; Vitale, V.; Cutispoto, G.; Ribasi, I.; Korhonen, H.; Andersen, M.; Granzer, T. Bibcode: 2006IAUSS...7E..18S Altcode: ICE-T is a fully robotic telescope for astrophysics and atmospheric research in Antarctica and is based on the ``Star Photometer'' project within TAVERN, the quantification of tropospheric aerosol and thin clouds variability over the east Antarctic plateau including the radiation budget. This poster introduces the joint science case, the conceptual design, and the anticipated data handling plan. ICE-T consists of two 60cm optical ultra-wide-field Schmidt telescopes and one 18cm narrow-field Maksutov spectrophotometric telescope on a single mount for the Antarctic station Concordia at Dome C. Title: A Fast Stokes Profile Synthesis for Zeeman-Doppler-Imaging Authors: Kopf, M.; Carroll, T. A.; Strassmeier, K. G. Bibcode: 2006IAUJD...8E..23K Altcode: We present a novel method for a fast LTE spectrum synthesis in magnetic stellar atmospheres suitable for Doppler-Imaging and Zeeman-Doppler-Imaging of active stars. The enormous computational demands for Doppler-Imaging and in particular Zeeman-Doppler-Imaging techniques require extensive calculations of local Stokes profiles over the entire stellar disk. Tabling techniques as used for conventional Doppler-Imaging to reduce the computational burden are not a feasible alternative for Zeeman-Doppler-Imaging of active stars with complex temperature and magnetic surface distributions. Also methods like the weak-field approximation which allows a fast estimate of Stokes V profiles do not provide the required accuracy in general. Artificial neural networks (ANN's) provide a new tool to approximate the full polarized radiative transfer under varying atmospheric conditions. Our method is based on a decomposition of Stokes line profiles, into their respective eigenspectra via a principal component analysis (PCA). A set of ANN's is then trained to calculate the reduced eigenspectrum of local Stokes line profiles as a function of the line of sight, effective temperature and the magnetic field configuration. The accuracy of the PCA-ANN synthesis is evaluated by comparison with a conventional numerical solution of the RTE which is based on a quadratic DELO method. Moreover, we present a number of test inversions with our Doppler-Imaging and Zeeman-Doppler-Imaging code to demonstrate the potential of this new method. The precision and the impressive speed of the PCA-ANN spectrum synthesis offers a viable and promising alternative for an on-the-fly calculation of local and disk integrated Stokes spectra. Title: Late-Type Active Stars: Rotation & Companions Authors: Dall, T. H.; Strassmeier, K. G.; Bruntt, H. Bibcode: 2006Ap&SS.304..195D Altcode: 2006Ap&SS.tmp...17D Rapid rotation has been established empirically as the controlling factor for the magnetic field strength and the magnetic activity level of single late-type (F-M) stars. The dynamo theories explain this fact as due to interaction between differential rotation and helical motion in the transition layer between the convective envelope and the radiative interior. The presence of a close companion even down to the size of a “hot Jupiter” could alter the physical processes responsible for the activity, by introducing longitude- and latitude-dependencies and inhomogenious chemical abundances effects that cannot be ignored in the attempt to understand magnetic activity on late type stars. Here we present first results for the well-known, single, active star, HD 27536. Binarity is established by very precise radial velocity (RV) measurements using HARPS spectra. The spectral line bisectors are examined for correlations between RV and bisector shape to distinguish between the effects of stellar activity and unseen companions. Title: Doppler Images of ζ Andromedae Authors: Kővári, Zsolt; Oláh, Katalin; Bartus, János; Strassmeier, Klaus G.; Weber, Michael; Washuettl, Albert; Rice, John B.; Csizmadia, Szilárd Bibcode: 2006Ap&SS.304..375K Altcode: 2006Ap&SS.tmp..110K Doppler images are presented for the RS CVn-type binary ζ And. Our upgraded Doppler imaging code TempMapɛ takes into account the distorted geometry of the primary giant component. On the maps several low latitude spots are restored with a temperature contrast of about 1000 K. Some weak polar features are also found. Cross-correlation of the consecutive Doppler-maps suggests solar-like differential surface rotation. Title: Challenges in optics for Extremely Large Telescope instrumentation Authors: Spanò, P.; Zerbi, F. M.; Norrie, C. J.; Cunningham, C. R.; Strassmeier, K. G.; Bianco, A.; Blanche, P. A.; Bougoin, M.; Ghigo, M.; Hartmann, P.; Zago, L.; Atad-Ettedgui, E.; Delabre, B.; Dekker, H.; Melozzi, M.; Snÿders, B.; Takke, R. Bibcode: 2006AN....327..649S Altcode: 2006astro.ph..3763S We describe and summarize the optical challenges for future instrumentation for Extremely Large Telescopes (ELTs). Knowing the complex instrumental requirements is crucial for the successful design of 30-60 m aperture telescopes. After all, the success of ELTs will heavily rely on its instrumentation and this, in turn, will depend on the ability to produce large and ultra-precise optical components like light-weight mirrors, aspheric lenses, segmented filters, and large gratings. New materials and manufacturing processes are currently under study, both at research institutes and in industry. In the present paper, we report on its progress with particular emphasize on volume-phase-holographic gratings, photochromic materials, sintered silicon-carbide mirrors, ion-beam figuring, ultra-precision surfaces, and free-form optics. All are promising technologies opening new degrees of freedom to optical designers. New optronic-mechanical systems will enable efficient use of the very large focal planes. We also provide exploratory descriptions of ``old'' and ``new'' optical technologies together with suggestions to instrument designers to overcome some of the challenges placed by ELT instrumentation. Title: Polar night operation at Dome C with "Star Photometer" and ICE-T Authors: Herber, A.; Gröschke, A.; Vitale, V.; Strassmeier, K. Bibcode: 2006IAUSS...7E..34H Altcode: Atmospheric aerosol optical depth (AOD) data from the Antarctic plateau are very sparse. Some AOD measurements were performed during austral summer but none during winter, although some night aerosol information has been gathered from Lidar measurements in the coastal areas. Satellite measurements are very difficult as a consequence of the low AOD values, the high surface reflectivity, and the long and cold polar night. The application of an astronomical "Star Photometer", by using stellar light as a pencil probe through the atmosphere, can close this gap. Year-round measurements based on Lidar, Sun and Star Photometers, and in-situ measurements will allow a detailed study of the inter-annual and seasonal variations of AOD over the high interior plateau, especially the effects and variability during polar night. The combined atmospheric and astronomical German activities at Dome C are part of the international project TAVERN (quantification of tropospheric aerosol and thin clouds variability including the radiation budget over the east Antarctic plateau) under responsibility of CNR-ISAC Bologna; and also recognized by the EU network ARENA (Antarctic Research: A European Network in Astronomy). With the "Star Photometer" we intend to observe bright stars for the atmospheric AOD program in 2009 but later on, roughly in 2012, to extend the nightly observations with the help of a more ambitious astronomical experiment called ICE-T (International Concordia Explorer Telescope). Both systems will be installed in a specially designed 4m Radom and should enable a combined analysis to study horizontal features of nightly aerosols. This activity is planned in extension of ICE-T's own astronomical program, i.e. planet transit search, stellar surface activity, and various miscellaneous topics. Title: Doppler Imaging of Rapidly-Rotating M Stars Authors: Strassmeier, Klaus G. Bibcode: 2006Ap&SS.304..333S Altcode: 2006Ap&SS.tmp...35S With the advent of 8 12m-class telescopes and powerful new spectrographs, we can now extend the Doppler-imaging technique to the cool (and faint) end of the main sequence. At a spectral type of approximately M2, stars are thought to become fully convective and cannot possess an overshoot layer between a radiative core and a convective envelope which, as in the case of the Sun and similar stars, likely harbors the dynamo. Therefore, one could expect a fundamentally different magnetic-field topology than on the Sun and thus a qualitatively different surface temperature distribution with new, hitherto unknown, magnetic activity phenomena. Unfortunately, most single M stars do not rotate sufficiently fast for Doppler imaging and one has to “use” binaries or pre-main-sequence stars in which M stars appear spun up or, in binaries, synchronized to the orbital motion. Title: Current and future observations of solar and stellar activity from the ground and space Authors: Strassmeier, K. G. Bibcode: 2006IAUJD...8E..37S Altcode: My main goal is to summarize the current and future instrumentation that is or will be used for solar and stellar activity work, with special emphasize on long-term status in relation to cycle studies. Many space and ground-based systems are or were not intentionally invented and designed for use on stellar activity issues, e.g. the exoplanet finding missions, but nevertheless bear a great potential for stellar cycle research. I also emphasize the potential of almost space-quality sites on Earth (Dome C, Dome A) or the commercialized approach with micro and even nano satellites. Title: The RS CVn binary HK Lacertae: long-term photometry from Sonneberg sky-patrol plates Authors: Fröhlich, H. -E.; Kroll, P.; Strassmeier, K. G. Bibcode: 2006A&A...454..295F Altcode: Long-term photographic photometry of the active long-period RS CVn binary HK Lac (HD 209813) was obtained from more than 2000 Sonneberg Sky-Patrol plates taken between 1956 and 1996. We achieve an internal accuracy of 0.07 m. The correspondence with contemporaneous high-precision photoelectric photometry from automatic telescopes is striking and successfully demonstrates the feasibility of our approach. Based on a Bayesian time series analysis, we improve the previously published cycle period to 13.37± 0.08 years, and present evidence of an additional period of 9.48± 0.13 years. This establishes the multi-periodicity of dynamo action in these overactive stars as compared to the Sun. The already known 6.7-years cycle turns out to be an overtone of the dominating 13.4-years cycle. Our long-term photographic photometry even allowed the detection of the star's mean rotational period of 24.35 days. Title: The new 1.5m solar telescope GREGOR: first light and start of commissioning Authors: Volkmer, Reiner; von der Lühe, Oskar; Kneer, Franz; Staude, Jürgen; Berkefeld, Thomas; Caligari, Peter; Halbgewachs, Clemens; Heidecke, Frank; Schmidt, Wolfgang; Soltau, Dirk; Nicklas, Harald; Wittmann, Axel; Balthasar, Horst; Hofmann, Axel; Strassmeier, Klaus; Sobotka, Michal; Klvana, Miroslav; Collados, Manuel Bibcode: 2006SPIE.6267E..0WV Altcode: 2006SPIE.6267E..29V The integration of the three main silicon carbide mirrors into the new 1.5 m solar telescope GREGOR at Izana on Tenerife, Spain is planned during 2006. We expect first light at the end of 2006. A progress report about integration of the optics and mechanics and planning of the commissioning phase of the telescope and post focus instruments will be presented at the meeting. The GREGOR telescope is build by a consortium of the Kiepenheuer Institut fur Sonnenphysik in Freiburg, the Astrophysikalische Institut Potsdam, the Institut fur Astronomie Gottingen and additional national and international Partners. Title: Study of FK Comae Berenices. VI. Spot motions, phase jumps and a flip-flop from time-series modelling Authors: Oláh, K.; Korhonen, H.; Kővári, Zs.; Forgács-Dajka, E.; Strassmeier, K. G. Bibcode: 2006A&A...452..303O Altcode: Aims.Time-series spot modelling was used to follow the longitude changes of active regions responsible for the light variability of FK Com between 1987-2004.
Methods: .The photometric data are analysed in the time-series mode of a spot modelling code. A scenario of one polar and two low-latitude active regions (hereafter spots, for simplicity) depicts the light variations very well. The role of the polar spot remains unclear because photometry in general does not provide direct latitudinal surface resolution, however, Doppler imaging results of FK Com also show very high latitude or even polar spots besides the low-latitude ones. We also used a light-curve inversion method to confirm some of the results.
Results: .The two low-latitude spots slowly migrate around 90° and 270° longitudes with quasiperiods of 5.8 and 5.2 years. The spots prefer to stay alternately on one or the other, but on the same hemisphere of the star, with a separation of typically 90-140°. We monitored a flip-flop in the light curve of FK Comae in 1999. The two low-latitude spots, being ≈140-180° from each other during the season, gradually decreased until they both practically vanished. Shortly thereafter, two new spots appeared and started to grow. One of the new spots was near the location of the old one, whereas the other turned up 90° shifted in longitude; consequently, the activity as a whole was shifted to the other hemisphere of the star. We followed a phase jump in 1997, when the two low-latitude spots got closer in longitude and finally merged, or else one of them vanished. A new spot appeared soon, shifted by 100° in longitude, but the activity remained on the same hemisphere.
Conclusions: .The difference between flip-flops and phase jumps is demonstrated. The derived longitude changes of activity centres may allow us to better constrain the theoretical modelling on the time-behaviour of stellar magnetic activity. Title: The International Robotic Antarctic Infrared Telescope (IRAIT) Authors: Tosti, Gino; Busso, Maurizio; Nucciarelli, Giuliano; Bagaglia, Marco; Roncella, Fabio; Mancini, Alberto; Castellini, Sonia; Mariotti, Mirco; Babucci, Ezio; Chiocci, Gianfranco; Straniero, Oscar; Dolci, Mauro; Valentini, Gaetano; di Varano, Igor; Pelusi, Danilo; Di Rico, Gianluca; Ragni, Maurizio; Abia, Carlos; Domínguez, Inma.; Corcione, Leonardo; Porcu, Francesco; Conconi, Paolo; De Caprio, Vincenzo; Riva, Alverto; Molinari, Emilio; Zerbi, Filippo M.; Bortoletto, Favio; Bonoli, Carlotta; D'Alessandro, Maurizio; Colomé, Josep; Isern, Jordi; Briguglio, Runa; Cacciani, Alessandro; Farnesini, Lucio; Checcucci, Bruno; Strassmeier, Klaus G. Bibcode: 2006SPIE.6267E..1HT Altcode: 2006SPIE.6267E..47T Thanks to exceptional coldness, low sky brightness and low content of water vapour of the above atmosphere Dome C, one of the three highest peaks of the large Antarctic plateau, is likely to be the best site on Earth for thermal infrared observations (2.3-300 μm) as well as for the far infrared range (30 μm-1mm). IRAIT (International Robotic Antarctic Infrared Telescope) will be the first European Infrared telescope operating at Dome C. It will be delivered to Antarctica at the end of 2006, will reach Dome C at the end of 2007 and the first winter-over operation will start in spring 2008. IRAIT will offer a unique opportunity for astronomers to test and verify the astronomical quality of the site and it will be a useful test-instrument for a new generation of Antarctic telescopes and focal plane instrumentations. We give here a general overview of the project and of the logistics and transportation options adopted to facilitate the installation of IRAIT at Dome C. We summarize the results of the electrical, electronics and networking tests and of the sky polarization measurements carried out at Dome C during the 2005-2006 summer-campaign. We also present the 25 cm optical telescope (small-IRAIT project) that will installed at Dome C during the Antarctic summer 2006-2007 and that will start observations during the 2007 Antarctic winter when a member of the IRAIT collaboration will join the Italian-French Dome C winter-over team. Title: Binarity, activity and metallicity among late-type stars. I. Methodology and application to HD 27536 and HD 216803 Authors: dall, T. H.; Bruntt, H.; Strassmeier, K. G. Bibcode: 2005A&A...444..573D Altcode: 2005astro.ph..8577D We present the first in a series of papers that attempt to investigate the relation between binarity, magnetic activity, and chemical surface abundances of cool stars. In the current paper, we lay out and test two abundance analysis methods and apply them to two well-known, active, single stars, HD 27536 (G8IV-III) and HD 216803 (K5V), presenting photospheric fundamental parameters and abundances of Li, Al, Ca, Si, Sc, Ti, V, Cr, Fe, Co and Ni. The abundances from the two methods agree within the errors for all elements except calcium in HD 216803, which means that either method yields the same fundamental model parameters and the same abundances. Activity is described by the radiative loss in the Ca ii H and K lines with respect to the bolometric luminosity, through the activity index R_HK. Binarity is established by very precise radial velocity (RV) measurements using HARPS spectra. The spectral line bisectors are examined for correlations between RV and bisector shape to distinguish between the effects of stellar activity and unseen companions. We show that HD 27536 exhibit RV variations mimicking the effect of a low-mass (m ∼ 4 M_J) companion in a relatively close (a ∼ 1 AU) orbit. The variation is strongly correlated with the activity, and consistent with the known photometric period P = 306.9 d, demonstrating a remarkable coherence between R_HK and the bisector shape, i.e. between the photosphere and the chromosphere. We discuss the complications involved in distinguishing between companion and activity induced RV variations. Title: Surface imaging with atomic and molecular features. I. A new inversion technique and first numerical tests Authors: Savanov, I. S.; Strassmeier, K. G. Bibcode: 2005A&A...444..931S Altcode: We present a new Doppler-imaging inversion code that uses quasi-optimal filtering of the object's principal components of a Fisher information matrix. The new code allows one to perform the reconstruction of stellar surface temperature maps using molecular features like TiO, CO, OH, CN etc. which are numerous in spectra of late-type dwarfs. It is possible to use atomic and molecular features simultaneously in the restoration. Our tests verify the robustness of OPC but also emphasize its dependency on the various atomic and molecular line lists. Without inclusion of molecules, Doppler imaging of stars with photospheric temperatures below ≈4250 K (K7-M0) remains unreliable. 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: VizieR Online Data Catalog: Long-term photographic photometry of HK Lac (Froehlich+, 2006) Authors: Froehlich, H. -E.; Kroll, P.; Strassmeier, K. G. Bibcode: 2005yCat..34540295F Altcode: A photographic light-curve, from 1956 to 1996, of the RS CVn binary HK Lacertae is presented. For each of the 2037 data points the Julian Date (geocentric) and the BT magnitude (Tycho-2 photometric system) is given. Brightnesses are with respect to the BT brightness of HD 210731 (BT=8.090mag).

(1 data file). Title: Spatially resolving the accretion shocks on the rapidly-rotating M0 T-Tauri star MN Lupi Authors: Strassmeier, K. G.; Rice, J. B.; Ritter, A.; Küker, M.; Hussain, G. A. J.; Hubrig, S.; Shobbrook, R. Bibcode: 2005A&A...440.1105S Altcode: We obtained high-resolution, high-quality VLT/UVES spectra to reconstruct the two-dimensional surface structure of the rapidly-rotating classical T-Tauri star MN Lupi on two separate nights. Both surface maps show a structured warm (5000 K) band centered around the pole at a latitude of ≈65°. Located within the band are two hot spots with temperatures of approximately or possibly even in excess of 5800 K, i.e. 2000 K above the effective photospheric temperature. Both maps appear with an adjacent equatorial band of temperature 3400 K, some 400-500 K below the effective photospheric temperature. While we interpret the two hot spots and the warm high-latitude band to be the heating points from two accretion impacts at the time of our observations and their redistributed energy trailed due to the fast stellar rotation, respectively, the cool equatorial band may not be cool after all but due to obscuration of the stellar surface by the innermost region of the disk. The fact that the hot spots appear at high stellar latitude is in agreement with the magnetospheric accretion model that proposes material funnelling onto the star along a predominantly dipolar magnetic field at roughly 50° latitude. The evidence of ongoing disk accretion, together with the very fast rotation of MN Lupi of just 3-4 times below its break-up velocity, suggests that the accretion mechanism is the cause of its rapid surface rotation. We present a model of magnetic star-disk coupling for MN Lupi that predicts a polar surface magnetic field of ≈3 kG. Title: Spots on EK Draconis. Active longitudes and cycles from long-term photometry Authors: Järvinen, S. P.; Berdyugina, S. V.; Strassmeier, K. G. Bibcode: 2005A&A...440..735J Altcode: We analyse photometric observations of the young active star EK Dra, altogether about 21 years. Similar to the ZAMS stars LQ Hya and AB Dor, EK Dra shows long-lived, non-axisymmetric spot distribution with active longitudes on opposite hemispheres. At least two activity cycle can be found from the data. The first cycle originates from repeated switches of the activity between two active longitudes in about (2-2.25)-year intervals, resulting in a cycle of about (4-4.5) years. The second cycle is of the order of 10.5 years and comes from migration of the active longitudes. Our data cover two consecutive cycles. The periodicity is also present in the maximum, the mean and the minimum stellar brightness. Additionally, there is a long-term trend. If we combine our data with the Sonneberg plate measurements, we can conclude that the overall brightness of EK Dra has been continuously decreasing at least for the last 45 years. A comparison with current sunspot activity reveals many similarities between the Sun and EK Dra. Title: Erratum: ``A High-Resolution Spectrum of the TrES-1 Parent Star'' Authors: Strassmeier, Klaus G.; Rice, John B. Bibcode: 2005IBVS.5648....1S Altcode: We present a high-resolution (R=120,000) spectrum of the lithium region of the parent star of the newly-discovered transiting planet TrES-1 (GSC02652-01324, K0V, V=11.8mag). No lithium seems to be present at the surface of TrES-1. Title: The new 1.5 solar telescope GREGOR: progress report and results of performance tests Authors: Volkmer, Reiner; von der Lühe, Oskar; Kneer, Franz; Staude, Jürgen; Berkefeld, Thomas; Caligari, Peter; Halbgewachs, Clemens; Schmidt, Wolfgang; Soltau, Dirk; Nicklas, Harald; Wittmann, Axel; Balthasar, Horst; Hofmann, Axel; Strassmeier, Klaus; Sobotka, Michal; Klvana, Miroslav; Collados, Manuel Bibcode: 2005SPIE.5901...75V Altcode: The telescope structure including control system and the complete retractable dome of the new 1.5 m solar telescope GREGOR were assembled during 2004 at Izana on Tenerife, Spain. The GREGOR telescope is build by a consortium of the Kiepenheuer Institut fuer Sonnenphysik, the Astrophysikalische Institut Potsdam, the Institut fuer Astrophysik Goettingen and additional national and international Partners. Pointing, tracking and thermal tests were made to verify the proposed performance. The results of these tests and a progress report of the project will be presented. Title: VizieR Online Data Catalog: V light curves of EK Dra (Jaervinen+, 2005) Authors: Jaervinen, S. P.; Berdyugina, S. V.; Strassmeier, K. G. Bibcode: 2005yCat..34400735J Altcode: We analyse photometric observations of the young active dwarf EK Dra, spanning altogether 21 years, and including previously unpublished data. The data in Table 2 was observed at the Fairbourn Observatory in southern Arizona using Amadeus, a 0.75m automatic photoelectric telescope (APT) of the University of Vienna. Amadeus is optimised for red wavelengths with an EMI-9828 tube and Johnson-Cousins V(RI)C filters. Differential V magnitudes are variable (EK Dra) - comparison (HD 129390) and check (HD 129798) - comparison (HD 129390). HD 129390 Vmag=7.567

(1 data file). Title: Indications for anti-solar differential rotation of giant stars Authors: Weber, M.; Strassmeier, K. G.; Washuettl, A. Bibcode: 2005AN....326..287W Altcode: Observational evidence of anti-solar differential rotation of K-type giant stars is presented. Time-series Doppler imaging based on 70 nights of spectroscopic data was used to derive the spot evolution of the stellar surfaces. The relative differential rotation parameters (α) of the binary stars IM Peg, HD 208472, and HK Lac were obtained using two techniques, cross-correlation analysis and the sheared-image method. Additionally, two previously published single giant stars are revisited and qualitatively compared to recent theoretical models. Title: Stellar activity cycles: observing the dynamo? Authors: Strassmeier, K. G. Bibcode: 2005AN....326..269S Altcode: The enormous complexity of the atmospheric structure observed on the Sun makes it very difficult to compare the Sun with ``solar-type stars''. Clearly, we need to identify parameters that can be observed on the Sun as well as on other stars which can be interpreted unambiguously. The most widely accepted dynamo signature is the presence of an activity cycle, well documented for the Sun and for main-sequence stars due to the Mount Wilson Ca II H&K project. Only recently have we detected spatial information, differential rotation and possibly meridional flows on other stars and thereby adding another constraint for its interpretation within a dynamo theory. Again, the picture is not complete yet, despite that there is just a single main ingredient that acts as the driving mechanism for activity in all atmospheric layers and the convective envelope of a solar-type star: the dynamo-related magnetic field. I stress the importance of mapping stellar surfaces as fingerprints of the underlying dynamo action over long periods of time. Title: Differential rotation of LQ Hya and IL Hya from a time-series of Doppler images Authors: Kővári, Zs.; Weber, M.; Strassmeier, K. G. Bibcode: 2005ESASP.560..731K Altcode: 2005csss...13..731K No abstract at ADS Title: Evolution of stellar active regions: differential rotation of five K giants Authors: Weber, M.; Strassmeier, K. G. Bibcode: 2005ESASP.560.1029W Altcode: 2005csss...13.1029W No abstract at ADS Title: Science with the STELLA robotic observatory Authors: Weber, M.; Strassmeier, K. G.; Bartus, J.; Korhonen, H.; Kővári, Zs.; Oláh, K.; Schwope, A.; Staude, A.; Steffen, M. Bibcode: 2005ESASP.560.1025W Altcode: 2005csss...13.1025W No abstract at ADS Title: First Doppler images of ζ Andromedae Authors: Kővári, Zs.; Bartus, J.; Strassmeier, K. G.; Oláh, K.; Rice, J. B.; Washuettl, A.; Csizmadia, Sz. Bibcode: 2005ESASP.560..727K Altcode: 2005csss...13..727K No abstract at ADS Title: PEPSI, the High-Resolution Optical-IR Spectrograph for the LBT Authors: Andersen, Michael; Strassmeier, Klaus; Hoffman, Axel; Woche, Manfred; Spano, Paolo Bibcode: 2005hris.conf...57A Altcode: PEPSI is a high resolution fibre feed optical-IR polarimetric echelle spectrograph for the Large Binocular Telescope (LBT). PEPSI utilizes the two 8.4m LBT apertures to simultaneously record four polarization states at a resolution of 120.000. The extension of the coverage towards the IR is mainly motivated by the larger Zeeman splitting of IR lines, which would allow to study weaker/fainter magnetic structures on stars. The two optical arms, which also have an integral light mode with R up to 300.000, are under construction, while the IR arm is being designed. Title: Doppler imaging of active binary stars Authors: Strassmeier, K. G. Bibcode: 2004ASPC..318...69S Altcode: 2004ssrc.conf...69S Binaries can be used as astrophysical laboratories to study a much larger range of parameters than nature would normally foresee for a single star. A good example is the evolution of the stellar magnetic field and its tracers. Solar analogy tells us that the surface starspot distribution, and its variation in time, is a fingerprint of the underlying dynamo process and its subsequent magnetic-field eruption as bipolar spots or spot groups. But is this also true for more massive and less massive stars, even for fully convective stars? I show how astronomers nowadays resolve a stellar surface by means of a tomographic imaging technique and recover the surface temperature distribution as a tracer of the magnetic field and, of course, also emphasize its limitations. The technique requires relatively high-resolution high-S/N spectra well sampled over a rotation period of the star and is, so far, mainly technology driven. Therefore, I will present also an update of future instrumentation for stellar-activity work. Finally, I focus the scientific discussion on three recent studies of active double-lined spectroscopic binaries as three representative proxies of stellar activity throughout the HR-diagram. Title: Robotic Astronomy. Proceedings of the 3rd Potsdam Thinkshop on Robotic Astronomy Authors: Strassmeier, K. G.; Hessman, F. V. Bibcode: 2004AN....325..455S Altcode: From July 12-15, 2004, the third Potsdam Thinkshop was held in the Hotel Dorint ``Sanssouci'' in Potsdam, Germany on the topic of ROBOTIC ASTRONOMY. Its aim was to bring together astronomers and technicians from any field in astronomy to review the current status of robotic telescope projects and to discuss the future science cases for such installations. Part of the ``Thinkshop'' concept of this meeting was to jointly think about new scientific projects tailored to the unique capabilities of modern robotic telescopes, small and large. Title: The STELLA robotic observatory Authors: Strassmeier, K. G.; Granzer, T.; Weber, M.; Woche, M.; Andersen, M. I.; Bartus, J.; Bauer, S. -M.; Dionies, F.; Popow, E.; Fechner, T.; Hildebrandt, G.; Washuettl, A.; Ritter, A.; Schwope, A.; Staude, A.; Paschke, J.; Stolz, P. A.; Serre-Ricart, M.; de la Rosa, T.; Arnay, R. Bibcode: 2004AN....325..527S Altcode: STELLA is a robotic observatory with two fully automatic telescopes (STELLA-I and STELLA-II) located at the Teide Observatory in Tenerife, Spain. Not only the telescopes are automatic but also the entire observatory, no human presence is needed for observing - not even in remote control. STELLA-I supports a high-resolution, fiber-fed and bench-mounted echelle spectrograph and a wide-field CCD imaging photometer while STELLA-II feeds a similar but wide-band imaging photometer and a testbed for prototype adaptive optics for robotic telescopes. The first telescope is scheduled for first light in November 2004, the second telescope for March 2005. Title: Progress report of the 1.5 m solar telescope GREGOR Authors: Volkmer, Reiner; von der Lühe, Oskar F.; Kneer, Franz; Staude, Jürgen; Berkefeld, Thomas; Caligari, Peter; Schmidt, Wolfgang; Soltau, Dirk; Nicklas, Harald; Wiehr, Eberhardt; Wittmann, Axel; Balthasar, Horst; Hofmann, Axel; Strassmeier, Klaus; Sobotka, Michal; Klvana, Miroslav; Collados, Manuel Bibcode: 2004SPIE.5489..693V Altcode: GREGOR is the new 1.5 m solar telescope assembled on Tenerife, Spain, by the German consortium of the Kiepenheuer Institut fur Sonnenphysik, the Astronomischen Institut Potsdam, the Universitats-Sternwarte Gottingen and other national and international Partners. The refurbishment of the building is almost finished. The manufacturing of the telescope structure and the optics is still in progress. After the integration of the new complete retractable dome in July 2004 the telescope structure, optic and post focus instruments will be assembled during the rest of the year. First light is planned during May 2005. Title: A robotic reflective Schmidt telescope for Dome C Authors: Strassmeier, K. G.; Andersen, M. I.; Steinbach, M. Bibcode: 2004AN....325..626S Altcode: This paper lays out a wide-field robotic Schmidt telescope (RST) for the Antarctic site Dome C. The telescope is based on 80/120cm reflective Schmidt optics, built originally for a space project, and a mosaic of four 7.5k×7.5k 8-μm thinned CCDs from the PEPSI/LBT wafer run. The telescope's total field of view (FOV) would be 5o circular (minimum 3o× 3o square) with a plate scale of 0.7 arcsec per pixel. Limiting magnitude is expected to be V=21.5mag in 60 sec for a field of 9 square degrees. Title: A High-Resolution Spectrum of the TrES-1 Parent Star Authors: Strassmeier, Klaus G.; Rice, John B. Bibcode: 2004IBVS.5566....1S Altcode: We present a high-resolution (R=120,000) spectrum of the lithium region of the parent star of the newly-discovered transiting planet TrES-1 (GSC02652-01324, K0V, V=11.8mag). No lithium seems to be present at the surface of TrES-1. Title: Can we use adaptive optics for UHR spectroscopy with PEPSI at the LBT? Authors: Sacco, Germano G.; Pallavicini, Roberto; Spano, Paolo; Andersen, Michael; Woche, Manfred F.; Strassmeier, Klaus G. Bibcode: 2004SPIE.5490..398S Altcode: We investigate the potential of using adaptive optics (AO) in the V, R, and I bands to reach ultra-high resolution (UHR, R >= 200,000) in echelle spectrographs at 8-10m telescopes. In particular, we investigate the possibility of implementing an UHR mode for the fiber-fed spectrograph PEPSI (Potsdam Echelle Polarimetric and Spectrographic Instrument) being developed for the Large Binocular Telescope (LBT). By simulating the performances of the advanced AO system that will be available at first light at the LBT, and by using first-order estimates of the spectrograph performances, we calculate the total efficiency and signal to noise ratio (SNR) of PEPSI in the AO mode for stars of different magnitudes, different fiber core sizes, and different fractions of incident light diverted to the wavefront sensor. We conclude that AO can provide a significant advantage, of up to a factor ~2 in the V, R and I bands, for stars brighter than mR ~ 12 - 13. However, if these stars are observed at UHR in non-AO mode, slit losses caused by the need to use a very narrow slit can be compensated more effectively by the use of image slicers. Title: Optical design of the PEPSI high-resolution spectrograph at LBT Authors: Andersen, Michael I.; Spano, Paolo; Woche, Manfred; Strassmeier, Klaus G.; Beckert, Erik Bibcode: 2004SPIE.5492..381A Altcode: PEPSI is a high-resolution, fiber fed echelle spectrograph with polarimetric capabilities for the LBT. In order to reach a maximum resolution R=120.000 in polarimetric mode and 300.000 in integral light mode with high efficiency in the spectral range 390-1050~nm, we designed a white-pupil configuration with Maksutov collimators. Light is dispersed by an R4 31.6 lines/mm monolithic echelle grating mosaic and split into two arms through dichroics. The two arms, optimized for the spectral range 390-550~nm and 550-1050~nm, respectively, consist of Maksutov transfer collimators, VPH-grism cross dispersers, optimized dioptric cameras and 7.5K x 7.5K 8~μ CCDs. Fibers of different core sizes coupled to different image-slicers allow a high throughput, comparable to that of direct feed instruments. The optical configuration with only spherical and cylindrical surfaces, except for one aspherical surface in each camera, reduces costs and guarantees high optical quality. PEPSI is under construction at AIP with first light expected in 2006. Title: An atmospheric model for UZ Librae from mean Hα-line profiles Authors: Zboril, M.; Strassmeier, K. G.; Avrett, E. H. Bibcode: 2004A&A...421..295Z Altcode: We present the results from fitting a semi-empirical atmospheric model including a chromosphere and a transition region to the mean (seasonal) Balmer Hα line profiles of the RS CVn-type K0-giant UZ Librae. As a first step, a static 1D spherical model was applied to the mean component of the Hα-emission core and its profile. The main result of the fitting is that the transition region begins at a log mass depth of -1.8 g cm-2 at a temperature of 7400 K (approximately 3000 K warmer than the photosphere) and then has a steep increase to the peak temperature of ≈106 K. A stellar model in plane-parallel mode with ``partial-frequency redistribution'' option in the line transfer gave roughly the best fit. Subsequently, two-Gaussian fitting of the phase-dependent Hα -line profiles yields a complex velocity field. The radial velocities, from both the absorption reversal and the main emission component, display rotational and/or orbital modulation. The largest differences between consecutive line profiles occur mostly in the red line wings, suggesting the existence of both an inward-pointed velocity field and sporadic radiation events possibly related to flares. The total Hα emission, as derived from the equivalent width, possibly also displays rotational modulation. Indirect evidence is presented for the existence of circumstellar matter in form of an Hα absorption shell. Finally, a preliminary elemental abundance analysis suggests sub-solar metallicity of [M/H]≈ -0.5 dex based on ATLAS models, or -0.7 dex based on PHOENIX models. Title: The science case of the PEPSI high-resolution echelle spectrograph and polarimeter for the LBT Authors: Strassmeier, K. G.; Pallavicini, R.; Rice, J. B.; Andersen, M. I. Bibcode: 2004AN....325..278S Altcode: We lay out the scientific rationale for and present the instrumental requirements of a high-resolution adaptive-optics Echelle spectrograph with two full-Stokes polarimeters for the Large Binocular Telescope (LBT) in Arizona. Magnetic processes just like those seen on the Sun and in the space environment of the Earth are now well recognized in many astrophysical areas. The application to other stars opened up a new field of research that became widely known as the solar-stellar connection. Late-type stars with convective envelopes are all affected by magnetic processes which give rise to a rich variety of phenomena on their surface and are largely responsible for the heating of their outer atmospheres. Magnetic fields are likely to play a crucial role in the accretion process of T-Tauri stars as well as in the acceleration and collimation of jet-like flows in young stellar objects (YSOs). Another area is the physics of active galactic nucleii (AGNs) , where the magnetic activity of the accreting black hole is now believed to be responsible for most of the behavior of these objects, including their X-ray spectrum, their notoriously dramatic variability, and the powerful relativistic jets they produce. Another is the physics of the central engines of cosmic gamma-ray bursts, the most powerful explosions in the universe, for which the extreme apparent energy release are explained through the collimation of the released energy by magnetic fields. Virtually all the physics of magnetic fields exploited in astrophysics is somehow linked to our understanding of the Sun's and the star's magnetic fields. Title: Doppler imaging of stellar surface structure. XXII. Time-series mapping of the young rapid rotator LQ Hydrae Authors: Kovári, Zs.; Strassmeier, K. G.; Granzer, T.; Weber, M.; Oláh, K.; Rice, J. B. Bibcode: 2004A&A...417.1047K Altcode: We reconstruct a time series of 28 surface temperature maps (Doppler-images) of the spotted single K2-dwarf LQ Hya from 35 consecutive stellar rotations in Nov.-Dec. 1996. Two more maps are obtained from data in late April and early May 2000. All maps show spot activity preferably at low latitudes between -20 deg and +50 deg, with a concentration in a band centered at around +30 deg, and with only occasional evidence for a higher-latitude spot extension. No trace of a polar spot is found at any of the above epochs. Most of this morphology can be reproduced by our flux-tube emergence model, except for the equatorial activity where the strong Coriolis force due to the rapid rotation always deflects flux tubes to higher latitudes. We also present the detection of weak differential surface rotation from a number of cross-correlation maps of the time-series images in late 1996. A solar-type differential rotation law, i.e. the equator rotating faster than the poles, with ΔΩ=+0.022 rad/day (lap time of ≈280 days) is in agreement with the data. Using the available photoelectric observations from 21 years we refine the rotation period to 1.60066±0.00013 days and find a remarkable phase coherence over the course of 21 years, supporting the recent finding of active longitudes by Berdyugina et al. Furthermore, our photometry shows a complex multi-cyclic long-term brightness variability with three periods of 13.8±2.8 years, its harmonic 6.9±0.8 and 3.7±0.3 years, respectively. The 3.7-year period would be in good agreement with the fundamental-mode oscillation period predicted by Kitchatinov et al. from a distributed-dynamo model, but remains to be confirmed.

Table 1 and Fig. 5 are only available in electronic form at http://www.edpsciences.org Title: Multisite observations of SU Aurigae Authors: Unruh, Y. C.; Donati, J. -F.; Oliveira, J. M.; Collier Cameron, A.; Catala, C.; Henrichs, H. F.; Johns-Krull, C. M.; Foing, B.; Hao, J.; Cao, H.; Landstreet, J. D.; Stempels, H. C.; de Jong, J. A.; Telting, J.; Walton, N.; Ehrenfreund, P.; Hatzes, A. P.; Neff, J. E.; Böhm, T.; Simon, T.; Kaper, L.; Strassmeier, K. G.; Granzer, Th. Bibcode: 2004MNRAS.348.1301U Altcode: 2004astro.ph..1081U We present results from the 1996 Multi-Site Continuous Spectroscopy (MUSICOS) campaign on the T Tauri star SU Aurigae. We find a 2.7-d periodicity in the HeI (587.6 nm) line, and somewhat longer, less well-pronounced periodicities in the Balmer lines and in Na D. Our observations support the suggestion that the wind and infall signatures are out of phase on SU Aur. We present Doppler images of SU Aur that have been obtained from least-squares deconvolved profiles. Images taken about one rotation apart show only limited overlap, in particular at low latitudes. This is due in part to limitations in signal-to-noise ratio, and in part to line-profile deformations that arise from short-lived and/or non-surface features. The agreement at high latitudes is better and suggests that at least some longer-lived features are present. The analysis of Stokes V profiles yields a marginal magnetic field detection during one of the phases. Title: The Solar-Stellar Connection and Disconnection Authors: Strassmeier, K. G. Bibcode: 2004IAUS..219...11S Altcode: 2003IAUS..219E..39S The study of stellar activity is now an almost classical astronomical topic because the first observations were made almost hundred years ago and many thousands of papers were published in the meantime. However the complexity of the atmospheric and interior structure as observed on the Sun is hard if not impossible to extrapolate to solar-type stars. Yet there is just a single main ingredient that acts as the driving mechanism for activity in all atmospheric layers and the convective envelope: the dynamo-driven magnetic field. In my talk I will try to give examples where the solar analogy holds and where ist is clearly not appropriate. I stress the importance of mapping stellar surfaces as fingerprints of the underlying dynamo action. Title: Eddington and stellar-rotation studies: light curve analysis tools and ground-based follow-up spectroscopy Authors: Strassmeier, K. G.; Oláh, K. Bibcode: 2004ESASP.538..149S Altcode: 2004sshp.conf..149S Eddington will produce a data stream of light curves for some tens of thousands of stars. This means that a clever algorithm must predetermine what type of variability is expected for a particular target, and then suggest and apply the proper analysis tool. We investigate the feasibility of such an algorithm by comparing the chances of detecting the solar rotational period from the long-term Sun-as-a-star ACRIM data by means of Fourier and wavelet period-search techniques. We first create artificial data with a spot-modelling code that includes differential surface rotation, and then try to recover the rotation signal from the Fourier spectrum. Then, we present the example of the rapidly-rotating spotted star UZ Librae, where ground-based time-series photometry obtained with automatic telescopes indeed revealed signal from a differentially rotating stellar surface. Finally, we discuss the urgent need for ground-based preparatory and follow-up spectroscopy and introduce our own support possibilities. We emphasise that all proposed joint Eddington-support efforts, with our Spanish colleagues on the Canary islands and our Italian and American colleagues in Arizona, strongly suggest that the planet-finding field is in the northern hemisphere. Title: Linking Thin Flux Tube MHD Models to Apparent Stellar Surface Activity Authors: Granzer, T.; Strassmeier, K. G. Bibcode: 2004IAUS..219..546G Altcode: 2003IAUS..219E.133G Doppler Imaging provides us with a growing number of surface maps of fast-rotating late-type stars. These maps often reveal solar-spot like star spots. As the resemblance to sun-spots is striking it appears feasible to apply an MHD model gained from studying our Sun's spots to these highly-active stars. In this poster we want to directly compare stellar spot patterns derived from theory with actual observations. The rise of thin magnetic flux-tubes from the bottom of an outer stellar convection zone up to the photosphere is followed numerically. The emergence points of the flux-tubes in the photosphere of the model stars are than compared to Doppler-imaging derived surface maps. With this comparison the feasibility of applying a solar-analog model is discussed. Title: Doppler imaging of stellar surface structure. XXI. The rapidly-rotating solar-type star HD 171488 = V889 Hercules Authors: Strassmeier, K. G.; Pichler, T.; Weber, M.; Granzer, T. Bibcode: 2003A&A...411..595S Altcode: We present the first Doppler image of the single G0-dwarf HD 171488. As a 30-Myr young field star with a lithium abundance of ~140-times that of the Sun and a rotation 20 times faster, it is hardly a ``solar analog'' but could be termed an ``infant Sun''. Its position in the H-R diagram suggests it to be in the rapid-braking phase just prior to arrival on the ZAMS. Our Doppler images from four spectral lines show a cool polar spot and various high-latitude spot features with a temperature contrast of 500-1600 K relative to the effective (photospheric) temperature. Low-to-medium latitude features may be present but appear to be biased by the uneven phase coverage of our spectra and are too weak to be conclusively judged significant. We determine the rotational period to be 1.3371 +/- 0.0002 days and find a long-term, possibly cyclic variation of the mean V brightness of ~7 yrs. A constant radial velocity of -23.6 +/- 1.5 km s-1 suggests that HD 171488 is indeed a single star. Rising flux-tube models indicate preferred surfacing latitudes between 25 degr-60 degr for HD 171488 while our Doppler images reveal mostly high-latitude spots in excess of 60 degr . We emphasize that this discrepancy exists for all rapidly rotating single G dwarfs observed so far. Title: Differential rotation on UZ Librae Authors: Oláh, K.; Jurcsik, J.; Strassmeier, K. G. Bibcode: 2003A&A...410..685O Altcode: We analysed a time series of nine consecutive years of high-precision photometry of the spotted RS CVn star UZ Lib by using a discrete Fourier-transform technique and a non-linear least-squares minimization. The main period of 4.77 days due to stellar rotation was resolved into three individual periods separated by -0.2% and +0.4% around the main period. The stability of the spot pattern over many years, as derived from our contemporaneous Doppler images, allowed us to relate the different periods to co-existing spots at different latitudes, and thus to the direct determination of the strength and the sign of the differential rotation. The main period originates from the equatorial surface regions and is practically the same as the orbital period from independent radial-velocity measurements, suggesting that the stellar equator is tidally locked to the orbital motion. The higher latitudes rotate slightly faster than the equator, suggesting non-solar differential rotation with a parameter of alpha =Delta Omega /Omega =-0.0026, 80 times weaker than on the solar surface, and a lap time of Pequator/alpha ~ -1800 days, i.e. 14 times longer than for the Sun. Title: Tracing the Spot Evolution on the Moderately-Rotating K1-Giant σ Geminorum Authors: Strassmeier, K. G.; Kovári, Z.; Washuettl, A.; Weber, M.; Rice, J. B.; Bartus, J. Bibcode: 2003csss...12..927S Altcode: We present a simultaneous photometric and spectroscopic imaging analysis of the long-period RS CVn binary σ Gem, covering 3.6 consecutive rotation cycles with high time resolution. From six overlapping but consecutive Doppler maps we trace the evolution of individual spots throughout the time range covered. All spots group either along a band at approximately +45 ° latitude and a width of 30 °, or appear centered at the equator. No polar spot is detected. We did not find a conclusive migration pattern from the cross-correlation maps from one rotation to the next and attribute this to a masking effect of short-term spot changes. Title: Doppler Imaging of Stellar Surface Structure: The Differential Rotation of the K-giant IL Hydrae Authors: Weber, M.; Strassmeier, K. G.; Washuettl, A. Bibcode: 2003csss...12..922W Altcode: We re-determined the differential rotation law at the surface of the K giant IL Hydrae (Prot≈12.9 days). Using new NSO and KPNO spectra covering five consecutive rotations in 1996 and two rotations 15 days apart in 2000, we cross-correlate three independent Doppler images from 1996 and two from 2000. Assuming a solar-like differential rotation law, we derive α=Ω1/Ω0≈ -0.047 and 1/ΔΩ≈277 days. This is more than double the solar value of 120 days and in the opposite direction, i. e. the polar regions rotate faster than the equatorial regions. This result is in contrast to earlier measurements showing a weak differential rotation in the same direction as the Sun, but based on only two Doppler images taken one year apart. This indicates, that average spot lifetimes on IL Hya are on the order of a few stellar rotations. Title: STELLA: Status Report Authors: Hempelmann, A.; Schmitt, J. H. M. M.; Hagen, H.; Strassmeier, K.; Arlt, K.; Granzer, T.; Hildebrandt, G.; Weber, M.; Woche, M. Bibcode: 2003csss...12.1085H Altcode: STELLA is a joint project between the Hamburger Sternwarte and the Astrophysical Institute Potsdam for an automatically operating spectroscopic telescope. The scientific goals are observation and monitoring of stellar activity. By agreement with the Astrophysical Institute of the Canary Islands, STELLA will be installed at the Teide Observatory on the island of Tenerife. The actual progress in design and construction of the telescope, the instruments and the control software is presented in this report. Title: Spotted Stars in the Pleiades and Orion Nebular Cluster Authors: Granzer, T.; Strassmeier, K. G. Bibcode: 2003csss...12..763G Altcode: We present the results of extensive MHD simulations aiming to predict star spot patterns on stars in two well-known stellar clusters, the Pleiades (100 Myr) and the Orion Nebular Cluster (2 Myr). The emergence of thin magnetic flux tubes is studied from their origin at the base of the convective zone up to the photosphere. The mass/rotational grid of the stellar models is wide enough to cover all stellar types where theory predicts the possibility of starspot formation. In particular, masses between 4.0 M⊙ and 0.4 M⊙ and rotational rates from 0.25 Ω⊙ to 25 Ω⊙ are considered. Title: MUSICOS Observations of the Chromospherically Active Binary Star EI Eridani Authors: Washuettl, A.; Strassmeier, K. G.; Foing, B.; MUSICOS98 Team Bibcode: 2003csss...12.1008W Altcode: We present first results on spectroscopic observations of the rapidly-rotating active binary star EI Eridani obtained during the MUSICOS multi-site campaign in 1998. Eight sites around the globe were involved in order to achieve surface images within a few rotations as EI Eridani's critical rotation period of 1.945 days makes it impossible to obtain time-resolved images from a single site. The data were split into groups in order to obtain consecutive, independent Doppler images. The preliminary results confirm the existence of a stable polar spot that changes in size and shape while low-latitute spots are found to be short lived. For the first time, it is possible to achieve consecutive, time-resolved Doppler images for EI Eridani. A preliminary investigation of differential rotation contradicts the results from Hatzes & Vogt (1992). Title: Doppler imaging of stellar surface structure. XX. The rapidly-rotating single K2-giant HD 31993 = V1192 Orionis Authors: Strassmeier, K. G.; Kratzwald, L.; Weber, M. Bibcode: 2003A&A...408.1103S Altcode: We present two Doppler images from two consecutive stellar rotations of the single K2-giant HD 31993. Each Doppler image is reconstructed from spectra obtained within a single stellar rotation. With its 25-day rotational period and a radius of ~18 solar radii, HD 31993 is considered a very rapidly rotating star and thus allows the application of the Doppler-imaging technique, despite the unusually long period. All maps reveal 7 isolated, predominantly low-latitude spots with a temperature difference, photosphere minus spot, of just ~200 K. No polar spot or high-latitude activity above, say, +60° is seen. A large warm feature is detected at high latitude and is believed to be real. These spots act as tracers for a cross correlation analysis and yield a clear signature of anti-solar differential surface rotation, i.e. the polar regions rotating faster than the equator, with alpha =0.125 +/-0.05 corresponding to a lap time of ~200 days. A detailed parameter study is carried out to verify the reality of the HD 31993 maps. Title: Halpha variations of the spotted G dwarf AP 149 Authors: Savanov, I.; Strassmeier, K.; Romanyuk, I.; Kudryavtsev, D. Bibcode: 2003IBVS.5440....1S Altcode: High resolution spectroscopic observations of G dwarf AP 149 in the alpha Persei cluster result in the estimations of variations of the equivalent widths and fluxes radiated in H-alpha line. Title: The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) for the LBT Authors: Strassmeier, K. G.; Hofmann, A.; Woche, M. Bibcode: 2003ANS...324...28S Altcode: 2003ANS...324..D02S No abstract at ADS Title: Das Large Binocular Telescope. Ein Projekt nimmt Gestalt an Authors: Strassmeier, Klaus G. Bibcode: 2003S&W....42e..30S Altcode: No abstract at ADS Title: The ICE spectrograph for PEPSI at the LBT: preliminary optical design Authors: Pallavicini, Roberto; Zerbi, Filippo M.; Spano, Paolo; Conconi, Paolo; Mazzoleni, Ruben; Molinari, Emilio; Strassmeier, Klaus G. Bibcode: 2003SPIE.4841.1345P Altcode: We present a preliminary design study for a high-resolution echelle spectrograph (ICE) to be used with the spectropolarimeter PEPSI under development at the LBT. In order to meet the scientific requirements and take full advantage of the peculiarities of the LBT (i.e. the binocular nature and the adaptive optics capabilities), we have designed a fiber-fed bench mounted instrument for both high resolution (R ≍ 100,000; non-AO polarimetric and integral light modes) and ultra-high resolution (R ≍ 300,000; AO integral light mode). In both cases, 4 spectra per order (two for each primary mirror) shall be accomodated in a 2-dimensional cross dispersed echelle format. In order to obtain a resolution-slit product of ≍ 100,000 as required by the science case, we have considered two alternative designs, one with two R4 echelles in series and the other with a sigle R4 echelle and fiber slicing. A white-pupil design, VPH cross-dispersers and two cameras of different focal length for the AO and non-AO modes are adopted in both cases. It is concluded that the single-echelle fiber-slicer solution has to be preferred in terms of performances, complexity and cost. It can be implemented at the LBT in two phases, with the long-camera AO mode added in a second phase depending on the availability of funds and the time-scale for implementation of the AO system. Title: PEPSI spectro-polarimeter for the LBT Authors: Strassmeier, Klaus G.; Hofmann, Axel; Woche, Manfred F.; Rice, John B.; Keller, Christoph U.; Piskunov, N. E.; Pallavicini, Roberto Bibcode: 2003SPIE.4843..180S Altcode: PEPSI (Postham Echelle Polarimetric and Spectroscopic Instrument) is to use the unique feature of the LBT and its powerful double mirror configuration to provide high and extremely high spectral resolution full-Stokes four-vector spectra in the wavelength range 450-1100nm. For the given aperture of 8.4m in single mirror mode and 11.8m in double mirror mode, and at a spectral resolution of 40,000-300,000 as designed for the fiber-fed Echelle spectrograph, a polarimetric accuracy between 10-4 and 10-2 can be reached for targets with visual magnitudes of up to 17th magnitude. A polarimetric accuracy better than 10-4 can only be reached for either targets brighter than approximately 10th magnitude together wiht a substantial trade-off wiht the spectral resolution or with spectrum deconvolution techniques. At 10-2, however, we will be able to observe the brightest AGNs down to 17th magnitude. Title: VizieR Online Data Catalog: sigma2 CrB radial velocities (Strassmeier+, Authors: Strassmeier, K. G.; Rice, J. B. Bibcode: 2003yCat..33990315S Altcode: High-resolution spectroscopic observations were obtained with the Gecko Coude spectrograph at the 3.6-m Canada-France-Hawaii telescope (CFHT) in two observing runs each two nights long in May 17-18, 2000 and May 21-22, 2000. This splitting of nights was mandatory in order to obtain full phase coverage because the orbital period (and the rotational periods) is 1.14 days, and thus close to the day-night cycle.

(2 data files). Title: Doppler imaging of stellar surface structure. XIX. The solar-type components of the close binary sigma2 Coronae Borealis Authors: Strassmeier, K. G.; Rice, J. B. Bibcode: 2003A&A...399..315S Altcode: We present the first Doppler image for both stellar components of the F9+G0 ZAMS binary sigma 2 CrB and found evidence for the coexistence of cool and warm spots on both stars. Cool spots appear mainly at polar or high latitudes while a confined equatorial warm belt appears on the trailing hemisphere of each of the two stars with respect to the orbital motion. We also present an update of the TempMap imaging code that allows us to solve the stellar surface temperature distribution on both binary components simultaneously, including photometric input. Several test reconstructions are performed to demonstrate its reliability and robustness. Our new orbital solution results in very precise masses for both components - good to 0.4% - and confirms the spectral classifications of F9 and G0 for the primary and secondary, respectively. The visual component, sigma 1 CrB, seems to be G4 rather than G0. All three components are on or very close to the ZAMS which is also confirmed by the relatively high lithium abundance of about twenty times the solar abundance. Photometric light variations are detected with a period of 1.157+/- 0.002 days that we interpret to be the rotation period of both binary components. A 0\fm04 dimming in y together with a reddening of 0\fm01 in b-y during the year 2000 suggests a long-term spot variability compatible with a period of at least 260 days. Title: Time-series photometric spot modelling VI. A new computer code and its application to 23 years of photometry of the active giant IM Pegasi Authors: Ribárik, G.; Oláh, K.; Strassmeier, K. G. Bibcode: 2003AN....324..202R Altcode: We present and apply a new computer program named SpotModeL to analyze single and multiple bandpass photometric data of spotted stars. It is based on the standard analytical formulae from Budding and Dorren. The program determines the position, size, and temperature of up to three spots by minimizing the fit residuals with the help of the Marquardt-Levenberg non-linear least-squares algorithm. We also expand this procedure to full time-series analysis of differential data, just as real observations would deliver. If multi-bandpass data are available, all bandpasses can be treated simultaneously and thus the spot temperature is solved for implicitly. The program may be downloaded and used by anyone. In this paper, we apply our code to an ~23 year long photometric dataset of the spotted RS CVn giant IM Peg. We extracted and modelled 33 individual light curves, additionally, we fitted the entire V dataset in one run. The resulting spot parameters reflect the long term light variability and reveal two active longitudes on the substellar point and on the antipode. The radius and longitude of the dominant spot show variations with 29.8 and 10.4 years period, respectively. Our multicolour data suggests that the spot temperature is increasing with the brightening of the star. The average spot temperature from V,I_C is 3550+/- 150 K or approximately 900 K below the effective temperature of the star. Title: EK Draconis: Long-term photometry on Sonneberg Sky-Patrol plates Authors: Fröhlich, H. -E.; Tschäpe, R.; Rüdiger, G.; Strassmeier, K. G. Bibcode: 2002A&A...391..659F Altcode: We performed long-term photometry of the young solar analog EK Draconis (HD 129333) using 1030 blue-sensitive Sky-Patrol plates taken at Sonneberg Observatory from 1958 onwards. A secular dimming of 0.0057+/- 0.0008 mag/y beginning around 1975 was found. Hence, the recent trend first observed with Automatic Photoelectric Telescopes (APTs) is confirmed and traced back to the mid-seventies. Title: Design study of the PEPSI polarimeter for the LBT Authors: Hofmann, A.; Strassmeier, K. G.; Woche, M. Bibcode: 2002AN....323..510H Altcode: We present the conceptual design of the two polarimetric channels of the PEPSI spectropolarimeter for the Large Binocular Telescope (LBT). The two direct Gregorian f/15 focii of the LBT will take up two identical but independent full-Stokes IQUV polarimeters that themselves fiberfeed a high-resolution Echelle spectrograph (see the accompanying paper by Zerbi et al.). The polarizing units will be based on super-achromatic Fresnel-rhomb retarders and Foster prisms. A total of four fibers are foreseen to simultaneously direct two ordinary and two extraordinary light beams to the Echelle spectrograph. Both polarimetric units are layed out in a modular design, each one optimized to the polarization state in which it is used. A number of observing modes can be chosen that are optimized to the type of polarization that is expected from the target, e.g. circularly and linearly polarized light simultaneously, or linearly polarized light in both polarimeters, or integral light from one and polarized light from the other telescope, a.s.o.. Calibration would be provided for each polarimeter separately. Title: Time series photometric spot modelling V. Phase coherence of spots on UZ Librae Authors: Oláh, K.; Strassmeier, K. G.; Granzer, T. Bibcode: 2002AN....323..453O Altcode: We present spot models for nine years of continuous VI_C photometry of UZ Lib from 1993-2001. The relatively stable double-humped light curve shape suggests extreme phase coherence. From the spot-modelling analysis, we found that the major spots or spot groups are always located on the hemisphere facing the secondary star and exactly in the opposite hemisphere anti-facing the secondary. Several single-humped light curves and our suggested binary scenario rule out a pure ellipsoidal variability as the cause of the double-humped light curve shape. We try to explain this preferred spot pattern with a magnetic-field structure that connects the two components, as suggested earlier for RS CVn stars in general. A possible 4.8 years spot cycle is found from the long-term brightness variations but needs confirmation. We rediscuss the basic astrophysical data of UZ Lib. The Hipparcos parallax is likely wrong, a possible reason could be that UZ Lib is e.g., a triple system. Title: Introduction to this volume. Proceedings of the 1st Potsdam Thinkshop on Sunspots & Starspots Authors: Strassmeier, K. G.; Washuettl, A.; Schwope, A. Bibcode: 2002AN....323..155S Altcode: This volume of AN contains the proceedings of the 1st Potsdam Thinkshop on Sunspots & Starspots held in Potsdam from May 6 to 10, 2002. The aim of this meeting was to bring together the solar and stellar community on a particular topic and discuss various inter-disciplinary results related to magnetic field. All contributions are fully refereed. Title: Doppler imaging of stellar surface structure. XVIII. The very active RS CVn binary UZ Librae revisited Authors: Oláh, K.; Strassmeier, K. G.; Weber, M. Bibcode: 2002A&A...389..202O Altcode: We present eight Doppler images of UZ Librae from the years 1994, 1996, 1997, 1998 and 2000. These maps indicate a preferred temperature distribution from one year to the other and suggest preferred spot locations for at least the seven years of our observations. Two equatorial active regions appear facing towards and opposite the (unseen) companion star. A large and cool polar spot, with two or maybe three appendages extending down to a latitude of 40 degr -50 degr , is present and causes the long-term light variability of UZ Lib. The appendages appear at longitudes very similar to the two equatorial active regions and sometimes are possibly even attached to them. No coherent sign of differential rotation is found for the equatorial regions up to a latitude of approximately +50 degr , but the polar appendages may indicate a general acceleration of the polar regions. If interpreted as being due to differential rotation, if real at all, then UZ Lib clearly exhibits a non-solar flow pattern. Title: A new concept and a preliminary design for a high resolution (HR) and very-high resolution (VHR) spectrograph for the LBT Authors: Zerbi, F. M.; Spanò, P.; Conconi, P.; Molinari, E.; Mazzoleni, R.; Pallavicini, R.; Strassmeier, K. G. Bibcode: 2002AN....323..499Z Altcode: 2002astro.ph..3039Z A way to fully exploit the large collecting area of modern 8-10m class telescopes is high resolution spectroscopy. Many astrophysical problems from planetary science to cosmology benefit from spectroscopic observations at the highest resolution currently achievable and would benefit from even higher resolutions. Indeed in the era of 8-10m class telescopes no longer the telescope collecting area but the size of the beam - which is related to the maximum size in which reflection gratings are manufactured - is what mainly limits the resolution. A resolution-slit product Rvarphi =~ 40,000 is the maximum currently provided by a beam of 20 cm illuminating the largest grating mosaics. We present a conceptual design for a spectrograph with Rvarphi =~ 80,000, i.e. twice as large as that of existing instruments. Examples of the possible exploitation of such a high Rvarphi value, including spectropolarimetry and very high resolution (R ~ 300,000), are discussed in detail. The new concept is illustrated through the specific case of a high resolution spectropolarimeter for the Large Binocular Telescope. Title: Starspot cycles from long-term photometry Authors: Oláh, K.; Strassmeier, K. G. Bibcode: 2002AN....323..361O Altcode: We continue investigating the photometric cycle lengths of some active stars. Using datasets now up to 34 years long we confirm previously derived activity cycles for the shorter period systems of our sample (LQ Hya, V833 Tau, EI Eri, V711 Tau, HU Vir and IL Hya), but find different cycle lengths for the two long-period giants HK Lac and IM Peg. We add UZ Lib to our previous sample. The connection between the rotational period and cycle length seems evident for the shortest derived cycle lengths. A similar connection between the rotational period and the longer cycle lengths is not as clear, taking into account recent results on the time variability of the longer term solar cycles. While the time base of the observations puts an upper limit to the detectable lengths of the longer cycles, a general dependence of the cycle period on the rotation rate is maintained. The length of the shortest cycle that we found for LQ Hya agrees with the cycle period derived from dynamo modelling of this star. Title: Doppler images of starspots Authors: Strassmeier, K. G. Bibcode: 2002AN....323..309S Altcode: I present a literature survey of the currently available Doppler images of cool stars. The 65 individual stars with Doppler images consist of 29 single stars and 36 components in close binaries. Out of the total, 31 were observed only once but 12 stars are (or were) being monitored for years. Each image for each star is identified with the time when it was observed, whether photometry was used in the imaging, the inclination of the stellar rotation axis, the vsin i, the stellar rotation period, and whether a polar spot and/or a high-latitude or low-latitude spot was seen. The type of variable star and its M-K spectral classification is also listed to identify the evolutionary status. The sample consists of 3 classical T Tauri stars, 8 weak-lined T Tauri's, 27 main-sequence stars, 9 subgiants, and 18 giants. The total number of Doppler images is 245 as of June 2002. Title: Stellar activity studies with Eddington Authors: Strassmeier, K. G. Bibcode: 2002ESASP.485..189S Altcode: 2002sshp.conf..189S I present a brief outline of the use of Eddington data for stellar activity studies. The most important stellar parameters that could be obtained from secondary targets within both main science fields are stellar rotation, differential rotation, meridional flows, stellar cycle morphology spot lifetimes, and flare activity. Due to the vast amount of data, one may hope to find relations between stellar pulsation and magnetic activity, and between stellar flares and the existence of Vulcan-type planets. Title: VizieR Online Data Catalog: Effective temperatures of K-M giants (Strassmeier+, 2000) Authors: Strassmeier, K. G.; Schordan, P. Bibcode: 2002yCatp001032103S Altcode: A high-resolution spectroscopic survey in the 6380-6460{AA} region of 224 slowly-rotating M-K class III giants is presented. Spectral line-depth ratio are calibrated against effective temperature obtained from B-V and V-I color indices in the range 3200-7500K (M6-A9). A table of polynomial coefficients for 12 line-ratio-Teff relations can be used to derive Teff of F-M stars to within 33K (rms), and of early-F and mid-to-late M stars to within 77-106K (rms).

(2 data files). Title: The Wolfgang and Amadeus Automatic Photoelectric Telescopes. A ``Kleine-Nacht-Musik'' during the first five years of routine operation Authors: Granzer, T.; Reegen, P.; Strassmeier, K. G. Bibcode: 2001AN....322..325G Altcode: We present a summary of five years of continuous operation of the University of Vienna twin Automatic Photoelectric Telescopes (APTs) -- Wolfgang and Amadeus. These two telescopes are part of the Fairborn Observatory facility located in the Sonoran desert close to Washington Camp in southern Arizona. The detection and distinction procedure between weather-induced data-quality loss and systematic data-quality loss turned out to be a crucial task. Therefore, special emphasis is laid on the data quality monitoring tools developed throughout the years. Furthermore, we summarize the scientific highlights from the first five years of operation Title: Automation hardware and software for the STELLA-I robotic telescope Authors: Granzer, T.; Weber, M.; Strassmeier, K. G. Bibcode: 2001AN....322..295G Altcode: STELLA-I will be among the first fully robotic telescopes for high-resolution Echelle spectroscopy. First light is scheduled for summer 2002. We present a first status report on the development of the computer hardware and the operating software for the STELLA facility. Title: Introduction to Volume 322 (5/6) Proceedings of the Joint-Discussion #1 and the Mini-Symposia #9 and #10 at the Joint European and National Astronomical Meeting (JENAM) for 2001 Authors: Strassmeier, K. G.; Staude, J.; Dreizler, S. Bibcode: 2001AN....322..271S Altcode: This volume of AN contains the proceedings of the Joint Discussion #1 (JD-1) ``Astronomy with Robotic Telescopes: Present and Future Projects'' and of the Mini Symposia #9 (MS-9) ``Hot subdwarfs, white dwarfs, and low-mass star evolution'', and #10 (MS-10) ``Large Telescopes for Solar Physics''. The meetings were held as part of the JENAM 2001 conference ``Five Days of Creation. Astronomy with Large Telescopes from Ground and Space'' in Munich, Germany, from September 10 through 15, 2001. Title: The STELLA project: two 1.2m robotic telescopes for simultaneous high-resolution Echelle spectroscopy and imaging photometry Authors: Strassmeier, K. G.; Granzer, T.; Weber, M.; Woche, M.; Hildebrandt, G.; Bauer, S. -M.; Paschke, J.; Roth, M. M.; Washuettl, A.; Arlt, K.; Stolz, P. A.; Schmitt, J. H. M. M.; Hempelmann, A.; Hagen, H. -J.; Ruder, H.; Palle, P. L.; Arnay, R. Bibcode: 2001AN....322..287S Altcode: We present an overview and a brief report on the status of the STELLA project (abbreviation for STELLar Activity). The STELLA-I telescope will be the first robotic telescope that feeds a bench-mounted high-resolution Echelle spectrograph with a set of 50 and 100 μm fibres and provides spectral resolutions of up to 47,000 with a 1 arcsec slit. The spectrograph is a white-pupil design located in a separated temperature-controlled room to guarantee long-term stability. The building will have a roll-off roof and is capable to host two telescopes. First light for STELLA-I is planned for summer 2002. STELLA-II is foreseen to be a photometric imaging telescope for the optical and near-infrared wavelengths and will follow in 2003. Title: The first close-up of the ``flip-flop'' phenomenon in a single star Authors: Korhonen, H.; Berdyugina, S. V.; Strassmeier, K. G.; Tuominen, I. Bibcode: 2001A&A...379L..30K Altcode: 2001astro.ph.10517K We present temperature maps of the active late-type giant FK Com which exhibit the first imagining record of the ``flip-flop'' phenomenon in a single star. The phenomenon, in which the main part of the spot activity shifts 180° in longitude, discovered a decade ago in FK Com, was reported later also in a number of RS CVn binaries and a single young dwarf. With the surface images obtained right before and after the ``flip-flop'', we clearly show that the ``flip-flop'' phenomenon in FK Com is caused by changing the relative strengths of the spot groups at the two active longitudes, with no actual spot movements across the stellar surface, i.e. exactly as it happens in other active stars. Based on the observations obtained at the Kitt Peak National Observatory, USA; the Automatic Photometric Telescope, Phoenix 10, Arizona, USA; the Nordic Optical Telescope, Observatorio Roque de los Muchachos, La Palma, Canary Islands, Spain. Title: Doppler imaging of stellar surface structure. XVII. The solar-type Pleiades star HII 314 = V1038 Tauri Authors: Rice, J. B.; Strassmeier, K. G. Bibcode: 2001A&A...377..264R Altcode: We present the first Doppler image of a solar-type G dwarf in the Pleiades open cluster. As such, the star represents the Sun at an age of approximately 100 Myr and could be an important target for further progress in magnetic-braking and angular-momentum-transport theories. Our image reconstructions were done from a full spectrum inversion with a total of 38 spectral lines but we also present single-line inversions using the prominent Li I 6707-Å line and the nearby Ca I 6717-Å line. The maps reveal cool spots at or near the pole and within the equatorial regions, in contradiction to our predictions from flux-tube modelling that only medium-latitude spots should be seen. The maps also show several warm spots near the equatorial regions but their reality needs to be confirmed. A polar spot is recovered but likely consists of several smaller spots at very high latitudes touching the visible pole instead of a big cap-like spot as seen on some RS CVn binaries. Title: Study of FK Comae Berenices. III. Photometry for the years 1993-2001 Authors: Korhonen, H.; Berdyugina, S. V.; Tuominen, I.; Andersen, M. I.; Piironen, J.; Strassmeier, K. G.; Grankin, K. N.; Kaasalainen, S.; Karttunen, H.; Mel'nikov, S. Yu.; Shevchenko, V. S.; Trisoglio, M.; Virtanen, J. Bibcode: 2001A&A...374.1049K Altcode: We present 8 years of previously unpublished photometric observations of FK Com together with the determination of the stability of the primary comparison star HD 117567. The observations have been carried out between 1993 and 2001 at four different observatories and they consist of 5157 data points in total: U(903), B(994), V(1643), R(166), I_c(573), b(461) and y(417). We also analyse this new data together with the previously published photometric observations. The V magnitude shows variations with dominant periods of about 3, 6, 12, 14 and 31 years. The short-term light curve variations appear to be caused by rearrangement of approximately constant amount of cool spots. From the values for different colours obtained during the brightest season observed, corresponding to the supposedly unspotted surface, the spectral type of FK Com is determined to be G7 III. Based on the observations obtained at Phoenix 10, Arizona, USA; Wolfgang and Amadeus, Arizona, USA; Mount Maidanak Observatory, Uzbekistan; La Palma KVA 0.6 m Cassegrain telescope, La Palma, Spain. Tables 2a-e are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http:/ /cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/374/1049 Title: Doppler imaging of stellar surface structure. XVI. A time-series analysis of the moderately-rotating K1-giant sigma Geminorum Authors: Kovári, Zs.; Strassmeier, K. G.; Bartus, J.; Washuettl, A.; Weber, M.; Rice, J. B. Bibcode: 2001A&A...373..199K Altcode: We present a simultaneous photometric and spectroscopic imaging analysis of the long-period RS CVn binary sigma Gem, covering 3.6 consecutive rotation cycles with high time resolution. From six overlapping but consecutive Doppler maps we trace the evolution of individual spots throughout the time range covered. All spots group either along a band at approximately +45 degrees latitude and a width of 30 degrees, or appear centered at the equator. No polar spot is detected. We did not find a conclusive migration pattern from the cross-correlation maps from one rotation to the next and attribute this to a masking effect of short-term spot changes. Title: VizieR Online Data Catalog: Photometry of FK Com for 1993-2001 (Korhonen+, 2001) Authors: Korhonen, H.; Berdyugina, S. V.; Tuominen, I.; Andersen, M. I.; Piironen, J.; Strassmeier, K. G.; Grankin, K. N.; Kaasalainen, S.; Karttunen, H.; Mel'Nikov, S. Yu.; Shevchenko, V. S.; Trisoglio, M.; Virtanen, J. Bibcode: 2001yCat..33741049K Altcode: We report 8 years of previously unpublished photometric observations of FK Com. The observations have been carried out between 1993 and 2001 with six different telescopes: 60 cm at Mt. Maidanak (Tashkent, Uzbekistan), Phoenix 10, Wolfgang and Amadeus located in Arizona, USA, and 20cm and 60 cm KVA on La Palma, Spain. Observations contain measurements at the following bands: Johnson U, B, V and R, Bessel R, Cousins I and Stromgren b and y. The observations are differential photometry in respect to the primary comparison star HD 117567. NOTE: Table 1 in the paper contains some small misprints in the Julian dates. Also for Wolfgang and Amadeus the number of observations given in Table1 at each band is slightly less than actually given in Table2c and Table2d. This is caused by accidentally using a limiting error of 0.01 in magnitudes when creating Table 1. In Table 2 the limiting error for Wolfgang and Amadeus is 0.02 mag, as mentioned in the paper itself. In Table2a-e 99.0000 means that no observations were available at that time at that band or that the error in the magnitude was larger than 0.02. (5 data files). Title: Doppler imaging of stellar surface structure. XV. A possible detection of differential rotation and local meridional flows on the rapidly-rotating giant HD 218153 = KU Pegasi Authors: Weber, M.; Strassmeier, K. G. Bibcode: 2001A&A...373..974W Altcode: Time-resolved Doppler images of the rapidly rotating, but long-period (25 days), giant KU Pegasi show several cool low-to-medium latitude spots as well as an asymmetric polar feature. The average spot temperature is about 700 K below the photospheric temperature of 4700 K. KU Peg is one of the most massive, and currently the most evolved, late-type star with a Doppler image. We obtained two independent images from two consecutive stellar rotations covering 50 nights with a total of 43 spectra. From a cross-correlation analysis of the two maps, we detect systematic longitudinal and latitudinal shifts that we tentatively interpret as latitude-dependent differential rotation and local meridional flows, respectively. The differential-rotation pattern is more complex than on the Sun, but on average in the sense that the poles rotate slower than the stellar equator, i.e. in the same direction and also of the same order than on the Sun. The latitudinal shifts are of the order of 0.4° day-1 towards the stellar pole and occur at longitudes of around 40° and 330°. The residual {Hα } profiles show a stationary emission component at rest wavelength and a blue-shifted absorption. The latter suggests an outward pointed velocity field with a flow velocity of approximately 35 km s-1. Title: Time-series photometric spot modeling. IV. The multi-periodic K5Ve binary V833 Tauri Authors: Oláh, K.; Strassmeier, K. G.; Kovári, Zs.; Guinan, E. F. Bibcode: 2001A&A...372..119O Altcode: We analysed all the existing photometric observations of V833 Tau and found long-term variability on time scales of ~70 years, 6.5 years and 2.4 years. Using V and IC-band data from 1990-2000, we obtained starspot surface distributions from 20 suitable light curves. We found that the spot-area changes generally follow the long-term light variations. Spot temperatures are determined for each of the datasets and an average value of 1230 K+/-270 K relative to the photosphere is found. This value agrees with previous results from TiO modeling (1330 K+/-110 K). Small scale spot temperature and area changes are recovered during 1997-1999, that we explain with a variable spot/faculae ratio. A powerful flare in UBV(RI)C was observed in 1993 November. A 10 000 K fit yielded a total emitted flare energy of more than 1034 ergs from an area of about 1.3% of the stellar surface, 60% of it in the V(RI)C bands. The flare characteristics are compared to another, 100-times smaller flare observed earlier in 1983. Title: High-Resolution Optical and Near-IR Spectropolarimetry and Spectroscopy with the LBT Authors: Strassmeier, K. G. Bibcode: 2001slbt.work..187S Altcode: No abstract at ADS Title: A study of the chromospherically active binaries UX Fornacis and AG Doradus Authors: Washuettl, A.; Strassmeier, K. G. Bibcode: 2001A&A...370..218W Altcode: This paper presents a time-series spectrum analysis of the two chromospherically active binary stars, UX Fornacis and AG Doradus. To investigate the rotational behaviour, in combination with activity in the Hα line, we obtained almost 40 high-resolution, high-S/N spectra for each system. Both binaries, UX For and AG Dor, show Hα of the primary star in absorption but filled in by chromospheric emission while the Hα line of the secondaries appear in pure emission. Line variations are seen and are approximately 5-sigma detections but are not linked to the orbital nor the rotational periods and seem to be erratic. We obtained new orbital elements for both systems and used them in combination with Hipparcos parallaxes and our Hα -spectrum synthesis to determine absolute parameters. We present the first Doppler image of the AG Dor primary using line-profile variations of the Fe i lambda 6546 line. The image reveals a cool polar feature and three equatorial spots with an average surface temperature difference, photosphere minus spots, of up to 1500 K for the polar spot and ~800 K for the equatorial spots. Since AG Dor is one of the slowest rotators (vsin i=18 km s-1 ) that has ever been Doppler imaged, we present several tests to demonstrate the external consistency of our map. Based on observations obtained at the European Southern Observatory, La Silla, Chile. Title: On the rotation period of Capella Authors: Strassmeier, K. G.; Reegen, P.; Granzer, T. Bibcode: 2001AN....322..115S Altcode: We present differential Hα and Hβ photometry of the very bright RS CVn-binary Alpha Aurigae (Capella) obtained with the Vienna automatic photoelectric telescope in the years 1996 through 2000. Low-level photometric variations of up to 0m.04 are detected in Hα. A multifrequency analysis suggests two real periods of 106 +/- 3 days and 8.64 +/- 0.09 days, that we interpret to be the rotation periods of the cool and the hot component of the Capella binary, respectively. These periods confirm that the hotter component of Capella rotates asynchronously, while the cooler component appears to be synchronized with the binary motion. The combined Hα data possibly contains an additional period of 80.4 days that we, however, believe is either spurious and was introduced due to seasonal amplitude variations or stems from a time-variable circumbinary mass flow. The rotational periods result in stellar radii of 14.3 +/- 4.6 Rsun and 8.5 +/- 0.5 Rsun for the cool and hot component, respectively, and are in good agreement with previously published radii based on radiometric and interferometric techniques. The long-period eclipsing binary Aurigae served as our check star, and we detected complex light variations outside of eclipse of up to 0m.15 in Hα and 0m.20 in Hβ. Our frequency analysis suggests the existence of at least three significant periods of 132, 89, and 73 days. One of our comparison stars (HD 33167, F5V) was discovered to be a very-low amplitude variable with a period of 2.6360 +/- 0.0055 days. Title: Differential Rotation Analysis of six Long-period K-giants Authors: Weber, M.; Strassmeier, K. G.; Washuettl, A. Bibcode: 2001AGM....18..P89W Altcode: 2001AGAb...18R.179W We computed Doppler maps for the stars IL Hya (K0III-IV, Prot=12.9 days), HK Lac (K0III, 24.4 days), HD 218153(K0III, 24.96 days), HD 208472 (K0III, 22.6 days), IM Peg (K1III, 24.6 days), and II Peg (K2IV, 6.7 days) based on observations taken at the National Solar Observatory (NSO) with the McMath-Pierce main telescope using the stellar spectrograph from October 1996 to January 1997 and, in the case of IL Hya, also at Kitt Peak National Observatory (KPNO) from March to May 2000. Depending on the rotational period of the star, two (HD 218153) to five (II Peg) independent Doppler maps were obtained. These consecutive Doppler maps were cross-correlated, which resulted in ccf-maps that show the spot changes on the stellar surface from one map to the other (typically with a time difference of one to 1.5 stellar rotations). We then tried to fit a solar-like differential rotation law (Ω(b) = Ω0 - Ω1 sin2 b) to the cross-correlation function (ccf) to get a quantitative measure of the differential rotation. In this poster, we present the full set of, so far unpublished, maps of our long-term Doppler imaging program on K giants. Title: MUSICOS Observations of the Chromospherically Active Binary Star EI Eridani Authors: Washuettl, A.; Strassmeier, K.; Foing, B. Bibcode: 2001AGM....18..P50W Altcode: 2001AGAb...18Q.160W We present results on spectroscopic observations of the rapidly-rotating active binary star EI Eridani obtained during the MUSICOS multi-site campaign in 1998. Seven sites around the globe were involved in order to achieve a surface image within a few rotations as EI Eridani's critical rotation period of 1.945 days makes it impossible to obtain time-resolved images from a single site. The data were split into groups in order to achieve consecutive, independent Doppler Images. Furthermore, simultaneous photospheric and chromospheric activity monitoring was carried out. Title: Doppler Imaging as a Test for Binary Star Formation Theories Authors: Strassmeier, Klaus G. Bibcode: 2001IAUS..200..305S Altcode: Photospheric Doppler images for both stellar components of the double-lined spectroscopic binary V824 Ara reveal surface temperature inhomogeneities of up to 1800 K on both stars. The absolute brightness and the mass of the two stars suggest that they are very close to the main sequence -- but not yet on the ZAMS -- if an inclination of the orbital plane (and rotational axes) of 52 degrees is adopted as suggested by the Doppler imaging. Since both stars are active, we solve for the inclinations of the rotation axes of both stellar components separately and emphasize that it can be used to test coplanarity predictions from binary star-formation theories. We find that the spin inclinations for the individual components of V824 Ara agree to within their uncertainties. Title: The Multiple Periods and Spot Temperatures of V833 Tau (CD-ROM Directory: contribs/olah1) Authors: Oláh, K.; Strassmeier, K. G. Bibcode: 2001ASPC..223.1030O Altcode: 2001csss...11.1030O No abstract at ADS Title: Latest Results in Doppler Imaging (CD-ROM Directory: contribs/strass1) Authors: Strassmeier, K. G. Bibcode: 2001ASPC..223..271S Altcode: 2001csss...11..271S No abstract at ADS Title: Magnetic Activity in Binary Stars Authors: Strassmeier, Klaus G. Bibcode: 2001LNP...563...48S Altcode: 2001bist.conf...48S "Activity" is a term that came originally from solar astrophysics, where astronomers refer to the quiet Sun and the active Sun depending on whether our star is in a state of sunspot minimum or maximum, respectively. More physically, we mean with activity all phenomena inside and outside of a star that are related to its magnetic field, e.g. the rise of flux tubes in a stellar convection zone and their appearance as spots and plages on the stellar surface or magnetically induced particle acceleration and its braking effect on the stellar rotation, or simply the interplay between a magnetic field and its surrounding plasma. Bear three things in mind, a magnetic field plays a key role in many astrophysical processes, its mathematical treatment can be somewhat complicated and, therefore, is always the first process that is neglected. The stellar magnetic field is intimately related to stellar rotation and the quest to understand stellar magnetic activity is thus always a quest to understand stellar rotation. In this lecture, we will focus on the many aspects of stellar rotation and compare the situation of binary stars with their single star counterparts whenever appropriate. I will concentrate on the available observations and their interpretations even though that fundamental progress will also come from the detailed inclusion of magnetic fields in, e.g., radiation hydrodynamics. We emphasize how important considerations of magnetic activity will become once the new generation of large telescopes is turned to late-type binary stars. Parts of the topics in this lecture are adapted and updated from my reference (111) which appeared in German language. I have tried, however, to avoid topics that were already covered in the excellent review by Guinan & Giménez (36). Title: Automation Hardware & Software for the STELLA Robotic Telescope Authors: Weber, M.; Granzer, Th.; Strassmeier, K. G. Bibcode: 2001AGM....18.P233W Altcode: The STELLA telescope (a joint project of the AIP, Hamburger Sternwarte and the IAC) is to operate in fully robotic mode, with no human interaction necessary for regular operation. Thus, the hardware must be kept as simple as possible to avoid unnecessary failures, and the environmental conditions must be monitored accurately to protect the telescope in case of bad weather. All computers are standard PCs running Linux, and communication with specialized hardware is done via a RS232/RS485 bus system. The high level (java based) control software consists of independent modules to ease bug-tracking and to allow the system to be extended without changing existing modules. Any command cycle consists of three messages, the actual command sent from the central node to the operating device, an immediate acknowledge, and a final done message, both sent back from the receiving device to the central node. This reply-splitting allows a direct distinction between communication problems (no acknowledge message) and hardware problems (no or a delayed done message). To avoid bug-prone packing of all the sensor-analyzing software into a single package, each sensor-reading and interaction with other sensors is done within a self-contained thread. Weather-decision making is therefore totally decoupled from the core control software to avoid dead-locks in the core module. Title: The STELLA Project: a 1.2m Robotic Telescope for High-resolution Echelle Spectroscopy Authors: Strassmeier, K. G.; Granzer, T.; Weber, M.; Woche, M.; Hildebrandt, J.; Arlt, K.; Washuettl, A.; Bauer, S. -M.; Paschke, J.; Roth, M.; Schmitt, J. H. M. M.; Hempelmann, A.; Hagen, A. Bibcode: 2001AGM....18.P232S Altcode: In this poster, we present a brief overview and report on the status of the STELLA project (abbreviation for STELLar Activity; see also poster by Weber et al.). The STELLA telescope at the Teide Observatory on the Island of Tenerife will be the first robotic telescope that feeds a bench-mounted echelle spectrograph with a set of 50 and 100μm fibres and provides resolutions of between 50,000 and 25,000. The spectrograph is a FEROS-like design and will be located in a separated temperature-controlled room within the STELLA building to guarantee long-term stability. The building will be a roll-off roof building capable of hosting two telescopes. First light for STELLA-1 is planned for fall 2002. Title: Temperature Surface Imaging as a Tracer for Stellar Magnetic Fields Authors: Strassmeier, K. G.; Rice, J. B.; Granzer, T.; Weber, M. Bibcode: 2001ASPC..248..223S Altcode: 2001mfah.conf..223S No abstract at ADS Title: Doppler Images of HD 218153 and HK Lac (CD-ROM Directory: contribs/weber) Authors: Weber, M.; Washuettl, A.; Strassmeier, K. G. Bibcode: 2001ASPC..223.1314W Altcode: 2001csss...11.1314W No abstract at ADS Title: Doppler Imaging from Artificial Data. Testing the Temperature-Inversion Code TempMap (CD-ROM Directory: contribs/strass3) Authors: Strassmeier, K. G.; Rice, J. B. Bibcode: 2001ASPC..223.1296S Altcode: 2001csss...11.1296S No abstract at ADS Title: Doppler Imaging of the Pre-Main-Sequence Binary V824 Ara = HD 155555 (CD-ROM Directory: contribs/strass4) Authors: Strassmeier, K. G.; Rice, J. B. Bibcode: 2001ASPC..223.1302S Altcode: 2001csss...11.1302S No abstract at ADS Title: Rapid Spot Changes on the RS CVn Binary V711 Tau = HR 1099 (CD-ROM Directory: contribs/bartus) Authors: Bartus, J.; Strassmeier, K. G. Bibcode: 2001ASPC..223.1189B Altcode: 2001csss...11.1189B No abstract at ADS Title: The Vienna-KPNO Search for Doppler-imaging Candidates. Photometric Results (CD-ROM Directory: contribs/granzer1) Authors: Granzer, Th.; Strassmeier, K. G. Bibcode: 2001ASPC..223.1226G Altcode: 2001csss...11.1226G No abstract at ADS Title: On the Rotation Period of Capella (CD-ROM Directory: contribs/strass5) Authors: Strassmeier, K. G.; Reegen, P.; Granzer, Th. Bibcode: 2001ASPC..223.1069S Altcode: 2001csss...11.1069S No abstract at ADS Title: STELLA: two new 1.2 m Robotic Telescopes for Monitoring Stellar Activity Authors: Strassmeier, Klaus G. Bibcode: 2001AGM....18JD102S Altcode: STELLA (abbreviation for STELLar Activity) is a long-term project for monitoring activity tracers on cool stars with fully robotic telescopes. The first telescope, STELLA-1, feeds a bench-mounted echelle spectrograph with a set of 50-100 μm fibres according to resolutions of 50,000 to 25,000. The spectrograph is located in a separated temperature controlled room to guarantee long-term stability. A second telescope, STELLA-2, with identical dimensions, is foreseen as a photometric/imaging telescope at the same site. STELLA-1 is a joint venture of the Astrophysical Institute Potsdam (AIP) and the Hamburger Sternwarte, STELLA-2 is a joint project of the AIP with the University of Tübingen, both in close collaboration with the Instituto de Astrofísica de Canarias. STELLA will be located at the Teide Observatory on Tenerife. First light for STELLA-1 is planned for fall 2002. I will briefly outline the technical and operational highlights. Title: Latest Doppler images of the RS CVn Binary EI Eridani (CD-ROM Directory: contribs/washuet) Authors: Washuettl, A.; Strassmeier, K. G.; Collier-Cameron, A. Bibcode: 2001ASPC..223.1308W Altcode: 2001csss...11.1308W No abstract at ADS Title: Star Spot Patterns on Young Stars: Theoretical Approach (CD-ROM Directory: contribs/granzer2) Authors: Granzer, Th.; Caligari, P.; Schüssler, M.; Strassmeier, K. G. Bibcode: 2001ASPC..223.1232G Altcode: 2001csss...11.1232G No abstract at ADS Title: The Vienna-KPNO Search for Doppler-Imaging Candidates. Spectroscopic Results (CD-ROM Directory: contribs/strass2) Authors: Strassmeier, K. G.; Washuettl, A.; Granzer, Th.; Scheck, M.; Weber, M. Bibcode: 2001ASPC..223.1291S Altcode: 2001csss...11.1291S No abstract at ADS Title: Doppler imaging from artificial data. Testing the temperature inversion from spectral-line profiles Authors: Rice, J. B.; Strassmeier, K. G. Bibcode: 2000A&AS..147..151R Altcode: We present extensive numerical tests of our temperature-based image reconstruction code TempMap. Two test cases that represent a rapidly-rotating low-inclination star and a moderately-rotating high-inclination star are used for the forward problem. Tests are then made to recover the original input map and include data errors and input-parameter errors. The former include variations of photon noise, continuum displacement, continuum slopes, scattered light in the spectrograph, and phase gaps with and without continuum information. The input-parameter tests include the confusion in the recovery of hot versus cool spots, uncertainties of atmospheric parameters such as radial-tangential macroturbulence and gravity, and the influence of line strength and line damping. In general, we find that the geometric information is less dependent on photon noise and on input errors than the temperature information. Our test inversions also show that, at the vsin i of these test cases, no significant gain in image quality is achieved once S/N of 300:1 is surpassed. Title: The BF Aurigae system. A close binary at the onset of mass transfer Authors: Kallrath, J.; Strassmeier, K. G. Bibcode: 2000A&A...362..673K Altcode: Because the question of the mass ratio of the early-type system BF Aur has not yet fully been clarified, we present and analyse new UBV photometry and nearly contemporaneous radial velocity observations. From a simultaneous least squares analysis of the photometric light curves and the new radial velocity curves we derive a mass ratio of q=1.048+/- 0.02. With even much more accurate photometric and spectroscopic data the mass ratio remains weakly defined. The resulting stellar parameters are consistent with line ratios derived from old and our new spectra and available Strömgren indices. We confirm earlier conclusions that BF Aur is detached and that the more massive component is almost filling its Roche lobe. New data indicating a period change support the interpretation that mass exchange has already started or is about to start. Tables A1-A5 are available electronically only at the CDS via anonymous ftp (130.79.128.5) ftp://cdsarc.u-strasbg.fr or http://cdsweb.u-strasbg.fr/index.htm Title: Study of FK Comae Berenices --- II. Spot evolution from 1994 to 1997 Authors: Korhonen, H.; Berdyugina, S. V.; Hackman, T.; Strassmeier, K. G.; Tuominen, I. Bibcode: 2000A&A...360.1067K Altcode: 2000astro.ph..7088K We present new surface (Doppler) images of the late-type single giant FK Com for June-July 1996, July-August 1996, April 1997 and June 1997. These images are compared with the previously published images from 1994 and 1995. The consecutive maps are cross- correlated to see the possible migration of the spots and the effects of differential rotation. The cross-correlation confirms an average longitudinal spot migration of 0.22 ± 0.03 in phase within a year. This movement is probably an artifact caused by a difference between the accepted rotation period and the real photometric period for these years. If this is true, then the photometric rotation period for these years is 2.d4037 ± 0.0005. Measurements from these four years and six maps limit the surface differential rotation to α = 0.0001 ± 0.0002, where α is the difference between polar and equatorial angular velocities relative to the equatorial angular velocity. Based on the observations obtained at the Nordic Optical Telescope, Observatorio Roque de los Muchachos, La Palma, Canary Islands, Spain; the National Astronomical Observatory, Rozhen, Bulgaria; the Kitt Peak National Observatory, USA; the Automatic Photometric Telescope, Phoenix 10, Arizona, USA. Title: Doppler imaging of stellar surface structure --- XIV. The double-lined pre-main-sequence binary V 824 Arae = HD 155555 Authors: Strassmeier, K. G.; Rice, J. B. Bibcode: 2000A&A...360.1019S Altcode: Photospheric Doppler images for both stellar components of the double-lined pre-main-sequence binary V 824 Ara reveal surface temperature inhomogeneities of up to 1800 K on both stars. The spot geometry on the hotter primary is dominated by an elongated, tilted, equatorial feature but our maps from two spectral regions consistently also show a polar spot cooler by 1700 K. The secondary star has spots mainly at low and very high latitudes but not a full-sized polar cap. A flux-tube simulation with appropriate stellar models for V 824 Ara suggests that any polar or high-latitude spot must have formed after flux-tube emergence. Generally, the low-latitude spots on both stellar components appear to be mostly concentrated on the hemispheres turned away from each other while the asymmetry of the polar spot on the primary points in the direction of the orbital motion. We present new radial velocities and use them to re- evaluate the orbital elements and to derive absolute parameters for both stellar components. The absolute brightness and mass of the two stars suggest that they are very close to the main sequence - but not yet on the ZAMS - if an inclination of the orbital plane (and rotational axes) of 52̂ is adopted as suggested by the Doppler imaging. Since both stars are active, we solve for the inclinations of both stellar components separately and find that the values agree to within their uncertainties. Based on observations collected at the European Southern Observatory Title: Wolfgang-Amadeus: the University of Vienna twin robotic photoelectric telescopes Authors: Strassmeier, Klaus G.; Granzer, Thomas; Boyd, Louis J.; Epand, Donald H. Bibcode: 2000SPIE.4011..157S Altcode: We describe the operations model for our two robotic photoelectric telescopes and give a brief status report after more than three years of routine operation in southern Arizona. The telescopes operate fully unattended, also the observatory itself is automatic. A site-control computer monitors weather sensors and operates the roof while the telescope control computers operate the photometers and accept input files from and provides nightly observations to the astronomer in Vienna. In the first three years of operation a total of 3.3 million individual scientific measurements were made. Title: VizieR Online Data Catalog: BF Aur UBV photometry (Kallrath+, 2000) Authors: Kallrath, J.; Strassmeier, K. G. Bibcode: 2000yCat..33620673K Altcode: Because the question of the mass ratio of the early-type system BF Aur has not yet fully been clarified, we present and analyse new UBV photometry and nearly contemporaneous radial velocity observations. From a simultaneous least squares analysis of the photometric light curves and the new radial velocity curves we derive a mass ratio of q=1.048+/-0.02. With even much more accurate photometric and spectroscopic data the mass ratio remains weakly defined. The resulting stellar parameters are consistent with the line ratios derived from old and our new spectra and available Stroemgren indices. We confirm earlier conclusions that BF Aur is detached and that the more massive component is almost filling its Roche lobe. New data indicating a period change support the interpretation that mass exchange has already started or is about to start. (5 data files). Title: Doppler imaging of stellar surface structure. XIII. The flaring RS CVn-binary HD 291095 = V1355 Orionis Authors: Strassmeier, K. G. Bibcode: 2000A&A...357..608S Altcode: We present the first Doppler images of the newly discovered RS CVn binary HD 291095. The star is a synchronuously rotating subgiant in a 4-day spectroscopic binary with an unseen companion and is particularly interesting because it is one of the few evolved stars that show large flares. Three consecutive years of moderate-resolution KPNO spectra and continuous VI and by photometry with our APTs reveal a large, cool, and long-living asymmetric polar spot. Its temperature is approximately 1100 K below the average photospheric temperature. Several low latitude and even equatorial spots were evident at the same time. We interpret this latitudinal spot bimodality to be due to a combination of poleward meridional circulation and more frequent magnetic reconnections near the pole than near the equator. During the 1998 Doppler-imaging observations, a strong flare in Hα was detected which coincided with a meridian passage of the most asymmetric part of the polar spot. We estimate a total flare energy of 5x1034 erg typical for flares on very active RS CVn systems. No photospheric heating is evident in our surface maps from optically thin spectral lines of various temperature sensitivities. Title: Multiperiodic light variations of active stars Authors: Oláh, K.; Kolláth, Z.; Strassmeier, K. G. Bibcode: 2000A&A...356..643O Altcode: We studied the long-term light behaviour of ten rapidly-rotating active stars (LQ Hya, V833 Tau, EI Eri, V711 Tau, BY Dra, HU Vir, IL Hya, VY Ari, HK Lac, IM Peg) with Fourier analysis. Using photometric databases of up to 30 years in length, we search for periodic or quasi-periodic long-term variations of the overall light levels. Out of the ten stars studied, nine show cyclic variability and six of those seem to vary on two or multiple time-scales. Using additional data from the literature, we found that cycle lengths were generally longer for stars with longer rotation periods. The inverse Rossby numbers of these stars show a correlation with omega cyc/Omega (= Prot/Pcyc) calculated from the shortest cycle length. The cycle lengths of several stars agree well with other types of cycles determined earlier. Using artificial test data, we found that the cyclic variation of the average light level is determined by the change in the spot/plage coverage alone and that spot migration does not play a significant role in the shape or length of the long-term brightness changes. Title: The Vienna-KPNO search for Doppler-imaging candidate stars. I. A catalog of stellar-activity indicators for 1058 late-type Hipparcos stars Authors: Strassmeier, K.; Washuettl, A.; Granzer, Th.; Scheck, M.; Weber, M. Bibcode: 2000A&AS..142..275S Altcode: We present the results from a spectroscopic Ca ii H&K survey of 1058 late-type stars selected from a color-limited subsample of the Hipparcos catalog. Out of these 1058 stars, 371 stars were found to show significant H&K emission, most of them previously unknown; 23% with strong emission, 36% with moderate emission, and 41% with weak emission. These spectra are used to determine absolute H&K emission-line fluxes, radial velocities, and equivalent widths of the luminosity-sensitive Sr ii line at 4077 Ä. Red-wavelength spectroscopic and Strömgren y photometric follow-up observations of the 371 stars with H&K emission are used to additionally determine the absolute Hα -core flux, the lithium abundance from the Li i 6708 Å equivalent width, the rotational velocity vsin i, the radial velocity, and the light variations and its periodicity. The latter is interpreted as the stellar rotation period due to an inhomogeneous surface brightness distribution. 156 stars were found with photometric periods between 0.29 and 64 days, 11 additional systems showed quasi-periodic variations possibly in excess of ~50 days. Further 54 stars had variations but no unique period was found, and four stars were essentially constant. Altogether, 170 new variable stars were discovered. Additionally, we found 17 new SB1 (plus 16 new candidates) and 19 new SB2 systems, as well as one definite and two possible new SB3 systems. Finally, we present a list of 21 stars that we think are most suitable candidates for a detailed study with the Doppler-imaging technique. Tables A1--A3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html Title: Distribution of starspots on cool stars. II. Pre-main-sequence and ZAMS stars between 0.4 Msun and 1.7 Msun Authors: Granzer, Th.; Schüssler, M.; Caligari, P.; Strassmeier, K. G. Bibcode: 2000A&A...355.1087G Altcode: We study the dynamics of magnetic flux tubes in young stars with masses between 0.4 Msun and 1.7 Msun and for rotation rates between 0.25 Omegasun and 63 Omegasun . The resulting latitudinal emergence patterns at the stellar surface are compared with observed distributions of starspots in stellar latitude. The stellar models considered cover the range of evolutionary stages from shortly after the Hayashi phase down to the ZAMS, i.e. from the classical and weak-line T Tauri stars to the alpha -Persei stars. We use numerical simulations to follow the evolution of magnetic flux tubes from their origin at the bottom of the convection zone up to near-surface layers. We find a strong increase of emergence latitude with increasing rotation rate, a moderate decrease with increasing stellar mass, and a stronger decrease with stellar age. At very early evolutionary stages, when the central radiative zone is still quite small, we find magnetic flux emergence both in low latitudes as well as in the polar areas. High-latitude emergence is predicted in slightly more evolved pre-main-sequence and young main-sequence stars, but truly polar spots on these stars require an additional transport mechanism acting after magnetic flux emergence at the surface, probably meridional circulation or poleward slip of the `anchored' part of the erupted flux tubes. We discuss our findings in the light of the results obtained from Doppler-imaging studies. Title: VizieR Online Data Catalog: Stellar activity of late-type stars (Strassmeier+ 2000) Authors: Strassmeier, K. G.; Washuettl, A.; Granzer, T.; Scheck, M.; Weber, M. Bibcode: 2000yCat..41420275S Altcode: We present the results from a spectroscopic CaII H&K survey of 1058 late-type stars selected from a color-limited subsample of the Hipparcos (Cat. <I/239>) catalog. Out of these 1058 stars, 371 stars were found to show significant H&K emission, most of them previously unknown; 23% with strong emission, 36% with moderate emission, and 41% with weak emission. These spectra are used to determine absolute H&K emission-line fluxes, radial velocities, and equivalent widths of the luminosity-sensitive Sr II line at 4077Å. Red-wavelength spectroscopic and Stroemgren y photometric follow-up observations of the 371 stars with H&K emission are used to additionally determine the absolute Hα-core flux, the lithium abundance from the Li I 6708Å equivalent width, the rotational velocity vsini, the radial velocity, and the light variations and its periodicity.

(3 data files). Title: Doppler imaging of stellar surface structure. XII. Rapid spot changes on the RS CVn binary V711 Tauri = HR 1099 Authors: Strassmeier, K. G.; Bartus, J. Bibcode: 2000A&A...354..537S Altcode: We present a time series of Doppler images of the RS CVn binary V711 Tauri from spectra taken during 57 consecutive nights in November and December 1996. VRI-band APT photometry throughout the entire observing season is used to support the Doppler imaging. A set of altogether 37 overlapping images from the Ca i-6439 line allows us to trace the latitudinal and longitudinal migration of individual starspots and their morphological evolution. We confirm the poleward migration scenario discovered by Vogt & Hatzes (\cite{vog:hat}) and obtain an average latitudinal migration rate of +0.41+/-0.23 (rms) °/day. Of the five spots detected, one was migrating clockwise and one counter clockwise with respect to the orbital period. One feature possibly changed its direction of migration. The two dominating polar features remained at their respective longitudes. Therefore, we are unable to fully attribute the poleward migration to differential rotation and suggest that a combination of differential rotation, meridional circulation, and local crosstalk between starspots causes the observed migration pattern. For one low-latitude spot, the latitudinal migration was briefly interrupted and seen to reverse before it resumed its poleward migration. We possibly witnessed the merging of two spots after they got too close to each other. One spot became significantly cooler shortly before it merged with the bigger and already cooler polar spot, suggesting that some flux exchange took place likely due to a partial reconnection of their magnetic field lines. The polar spot appeared in our images as a non-axisymmetric feature barely covering the actual stellar rotation pole and was not a cap-like feature as seen in several previous maps. Relative spot temperatures varied between 400 K for the weakest features and 1100 K for the main polar spot. Title: Doppler imaging of magnetically-active stars Authors: Strassmeier, Klaus G.; Weber, Michael; Washuettl, Albert; Granzer, Thomas; Pichler, Thomas Bibcode: 2000noao.prop...44S Altcode: Recent images from our KPNO Coude-feed program of long-period spotted giant stars showed the largest surface spots yet discovered. Spots sixty times larger than the entire Sun were recorded. In this proposal, we will attempt to continue the mapping of further candidate stars. The new targets are selected from the just finished Vienna-KPNO Ca II H& K survey (also done at the Coude feed) which discovered 371 new active stars and produced twenty new Doppler-imaging candidates. Some of these stars are the targets of this proposal. If the proposed targets of M-K class IV and III indeed also show such large spots at intermediate and/or high latitudes as suggested from our previous images, the solar-based flux-tube model of Schussler et al. for the origin of starspots must be reconsidered. Title: Doppler imaging of HD 218153 and HK Lac Authors: Weber, M.; Strassmeier, K. G.; Washuettl, A. Bibcode: 2000ASPC..198..495W Altcode: 2000scac.conf..495W No abstract at ADS Title: Doppler Imaging of Cool Dwarf Stars Authors: Strassmeier, K. G. Bibcode: 2000vlms.conf..215S Altcode: No abstract at ADS Title: The Vienna-KPNO search for Doppler-imaging candidate stars. I. First spectroscopic results Authors: Strassmeier, K. G.; Washuettl, A.; Granzer, Th.; Scheck, M.; Weber, M. Bibcode: 2000ASPC..198..487S Altcode: 2000scac.conf..487S No abstract at ADS Title: The Vienna-KPNO search for Doppler-imaging candidate stars. II. First photometric results Authors: Granzer, Th.; Strassmeier, K. G. Bibcode: 2000ASPC..198..491G Altcode: 2000scac.conf..491G No abstract at ADS Title: A temperature calibration for MK-class III giants from high-resolution spectral line-depth ratios Authors: Strassmeier, K. G.; Schordan, P. Bibcode: 2000AN....321..277S Altcode: A high-resolution spectroscopic survey in the 6380-6460 Å \ region of 224 slowly-rotating M-K class III giants is presented. Spectral line-depth ratios are calibrated against effective temperature obtained from B-V and V-I color indices in the range 3200-7500 K (M6-A9). A table of polynomial coefficients for 12 line-ratio-T_eff relations can be used to derive T_eff of F-M stars to within 33 K (rms), and of early-F and mid-to-late M stars to within 77-106 K (rms). Title: VizieR Online Data Catalog: Photometric monitoring of 47 late-type stars (Strassmeier+, 1999) Authors: Strassmeier, K. G.; Serkowitsch, E.; Granzer, T. Bibcode: 1999yCat..41400029S Altcode: We present continuous multicolor photometry for 47 stars from October 1996 through June 1997. Altogether, 7073 V(RI)c, UBV, and by data points, each the average of three individual readings, were acquired with three automatic photoelectric telescopes (APTs) at Fairborn Observatory in southern Arizona. Most of our targets are chromospherically active single and binary stars of spectral type G to K but there are also four pre-main-sequence objects and three pulsating stars in our sample. The light variability is generally due to rotational modulation of an asymmetrically spotted stellar surface and therefore precise rotational periods and their seasonal variations are determined from Fourier analysis. We also report on photometric variations of γ CrB (A0V) with a period of 0.44534 days. All data are available in numerical form.

(6 data files). Title: Starspot photometry with robotic telescopes. UBV(RI)_C and by light curves of 47 active stars in 1996/97 Authors: Strassmeier, K. G.; Serkowitsch, E.; Granzer, Th. Bibcode: 1999A&AS..140...29S Altcode: We present continuous multicolor photometry for 47 stars from October 1996 through June 1997. Altogether, 7073 V(RI)_c, UBV, and by data points, each the average of three individual readings, were acquired with three automatic photoelectric telescopes (APTs) at Fairborn Observatory in southern Arizona. Most of our targets are chromospherically active single and binary stars of spectral type G to K but there are also four pre-main-sequence objects and three pulsating stars in our sample. The light variability is generally due to rotational modulation of an asymmetrically spotted stellar surface and therefore precise rotational periods and their seasonal variations are determined from Fourier analysis. We also report on photometric variations of gamma CrB (A0V) with a period of 0.44534 days. All data are available in numerical form. All data are available from CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html Title: Doppler imaging of stellar surface structure. XI. The super starspots on the K0 giant HD 12545: larger than the entire Sun Authors: Strassmeier, K. G. Bibcode: 1999A&A...347..225S Altcode: The active K0 giant HD 12545 is the star with the largest starspots ever observed. We report a record light-curve amplitude of 0\fm63 in V and 0\fm17 in V-I in January 1998. At the same time, HD 12545 was at its brightest magnitude since the discovery of its light variability in 1985. We present the first Doppler image of HD 12545 from observations during this state of high-amplitude light variability and find that the star exhibits one cool high-latitude spot of gigantic dimensions (~12x20 solar radii, i.e. 60 times the extension of the largest sunspot group or 10,000 times larger areal coverage). Furthermore, our map shows one smaller cool spot and one equatorial warm (bright) spot. The warm spot is situated approximately 180 degr from the large cool spot in the opposite hemisphere and is the cause of the exceptionally large light-curve amplitude and the stellar brightening. Within our model, no light-curve nor a reasonable line-profile solution with only cool spots was possible. Surprisingly, the fact that HD 12545 is brighter at a time of high spot activity is in agreement with solar analogy. Our data also allow to refine the orbital elements of HD 12545 and we use the Hipparcos parallax to determine absolute astrophysical quantities for this rapidly rotating K giant. Title: Doppler imaging of stellar surface structure. X. The FK Comae-type star HD 199178 = V 1794 Cygni Authors: Strassmeier, K. G.; Lupinek, S.; Dempsey, R. C.; Rice, J. B. Bibcode: 1999A&A...347..212S Altcode: Doppler imaging is used to derive the surface temperature distribution of the FK Comae star HD 199178 for five observing epochs between 1988 and 1997. Our maps are mainly based on Ca i 6439-Ä line profiles and simultaneous and contemporary BV and VI photometry. All images of HD 199178 are characterized by a large polar spot and several low-latitude spots with an average surface temperature difference, photosphere minus spots, of 710+/-260(rms) K for the equatorial spots, ~1700 K for the polar spot, and 1300+/-300(rms) K for the polar-spot appendages. The lifetime of some of the low-latitude spots was found to be as short as one month or even less. The lifetime of the polar spot and most of its very cool appendages must exceed the time of our observations, i.e. 9 years or approximately 1000 stellar rotations, and could be as long as 12 years since its discovery by Vogt in 1985. Two consecutive Doppler maps in 1989 show no evidence for differential surface rotation, nor is there substantial evidence for the existence of active longitudes in any of our five images. Instead, we suspect that most of the time variability of the surface features on HD 199178 is short term and possibly chaotic in origin. We conclude that spot lifetimes estimated from the timing of light-curve minima could lead to grossly overestimated lifetimes of individual spots. With the aid of our optical spectra and the Hipparcos parallax, we redetermine the absolute stellar parameters of HD 199178 and confirm it to be a single G5III-IV star and find 1.65 M_sun and 11 L_sun with T_eff~ 5450 K, log g=2.5, and solar abundances. Title: Wechselvolles Antlitz: Flecken auf der Sonne und auf Sternen. Authors: Strassmeier, K. G. Bibcode: 1999S&WSp...4...42S Altcode: No abstract at ADS Title: Orbital elements and physical parameters of ten chromospherically active binary stars Authors: Fekel, F. C.; Strassmeier, K. G.; Weber, M.; Washuettl, A. Bibcode: 1999A&AS..137..369F Altcode: Orbital elements have been determined for 10 chromospherically active binaries from a combination of new velocities and velocities in the literature. First orbits for three binaries, HD 33363, HD 152178, and HD 208472, are presented, as well as updated orbits for seven other binaries. Two of the latter systems, LN Peg and HD 106225 were discovered to be triple, and both short- and long-period orbits have been computed for each. Fundamental properties have been determined for the chromopherically active primary in each system. Appendix A and Tables A1 to A15 only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html Title: VizieR Online Data Catalog: 10 active binary radial velocities (Fekel+, 1999) Authors: Fekel, C.; Strassmeier, K. G.; Weber, M.; Washuettl, A. Bibcode: 1999yCat..41370369F Altcode: Orbital elements have been determined for 10 chromospherically active binaries from a combination of new velocities and velocities in the literature. First orbits for three binaries, HD 33363, HD 152178, and HD 208472, are presented, as well as updated orbits for seven other binaries. Two of the latter systems, LN Peg and HD 106225 were discovered to be triple, and both short- and long-period orbits have been computed for each. Fundamental properties have been determined for the chromospherically active primary in each system. (2 data files). Title: Evolved, single, slowly rotating ... but magnetically active. The G8-giant HR 1362 = EK Eridani revisited Authors: Strassmeier, K. G.; Stȩpień , K.; Henry, G. W.; Hall, D. S. Bibcode: 1999A&A...343..175S Altcode: We rediscuss the unusual case of the slowly rotating late-type giant HR 1362, which exhibits a very unusual high level of magnetic activity. New BVRI photometry from two robotic telescopes from 1991 through 1998 together with previously published photometric data gives a very precise photometric period of 306.9+/-0.4 days. With the aid of high-resolution (R=120,000) optical spectra and the Hipparcos parallax we redetermine the absolute parameters of HR 1362 and find it to be a single G8IV-III star of 14 L_sun and a mass of 1.85 M_sun with T_eff=5125 K, log g=3.25, and solar abundances. Lithium is not significantly different from solar and we obtain log n(Li)=1.14 from a detailed spectrum synthesis including both isotopes at 6708 Angstroms. Vsin i and macroturbulence are determined from fits of disk-integrated models to the observed line profiles as well as their Fourier transforms and are 1.5+/-0.5 km s(-1) \ and ~5 km s(-1) , respectively. The minimum radius from vsin i and P_rot is only then in agreement with the spectral classification and the bolometric luminosity from the Hipparcos parallax if the inclination of the stellar rotation axis is nearly 90°. We concur with the arguments of Stȩpień (\cite{step}) that HR 1362 is an evolved Ap star, and therefore the magnetic field is possibly of galactic origin rather than dynamo generated. Title: a Survey for Rapidly-Rotating ca II H& K Emission-Line Stars Authors: Strassmeier, Klaus G.; Washuettl, Albert; Granzer, Thomas Bibcode: 1999noao.prop...22S Altcode: The existence of ultra-rapidly rotating G-K stars in open clusters has been explained by a loss of braking due to dynamo saturation. However, there is an alternative explanation, namely that these stars all have their magnetic fields concentrated in polar spots and thus have no torque arms for efficient braking. In the present program, we propose to search for new G-K rapid rotators in the field (because they are much brighter) - especially in the Hertzsprung gap - by means of a spectroscopic survey of Ca II H& K emission in a brightness and color-limited sample of Hipparcos stars. Strong Ca II H& K emission is indirectly a sign of rapid rotation and an extended sample, especially of evolved G-K stars, is urgently needed to test the polar- spot hypothesis. In the first part of this survey, carried out with the coudee feed in September 1998, covering right ascensions between 18^h and 5^h, we identified 118 new H& K emission line stars out of 469 targets observed. The present proposal aims to complete the sky coverage for right ascensions between 6^h and 17^h. Title: Doppler imaging of stellar surface structure. IX. A high-resolution image of the weak-lined T Tauri star HDE 283572 = V987 Tauri Authors: Strassmeier, K. G.; Rice, J. B. Bibcode: 1998A&A...339..497S Altcode: We present a Doppler image of the T Tauri star HDE 283572 from a set of high-quality spectroscopic line profiles and simultaneous multicolor photometry from October 1997. Additional photometry throughout the entire observing season was obtained with a robotic telescope and is used to determine the precise photometric period of 1.5495+/-0.0002 days that we interpret to be the stellar rotation period. Further relevant astrophysical parameters like mass, luminosity, radius, effective temperature, gravity, and elemental abundances are obtained and discussed. HDE 283572 shows one of the largest and coolest polar spots ever observed and confirms an earlier map by Joncour et al. from Pic-du-Midi data. We also compare our map with predicted magnetic flux-tube distributions from MHD simulations and suggest that the polar spot on HDE 283572 was possibly created by a strong poleward meridional flow. Title: Doppler imaging of stellar surface structure. VII. The very young, single K2-dwarf LQ Hydrae Authors: Rice, J. B.; Strassmeier, K. G. Bibcode: 1998A&A...336..972R Altcode: A Doppler image of the young K2V star LQ Hya is presented for March 1995 and is compared with earlier images taken in 1991 and 1993. Comparison is also made with a recently completed image of EK Dra, another young star that is more nearly one solar mass than LQ Hya. The image for 1995 seems to show a consistent pattern of spot concentration to the equatorial region in either a continuous wide band of features averaging only about 600 K cooler than photospheric or perhaps a double band symmetrically located either side of the equator like the solar pattern. A weak polar feature is evident but it is apparently a somewhat less pronounced depression in temperature than seen in 1991 and of reduced area. The polar feature is less pronounced than that of EK Dra and the spot pattern at the equator of LQ Hya does not extend to latitudes as far toward the poles as does the pattern of spots at the equatorial and mid-latitudes of EK Dra. When these results are compared with theoretical predictions for the location of spots on such young stars of solar mass, it appears surprising that the observations for LQ Hya and EK Dra are not reversed given that LQ Hya is apparently significantly less massive than EK Dra. Title: Doppler imaging of stellar surface structure. VIII. The effectively single and rapidly-rotating G8-giant HD 51066 = CM Camelopardalis Authors: Strassmeier, K. G.; Bartus, J.; Kovari, Zs.; Weber, M.; Washuettl, A. Bibcode: 1998A&A...336..587S Altcode: We present first Doppler images of HD 51066 from observations in 1994, 1995, 1996 and 1997, and find evidence for a vanishing polar spot in accordance with the system's long-term brightness increase. Several small spots with Delta T~500 K appear also at low latitudes. Our cross-correlation maps indicate a latitude-dependent phase-shift pattern between annual maps. New and continuous BVRI photometry from 1996 to 1998 is presented and suggest a photometric period of 16.053+/-0.004 days, that we interpret to be the stellar rotation period. Additional optical spectroscopy and the Hipparcos data are used to obtain absolute stellar parameters for HD 51066. A comparison with evolutionary tracks and the assumption of angular-momentum and magnetic-flux conservation suggest that the main-sequence progenitor was a very rapidly-rotating Bp star with a several kiloGauß\ magnetic field. We also examine the Hα line profiles in this star and find some evidence that its equivalent width is modulated with the stellar rotation period in phase with the photospheric starspots. Our radial velocities indicate that HD 51066 is likely a long-period (~10 yrs) spectroscopic binary and a preliminary orbit is presented. We emphasize that HD 51066 is an interesting target for studies of evolutionary angular-momentum loss because it is effectively single, significantly evolved but still rapidly rotating. Title: Pulsation in lambda Bootis stars Authors: Paunzen, E.; Weiss, W. W.; Kuschnig, R.; Handler, G.; Strassmeier, K. G.; North, P.; Solano, E.; Gelbmann, M.; Kuenzli, M.; Garrido, R. Bibcode: 1998A&A...335..533P Altcode: In this paper we present a further step in applying asteroseismic techniques to the group of lambda Bootis stars which can be characterized as nonmagnetic A to F-type Population I dwarfs with significant (surface) underabundances of Fe-peak elements. Since no conclusive theory explaining the origin of the observed abundance anomalies exists, an extensive photometric survey for pulsation in this group has been initiated. Knowledge about the pulsational properties (most members are located within the classical instability strip) could help to establish constrains about the overall abundance of these stars as well as on the evolutionary status. New photometric observations were carried out for eleven stars. Variability was detected in four stars (e.g. lambda Bootis itself) whereas the remaining seven objects are probably constant. In total, 52 members of this group have been photometrically investigated so far. With 22 pulsating and 30 ``constant'' stars, we derive a ratio of at least 50 % for variable to nonvariable members inside the classical instability strip. This result is based on high quality Hipparcos and new photometric data. The observed log /lineρ//lineρ_⊙ and log P values for the pulsating members are compatible with standard (solar abundant) delta Scuti models supporting the hypothesis that the found abundance anomalies are restricted to the surface only. Otherwise the pulsational properties of this group are not outstanding compared to ``normal'' delta Scuti stars, indicating that the mechanism driving the pulsations is very similar. Based on observations obtained at ESO-La\,Silla, CTIO, SAAO, McDonald Observatory, Instituto Astrofisica Andalucia Observatory and with the Hipparcos satellite Title: Aktive Sterne. Laboratorien der solaren Astrophysik. Authors: Strassmeier, K. G. Bibcode: 1998S&W....37..622S Altcode: Magnetically active stars show similar activity cycles as one can observe on the Sun. In this paper an overview of the solar activity cycle and its relation to the magnetic field is given and compared with observations of solar-like stars. Furthermore observations concerning extrasolar planets around solar-like stars are briefly discussed. Title: HD 84800: A new delta Scuti variable Authors: Paunzen, E.; Strassmeier, K. G.; Weiss, W. W. Bibcode: 1998IBVS.4566....1P Altcode: No abstract at ADS Title: Spectroscopic and photometric variations of HR 5 Authors: Weber, M.; Strassmeier, K. G. Bibcode: 1998IBVS.4573....1W Altcode: No abstract at ADS Title: A CAII H&K survey of gamma Doradus candidates Authors: Kaye, Anthony B.; Strassmeier, Klaus G. Bibcode: 1998MNRAS.294L..35K Altcode: In an investigation of the starspot hypothesis as it applies to the `slowly variable' F-type dwarfs, we spectroscopically observed eight promising gamma Doradus candidates to search for Caii H&K emission. We found that there are no significant emission reversals in the cores of these resonance lines. Based on the ceiling flux calculations of the Caii K line and on calculations of the Rossby number, we conclude that there is no support for the presence of strong magnetic activity and the starspot hypothesis in these objects. Title: Doppler imaging of stellar surface structure. VI. HD 129333 = EK Draconis: a stellar analog of the active young Sun Authors: Strassmeier, K. G.; Rice, J. B. Bibcode: 1998A&A...330..685S Altcode: We present the first Doppler images of the single G1.5V-star EK Draconis from high-resolution CFHT spectra obtained in 1995. EK Dra is an important target for investigating the evolution of stellar magnetism because it resembles the rapidly-rotating young Sun. From the inversion of a total of 12 spectral lines we reconstruct several cool spots at low and medium latitudes but the dominating feature is located consistently at a latitude of ~70-80° , thus, at far higher latitudes than where our Sun shows spots. In fact, our data indicate that this feature could be an appendage of a larger polar cap-like spot as seen on other rapidly-rotating stars, however, due to the small vsin i of just 17.3+/-0.4 kms(-1) \ the cap's existence remains inconclusive. Spot temperatures between Delta T~1200 K and 400 K are recovered. We have used the non-parametrized convective-flux description of Canuto & Mazzitelli for our input model atmospheres and found good agreement with local line profiles computed from standard mixing-length atmospheres. New phase-resolved UBVRI data spanning the 1996/97 observing season indicate a surprisingly short photometric period of 2.599+/-0.001 days, which is different by 7% from the longest seasonal period found so far but in good agreement with the long-term photometric period of 2.605 days. We interpret these differences as being due to differential surface rotation and adopt the long-term photometric period to be the rotation period of EK Dra. Our data also confirms the continuing decline of the mean brightness seen since 1994 and we suspect the high-latitude feature to be the cause. Title: Doppler imaging of stellar surface structure. V. The long-period RSCVn binary HD81410 = ILHydrae Authors: Weber, M.; Strassmeier, K. G. Bibcode: 1998A&A...330.1029W Altcode: Multiwavelength Doppler images of the long-period RS CVn binary IL Hydrae from March 1994 and Feb.-March 1995 reveal a cool polar spot and several features at low latitudes. Their average temperature is approximately 500K below the photospheric temperature of 4700K. Due to the relatively small rotational velocity of 26.5+/-1 kms(-1) \ and the relatively cool, low-gravity atmosphere with many weak absorption blends, Doppler imaging of IL Hydrae is challenging but resulted in encouragingly similar maps from altogether seven spectral regions near 6400 Angstroms. Latitude-dependent differential rotation is detected from our Doppler maps and indicate faster rotation at the stellar equator as compared to the polar regions. Lines from the secondary component are sometimes seen in our red-wavelength spectra and a double-lined spectroscopic orbit is presented. We also give a more precise rotational period from three consecutive years of V-band photometry. A spectral classification of K0III-IV and a mass of 2.2+/-0.2 M_sun for the primary, and mid to late F main sequence or maybe ~G0V-IV and a mass of 1.3+/-0.2 M_sun for the secondary, are suggested. Hα \ equivalent widths measured over a single rotation cycle exhibit a sinusoidal variation in phase with the photospheric V-band light curve. The maximum of the residual Hα \ emission coincides with the lightcurve minimum and is thus likely linked to the starspot-covered stellar surface. A steady, redshifted absorption component possibly indicates an isotropic inward flow at the Hα \ line-forming region at approximately 60 kms(-1) . Title: Doppler Imaging of the Young, Single, Solar-Type Stars LQ Hya and EK DRA Authors: Strassmeier, K. G.; Rice, J. B. Bibcode: 1998ASPC..154.2048S Altcode: 1998csss...10.2048S This poster paper presents the first Doppler image of a truly solar-like star (EK Dra) and a further image of the ZAMS K-dwarf LQ Hya from 1995. EK Dra shows a very high latitude spot feature close to the rotation pole while the more rapidly-rotating star LQ Hya has more like a low-latitude band of spots. Title: MUSICOS Observations of SU AUR Authors: Unruh, Yvonne C.; Donati, J. -F.; Balona, L.; Bohm, T.; Cao, H.; Catala, C.; Collier Cameron, A.; Ehrenfreund, P.; Foing, B.; Granzer, T.; Hao, J.; Hatzes, A.; Henrichs, H.; Johns-Krull, C.; de Jong, J.; Kennelly, T.; Landstreet, J.; Morrison, N.; Mullis, C.; Neff, J.; Oliveira, J.; Schrijvers, C.; Simon, T.; Stempels, E.; Strassmeier, K. G.; Telting, J.; Walton, N. Bibcode: 1998ASPC..154.2064U Altcode: 1998csss...10.2064U We present first results of the high-resolution observations of SU Aur obtained through the MUSICOS network in 1996 Nov. The data set is unique in that it gives us complete phase coverage for almost two rotation periods of SU Aur. This is particularly valuable for T Tauri stars as they can vary dramatically on the time scale of one rotation period. Title: From Top to Bottom --- the Multiwavelength Campaign of V824 ARA (HD 155555) Authors: Dempsey, Robert; Neff, James; Strassmeier, Klaus; Linsky, Jeffrey; Lim, Jeremy; Donati, J. -F.; Walter, Fred; Budding, Edwin; Marang, Fred; Jordan, Ian; Walker, Stan; Downing, David G.; Inwood, Doug; Petterson, Orlon Bibcode: 1998ASPC..154.1402D Altcode: 1998csss...10.1402D In the spring of 1996, we conducted a multiwavelength campaign on V824 Ara (HD 155555, P=1.68d, G5 IV + K0 IV-V) covering one continuous, complete rotation cycle. At the core of this campaign were observations using the GHRS on HST. In all, ~46,000 spectra, many in rapid readout mode, were obtained with the GHRS covering the C IV, Mg II, and Fe XXI wavelength regions at 11-15 separate phases. Simultaneous observations were made with the EUVE. Radio observations (3.5 & 6 cm) were conducted at the Australian Telescope while ground based optical spectroscopic and photometric observations were made at ESO, CTIO, AAT and SAAO. Additional amateur photometry were obtained from New Zealand before, during, and after the campaign. Our primary intent is to obtain a 3-D model of the atmosphere, extending from the photosphere to the corona. Variability was clearly detected including several flares observed in the HST, EUVE and radio data. We present preliminary results from modeling the UV Transition region (TR) lines using an anisotropic macroturbulence model proposed by Gray (1976, The Observation and Analysis of Stellar Photospheres, Cambridge Astrophysics Series). Previous studies of TR lines in late-type active stars have used multiple gaussians to fit the observed line profiles, adding additional, broad components to account for the extended wings observed in several active systems including V711 Tau (HR 1099). This broad component has been interpreted as arising from the continuous presence of microflaring (Wood et al., 1995, ApJ, 458, 761). We discuss how anisotropic macroturbulence can also fit the Mg II profiles and, in some cases, with smaller residuals than is possible using only gaussians. Title: From Top to Bottom: The Multiwavelength Campaign of V824 ARA (HD 155555) Authors: Dempsey, Robert; Neff, James; Strassmeier, Klaus; Linsky, Jeffrey; Lim, Jeremy; Donati, J. -F.; Walter, Fred; Budding, Edwin; Marang, Fred; Jordan, Ian; Walker, Stan; Downing, David G.; Inwood, Doug; Petterson, Orlon Bibcode: 1998fmml.conf.....D Altcode: A great deal of progress has been made in recent years in decomposing the 2-D structure in the atmospheres of late-type stars. Doppler images of many photospheres - single stars, T Tauri stars, Algols, RS CVn binaries to name a few are regularly published. Ultraviolet spectral images of chromospheres appear in the literature but are less common owing to the difficult nature of obtaining complete phase coverage. Zeeman doppler images of magnetic fields are now feasible. Performing Doppler imaging of the same targets over many seasons has also been accomplished. Even when a true image reconstruction is not possible due to poor spectral resolution, we can still infer a great deal about spatial structure if enough phases are observed. However, it is increasingly apparent that to make sense of recent results, many different spectral features spanning a range of formation temperature and density must be observed simultaneously for a coherent picture to emerge. Here we report on one such campaign. In 1996, we observed the southern hemisphere RS CVn binary V824 Ara (P=1d.68, G51V+K0V-IV) over one complete stellar rotation with the Hubble Space Telescope and EUVE. In conjunction, radio and optical photometry and spectroscopy were obtained from the ground. Unique to this campaign is the complete phase coverage of a number of activity proxy indicators that cover source temperatures ranging from the photosphere to the corona. Title: Doppler Imaging of the RS CVn Binary IL Hydrae Authors: Weber, M.; Strassmeier, K. G. Bibcode: 1998ASPC..154.1366W Altcode: 1998csss...10.1366W We present preliminary results of a study linking rotational period to photospheric surface activity derived from Doppler images. New Doppler images of 15 stars of spectral classification G to K, luminosity class III to V and rotational periods of 1.5 to 25 days have been computed. These Doppler images - along with previously published material - were averaged into latitudinal strips and their temperature distribution correlated with evolutionary status and rotational period. Title: Photometric Monitoring of Spotted T Tauri Stars Authors: Granzer, Th.; Strassmeier, K. G. Bibcode: 1998cvsw.conf..229G Altcode: No abstract at ADS Title: Stellar Variability as a Tool in Astrophysics. A Joint Research Initiative in Austria Authors: Strassmeier, Klaus G. Bibcode: 1998RvMA...11..197S Altcode: No abstract at ADS Title: Hα Line-Profile Variability in Chromospherically Active Stars Authors: Weber, M.; Washuettl, A.; Strassmeier, K. G. Bibcode: 1998cvsw.conf..231W Altcode: No abstract at ADS Title: Evolved Stars: What Happens to Activity Off the Main Sequence Authors: Strassmeier, K. G.; Fekel, F. C.; Gray, D. F.; Hatzes, A. P.; Schmitt, J. H. M. M.; Solanki, S. K. Bibcode: 1998ASPC..154..257S Altcode: 1998csss...10..257S Magnetic activity on the main sequence has been well studied, in contrast to researches on sub-giants, giants, and supergiant stars. In this discussion we will address three main topics associated with activity in evolved stars: (1) rotation regimes for evolved stars; (2) rotation-activity relations in the H-R diagram; (3) polar spots. Title: Doppler Imaging of EI Eridani Authors: Washuettl, Albert; Strassmeier, Klaus G.; Collier-Cameron, Andrew Bibcode: 1998ASPC..154.2073W Altcode: 1998csss...10.2073W We present Doppler images of the rapidly rotating active close binary star EI Eridani. Several Doppler images have been produced since 1984 making use of different versions of the Doppler imaging technique. They all show high-latitude spots surrounding or covering the rotational pole as well as some smaller spots on lower latitudes. The high-latitude/polar spot seems to be long-lived (at least a decade) but changes its shape on comparatively short timescales (of the order of one month). From time to time spots along the stellar equator also occur, but their lifetimes tend to be relatively short (weeks). Furthermore, long-term photometric observations revealed the existence of a magnetic cycle which has been estimated to be around 11 years. We also present time-resolved Doppler images from EI Eri obtained at McMath/NSO in fall 1996 during 70 consecutive nights. The final aim of this program is to investigate the spot evolution over the whole activity cycle. Title: Predicted Starspot Distributions on Pre-MS Stars Authors: Granzer, Th.; Strassmeier, K. G.; Schussler, M.; Caligari, P. Bibcode: 1998ASPC..154.1977G Altcode: 1998csss...10.1977G We present an application of the magnetic flux-tube model of Caligari (1995, 1991) to pre-main-sequence stars. This model was originally designed as an explanation for sunspots. The primary goal is to derive the emerging latitude of flux tubes for a large parameter volume including stellar mass, age, and rotational period. Since the original model worked well in explaining certain sunspot features, the next step would be to compare our model predictions with observed starspot distributions obtained by Doppler imaging techniques. Title: Photospheric and chromospheric activity of the bright and single G5 dwarf HR 4864 = HD 111395 Authors: Strassmeier, K. G.; Granzer, Th.; Weber, M. Bibcode: 1997IBVS.4538....1S Altcode: We present new photometric and spectroscopic data for HR 4864 and conclude that the star is a spotted and chromospherically active solar-type star. Title: A large X-ray flare on HU Virginis Authors: Endl, M.; Strassmeier, K. G.; Kurster, M. Bibcode: 1997A&A...328..565E Altcode: We present two ROSAT-HRI observations of the RS CVn-type binary HU Virginis (=HD 106225). The first observation covers almost three consecutive rotation cycles of HU Virginis or a total of 26.7 days and an exposure time of 35 ksec. On JD 2,449,544 a long duration flare was detected and observed for 1.5 days. This event was releasing a total energy of ~ 7.7(+3.3}_{-1.9) x 10(36) erg in the 0.1-2.4 keV bandpass. The good coverage of the onset and maximum phase of the flare light curve allowed a detailed comparison with two solar flare models. We derived an estimate for the size of the active region responsible for the flare. The resulting loop size is of the order of one stellar radius. One year later, in 1995, HU Virginis was again observed by ROSAT continuously for 8 days and a total exposure time of 69 ksec. The X-ray flux shows variability on time scales shorter than the rotational period. Title: Starspot photometry with robotic telescopes: Continuous UBV and V(RI)_C photometry of 23 stars in 1991-1996 Authors: Strassmeier, K. G.; Bartus, J.; Cutispoto, G.; Rodono, M. Bibcode: 1997A&AS..125...11S Altcode: We report on the progress of our ongoing photometric monitoring program of spotted late-type stars with automatic photoelectric telescopes (APTs) on Mt. Hopkins in Arizona and on Mt. Etna in Sicily. We present 9,250 differential UBV and/or V(RI)_C observations for altogether 23 chromospherically active stars, singles and binaries, pre main sequence and post main sequence, taken between 1991 and 1996. The variability mechanism of our target stars is mostly rotational modulation by an asymmetrically spotted stellar surface. Therefore, precise rotational periods and their seasonal variations are determined using baselines between 3 years for HD 129333 to 34 years for V410 Tauri. We report the largest V light-curve amplitude of any spotted star observed to date: 0.65" for V410 Tau in 1994-95. Long-term variations of the overall light levels of our target stars are sometimes of similar amplitude as the rotational modulation itself and are most likely caused by an analog of the solar 11-year spot cycle but mostly without a well-defined periodicity. For some of our target stars (HD 12545, HD 17433, EI Eri, V410 Tau, LQ Hya, and HD 106225) we estimate a probable cycle period. A complete light curve of the semi-regular S-type giant HR Pegasii is presented. All data are available via the WorldWideWeb. Data are available at the CDS via anonymous ftp. Title: Wolfgang-Amadeus: The University of Vienna Twin Automatic Photoelectric Telescope Authors: Strassmeier, K. G.; Boyd, L. J.; Epand, D. H.; Granzer, Th. Bibcode: 1997PASP..109..697S Altcode: We describe the University of Vienna twin automatic photoelectric telescope (APT) located at the new Fairborn Observatory at Washington Camp in southern Arizona. Not only are the telescopes fully automatic, also the observatory itself is automatic. A site-control computer monitors weather sensors and operates the roof while the telescope control computer operates the photometer and accepts input files from and provides nightly observations to the astronomer; no direct operating personnel is needed. Both telescopes have 0.75-m primary mirrors, a CCD finder camera, and an environmentally controlled single-channel photoelectric photometer with filter combinations optimized for use in the blue (Wolfgang) and in the red (Amadeus) wavelength for asteroseismology of non-radially pulsating variables, and for monitoring asymtotic-giant-branch stars. Some first results are presented. (SECTION: Astronomical Instrumentation) Title: Doppler imaging of stellar surface structure. IV. The rapidly-rotating G5III-IV star HD 112313 = IN Comae. Authors: Strassmeier, K. G.; Hubl, B.; Rice, J. B. Bibcode: 1997A&A...322..511S Altcode: We present the first Doppler image of the rapidly-rotating G5 giant in the unusual IN Comae triple system. Our average image from three spectral regions and two continuum color indices shows mostly low to high latitude features but not a prominent polar cap-like spot. A parameter study of the stellar and atomic input quantities aims to better quantify the reliability of our Doppler image. A time series of 330 high-precision Stroemgren by and Johnson V measurements in 1996 show only one real photometric period (5.913+/-0.005days) that we interpret to be the rotation period of the G5 giant. We found no evidence for the 0.25-day period claimed earlier by Kuczawska & Mikolajewski (1993AcA....43..445K). Optical spectra of several activity indicators are presented and discussed. IN Comae exhibits an unusual broad Hα emission line and a central absorption feature. This profile shape is also seen for the CaII infrared-triplet lines as well as for the sodium doublet and the HeI D_3_ line. No LiI 6707.8 line is present. New radial velocity measurements from our red-wavelength spectra do not indicate a short-period binary but would be consistent with the G5 star being the outer, third component of this triple system. Title: Time-series photometric SPOT modeling. III. Thirty years in the life of HK Lacertae. Authors: Olah, K.; Kővári, Zs.; Bartus, J.; Strassmeier, K. G.; Hall, D. S.; Henry, G. W. Bibcode: 1997A&A...321..811O Altcode: We present a spot modeling analysis of the active late-type giant HK Lac using 30 years of photometry, including 600 new data points from the last six years. We have analyzed folded light curves and, when we had long continuous data sets, applied a new computer code for time-series modeling. The validity of the modeling results was tested as a function of the photometric noise. We have determined the unspotted brightness of HK Lac in the BV(RI)_C_ bandpasses and obtained a spot temperature of {DELTA}T=1200+/-100K. Polar active regions were recovered throughout the modeling because no other scenario was able to describe both the mean light variability of over 0.25mag accompanied by rotational modulation of similar amplitude. This result has gotten strong theoretical support recently (see Schuessler). The active regions preferably cluster around two orbital phases separated by =~110°. New spot appearances within active regions and, possibly, their interactions with the old ones could be the cause of rapid changes in the light curves. Title: Doppler imaging of stellar surface structure. III. The X-ray source HD 116544 = IN Virginis. Authors: Strassmeier, K. G. Bibcode: 1997A&A...319..535S Altcode: We present the first Doppler image of the EXOSAT X-ray source EXO 1321.8-0203, recently identified to be a chromospherically active star exhibiting periodic light variations and consequently named INVirginis. Our high-resolution spectra show INVirginis to be a single-lined spectroscopic binary with an orbital period of 8.2 days, very strong CaII emission, and an inverse P-Cygni type Hα line profile. A detailed spectrum synthesis yields a photospheric temperature of 4600+/-70 K and logg=3.5-4.0 and slight overabundance of the heavy elements but otherwise solar abundances. We redetermine the photometric period from a new set of photometry obtained with a robotic photoelectric telescope in the years 1994 and 1995 and conclude that IN Virginis is more likely a K2-3 subgiant instead of a K5 dwarf or K4 subgiant as previously published. The Doppler images from March 1994 show a cool polar spot that is dominated by a large appendage reaching a latitude of +40°. Its average temperature difference, photosphere minus polar spot, is 1000K. Additionally, three equatorial spots are clearly recovered but have ΔT=~400K. Possibly, we also detected a warm equatorial feature with ΔT=~-150K. We emphasize that Doppler imaging of IN Virginis is very challenging because of both the small vsin i of the star (24.0km/s) and its relatively cool photosphere causing many weak absorption-line blends. Still, maps from the different lines appear encouragingly similar. Title: Aktive Sterne. Laboratorien der solaren Astrophysik. Authors: Strassmeier, K. G. Bibcode: 1997asld.book.....S Altcode: Contents: 1. Das Weltbild, in dem wir leben. 2. Stellare Aktivitäten. 3. "Alles Walzer" - die Rotation der Sterne. 4. Rotation in Doppelsternen. 5. Rotationsmodulierte Datenanalyse. 6. Stellare Magnetfelder. 7. Unsere Sonne als Stern. 8. Sternflecken: Aktivitätsphänomene der Photosphäre. 9. Aktive Chromosphären. 10. Röntgenstrahlung aktiver Sterne. 11. Alles fließt: Geschwindigkeitsfelder. 12. Extrasolare Planeten: Endlich! Title: VizieR Online Data Catalog: UBV & V(RI)c photometry of 23 active stars (Strassmeier+ 1997) Authors: Strassmeier, K. G.; Bartus, J.; Cutispoto, G.; Rodono, M. Bibcode: 1997yCat..41250011S Altcode: We report on the progress of our ongoing photometric monitoring program of spotted late-type stars with automatic photoelectric telescopes (APTs) on Mt. Hopkins in Arizona and on Mt. Etna in Sicily. We present 9250 differential UBV and/or V(RI)c observations for altogether 23 chromospherically active stars, singles and binaries, pre-main-sequence and post-main-sequence, taken between 1991 and 1996. For a description of the UBV and (RI)c photometric system, see e.g. <GCPD/01> and <GCPD/54> (6 data files). Title: Aktive Sterne Authors: Strassmeier, Klaus G. Bibcode: 1997akst.book.....S Altcode: Die Sonne ist ein ziemlich durchschnittlicher Stern, der sich vor allem durch seine geringe Entfernung zur Erde auszeichnet. Bei näherer Betrachtung entpuppt sich die Sonnenoberfläche jedoch als wahrer "Hexenkessel" mit Magnetfeldern aller Art, Sonnenflecken, Plasmaeruptionen und plötzlichen Explosionen, die alle einen fundamentalen Einfluß auf unseren Planeten haben, einen Einfluß, den wir erst mit modernster Astronomie messen und verstehen gelernt haben. Dieses Buch erklärt die spannenden Innenwelten, die physikalischen Grundlagen und Funktionsweisen der Sonne und der anderen aktiven Sterne. Die aktuellsten Forschungsergebnisse und neuestes Datenmaterial werden fundiert, aber auch für Laien verständlich, aufbereitet und mit über 200 Bildern, teilweise Aufnahmen mit dem Hubble Weltraumteleskop, illustriert. Title: From Top to Bottom - the Multiwavelength Campaign of V824 ARA (HD 155555) Authors: Dempsey, Robert; Neff, James; Strassmeier, Klaus; Linsky, Jeffrey; Lim, Jeremy; Donati, J. -F.; Walter, Fred; Marang, Fred; Budding, Edwin; Jordan, Ian; Walker, Stan; Downing, David G.; Inwood, Doug; Petterson, Orlon; Petterson, Orlon Bibcode: 1997stsc.rept.....D Altcode: A great deal of progress has been made in recent years in decomposing the 2-D structure in the atmospheres of late-type stars. Doppler images of many photospheres single stars, T Tauri stars, Algols, RS CVn binaries to name a few - are regularly published (Strassmeier 1996; Richards and Albright 1996; Rice and Strassmeier 1996; Kuerster et al. 1994). Ultraviolet spectral images of chromospheres appear in the literature (e.g., Walter et al. 1987; Neff et al. 1989) but are less common owing to the difficult nature of obtaining complete phase coverage. Zeeman doppler images of magnetic fields are now feasible (e.g., Donati et al. 1992). Performing Doppler imaging of the same targets over many seasons has also been accomplished (e.g, Vogt et al. 1997). Even when a true image reconstruction is not possible due to poor spectral resolution, we can still infer a great deal about spatial structure if enough phases are observed. However, it is increasingly apparent that to make sense of recent results, many different spectral features spanning a range of formation temperature and density must be observed simultaneously for a coherent picture to emerge. Here we report on one such campaign. In 1996, we observed the southern hemisphere RS CVn binary V824 Ara (P=1d.68, G5IV+K0V-IV-IV) over one complete stellar rotation with the Hubble Space Telescope and EUVE. In conjunction, radio and optical photometry and spectroscopy were obtained from the ground. Unique to this campaign is the complete phase coverage of a number of activity proxy indicators that cover source temperatures ranging from the photosphere to the corona. Title: Doppler imaging of stellar surface structure. II. The weak-lined T Tauri star V410 Tauri. Authors: Rice, J. B.; Strassmeier, K. G. Bibcode: 1996A&A...316..164R Altcode: We present a new Doppler image of the rapidly-rotating weak-lined T Tauri star V410 Tauri and compare this new map with one previously published from observations taken over a year earlier. We find cool spots at both equatorial latitudes and at high latitudes with the high latitude spots being cooler and showing greater area and having greater longevity than the equatorial spots. A comparison of the two maps shows little relative change in the positions of the equatorial spots compared to the spots at high latitude suggesting very little differential rotation and what there is appears to be in the same sense as the Sun. Global spot lifetime would appear to be on the order of the time interval between the two maps, that is about a year. There are several hot features evident supporting the claim for the existence of such features based on our map of Nov. 1992. Title: Doppler imaging of stellar surface structure. I. The rapidly-rotating RS CVn binary UZ Librae. Authors: Strassmeier, K. G. Bibcode: 1996A&A...314..558S Altcode: We present the first Doppler image of the rapidly-rotating K0III star of the single-lined RS CVn binary UZ Librae. Our analysis incorporates line profile variations from three spectral regions (around CaI 6439A, FeI 6411A and FeI 6393A) and continuum variations from simultaneous VRI photometry. All images recover a polar feature consisting of mainly three "appendages" between latitudes of +60deg and +80deg. This polar feature is not like a polar cap as previously seen on other RS CVn stars but consists primarly of the three appendages. Up to six equatorial features were also detected and have temperature differences between 200 and 400K cooler than the photospheric temperature of 4800K. Images from individual spectral lines show an encouraging amount of consistent detail, especially for the location but also for the shape of certain features. The recovery of the temperature scale is on average also similar but can be somewhat different for particular surface features. This is most noticeable for the larger of the three polar appendages; we found it 30% cooler from the CaI line and the FeI 6411-A line than from the FeI 6393-A line. We suspect such differences are partially due to external errors of the line profile data and slightly inaccurate input physics. New photometry and radial velocity measurements are used to recompute the photometric period and the orbital elements of UZ Librae. Title: VizieR Online Data Catalog: Chromospherically Active Binaries (Strassmeier+ 1993) Authors: Strassmeier, K. G.; Hall, D. S.; Fekel, F. C. Bibcode: 1996yCat.5076....0S Altcode: Stars always appear in order of increasing right-ascension for the epoch 2000.0. For the current version of the catalog, the literature was searched through December 31, 1991 although a few later references are included. Additionally, some entries are cited with "private communication", which make this catalog also a first-hand source. A number in parentheses behind an entry always corresponds to a reference given in the bibliography. See the 1988 publication for specific requirements and restrictions in compiling these catalogs. See the source reference for more details about this catalog.

The following binary systems, which were listed in the first edition of the catalog, were not included in the present edition due to insufficient evidence for chromospheric activity: eta And 26 Aql 4 UMi nu2 Sgr tau Sgr

the following stars are chromospherically active but are components in a "wide" binary and were not included. HD 25893 HD 79211

Forty three new binary systems have been included in the present edition.

(12 data files). Title: Photometry of the Active Star UZ Librae Authors: Paunzen, E.; Strassmeier, K. G. Bibcode: 1996IBVS.4294....1P Altcode: No abstract at ADS Title: Observational evidence for polar spots Authors: Strassmeier, K. G. Bibcode: 1996IAUS..176..289S Altcode: No abstract at ADS Title: Stellar surface structure: proceedings of the 176th Symposium of the International Astronomical Union, held in Vienna, Austria, October 9-13, 1995. Authors: Strassmeier, Klaus G.; Linsky, Jeffrey L. Bibcode: 1996IAUS..176.....S Altcode: No abstract at ADS Title: Austrian astronomy today: a joint research initiative in stellar astrophysics Authors: Breger, M.; Dorfi, E. A.; Hron, J.; Strassmeier, K. G.; Weiss, W. W.; Oberhummer, H.; Hanslmeier, A.; Lustig, G.; Schober, H. J. Bibcode: 1995IAUS..176P...4B Altcode: No abstract at ADS Title: Hα line-profile variations of the two active binary systems AG Dor and UX For Authors: Washüttl, A.; Strassmeier, K. G. Bibcode: 1995IAUS..176P.172W Altcode: No abstract at ADS Title: Stellar temperatures from line-depth ratios: the influence of macroscopic velocity fields Authors: Stift, M. J.; Strassmeier, K. G. Bibcode: 1995IAUS..176P..29S Altcode: No abstract at ADS Title: Doppler imaging of IN Comae: two possible rotation periods Authors: Hubl, B.; Strassmeier, K. G. Bibcode: 1995IAUS..176P..96H Altcode: No abstract at ADS Title: Detection of a large X-ray flare on the RS CVn binary HU Virginis Authors: Endl, M.; Strassmeier, K. G.; Kürster, M. Bibcode: 1995IAUS..176P.203E Altcode: No abstract at ADS Title: Stellar Surface Structure: Doppler Imaging with the VLT-UVES Authors: Strassmeier, K. G. Bibcode: 1995svlt.conf...87S Altcode: No abstract at ADS Title: Stellar surface structure Authors: Strassmeier, Klaus G. Bibcode: 1995IAUS..176P....S Altcode: No abstract at ADS Title: Photometry of the Active Stars HD127535 and HD202077 Authors: Strassmeier, K. G.; Paunzen, E.; North, P. Bibcode: 1994IBVS.4066....1S Altcode: No abstract at ADS Title: Stellar Irradiance Variations due to Surface Temperature Inhomogeneities Authors: Strassmeier, K. G. Bibcode: 1994SoPh..152..314S Altcode: 1994IAUCo.143..314S; 1994svs..coll..314S Observations of rotational modulation of continuum brightness and photospheric and chromospheric spectral-line profiles of late-type stars indicate the presence of very inhomogeneous surface temperature distributions. We present three stellar examples (VY Ari, HR 7275, HU Vir) where time-series photometry is used to trace the evolution of spotted regions. Simultaneous spectroscopy and Doppler imaging for one of the three stars (HU Virgo, Fig. 1) makes it possible to compute the temperature distribution of the photosphere and the relative intensity distribution of parts of the chromosphere (from CaII K and Hα line profiles). The combination of time-series spot modeling and Doppler imaging enabled us to determine thesign and amount of differential surface rotation on HU Vir. We found a big, cool polar spot (see figure below) and a differential (surface) rotation law where higher-latitude regions rotate faster than lower-latitude regions (opposite to what we see on the Sun). Currently, this ensemble of techniques -- is only applicable to stars overactive by approximately a factor of 100 as compared to the active Sun, e.g. the evolved components in RS CVn-type binaries and some rapidly-rotating, single, pre-main sequence stars or giant stars. Stellar rotation is a fundamental parameter for (magnetic) activity. Starspots, or any other surface inhomogeneities, allow one to derive very precise stellar rotation rates and, if coupled with seismological observations of solar-type stars, could provide information on the internal angular momentum distribution in overactive late-type stars. Title: A Doppler image of the weak T Tauri star V410 Tau Authors: Strassmeier, K. G.; Welty, A. D.; Rice, J. B. Bibcode: 1994A&A...285L..17S Altcode: We have monitored the weak-lined T Tauri star V410 Tau spectroscopically for six nights in 1992. We detected periodic line-profile variations that are used to obtain a Doppler image of this star, the first of a pre-main sequence T Tauri star. Inverse solutions from three moderately-strong absorption lines show consistent surface inhomogeneities of the effective temperature distribution of up to 1200K cooler and at least 500K hotter than the nominal photospheric temperature of 4400K. Our maps thus verify the proposed existence of hot spots on weak-lined T Tauri stars. All features are evident at low and very high latitudes even covering the rotational pole but not a cool polar cap-like spot as seen previously for several other active stars. Title: Chromospheric activity in G and K giants: the spectroscopic data base Authors: Strassmeier, K. G. Bibcode: 1994A&AS..103..413S Altcode: I present high-resolution CCD spectra of CaII H and K emission lines of 59 evolved stars of spectral type G and K and luminosity Class III, III-IV, and IV. This includes active stars like RS CVn binaries but also active and inactive single stars. Most of the objects were observed for the first time and several were discovered to be chromospherically active. Spectra for ten stars of luminosity Class V are also given. Title: Starspot Activity on the G0III Star 31 Comae Authors: Strassmeier, K. G.; Washuttl, A.; Rice, J. B. Bibcode: 1994IBVS.3994....1S Altcode: No abstract at ADS Title: Time-series photometric SPOT modeling. II. Fifteen years of photometry of the bright RS CVN binary HR 7275. Authors: Strassmeier, K. G.; Hall, D. S.; Henry, G. W. Bibcode: 1994A&A...282..535S Altcode: We present a time-dependent spot modeling analysis of 15 consecutive years of V-band photometry of the long-period (Porb = 28.6 days) RS CVn binary HR 7275. This baseline in time is one of the longest, uninterrupted intervals a spotted star has been observed. The spot modeling analysis yields a total of 20 different spots throughout the time span of our observations. The distribution of the observed spot migration rates is consistent with solar-type differential rotation and suggests a lower limit of the differential-rotation coefficient of 0.022 +/-0.004. The observed, maximum lifetime of a single spot (or spot group) is 4.5 years, the minimum lifetime is approximately one year, but an average spot lives for 2.2 years. If we assume that the mechanical shear by differential rotation sets the upper limit to the spot lifetime, the observed maximum lifetime in turn sets an upper limit to the differential-rotation coefficient, namely 0.04 +/- 0.01. This would be differential rotation just 5 to 8 times less than the solar value and one of the strongest among active binaries. We found no conclusive evidence for the existence of a periodic phenomenon that could be attributed to a stellar magnetic cycle. Title: Three-Dimensional Doppler Imaging of the Active Atmosphere of HU Virgo Authors: Strassmeier, Klaus G. Bibcode: 1994ASPC...64..480S Altcode: 1994csss....8..480S No abstract at ADS Title: Stellar Photometry with a Whole-Earth Robotic Telescope Authors: Strassmeier, Klaus G. Bibcode: 1994ASPC...55..205S Altcode: 1994oaem.conf..205S No abstract at ADS Title: Rotational-modulation mapping of the active atmosphere of the RS Canum Venaticorum binary HD 106225. Authors: Strassmeier, K. G. Bibcode: 1994A&A...281..395S Altcode: Observations of rotational modulation of photospheric absorption lines, chromospheric emission lines, and the continuum brightness of the RS CVn binary HD 106225 Pord = 10.4 days) are reported. From Doppler imaging of four photosperic lines we obtain the surface temperatures distribution at two observing epochs in 1991. Spot temperatures on HD 106225 were determined from three different proxy indicators (photometric broad-band colors, line-depth ratios, and line-profile shapes) and yield values between 1000-1500 K. Simultaneous Ca II H and K and H-alpha line-profile variations provide some clues on the spatial relation between the temperature distribution of the photosphere and the location of active regions in the chromosphere and we present, for the first time, a crude three-dimensional picture of a stellar atmosphere. Simultaneous and contemporaneous UBV photometry is used to trace the evolution of spotted regions in 1991. We applied a time-series spot modeling code and found a fairly stable spot configuration with two major spots. Only small and sporadic spot-area changes were present in 1991, which likely are unrelated to a long-term cycle. Title: Chromospheric activity in G an K giants and their rotation-activity relation. Authors: Strassmeier, K. G.; Handler, G.; Paunzen, E.; Rauth, M. Bibcode: 1994A&A...281..855S Altcode: We obtained high-resolution CCD spectra of Ca II H and K emission lines of 59 evolved stars of spectral type G and K and luminosity class III, III-IV, and IV. Our sample includes active stars like RS CVn binaries but also active and inactive single stars. Whenever possible we determine absolute emission line surface fluxes and use them, supplemented by previously published fluxes from high-resolution spectra, to quantify the rotation-activity relation for evolved stars. We find that the Ca II surface fluxes from evolved stars scale linearly with stellar rotational velocity and that the flux from the cooler stars depends stronger upon rotation than the flux from the hotter stars, in agreement with previous findings for main-sequence stars. However, large scatter indicates that rotational velocity might not be the only relevant parameter. We also present some evidence for the existence of a 'basal' flux for evolved stars that scales approximately with the eight power of the effective surface temperature. Title: Doppler Imaging of Stars Authors: Rice, J.; Wehlau, W.; Strassmeier, K.; Matthews, J.; Hill, G. Bibcode: 1994BCFHT..30...20R Altcode: No abstract at ADS Title: Time-Series Photometric SPOT Modeling of the RS CVn Binary HR 7275 Authors: Strassmeier, Klaus G.; Hall, Douglas S. Bibcode: 1994ASPC...64..483S Altcode: 1994csss....8..483S No abstract at ADS Title: A catalog of chromospherically active binary stars (second edition). Authors: Strassmeier, K. G.; Hall, D. S.; Fekel, F. C.; Scheck, M. Bibcode: 1993A&AS..100..173S Altcode: The catalog contains 206 spectroscopic binary systems with at least one late-type component that shows Ca II H and K emission in its spectrum. These systems include the classical RS CVn binaries and BY Dra binaries. The catalog summarizes information on the photometric, spectroscopic, orbital, and physical properties of the systems as well as space motions and positions. Up to 42 'parameters' for each stellar system are listed followed by the appropriate reference to direct interested colleagues to the original papers. A comprehensive selection of further information for each star is given in the individual notes. In addition, the catalog contains a candidate list of 138 stars that have similar characteristics but are not definitely known binaries or have not had Ca II H and K emission observed. Title: Sternflecken - Die Beobachtung solarer Phänomene auf anderen Sternen. Authors: Strassmeier, K. G. Bibcode: 1993Sterb..36...42S Altcode: No abstract at ADS Title: Surface features of the lower atmosphere of HD 82558 (=LQ Hydrae). Authors: Strassmeier, K. G.; Rice, J. B.; Wehlau, W. H.; Hill, G. M.; Matthews, J. M. Bibcode: 1993A&A...268..671S Altcode: We present simultaneous high-resolution CCD spectra and UBVRI photometry of the very active young single K2 dwarf star LQ Hya. The star displays extreme chromospheric activity as well as having a large and variable spot distribution. We applied the Doppler-imaging technique to nine different photospheric absorption lines of various strengths. By averaging all individual maps together spurious surface features from one spectral line are suppressed in the final map and only consistent features show up. This greatly enhances the reliability of our Doppler image of LQ Hya. Individual images obtained from the weak line profiles together with the photometry yielded mainly low-latitude surface features. The strongest lines together with photometry yielded large features at the rotation pole. The surface temperature range is only a few hundred degrees. Four starspot regions were detected from Doppler imaging. Extended regions of lesser temperature depression are also evident. Additionally we found rotational modulation of certain temperature-sensitive line ratios in agreement with simultaneous NIR continuum photometry, verifying the 'cool' nature of the starspots on LQ Hya. Chromospheric parameters were computed from H-alpha as a function of rotational phase. We present evidence that lower electron densities occur at times when a cool starspot is in view, indicating a less dense chromosphere above a spotted region. Title: Activity tracers. Authors: Strassmeier, Klaus G. Bibcode: 1993ASPC...40..605S Altcode: 1993IAUCo.137..605S; 1993ist..proc..605S The vast variety of solar-like phenomena on other late-type stars, so-called activity tracers, provide an important tool for studying the structure of active stellar atmospheres and their connection to the stellar interior via strong magnetic fields. These "chromospherically active" stars include single and binary stars as well as pre- and post-main sequence objects and have rapid rotation and deep convective layers in common. They serve as astrophysical laboratories to study the vast phenomenology of activity tracers: starspots, plages, flares, prominences, which might be seen as enhanced analogs of solar activity and could be spatially resolved due to rotationally modulated indicators. In this paper the author reviews the current observational material and discusses its impact on the knowledge of "active" atmospheres, especially in the context of stellar rotation. Title: No Chromospheric Activity Seen in the Very Eccentric Double-Lined Binary Gliese 586A Authors: Strassmeier, K. G. Bibcode: 1992IBVS.3781....1S Altcode: No abstract at ADS Title: Line Profile Asymmetries in Chromospherically Active Stars Authors: Dempsey, Robert C.; Bopp, Bernard W.; Strassmeier, Klaus G.; Granados, Arno F.; Henry, Gregory W.; Hall, Douglas S. Bibcode: 1992ApJ...392..187D Altcode: A powerful, new probe of chromospheric activity, cross-correlation, has been developed and applied to a variety of stars. In this particular application, an entire CCD spectrum of an active star is correlated with the spectrum of a narrow-line, inactive star of similar spectral type and luminosity class. Using a number of strong lines in this manner enables the detection of absorption profile asymmetries at moderate resolution (lambda/Delta lambda about 40,000) and S/N 150:1. This technique has been applied to 14 systems mostly RS CVn's, with 10 not greater than nu sin i not greater than 50 km/s and P not less than 7 d. Distortions were detected for the first time in five systems: Sigma Gem, IM Peg, GX Lib, UV Crb, and Zeta And. Detailed modeling, incorporating both spectral line profiles and broad-band photometry, is applied to Sigma Gem. Profile asymmetries for this star are fitted by two high-latitude spots covering 5 percent of the stellar surface. The derived spot temperature of 3400 K is lower than found in previous studies. In addition, two well-known systems have been studied: HD 199178 and V711 Tau. Polar spots are found on both. Title: Time-series photometric SPOT modeling. I. Parameter study and applicationto HD 17433 = VY Arietis. Authors: Strassmeier, K. G.; Bopp, B. W. Bibcode: 1992A&A...259..183S Altcode: New UBVRI photometry of the active chromosphere binary HD 17433 (VY) Ari from 1987 through 1991 is presented, and the long-term and short-term spot behavior is studied. A 0.2 mag variation of the mean brightness and a maximum wave amplitude of up to 0.4 mag in 1988 are found. The newly measured photometric period of 16.42 d suggests asynchronous rotation of the primary component by about 30 percent. Title: On the starspot temperature of HD 12545. Authors: Strassmeier, K. G.; Olah, K. Bibcode: 1992A&A...259..595S Altcode: We have applied two different versions of the photometric spot-modeling technique to the spotted RS CVn-type binary HD 12545. New UBV(RI)c photometry from early 1991 showed the star with an exceptionally large amplitude of 0.50 mag in V and 0.12 mag in V - I and a rotation period of 24.30 +/- 0.02 d which suggests a spot coverage of approximately 20 percent of the entire stellar surface. Such large light and color amplitudes allowed us to separate effects of wavelength-dependent limb darkening from spot temperature with high confidence. This in turn makes it possible to obtain the, so far, most precise relative starspot temperature of 1100 +/- 35 K for a spotted, late-type star other than the sun. The U - B and B - V values and the minimum radius for HD 12545 suggest a K0III classification rather than the G5IV reported earlier. From a single, high-resolution spectrum of HD 12545 we found a strong LiI 6707 A line with an equivalent width of 100 +/- 15 mA (log n(Li) is approximately equal to 1.75), suggestive of a relatively young giant. In contrast, with our new spectral type classification, minimum stellar radius, and the observed mass function, we determine a space-velocity vector of 105 km/s, suggestive of an old disk star. Title: Stellar Atmosphere Inhomogeneities from High-Resolution Spectroscopy Authors: Strassmeier, K. G. Bibcode: 1992ESOC...40..167S Altcode: 1992hrsw.conf..167S No abstract at ADS Title: On the Rotation Period of HD 39576 Authors: Strassmeier, K. G.; Maitzen, H. M.; Pranka, M. Bibcode: 1992IBVS.3735....1S Altcode: No abstract at ADS Title: The Polar-spot Structure on HD26337 Authors: Strassmeier, K. G. Bibcode: 1992LNP...397...50S Altcode: 1992sils.conf...50S No abstract at ADS Title: Starspot photometry: observational review and interplay with spectroscopy. Authors: Strassmeier, Klaus G. Bibcode: 1992ASPC...34...39S Altcode: 1992robt.proc...39S Most of what we know about starspots comes from time variations of broad-band lightcurves. A review is presented of the current observational knowledge of starspots on RS CVn-like F, G, and K stars, T Tauri, and W UMa-type stars. Recent Doppler maps are compared with photometric results. Title: Doppler imaging of hig-latitude SPOT activity on HD 26337. Authors: Strassmeier, K. G.; Rice, J. B.; Wehlau, W. H.; Vogt, S. S.; Hatzes, A. P.; Tuominen, I.; Piskunov, N. E.; Hackman, T.; Poutanen, M. Bibcode: 1991A&A...247..130S Altcode: Three different versions of the Doppler-imaging technique are applied to the spotted RS CVn-type binary HD 26337 = Ei Eri. New high-resolution high-S/N spectroscopy was obtained along with simultaneous BV photometry during 1988. Images were generated independently by three separate groups using different versions of the Doppler-imaging technique but the same data. All maps from Ca I 6439 A showed a cool asymmetric spot at the pole or at high latitudes generally surrounding the rotation pole and also some smaller equatorial spots. The maps from Fe I exhibit detailed differences to the maps from Ca I. The equatorial features were found to change on short time-scales (weeks). It is inferred that the polar spot is short-lived (years) but changes its appearance on the same several-week time-scale. Simultaneous and contemporary broad-band photometry was found to be crucial as additional data in the mapping procedure and as a reliability test of the Doppler-imaging solution. Title: HD 181943: an Active Single Subgiant with Lithium Authors: Strassmeier, K. G. Bibcode: 1991IBVS.3618....1S Altcode: No abstract at ADS Title: Surface Imaging of Ei-Eridani Authors: Hackman, T.; Piskunov, N. E.; Poutanen, M.; Strassmeier, K. G.; Tuominen, I. Bibcode: 1991LNP...380..321H Altcode: 1991IAUCo.130..321H; 1991sacs.coll..321H We present maps of the temperature distribution on the spotted RS CVn-type binary EI Eri (HD 26337), obtained by means of the surface imaging technique described in the Colloquium (Piskunov, 1991). Images were calculated for two separate lines for two epochs of observation. For one epoch we also calculated an image using a blend of several lines. The reliability of the maps is confirmed by comparing the simultaneous photometric observations with the light curves calculated from the temperature maps. Title: Line Profile Asymmetries in Chromospherically Active Stars Authors: Dempsey, R. C.; Bopp, B. W.; Strassmeier, K. G. Bibcode: 1991BAAS...23Q.822D Altcode: No abstract at ADS Title: No "Chromospheric Activity" Seen in eta And Authors: Strassmeier, K. G.; Hron, J. Bibcode: 1990IBVS.3545....1S Altcode: No abstract at ADS Title: The spectral classification of chromospherically active binary stars with composite spectra. Authors: Strassmeier, K. G.; Fekel, F. C. Bibcode: 1990A&A...230..389S Altcode: This paper presents and analyzes blue and red-wavelength high-resolution spectra of twelve chromospherically active binary or triple systems with composite spectra. Spectral classifications for the individual stellar components are derived by means of the 'spectrum-synthesis' technique and are compared to stellar evolutionary models and observed masses and/or mass ratios. Also presented is a carefully selected set of MK reference stars of luminosity class III, IV, and V, and spectral type A9-K5, and v sin i less than 10 km/s, to cover the spectral range of the components of chromospherically active binary systems of the RS CVn-type. New values of v sin i are determined for some of the reference and program stars. Two spectroscopic binaries have been discovered. Title: HR 1362: A Test Case for Stellar Dynamo Theories Authors: Strassmeier, Klaus G.; Hall, Douglas S.; Barksdale, William S.; Jusick, Anthony T.; Henry, Gregory W. Bibcode: 1990ApJ...350..367S Altcode: An analysis of 11 yr of photometry of HR 1362 = EK Eri has shown a well-established photometric period of 335 days. This confirms an earlier period determination of about 310 days from 3 yr of APT data and is consistent with a new v sin i determination of 2 + or - 2 km/s. Recent Ca II H and K observations show moderately strong H and K emission lines at a flux level of log F prime (K) of about 6.5 ergs sq m/s. If the photometric period is interpreted as the rotation period, this surface flux is more than one order of magnitude larger than what can be expected from empirical activity versus rotation relationships. The spectrum and the U-B and B-V colors are consistent with a single G8 III-IV spectral classification, while the V-R and V-I values indicate a small color excess, typical of chromospherically active stars. Title: Chromospheric CA II H and K and H alpha Emission in Single and Binary Stars of Spectra Types F6--M2 Authors: Strassmeier, Klaus G.; Fekel, Francis C.; Bopp, Bernard W.; Dempsey, Robert C.; Henry, Gregory W. Bibcode: 1990ApJS...72..191S Altcode: New observations of the Ca II H and K and H-epsilon region and/or the Balmer H-alpha line are presented for 100 mostly very active stars but also for weak or inactive stars with suspected activity. Correlations between chromospheric activity at Ca II H and K and H-alpha and effective surface temperature and rotation are identified, and several new stars with chromospheric Ca II H and K emission are discovered. No single activity-rotation relation can be derived for all luminosity classes, and there is clear evidence that evolved stars are generally more active than main-sequence stars of the same rotation period. Binary within the evolved stars appears to play no role, while main-sequence binary stars show generally higher levels of activity than their single counterparts. Chromospheric emission in the Ca II H and K lines depends on surface temperature in that flux declines with cooler temperature. Title: On Chromospheric Emission and Photometric Variability of Active Late Type Stars Authors: Strassmeier, K. G. Bibcode: 1990ASIC..319..509S Altcode: 1990acb..proc..509S No abstract at ADS Title: Synoptic Doppler Imaging and Photometry of Spotted Chromospherically Active Stars Authors: Strassmeier, K. G. Bibcode: 1990ASIC..319..485S Altcode: 1990acb..proc..485S No abstract at ADS Title: Photometric and Spectroscopic Modeling of Starspots on the RS Canum Venaticorum Binary HD 26337 Authors: Strassmeier, Klaus G. Bibcode: 1990ApJ...348..682S Altcode: Results are presented on photometric and spectroscopic observations made in 1987-1988 on the rapidly rotating G5 subgiant in the single-lined RS CVn binary HD 26337. Results show the existence of a cool polar spot on HD 26337, which is rather long lived, persisting at least the nine years of the photometry observations. The polar spot contributes only insignificantly to the light curve amplitude, but is crucial for the overall brightness of the system. Evidence is also found for extremely rapid light curve shape variations on a time scale of only one or two rotation cycles. These changes could be modeled by rapidly decreasing a spot area. Title: Photoelectric Photometry of the Rs-Canum Binary Ei-Eridani = HD26337 Authors: Hooten, J. T.; Strassmeier, K. G.; Hall, D. S.; Barksdale, W. S., Jr.; Bertoglio, A.; Cortesi, S.; Cutispoto, G.; Engelbrektson, S.; Ganis, M.; Gómez, J. M.; Casas, R.; Gallart, C.; Jariod, E.; Ito, Y.; Melillo, F. J.; Ohshima, O.; Poole, R. S.; McLaughlin, T. A.; Powell, H. D.; Nix, R. M.; Soder, J.; Wasson, R. Bibcode: 1989Ap&SS.155...45H Altcode: DifferentialUBV(RI) KC andUBVRI photometry of the RS CVn binary EI Eridani obtained during December 1987 and January 1988 at fourteen different observatories is presented. A combined visual bandpass light curve, corrected for systematic errors of different observatories, utilizes the photometric period of 1.945 days to produce useful results. Analysis shows the visual light curve to have twin maxima, separated by about 0.4 phase, and a full amplitude of approximately 0.06 mag for the period of observation, a smaller amplitude than reported in the past. The decrease in amplitude may be due to a decrease or homogenization of spot coverage. To fit the asymmetrical light curve, a starspot model would have to employ at least two spotted regions separated in longitude. Title: Sternflecken. Authors: Strassmeier, Klaus G.; Hall, Douglas S. Bibcode: 1989S&W....28..230S Altcode: The study of starspots is discussed. The history of starspot observation is summarized, and observational methods are described. The possibilities for amateur observations are briefly addressed. The chromospheres of active stars are examined. Whether 'superstarspots' are coronal holes or active regions is discussed. Title: Ultraviolet, Visible, and Radio Observations of EI Eri Authors: Neff, J. E.; Walter, F. M.; Skinner, S. L.; Brown, A.; Strassmeier, K. G.; Rodono, M.; Cutispoto, G.; Jankov, S.; Char, S. Bibcode: 1989BAAS...21..747N Altcode: No abstract at ADS Title: Variability of LR Hya = HD 91816 not Confirmed Authors: Strassmeier, K. G. Bibcode: 1989IBVS.3290....1S Altcode: No abstract at ADS Title: The Photometric Variability of the Chromospherically Active Binary Star HD 80715 Authors: Strassmeier, Klaus G.; Hooten, James T.; Hall, Douglas S.; Fekel, Francis C. Bibcode: 1989PASP..101..107S Altcode: Differential UBVRI photometry of the double-lined BY Dra system HD 80715 (K3 V + K3 V) obtained in December 1987 is presented. The star is found to be a variable with a full amplitude of 0.06 mag in V and a period similar or equal to the orbital period of 3.804 days. The mechanism of the variability is interpreted as rotational modulation due to dark starspots. In an attempt to detect chromospheric activity, high-resolution CCD spectra were obtained at Ca II H and K and at Fe I 6430 A and Ca I 6439 A, the photospheric lines normally used for Doppler imaging. HD 80715 shows double H and K emission features at a constant flux level for each component. Title: Chromospherically Active Stars. VI. HD 136901 = UV CrB: A Massive Ellipsoidal K Giant Single-Lined Spectroscopic Binary Authors: Fekel, Francis C.; Kirkpatrick, J. Davy; Yang, Xinxing; Strassmeier, Klaus G. Bibcode: 1989AJ.....97..202F Altcode: The variable star HD 136901 = UV CrB is a chromospherically active K2 III single-lined spectroscopic binary with an orbital period of 18.665 days. It has modest-strength Ca H and K emission and UV features, while H-alpha is a strong absorption feature containing little or no emission. The inclination of the system is 53 + or - 12 deg. The v sin i of the primary is 42 + or - 2 km/s, resulting in a minimum radius of 15.5 + or - 0.8 solar. When compared with the Roche lobe radius, this results in a mass ratio of 2.90 or larger. Additional constraints indicate that the secondary has a mass between 0.85 and 1.25 solar. Thus, the mass of the primary is at least 2.5 solar and probably is in the range 2.5-4 solar. Title: Photometric Variability in Chromospherically Active Stars. III. The Binary Stars Authors: Strassmeier, Klaus G.; Hall, Douglas S.; Boyd, Louis J.; Genet, Russell M. Bibcode: 1989ApJS...69..141S Altcode: Differential UBV photometry of 49 late-type chromospherically active binary stars has been obtained. A total of 12,353 differential UBV magnitudes have been acquired and are used to determine seasonal photometric periods, amplitudes, mean brightnesses, maximum spot amplitudes, 'unspotted' differential magnitudes, and times of minimum light. Standard Fourier techniques are used to investigate the cause of the light variability. Eight stars are found which exhibit light variations due not to spot activity but rather to ellipticity and/or reflection effect. Others show combinations of all three effects. Some of the systems also show substantial differences between their rotational and orbital period. Title: Status Report on the International Campaign of Simultaneous VRI Photometry and Spectroscopy of EI Eri = HD 26337 Authors: Strassmeier, K. G.; Hooten, J. T. Bibcode: 1988IAPPP..34...21S Altcode: No abstract at ADS Title: Photometric Variability of Chromospherically Active Stars. I. The Constant Stars Authors: Strassmeier, Klaus G.; Hall, Douglas S. Bibcode: 1988ApJS...67..439S Altcode: Over 3800 differential UBV observations for 15 known or suspected chromospherically active stars are presented. All stars turned out to exhibit no light variations over the period of observation from 1983 through 1987. Three additional nonactive stars already known to be constant have been used to determine the external and internal precision of the data. Title: Photometric Variability in Chromospherically Active Stars. II. The Rapidly Rotating Single Stars Authors: Strassmeier, Klaus G.; Hall, Douglas S. Bibcode: 1988ApJS...67..453S Altcode: Differential UBV photometry of five variable chromospherically active single stars carried out from 1983 through 1987 is reported. About 1000 individual measures are used to determine their photometric behavior, a result presumably of spot activity. All observations were made with a fully automatic telescope. Title: Starspot modeling of ten years of photometry of the long-period RS CVn binary sigma Geminorum. Authors: Strassmeier, K. G.; Hall, D. S.; Eaton, J. A.; Landis, H. J.; Barksdale, W. S.; Reisenweber, R. C.; Powell, B. E.; Fernandes, M.; Zeigler, K. W.; Renner, T. R.; Wasson, R.; Nielsen, P.; Louth, H.; Chambliss, C. R.; Fortier, G.; Grim, B. S.; Turner, L. C.; Stelzer, H. J.; Slauson, D. M.; Fried, R. E.; Brettman, O. H.; Engelbrektson, S.; Krisciunas, K.; Miles, R. Bibcode: 1988A&A...192..135S Altcode: The authors present new UBV photometry of the long period (Porb = 19.6 days) RS CVn binary σ Gem made between 1981 and 1986 at 22 different observatories. Together with earlier data presented by Fried et al. (1983), σ Gem has now been monitored since the discovery of its light variability in 1977. With these ten years of differential photometry in hand the authors investigate the long-term spot behavior with a standard spot-modeling computer program. They found a cyclic variation of the total spotted area with a period of ≈2.7 yr, a maximum spot coverage of 12% in 1986, a maximum wave amplitude of 0.15 mag in 1984, and mean colors which are not entirely consistent with the K1 III spectral classification. From the spot-migration rate the authors derived a more recent photometric period of 19.410 days. They also discuss some anomalies in the spot motions which occurred between 1984 and 1985. Title: A catalog of chromospherically active binary stars. Authors: Strassmeier, K. G.; Hall, D. S.; Zeilik, M.; Nelson, E.; Eker, Z.; Fekel, F. C. Bibcode: 1988A&AS...72..291S Altcode: The authors have compiled a catalog of 168 chromospherically active binary stars including the class of RS Canum Venaticorum binaries, BY Draconis binaries and other binaries which show "strong" Ca II H and K emission in their spectra. The catalog contains information on the photometric, spectroscopic, orbital and physical properties of the systems as well as the space motions and positions. Summarized in a candidate list are an additional 37 stars having similar characteristics but which are not definitely known binaries or have not had H and K emission observed. A bibliography and notes for each star are included to direct interested workers to primary references for each of the systems. The catalog contains stars in both the northern and the southern sky. Title: A multiple spot model for simultaneous solution of light curves and distorted line profiles of spotted stars Authors: Strassmeier, Klaus G. Bibcode: 1988Ap&SS.140..223S Altcode: This paper is devoted to the effects of dark starspots on observed light curves and line profiles. A new formulation of the starspot model with multiple spots and arbitrary spot shapes is derived which allows for a numerical solution of light and colour curves and distorted line profiles simultaneously. The effects of differential rotation and the existence of a penumbra have also been considered. A parameter study demonstrates the influences of different spot parameters on the theoretical light curves and rotation profiles. The computer code is applicable for single stars as well as for eclipsing close binaries allowing for ellipticity effect and reflection effect. Title: Request for VRI Photometry of the RS CVn Type Binary HD 26337 during 15. through 30. December 1987 Authors: Strassmeier, Klaus G. Bibcode: 1987IBVS.3049....1S Altcode: No abstract at ADS Title: Request for VRI Photometry of the RS CVn Type Binary HD 26337 Authors: Strassméier, K. G. Bibcode: 1987IAPPP..28...24S Altcode: No abstract at ADS Title: H-alpha and LiI Observations of the RS CVn Type Binaries: sigma Gem, alpha Aur, 93 Leo and HR 6469 Authors: Strassmeier, K. G.; Weichinger, S.; Hanslmeier, A. Bibcode: 1986IBVS.2937....1S Altcode: No abstract at ADS