Author name code: pavlenko ADS astronomy entries on 2022-09-14 author:"Pavlenko, Yakov V." ------------------------------------------------------------------------ Title: Bands of NaH lines in spectra of late type stars Authors: Lyubchyk, Y. P.; Pavlenko, Y. V.; Lyubchyk, O. K.; Jones, H. R. A. Bibcode: 2022KFNT...38c..65L Altcode: No abstract at ADS Title: Analysis of actinium abundances in the atmosphere of Cepheid HIP13962 Authors: Gopka, V. F.; Shavrina, A. V.; Yushchenko, V. A.; Pavlenko, Y. V.; Yushchenko, A. V.; Glazunova, L. V. Bibcode: 2022KFNT...38...63G Altcode: No abstract at ADS Title: Exocomet activity around the stars at different evolution stages: current issues Authors: Pavlenko, Y. V.; Shubina, O. C.; Kulyk, I. V.; Kuznyetsova, Y. G.; Zakhozhay, O. V.; Korsun, P. P.; Borysenko, S. A.; Krushevska, V. M.; Andreev, M. V. Bibcode: 2021KFNT...37b..19P Altcode: 2021KFNT...37...19P No abstract at ADS Title: VizieR Online Data Catalog: HARPS and X-shooter spectra of Southern M dwarfs (Kuznetsov+ 2019) Authors: Kuznetsov, M. K.; Del Burgo, C.; Pavlenko, Y. V.; Frith, J. Bibcode: 2020yCat..18780134K Altcode: The High-accuracy Radial-velocity Planet Searcher (HARPS) is a high-resolution spectrograph installed on the 3.6m telescope in La Silla. It has a resolving power of R~115000 over a spectral range of 3830-6930Å. Using the ESO Science Archive Facility, we downloaded 5567 spectra, obtained during a period between 2003 October and 2017 February, which corresponded to 420 M dwarfs from our sample.

The X-shooter (Intermediate Resolution, High-Efficiency Spectrograph) spectrograph is mounted on the VLT at the European Southern Observatory (ESO) in Paranal, Chile. In this paper, we focused on data obtained from the VIS spectroscopic arm of the X-shooter (5340-10200Å). The available VIS spectra associated with the stars from our sample were retrieved from the European Southern Observatory (ESO) science archive. The spectra were observed between 2009 June and 2017 November. In total, we collected spectroscopic data for 153 stars.

(2 data files). Title: Isotopic ratios in the red giant component of the recurrent nova T Coronae Borealis Authors: Pavlenko, Y. V.; Evans, A.; Banerjee, D. P. K.; Geballe, T. R.; Munari, U.; Gehrz, R. D.; Woodward, C. E.; Starrfield, S. Bibcode: 2020MNRAS.498.4853P Altcode: 2020arXiv200812150P; 2020MNRAS.tmp.2568P We report the determination of abundances and isotopic ratios for C, O, and Si in the photosphere of the red giant (RG) component of the recurrent nova (RN) T Coronae Borealis from new 2.284-2.402 μm and 3.985-4.155 μm spectroscopy. Abundances and isotopic ratios in the photosphere may be affected by (i) processes in the RG interior which are brought to the surface during dredge-up and (ii) contamination of the RG, either during the common envelope phase of the binary evolution or by material synthesized in RN eruptions, or a combination of the two. We find that the abundances of C, O, and Si are reasonably consistent with the expected composition of an RG after first dredge-up, as is the 16O/17O ratio. The 28Si/29Si ratio is found to be 8.6 ± 3.0, and that for 28Si/30Si is 21.5 ± 3.0. The 12C/13C ratio (10 ± 2) is somewhat lower than expected for first dredge-up. The 16O/18O ratio (41 ± 3) is highly inconsistent with that expected either from RG evolution (~550) or from contamination of the RG by the products of a nova thermonuclear runaway. In particular, the C and O isotopic ratios taken in combination are a puzzle. We urge confirmation of our results using spectroscopy at high resolution. We also encourage a thorough theoretical study of the effects on the secondary star in an RN system of contamination by ejecta having anomalous abundances and isotopic ratios. Title: Erratum: The first planet detected in the WTS: an inflated hot-Jupiter in a 3.35 day orbit around a late F-star Authors: Cappetta, M.; Saglia, R. P.; Birkby, J. L.; Koppenhoefer, J.; Pinfield, D. J.; Hodgkin, S. T.; Cruz, P.; Kovács, G.; Sipőcz, B.; Barrado, D.; Nefs, B.; Pavlenko, Y. V.; Fossati, L.; del Burgo, C.; Martín, E. L.; Snellen, I.; Barnes, J.; Campbell, D.; Catalan, S.; Gálvez-Ortiz, M. C.; Goulding, N.; Haswell, C.; Ivanyuk, O.; Jones, H.; Kuznetsov, M.; Lodieu, N.; Marocco, F.; Mislis, D.; Murgas, F.; Napiwotzki, R.; Palle, E.; Pollacco, D.; Sarro Baro, L.; Solano, E.; Steele, P.; Stoev, H.; Tata, R.; Zendejas, J. Bibcode: 2020MNRAS.497..916C Altcode: No abstract at ADS Title: VizieR Online Data Catalog: Post-AGB candidates in LMC and SMC SALT spectra (Szczerba+, 2020) Authors: Szczerba, R.; Hajduk, M.; Pavlenko; Ya. V.; Hrivnak, B. J.; Kaminsky; B. M.; Volk, K.; Siodmiak, N. Gezer I.; Zacs, L.; Pych, W.; Sarna, M. Bibcode: 2020yCat..36410142S Altcode: Spectroscopic data from the South African Large Telescope shown on Figs. 2, 3 and 4 are available in fig2.dat, fig3.dat and fig4.dat, respectively. Each spectrum has 2 gaps: in the red setting (Figs.2 and 3) 7130-7200Å and 8170-8220Å, in the blue setting (Fig.4) 3550-3580Å and 3840-3850Å. In the notes to the tables description we use "the left part" of the spectrum for spectrum before the first gap, "the middle part" of the spectrum for spectrum between the two gaps, and "the right part" of the spectrum for spectrum above the second gap.

(4 data files). Title: HD 54361: evidence for the status of a low mass TP-AGB star Authors: Začs, L.; Pukïtis, K.; Sperauskas, J.; Pavlenko, Y.; Schmidt, M.; Alksnis, O. Bibcode: 2020Ap&SS.365...27Z Altcode: The mass of the cool carbon star HD 54361 was suspected to be high, assuming the membership in the stellar association CMa OB1, in conflict with the theory of stellar evolution. The Gaia parallax and a high-resolution spectrum in the wavelength region from about 4800 to 6900 Å was employed in order to update the distance, atmospheric parameters and abundances using the method of spectral synthesis and new model atmospheres. Absorption lines are broad in the spectrum presumably because of a large macroturbulence, ξRT=10 ±1 kms-1. Radial-velocity monitoring revealed a scatter of about 4 km s-1, which reflects probably a large scale convection in the atmosphere. The effective temperature was found to be about 3200 K by modelling the wings of Na I D doublet, a somewhat higher than that estimated from the angular diameter. The difference in the temperature could be due to the light/colour variation. The abundances of iron peak elements calculated from less blended lines blueward of 5000 Å are near solar, [M/H]=0.0 ±0.2 dex. The neutron-capture elements are enhanced up to 1 dex. The parallax leads to the distance of 554-41+49pc, the absolute magnitude, MK=-7.7 ±0.2 mag, and the bolometric magnitude, Mbol(K )=-4.6 ±0.2 mag. The observed stellar parameters and abundances are typical values for the low mass ∼1.8 M⊙ star on the TP-AGB branch according to the isochrone calculated for logAge (yr )=9.20 with solar initial metallicity. HD 54361 possibly belongs to the spike in the TP-AGB star numbers associated with the AGB-boosting effect. Title: Metallicity, temperature, and gravity scales of M subdwarfs Authors: Lodieu, N.; Allard, F.; Rodrigo, C.; Pavlenko, Y.; Burgasser, A.; Lyubchik, Y.; Kaminsky, B.; Homeier, D. Bibcode: 2019A&A...628A..61L Altcode: 2019arXiv190703674L
Aims: The aim of the project is to define metallicity/gravity/temperature scales for different spectral types of metal-poor M dwarfs.
Methods: We obtained intermediate-resolution ultraviolet (R ∼ 3300), optical (R ∼ 5400), and near-infrared (R ∼ 3900) spectra of 43 M subdwarfs (sdM), extreme subdwarfs (esdM), and ultra-subdwarfs (usdM) with the X-shooter spectrograph on the European Southern Observatory Very Large Telescope. We compared our atlas of spectra to the latest BT-Settl synthetic spectral energy distribution over a wide range of metallicities, gravities, and effective temperatures to infer the physical properties for the whole M dwarf sequence (M0-M9.5) at sub-solar metallicities and constrain the latest atmospheric models.
Results: The BT-Settl models accurately reproduce the observed spectra across the 450-2500 nm wavelength range except for a few regions. We find that the best fits are obtained for gravities of log (g) = 5.0-5.5 for the three metal classes. We infer metallicities of [Fe/H] = -0.5, -1.5, and -2.0 ± 0.5 dex and effective temperatures of 3700-2600 K, 3800-2900 K, and 3700-2900 K for subdwarfs, extreme subdwarfs, and ultra-subdwarfs, respectively. Metal-poor M dwarfs tend to be warmer by about 200 ± 100 K and exhibit higher gravity than their solar-metallicity counterparts. We derive abundances of several elements (Fe, Na, K, Ca, Ti) for our sample but cannot describe their atmospheres with a single metallicity parameter. Our metallicity scale expands the current scales available for mildly metal-poor planet-host low-mass stars. Our compendium of moderate-resolution spectra covering the 0.45-2.5 micron range represents an important resource for large-scale surveys and space missions to come.

All observed spectra 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/628/A61Based on observations collected at the European Southern Observatory, Chile, under programmes 089.C-0140(A), 091.C-0264(A), 092.D-0600(A), and 093.C-0610(A). Title: VizieR Online Data Catalog: X-shooter spectra of 43 metal-poor M dwarfs (Lodieu+, 2019) Authors: Lodieu, N.; Allard, F.; Rodrigo, C.; Pavlenko, Y.; Burgasser, A.; Lyubchik, Y.; Kaminsky, B.; Homeier, D. Bibcode: 2019yCat..36280061L Altcode: We make public the ESO VLT X-shooter spectra of 43 subdwarfs spanning the 560-2500nm wavelength range. Each file contains wavelength (in nm) and the flux (in ergs/cm2/s/Angstroem) in the first and second column, respectively. Spectra are corrected for telluric absorption. Names of files are composed of spectral types of the source followed by the date of observations.

(2 data files). Title: SiO bands in infrared spectra of late spectral stars Authors: Pavlenko, Y. V. Bibcode: 2019KFNT...35d..21P Altcode: No abstract at ADS Title: Masses, oxygen, and carbon abundances in CHEPS dwarf stars Authors: Pavlenko, Y. V.; Kaminsky, B. M.; Jenkins, J. S.; Ivanyuk, O. M.; Jones, H. R. A.; Lyubchik, Y. P. Bibcode: 2019A&A...621A.112P Altcode: 2018arXiv181105011P Context. We report the results from the determination of stellar masses, carbon, and oxygen abundances in the atmospheres of 107 stars from the Calan-Hertfordshire Extrasolar Planet Search (CHEPS) programme. Our stars are drawn from a population with a significantly super-solar metallicity. At least 10 of these stars are known to host orbiting planets.
Aims: In this work, we set out to understand the behaviour of carbon and oxygen abundance in stars with different spectral classes, metallicities, and V sin i within the metal-rich stellar population.
Methods: Masses of these stars were determined using data from Gaia DR2. Oxygen and carbon abundances were determined by fitting the absorption lines. We determined oxygen abundances with fits to the 6300.304 Å O I line, and we used 3 lines of the C I atom and 12 lines of the C2 molecule for the determination of carbon abundances.
Results: We determine masses and abundances of 107 CHEPS stars. There is no evidence that the [C/O] ratio depends on V sin i or the mass of the star within our constrained range of masses, i.e. 0.82 < M*/M⊙ < 1.5 and metallicities - 0.27 < [Fe/H] < +0.39. We also confirm that metal-rich dwarf stars with planets are more carbon rich in comparison with non-planet host stars with a statistical significance of 96%.
Conclusions: We find tentative evidence that there is a slight offset to lower abundance and a greater dispersion in oxygen abundances relative to carbon. We interpret this as potentially arising because the production of oxygen is more effective at more metal-poor epochs. We also find evidence that for lower mass stars the angular momentum loss in stars with planets as measured by V sin i is steeper than stars without planets. In general, we find that the fast rotators (V sin i > 5 km s-1) are massive stars.

Table A.3 is also 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/621/A112 Title: Accuracies of abundance determinations in large spectroscopic surveys Authors: Ivanyuk, Oleksiy; Pavlenko, Y. V.; Jenkins, J. S.; Jones, H. R. A. Bibcode: 2018gbx..confE..18I Altcode: Along with our own results from the high resolution spectral analysis of the 107 metal rich F, G, K stars from the Calan-Hertfordshire Extrasolar Planet Search program (CHEPS) we discuss differences in the abundances of Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn between a number of large spectroscopic surveys. Most authors tend to use stellar spectra to determine virtually all fundamental parameters including effective temperature and surface gravity. We attempted to recreate results for a dozen of common stars using available input parameters to highlight the real scale of errors this approach might induce. We confirm overabundance and light decline of α-elements versus metallicity in the metal-deficient domain from -0.4 to -0.2 dex. This trend changes for the metal-rich stars between 0.0 and 0.4 dex, but among α-elements only Na follows positive trend - along with Mn, Ni, Cu and Zn. Slight increase is also visible for Al. Ca continued to show a negative trend. Title: VizieR Online Data Catalog: Carbon and oxygen in 107 dwarf stars (Pavlenko+, 2019) Authors: Pavlenko, Y. V.; Kaminsky, B. M.; Jenkins, J. S.; Ivanyuk, O. M.; Jones, H. R. A.; Lyubchik, Y. P. Bibcode: 2018yCat..36210112P Altcode: We used the observed spectra obtained in the framework of the Calan-Hertfordshire Extrasolar Planet Search (CHEPS) programme (Jenkins et al., 2009ApJ...704..975J, Cat. J/ApJ/704/975).

All stars in our work were observed with the HARPS spectrograph (Mayor et al., 2003Msngr.114...20M) at a resolving power of 115,000, and since the spectra were taken as part of the CHEPS programme, whose primary goal is the detection of small planets orbiting these stars, the S/N of the spectra are all over 100 at a wavelength of 6000Å. The 107 stars in this work are primary targets for CHEPS.

Carbon and Oxygen in the CHEPS stars. Cases of the problematic determination of oxygen abundance due to the strong blending 6300.304Å OI line by telluric lines are marked by (*). The oxygen abundances determined by visual comparison of computed and observed spectra are marked by (+).

(1 data file). Title: The analysis of actinium abundance in the atmospheres of three Magellanic Clouds red supergiants stars Authors: Gopka, V. F.; Shavrina, A. V.; Yushchenko, V. A.; Yushchenko, A. V.; Pavlenko, Y. V.; Andrievsky, S. M.; Vasileva, S. V.; Kim, C.; Jeong, Y.; Lyubchik, Y. P. Bibcode: 2018KFNT...34c..25G Altcode: No abstract at ADS Title: Flare activity and photospheric analysis of Proxima Centauri Authors: Pavlenko, Y.; Suárez Mascareño, A.; Rebolo, R.; Lodieu, N.; Béjar, V. J. S.; González Hernández, J. I. Bibcode: 2017A&A...606A..49P Altcode: 2017arXiv170604678P Context. We present the analysis of emission lines in high-resolution optical spectra of the planet-host star Proxima Centauri (Proxima) classified as a M5.5V.
Aims: We carry out a detailed analysis of the observed spectra to get a better understanding of the physical conditions of the atmosphere of this star.
Methods: We identify the emission lines in a series of 147 high-resolution optical spectra of the star at different levels of activity and compare them with the synthetic spectra computed over a wide spectral range.
Results: Our synthetic spectra computed with the PHOENIX 2900/5.0/0.0 model atmosphere fits the observed spectral energy distribution from optical to near-infrared quite well. However, modelling strong atomic lines in the blue spectrum (3900-4200 Å) requires implementing additional opacity. We show that high-temperature layers in Proxima Centauri consist of at least three emitting parts: a) a stellar chromosphere where numerous emission lines form; we suggest that some emission cores of strong absorption lines of metals form there; b) flare regions above the chromosphere, where hydrogen Balmer lines up to high transition levels (10-2) form; and c) a stellar wind component with Vr = -30 km s-1 seen in some Balmer lines as blueshifted emission lines. We believe that the observed He line at 4026 Å in emission can be formed in that very hot region.
Conclusions: We show that the real structure of the atmosphere of Proxima is rather complicated. The photosphere of the star is best fit by a normal M5 dwarf spectrum. On the other hand, emission lines form in the chromosphere, flare regions, and extended hot envelope.

The movies are available at http://www.aanda.org Title: VizieR Online Data Catalog: Spectroscopic properties for 107 stars (Ivanyuk+, 2017) Authors: Ivanyuk, O. M.; Jenkins, J. S.; Pavlenko, Y. V.; Jones, H. R. A.; Pinfield, D. J. Bibcode: 2017yCat..74684151I Altcode: The tables contain derived stellar parameters and abundances along with the spectral ranges that we used for the line profile fitting.

(2 data files). Title: New planetary systems from the Calan-Hertfordshire Extrasolar Planet Search Authors: Jenkins, J. S.; Jones, H. R. A.; Tuomi, M.; Díaz, M.; Cordero, J. P.; Aguayo, A.; Pantoja, B.; Arriagada, P.; Mahu, R.; Brahm, R.; Rojo, P.; Soto, M. G.; Ivanyuk, O.; Becerra Yoma, N.; Day-Jones, A. C.; Ruiz, M. T.; Pavlenko, Y. V.; Barnes, J. R.; Murgas, F.; Pinfield, D. J.; Jones, M. I.; López-Morales, M.; Shectman, S.; Butler, R. P.; Minniti, D. Bibcode: 2017MNRAS.466..443J Altcode: 2016arXiv160309391J We report the discovery of eight new giant planets, and updated orbits for four known planets, orbiting dwarf and subgiant stars using the CORALIE, HARPS, and MIKE instruments as part of the Calan-Hertfordshire Extrasolar Planet Search. The planets have masses in the range 1.1-5.4 MJ's, orbital periods from 40 to 2900 d, and eccentricities from 0.0 to 0.6. They include a double-planet system orbiting the most massive star in our sample (HD147873), two eccentric giant planets (HD128356b and HD154672b), and a rare 14 Herculis analogue (HD224538b). We highlight some population correlations from the sample of radial velocity detected planets orbiting nearby stars, including the mass function exponential distribution, confirmation of the growing body of evidence that low-mass planets tend to be found orbiting more metal-poor stars than giant planets, and a possible period-metallicity correlation for planets with masses >0.1 MJ, based on a metallicity difference of 0.16 dex between the population of planets with orbital periods less than 100 d and those with orbital periods greater than 100 d. Title: Determination of abundances in atmospheres of F-, G-, K-dwarfs Authors: Pavlenko, Y. V. Bibcode: 2017KFNT...33v..24P Altcode: No abstract at ADS Title: Acne at The Bottom Of The Main Sequence Authors: Barnes, John; Haswell, C.; Jenkins, J.; Jeffers, S.; Jones, H. R. A.; Lohr, M.; Pavlenko, Y. Bibcode: 2016csss.confE..10B Altcode: Starspots are an important manifestation of stellar activity and yet their distribution patterns on the lowest mass stars is not well known. Time series spectra of fully convective M dwarfs taken in the red-optical with UVES reveal numerous line profile distortions which are interpreted as starspots. We derive Doppler images for four M4.5V - M9V stars and find that contrast ratios corresponding to photosphere-spot temperature differences of only 200-300 K are sufficient to model the timeseries spectra. Although more starspot structure is found at high latitudes, spots are reconstructed at a range of phases and latitudes with mean spot filling factors of only a few per cent. The occurrence of low-contrast spots at predominantly high latitudes is in general likely to be responsible for the low amplitude photometric variability seen in late-M dwarfs. The recovered starspot patterns are used to assess their effect on precision radial velocity surveys aimed at detecting planets around this population of stars. Title: VLT X-Shooter spectroscopy of the nearest brown dwarf binary Authors: Lodieu, N.; Zapatero Osorio, M. R.; Rebolo, R.; Béjar, V. J. S.; Pavlenko, Y.; Pérez-Garrido, A. Bibcode: 2015A&A...581A..73L Altcode: 2015arXiv150608848L
Aims: The aim of the project is to characterise the two components of the brown dwarf system nearest to the Sun, WISE J104915.57-531906.1 (also called Luhman 16AB) at optical and near-infrared wavelengths.
Methods: We obtained high signal-to-noise intermediate-resolution (R ~ 6000-11 000) optical (600-1000 nm) and near-infrared (1000-2480 nm) spectra of each component of Luhman 16AB with the X-Shooter instrument on the Very Large Telescope.
Results: We classify the primary and secondary of the Luhman 16 system as L6-L7.5 and T0±1, respectively, in agreement with previous measurements published in the literature. We present measurements of the lithium pseudo-equivalent widths, which appear of similar strength in both components (8.2 ± 1.0 Å for the L and 8.4 ± 1.5 Å for the T component). The presence of lithium (7Li) in both components implies masses lower than 0.06 M⊙, while the comparison with models suggests lower limits of 0.04 M⊙. The detection of lithium in the T component is the first of its kind. Similarly, we assess the strength of other alkali lines (e.g. pseudo-equivalent widths of 6-7 Å for RbI and 4-7 Å for CsI) present in the optical and near-infrared regions and compare with estimates for L and T dwarfs. We also derive effective temperatures and luminosities of each component of the binary: -4.66 ± 0.08 dex and 1305 K for the L dwarf and -4.68 ± 0.13 dex and 1320 K for the T dwarf. According to our radial velocity determinations, the binary does not appear to belong to any of the well-known moving group. Our preliminary theoretical analysis of the optical and J-band spectra indicates that the L- and T-type spectra can be reproduced with a single temperature and gravity but different relative chemical abundances, which strongly affects the spectral energy distribution of L/T transition objects.

Based on observations collected at the European Southern Observatory, Chile, under DDT programme 290.C-5200(B) (PI Lodieu).FITS files of the reduced 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/qcat?J/A+A/581/A73 Title: VizieR Online Data Catalog: Luhman 16AB X-shooter spectra (Lodieu+, 2015) Authors: Lodieu, N.; Zapatero Osorio, M. R.; Rebolo, R.; Bejar, V. J. S.; Pavlenko, Y.; Perez-Garrido, A. Bibcode: 2015yCat..35810073L Altcode: VLT X-shooter optical and near-infrared spectra of each component of the nearest brown dwarf binary system Luhman 16AB are made public. The spectra cover the ~670nm to ~2480nm with a resolution of 11000 in the optical (670-1000nm) and 6200 in the near-infrared (1000-2480nm). Note: We observe a peak and a dip around 2080-2090nm in the spectra of the components of the system not seen in other T dwarfs, as a potential artefact in our X-shooter data. No other strong artefact is present in our data.

(2 data files). Title: VizieR Online Data Catalog: Ji light curves of WTS-2 (Birkby+, 2014) Authors: Birkby, J. L.; Cappetta, M.; Cruz, P.; Koppenhoefer, J.; Ivanyuk, O.; Mustill, A. J.; Hodgkin, S. T.; Pinfield, D. J.; Sipocz, B.; Kovacs, G.; Saglia, R.; Pavlenko, Y.; Barrado, D.; Bayo, A.; Campbell, D.; Catalan, S.; Fossati, L.; Galvez-Ortiz, M. -C.; Kenworthy, M.; Lillo-Box, J.; Martin, E. L.; Mislis, D.; de Mooij, E. J. W.; Nefs, S. V.; Snellen, I. A. G.; Stoev, H.; Zendejas, J.; Del Burgo, C.; Barnes, J.; Goulding, N.; Haswell, C. A.; Kuznetsov, M.; Lodieu, N.; Murgas, F.; Palle, E.; Solano, E.; Steele, P.; Tata, R. Bibcode: 2015yCat..74401470B Altcode: The infrared light curves of the WTS were generated from time series photometry taken with the WFCAM imager mounted at the prime focus of UKIRT.

In order to confirm the transit of WTS-2 b and to help constrain the transit model, on 2010 July 18 we obtained further time series photometry in the Sloan i band using the Wide Field Camera (WFC) on the 2.5m Isaac Newton Telescope (INT) at Roque de Los Muchachos, La Palma.

(2 data files). Title: A search for lithium in metal-poor L dwarfs Authors: Lodieu, N.; Burgasser, A. J.; Pavlenko, Y.; Rebolo, R. Bibcode: 2015A&A...579A..58L Altcode: 2015arXiv150506858L
Aims: The aim of the project is to search for lithium in absorption at 6707.8 Å to constrain the nature and mass of the brightest low-metallicity L-type dwarfs (referred to as L subdwarfs) identified in large-scale surveys.
Methods: We obtained low- to intermediate-resolution (R ~ 2500-9000) optical (~560-770 nm) spectra of two mid-L subdwarfs, SDSS J125637.13-022452.4 (SDSS1256; sdL3.5) and 2MASS J162620.14+392519.5 (2MASS1626; sdL4) with spectrographs on the European Southern Observatory Very Large Telescope and the Gran Telescopio de Canarias.
Results: We report the presence of a feature at the nominal position of the lithium absorption doublet at 6707.8 Å in the spectrum of SDSS1256, with an equivalent width of 66 ± 27 Å at 2.4σ, which we identify as arising from a CaH molecular transition based on atmosphere models. We do not see any feature at the position of the lithium feature in the spectrum of 2MASS1626. The existence of overlapping molecular absorption sets a confusion detection limit of [Li/H] = -3 for equivalently typed L subdwarfs. We provided improved radial velocity measurements of -126±10 km s-1 and -239±12 km s-1 for SDSS1256 and 2MASS1626, respectively, as well as revised Galactic orbits. We implemented adjusting factors for the CaH molecule in combination with the NextGen atmosphere models to fit the optical spectrum of SDSS1256 in the 6200-7300 Å range. We also estimate the expected Li abundance from interstellar accretion ([Li/H] = -5), place limits on circumstellar accretion (109 g/yr), and discuss the prospects of Li searches in cooler L and T subdwarfs.

Optical spectra of SDSS1256 and 2MASS 1626 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/A58Based on observations collected at the European Southern Observatory, Chile, under programmes 089.C-0883 and 091.C-0594A.Based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma (programmes GTC64_10B and GTC38_11A). Title: VizieR Online Data Catalog: Spectra of two mid-L subdwarfs (Lodieu+, 2015) Authors: Lodieu, N.; Burgasser, A. J.; Pavlenko, Y.; Rebolo, R. Bibcode: 2015yCat..35790058L Altcode: Intermediate-resolution optical spectra of SDSS J125637.13-022452.4 and 2MASS J162620.14+392519.5 are provided. They have been obtained with FORS2 on the ESO Very Large Telescope (grism GRIS1200R+93) and OSIRIS on the Gran Telescopio de Canarias (grating R2500R), respectively.

(2 data files). Title: Silicate Dust in RS Ophiuchi Authors: Rushton, M. T.; Woodward, C. E.; Helton, L. A.; Gehrz, R. D.; Evans, A.; Kaminsky, B.; Pavlenko, Y. V.; Eyres, S. P. S.; Maxwell, M. Bibcode: 2014ASPC..490..249R Altcode: We present Spitzer IRS spectra of the recurrent nova RS Ophiuchi obtained between 2006 and 2009. The data show emission lines due to HI, [Ne II], [Ne V], [Ne VI] and [O IV] and the well known silicate features at 10 μm and 18 μm, whose behaviour are reported here. The silicate features are variable in the period covered by the observations, appearing strongest in our 2007 data. Interestingly, the central wavelength of the 18 μm band is shorter than observed in other symbiotic systems and other circumstellar environments, suggesting unusual grain properties in RS Oph. We report changes that have taken place in the dusty environment in RS Oph and investigate the properties of the dust grains. Title: Erratum: The first planet detected in the WTS: an inflated hot-Jupiter in a 3.35 d orbit around a late F star Authors: Cappetta, M.; Saglia, R. P.; Birkby, J. L.; Koppenhoefer, J.; Pinfield, D. J.; Hodgkin, S. T.; Cruz, P.; Kovács, G.; Sipőcz, B.; Barrado, D.; Nefs, B.; Pavlenko, Y. V.; Fossati, L.; del Burgo, C.; Martín, E. L.; Snellen, I.; Barnes, J.; Campbell, D.; Catalan, S.; Gálvez-Ortiz, M. C.; Goulding, N.; Haswell, C.; Ivanyuk, O.; Jones, H.; Kuznetsov, M.; Lodieu, N.; Marocco, F.; Mislis, D.; Murgas, F.; Napiwotzki, R.; Palle, E.; Pollacco, D.; Sarro Baro, L.; Solano, E.; Steele, P.; Stoev, H.; Tata, R.; Zendejas, J. Bibcode: 2014MNRAS.444.3150C Altcode: 2014arXiv1410.3235C We report the discovery of WTS-1b, the first extrasolar planet found by the WFCAM Transit Survey, which began observations at the 3.8-m United Kingdom Infrared Telescope (UKIRT) in August 2007. Light curves comprising almost 1200 epochs with a photometric precision of better than 1 per cent to J ~ 16 were constructed for ~60000 stars and searched for periodic transit signals. For one of the most promising transiting candidates, high-resolution spectra taken at the Hobby-Eberly Telescope (HET) allowed us to estimate the spectroscopic parameters of the host star, a late-F main sequence dwarf (V=16.13) with possibly slightly subsolar metallicity, and to measure its radial velocity variations. The combined analysis of the light curves and spectroscopic data resulted in an orbital period of the substellar companion of 3.35 days, a planetary mass of 4.01 +- 0.35 Mj and a planetary radius of 1.49+0.16-0.18 Rj. WTS-1b has one of the largest radius anomalies among the known hot Jupiters in the mass range 3-5 Mj. The high irradiation from the host star ranks the planet in the pM class. Title: VizieR Online Data Catalog: Catalogue of bright (K<9) M dwarfs (Frith+, 2013) Authors: Frith, J.; Pinfield, D. J.; Jones, H. R. A.; Barnes, J. R.; Pavlenko, Y.; Martin, E. L.; Brown, C.; Kuznetsov, M. K.; Marocco, F.; Tata, R.; Cappetta, M. Bibcode: 2014yCat..74352161F Altcode: Using the Position and Proper Motion Extended-L (PPMXL) catalogue, we have used optical and near-infrared colour cuts together with a reduced proper motion cut to find bright M dwarfs for future exoplanet transit studies. PPMXL's low proper motion uncertainties allow us to probe down to smaller proper motions than previous similar studies. We have combined unique objects found with this method to that of previous work to produce 8479 K<9 M dwarfs. Low-resolution spectroscopy was obtained of a sample of the objects found using this selection method to gain statistics on their spectral type and physical properties. Results show a spectral-type range of K7-M4V. This catalogue is the most complete collection of K<9 M dwarfs currently available and is made available here.

(1 data file). Title: WTS-2 b: a hot Jupiter orbiting near its tidal destruction radius around a K dwarf Authors: Birkby, J. L.; Cappetta, M.; Cruz, P.; Koppenhoefer, J.; Ivanyuk, O.; Mustill, A. J.; Hodgkin, S. T.; Pinfield, D. J.; Sipőcz, B.; Kovács, G.; Saglia, R.; Pavlenko, Y.; Barrado, D.; Bayo, A.; Campbell, D.; Catalan, S.; Fossati, L.; Gálvez-Ortiz, M. -C.; Kenworthy, M.; Lillo-Box, J.; Martín, E. L.; Mislis, D.; de Mooij, E. J. W.; Nefs, S. V.; Snellen, I. A. G.; Stoev, H.; Zendejas, J.; del Burgo, C.; Barnes, J.; Goulding, N.; Haswell, C. A.; Kuznetsov, M.; Lodieu, N.; Murgas, F.; Palle, E.; Solano, E.; Steele, P.; Tata, R. Bibcode: 2014MNRAS.440.1470B Altcode: 2014MNRAS.tmp..557B; 2014arXiv1402.5416B We report the discovery of WTS-2 b, an unusually close-in 1.02-d hot Jupiter (MP = 1.12MJ, RP = 1.30RJ) orbiting a K2V star, which has a possible gravitationally bound M-dwarf companion at 0.6 arcsec separation contributing ∼20 per cent of the total flux in the observed J-band light curve. The planet is only 1.5 times the separation from its host star at which it would be destroyed by Roche lobe overflow, and has a predicted remaining lifetime of just ∼40 Myr, assuming a tidal dissipation quality factor of Q_{*}^'}=106. Q_{*}^'} is a key factor in determining how frictional processes within a host star affect the orbital evolution of its companion giant planets, but it is currently poorly constrained by observations. We calculate that the orbital decay of WTS-2 b would correspond to a shift in its transit arrival time of Tshift ∼ 17 s after 15 yr assuming Q_{*}^'}=106. A shift less than this would place a direct observational constraint on the lower limit of Q_{*}^'} in this system. We also report a correction to the previously published expected Tshift for WASP-18 b, finding that Tshift = 356 s after 10 yr for Q_{*}^'}=106, which is much larger than the estimated 28 s quoted in WASP-18 b discovery paper. We attempted to constrain Q_{*}^'} via a study of the entire population of known transiting hot Jupiters, but our results were inconclusive, requiring a more detailed treatment of transit survey sensitivities at long periods. We conclude that the most informative and straightforward constraints on Q_{*}^'} will be obtained by direct observational measurements of the shift in transit arrival times in individual hot Jupiter systems. We show that this is achievable across the mass spectrum of exoplanet host stars within a decade, and will directly probe the effects of stellar interior structure on tidal dissipation. Title: Abundances in the atmosphere, effective temperature and surface gravity of the subdwarf metal-poor star G 224-58 A Authors: Kushniruk, I.; Pavlenko, Y. V. Bibcode: 2014ysc..conf...18K Altcode: No abstract at ADS Title: A catalogue of bright (K < 9) M dwarfs Authors: Frith, J.; Pinfield, D. J.; Jones, H. R. A.; Barnes, J. R.; Pavlenko, Y.; Martin, E. L.; Brown, C.; Kuznetsov, M. K.; Marocco, F.; Tata, R.; Cappetta, M. Bibcode: 2013MNRAS.435.2161F Altcode: 2013MNRAS.tmp.2106F; 2013arXiv1308.0501F Using the Position and Proper Motion Extended-L (PPMXL) catalogue, we have used optical and near-infrared colour cuts together with a reduced proper motion cut to find bright M dwarfs for future exoplanet transit studies. PPMXL's low proper motion uncertainties allow us to probe down to smaller proper motions than previous similar studies. We have combined unique objects found with this method to that of previous work to produce 8479 K < 9 M dwarfs. Low-resolution spectroscopy was obtained of a sample of the objects found using this selection method to gain statistics on their spectral type and physical properties. Results show a spectral-type range of K7-M4V. This catalogue is the most complete collection of K < 9 M dwarfs currently available and is made available here. Title: A hot Jupiter transiting a mid-K dwarf found in the pre-OmegaCam Transit Survey Authors: Koppenhoefer, J.; Saglia, R. P.; Fossati, L.; Lyubchik, Y.; Mugrauer, M.; Bender, R.; Lee, C. -H.; Riffeser, A.; Afonso, P.; Greiner, J.; Henning, Th.; Neuhäuser, R.; Snellen, I. A. G.; Pavlenko, Y.; Verdugo, M.; Vogt, N. Bibcode: 2013MNRAS.435.3133K Altcode: 2013MNRAS.tmp.2185K; 2013arXiv1308.6574K We describe the pre-OmegaTranS project, a deep survey for transiting extra-solar planets in the Carina region of the Galactic disc. In 2006-2008, we observed a single dense stellar field with a very high cadence of ∼2 min using the European Southern Observatory Wide Field Imager at the La Silla Observatory.

Using the Astronomical Wide-field Imaging System for Europe environment and the Munich Difference Imaging Analysis pipeline, a module that has been developed for this project, we created the light curves of 16 000 stars with more than 4000 data points which we searched for periodic transit signals using a box-fitting least-squares detection algorithm. All light curves are publicly available. In the course of the pre-OmegaTranS project, we identified two planet candidates - POTS-1b and POTS-C2b - which we present in this work.

With extensive follow-up observations we were able to confirm one of them, POTS-1b, a hot Jupiter transiting a mid-K dwarf. The planet has a mass of 2.31 ± 0.77 MJup, a radius of 0.94 ± 0.04 RJup and a period of P = 3.16 d. The host star POTS-1 has a radius of 0.59 ± 0.02 R⊙ and a mass of 0.70 ± 0.05 M⊙. Due to its low apparent brightness of I = 16.1 mag, the follow-up and confirmation of POTS-1b was particularly challenging and costly. Title: A Hot Uranus Orbiting the Super Metal-rich Star HD 77338 and the Metallicity-Mass Connection Authors: Jenkins, J. S.; Jones, H. R. A.; Tuomi, M.; Murgas, F.; Hoyer, S.; Jones, M. I.; Barnes, J. R.; Pavlenko, Y. V.; Ivanyuk, O.; Rojo, P.; Jordán, A.; Day-Jones, A. C.; Ruiz, M. T.; Pinfield, D. J. Bibcode: 2013ApJ...766...67J Altcode: 2012arXiv1207.1012J We announce the discovery of a low-mass planet orbiting the super metal-rich K0V star HD 77338 as part of our ongoing Calan-Hertfordshire Extrasolar Planet Search. The best-fit planet solution has an orbital period of 5.7361 ± 0.0015 days and with a radial velocity semi-amplitude of only 5.96 ± 1.74 ms-1, we find a minimum mass of 15.9^{+4.7}_{-5.3} M ⊕. The best-fit eccentricity from this solution is 0.09^{+0.25}_{-0.09}, and we find agreement for this data set using a Bayesian analysis and a periodogram analysis. We measure a metallicity for the star of +0.35 ± 0.06 dex, whereas another recent work finds +0.47 ± 0.05 dex. Thus HD 77338b is one of the most metal-rich planet-host stars known and the most metal-rich star hosting a sub-Neptune-mass planet. We searched for a transit signature of HD 77338b but none was detected. We also highlight an emerging trend where metallicity and mass seem to correlate at very low masses, a discovery that would be in agreement with the core accretion model of planet formation. The trend appears to show that for Neptune-mass planets and below, higher masses are preferred when the host star is more metal-rich. Also a lower boundary is apparent in the super metal-rich regime where there are no very low mass planets yet discovered in comparison to the sub-solar metallicity regime. A Monte Carlo analysis shows that this low-mass planet desert is statistically significant with the current sample of 36 planets at the ~4.5σ level. In addition, results from Kepler strengthen the claim for this paucity of the lowest-mass planets in super metal-rich systems. Finally, this discovery adds to the growing population of low-mass planets around low-mass and metal-rich stars and shows that very low mass planets can now be discovered with a relatively small number of data points using stable instrumentation.

Based on observations collected at the La Silla Paranal Observatory, ESO (Chile) with the HARPS spectrograph on the ESO 3.6 m telescope, under the program IDs 079.C-0927, 081.C-0148, 087.C-0368, and 088.C-0662. Title: WTS-2 b: Too close for comfort? Authors: Birkby, J. L.; Cappetta, M.; Cruz, P.; Koppenhoefer, J.; Ivanyuk, O.; Mustill, A.; Hodgkin, S. T.; Pinfield, D. J.; Sipőcz, B.; Kovács, G.; Saglia, R.; Pavlenko, Y.; RoPACS Collaboration; del Burgo, Carlos Bibcode: 2013EPJWC..4701004B Altcode: We report the discovery of WTS-2 b, a typical hot Jupiter in an unusually close 1.02-day orbit to a K-dwarf star. This is the second planet to be discovered in the infrared light curves of the WFCAM Transit Survey (WTS) and is only one-and-a-half times the separation from its host star at which is would be destroyed by Roche lobe overflow. The predicted remaining lifetime of the planet is just 38 Myrs, assuming a tidal dissipation quality factor of Q'* = 106. The magnitude of Q'* is largely unconstrained by observations, thus WTS-2 b provides a useful calibration point for theories describing how frictional processes within a host star affect the tidal orbital evolution of its companion giant planets. It is expected that stars with large convective envelopes are more efficient at dissipating the orbital energy of the planet, and WTS-2 b provides an observational constraint in the sparsely populated K-dwarf regime. In addition, despite its relatively faint magnitude, the favourable size ratio of the WTS-2 star-planet system and the predicted hot equilibrium temperature of the planet will make it possible to characterise the planet's atmosphere via secondary eclipse measurements using existing ground-based instrumentation. Title: VizieR Online Data Catalog: Detached M dwarf eclipsing binaries in WTS (Birkby+, 2012) Authors: Birkby, J.; Nefs, B.; Hodgkin, S.; Kovacs, G.; Sipocz, B.; Pinfield, D.; Snellen, I.; Mislis, D.; Murgas, F.; Lodieu, N.; de Mooij, E.; Goulding, N.; Cruz, P.; Stoev, H.; Cappetta, M.; Palle, E.; Barrado, D.; Saglia, R.; Martin, E.; Pavlenko, Y. Bibcode: 2013yCat..74261507B Altcode: We identified our new MEBs using observations from the WTS (WFCAM Transit Survey). The WTS is an ongoing photometric monitoring campaign that operates on the 3.8-m United Kingdom Infrared Telescope (UKIRT) at Mauna Kea, Hawaii.

The survey began on 2007 August 5, and the eclipsing systems presented in this paper are all found in just one of the four WTS fields.

Photometric follow-up observations to help test and refine our light-curve models were obtained in the Sloan i band using the Wide-Field Camera (WFC) on the 2.5-m INT at Roque de Los Muchachos, La Palma.

(6 data files). Title: The spectroscopic study of M8.5-M9.5 stars and brown dwarfs Authors: Kuznetsov, M. K.; Pavlenko, Y. V.; Galvez-Ortiz, M. C. Bibcode: 2013EPJWC..4704002K Altcode: We present high-resolution spectra analysis of the three late-M dwarfs LP944-20, SIPS J2045-6332 and DENIS-P J0021.0-4244. The stellar spectra were observed with Very Large Telescope/Ultraviolet-Visual Echelle Spectrograph (VLT/UVES) in optical and near-infrared regions. The effective temperatures Teff and log g was defined by comparing observed and theoretical energy distributions for the investigated objects. Synthetic spectra were calculated for PHOENIX atmosphere models - COND and DUSTY, as well as for Semi-empirical atmosphere model. We discuss the influence of the effects associated with dust in stellar atmosphere on the energy distribution in the stellar spectra. Title: The Abundances of Heavy Elements in Red Supergiants of Magellanic Clouds Authors: Gopka, V.; Yushchenko, A.; Kovtyukh, V.; Shavrina, A.; Yushchenko, V.; Vasilyeva, S.; Pavlenko, Y.; Andrievsky, S. Bibcode: 2013OAP....26...54G Altcode: The spectra of Magellanic Clouds (MC) supergiants PMMR23, PMMR144 and RM 1-667 with resolving power R=30,000 and signal to noise ratio near 100 obtained at 3.6 meter telescope in Chile were analysed. We present are port on the detailed investigation of MC supergiants, with special attention to the thorium abundance in these stars. The abundance patterns of three supergiants show that r-process elements are clearly detected in the atmospheres of investigated stars, but the bundances of s-processes elements can vary from star to star. Title: The first planet detected in the WTS: an inflated hot Jupiter in a 3.35 d orbit around a late F star Authors: Cappetta, M.; Saglia, R. P.; Birkby, J. L.; Koppenhoefer, J.; Pinfield, D. J.; Hodgkin, S. T.; Cruz, P.; Kovács, G.; Sipőcz, B.; Barrado, D.; Nefs, B.; Pavlenko, Y. V.; Fossati, L.; del Burgo, C.; Martín, E. L.; Snellen, I.; Barnes, J.; Bayo, A.; Campbell, D. A.; Catalan, S.; Gálvez-Ortiz, M. C.; Goulding, N.; Haswell, C.; Ivanyuk, O.; Jones, H. R.; Kuznetsov, M.; Lodieu, N.; Marocco, F.; Mislis, D.; Murgas, F.; Napiwotzki, R.; Palle, E.; Pollacco, D.; Sarro Baro, L.; Solano, E.; Steele, P.; Stoev, H.; Tata, R.; Zendejas, J. Bibcode: 2012MNRAS.427.1877C Altcode: 2012arXiv1210.1217C We report the discovery of WTS-1b, the first extrasolar planet found by the WFCAM Transit Survey, which began observations at the 3.8-m United Kingdom Infrared Telescope (UKIRT) in 2007 August. Light curves comprising almost 1200 epochs with a photometric precision of better than 1 per cent to J ∼ 16 were constructed for ∼60 000 stars and searched for periodic transit signals. For one of the most promising transiting candidates, high-resolution spectra taken at the Hobby-Eberly Telescope (HET) allowed us to estimate the spectroscopic parameters of the host star, a late-F main-sequence dwarf (V = 16.13) with possibly slightly subsolar metallicity, and to measure its radial velocity variations. The combined analysis of the light curves and spectroscopic data resulted in an orbital period of the substellar companion of 3.35 d, a planetary mass of 4.01 ± 0.35 MJ and a planetary radius of 1.49-0.18+0.16 RJ. WTS-1b has one of the largest radius anomalies among the known hot Jupiters in the mass range 3-5 MJ. The high irradiation from the host star ranks the planet in the pM class. Based on observations collected at the 3.8-m United Kingdom Infrared Telescope (Hawaii, USA), the Hobby-Eberly Telescope (Texas, USA), the 2.5-m Isaac Newton Telescope (La Palma, Spain), the William Herschel Telescope (La Palma, Spain), the German-Spanish Astronomical Centre (Calar Alto, Spain), the Kitt Peak National Observatory (Arizona, USA) and the Hertfordshire's Bayfordbury Observatory. Title: Lithium abundance in atmospheres of F- and G-type supergiants and bright giants Authors: Lyubimkov, Leonid S.; Lambert, David L.; Kaminsky, Bogdan M.; Pavlenko, Yakov V.; Poklad, Dmitry B.; Rachkovskaya, Tamara M. Bibcode: 2012MNRAS.427...11L Altcode: 2012arXiv1212.6057L Lithium in the atmosphere of a F or G supergiant reflects the initial Li abundance and the internal history of the star. During evolution of a star from the main sequence (MS) to the supergiant phase, lithium may be destroyed by, for example, rotationally induced mixing in the MS stars and strongly diluted by development of the supergiant's convective envelope. In order to probe the connection between atmospheric Li abundance and evolutionary predictions, we present a non-local thermodynamic equilibrium abundance analysis of the resonance doublet Li I at 6707.8 Å for 55 Galactic F and G supergiants and bright giants (we observed 43 of them, the remaining 12 are added from Luck and Wepfer's list). The derived lithium abundances log ɛ(Li) may be considered in three groups, namely: (i) 10 Li-rich giants with log ɛ(Li) = 2.0-3.2 (all 10 are F-type or A9 stars); (ii) 13 G- to K0-type stars with Li abundances in the narrow range log ɛ(Li) = 1.1-1.8; (iii) all other stars provide just upper limits to the Li abundance.

The derived Li abundances are compared with theoretical predictions of 2-15 M⊙ stars (both rotating and non-rotating). Our results are generally in good agreement with theory. In particular, the absence of detectable lithium for the majority of programme stars is explainable. The comparison suggests that the stars may be separated by mass M into two groups, namely M ≲ 6 M⊙ and M > 6 M⊙. All Li-rich giants and supergiants with log ɛ(Li) ≥ 2.0 have masses M < 6 M⊙; this conclusion follows not only from our work but also from a scrutiny of published data. 11 of 13 stars with log ɛ(Li) = 1.1-1.8, specifically the stars with M < 6 M⊙, show good agreement with the post-first dredge-up surface abundance log ɛ(Li) ≈ 1.4 predicted for the non-rotating 2-6 M⊙ stellar models. An absence of Li-rich stars in the range M > 6 M⊙ agrees with the theoretical prediction that F and G supergiants and giants with M > 6 M⊙ cannot show detectable lithium.

We note that present theory appears unable to account for the derived Li abundances for some stars, namely for (i) a few relatively low-mass Li-rich giants (M < 6 M⊙), whose high Li abundances accompanied by rather high rotational velocities or substantial nitrogen excess contradict theoretical predictions; (ii) the relatively high-mass supergiants HR 461 and HR 8313 (M > 6 M⊙) with the detected abundances log ɛ = 1.3-1.5. It is possible that the lithium in such stars was synthesized recently. Title: Intermediate Resolution Near-infrared Spectroscopy of 36 Late M Dwarfs Authors: Deshpande, R.; Martín, E. L.; Montgomery, M. M.; Zapatero Osorio, M. R.; Rodler, F.; del Burgo, C.; Phan Bao, N.; Lyubchik, Y.; Tata, R.; Bouy, H.; Pavlenko, Y. Bibcode: 2012AJ....144...99D Altcode: 2012arXiv1207.2781D We present observations of 36 late M dwarfs obtained with the Keck II/NIRSPEC in the J band at a resolution of ~20,000. We have measured projected rotational velocities, absolute radial velocities, and pseudo-equivalent widths of atomic lines. Twelve of our targets did not have previous measurements in the literature. For the other 24 targets, we confirm previously reported measurements. We find that 13 stars from our sample have v sin i below our measurement threshold (12 km s-1) whereas four of our targets are fast rotators (v sin i > 30 km s-1). As fast rotation causes spectral features to be washed out, stars with low projected rotational velocities are sought for radial velocity surveys. At our intermediate spectral resolution, we have confirmed the identification of neutral atomic lines reported in McLean et al. We also calculated pseudo-equivalent widths of 12 atomic lines. Our results confirm that the pseudo-equivalent width of K I lines is strongly dependent on spectral types. We observe that the pseudo-equivalent width of Fe I and Mn I lines remains fairly constant with later spectral type. We suggest that these lines are particularly suitable for deriving metallicities for late M dwarfs. Title: Four ultra-short-period eclipsing M-dwarf binaries in the WFCAM Transit Survey Authors: Nefs, S. V.; Birkby, J. L.; Snellen, I. A. G.; Hodgkin, S. T.; Pinfield, D. J.; Sipőcz, B.; Kovacs, G.; Mislis, D.; Saglia, R. P.; Koppenhoefer, J.; Cruz, P.; Barrado, D.; Martin, E. L.; Goulding, N.; Stoev, H.; Zendejas, J.; del Burgo, C.; Cappetta, M.; Pavlenko, Y. V. Bibcode: 2012MNRAS.425..950N Altcode: 2012MNRAS.tmp.3514N; 2012arXiv1206.1200N We report on the discovery of four ultra-short-period (P ≤ 0.18 d) eclipsing M-dwarf binaries in the Wide-Field Camera (WFCAM) Transit Survey. Their orbital periods are significantly shorter than that of any other known main-sequence binary system, and are all significantly below the sharp period cut-off at P ∼ 0.22 d as seen in binaries of earlier-type stars. The shortest-period binary consists of two M4-type stars in a P = 0.112 d orbit. The binaries are discovered as part of an extensive search for short-period eclipsing systems in over 260 000 stellar light curves, including over 10 000 M-dwarfs down to J = 18 mag, yielding 25 binaries with P ≤ 0.23 d. In a popular paradigm, the evolution of short-period binaries of cool main-sequence stars is driven by the loss of angular momentum through magnetized winds. In this scheme, the observed P ∼ 0.22 d period cut-off is explained as being due to time-scales that are too long for lower-mass binaries to decay into tighter orbits. Our discovery of low-mass binaries with significantly shorter orbits implies that either these time-scales have been overestimated for M-dwarfs, e.g. due to a higher effective magnetic activity, or the mechanism for forming these tight M-dwarf binaries is different from that of earlier-type main-sequence stars. Title: Coupled azimuthal modes propagating in current-carrying plasma waveguides Authors: Girka, V.; Girka, I.; Pavlenko, I.; Girka, O.; Girka, A. Bibcode: 2012JPlPh..78..105G Altcode: The paper is devoted to the theory of electromagnetic surface waves propagating along the azimuthal direction in cylindrical metal waveguides, which are filled with current-carrying plasmas. The problem is solved by the method of successive approximation. Adequacy of this method application is proved here. To study the coupling of ordinary (O-) and extraordinary (X-) azimuthal modes, the linear theory of the eigenazimuthal X- and O-modes is applied as zero approximation. Plasma particles are described in the framework of magneto-hydrodynamics, electromagnetic fields of the coupled azimuthal modes are determined from Maxwell equations. Spatial distribution of electromagnetic field of these coupled modes and their damping caused for different reasons are studied. Possibility to observe experimentally the phenomena, which accompany propagation of these coupled modes, is estimated numerically. Branches of their possible utilization are discussed as well. Title: Benchmark cool companions: ages and abundances for the PZ Telescopii system Authors: Jenkins, J. S.; Pavlenko, Y. V.; Ivanyuk, O.; Gallardo, J.; Jones, M. I.; Day-Jones, A. C.; Jones, H. R. A.; Ruiz, M. T.; Pinfield, D. J.; Yakovina, L. Bibcode: 2012MNRAS.420.3587J Altcode: 2011arXiv1111.7001J We present new ages and abundance measurements for the pre-main-sequence star PZ Telescopii (more commonly known as PZ Tel). PZ Tel was recently found to host a young and low-mass companion. Such companions, whether they are brown dwarfs or planetary systems, can attain benchmark status by detailed study of the properties of the primary, and then evolutionary and bulk characteristics can be inferred for the companion. Using Fibre-fed Extended Range Optical Spectrograph spectra, we have measured atomic abundances (e.g. Fe and Li) and chromospheric activity for PZ Tel and used these to obtain the metallicity and age estimates for the companion. We have also determined the age independently using the latest evolutionary models. We find PZ Tel A to be a rapidly rotating (v sin i= 73 ± 5 km s-1), approximately solar metallicity star [log N(Fe) =-4.37 ± 0.06 dex or [Fe/H] = 0.05 ± 0.20 dex]. We measure a non-local thermodynamic equilibrium lithium abundance of log N(Li) = 3.1 ± 0.1 dex, which from depletion models gives rise to an age of 7? Myr for the system. Our measured chromospheric activity (? of -4.12) returns an age of 26 ± 2 Myr, as does fitting pre-main-sequence evolutionary tracks (τevol= 22 ± 3 Myr), both of these are in disagreement with the lithium age. We speculate on reasons for this difference and introduce new models for lithium depletion that incorporate both rotation and magnetic field effects. We also synthesize solar, metal-poor and metal-rich substellar evolutionary models to better determine the bulk properties of PZ Tel B, showing that PZ Tel B is probably more massive than previous estimates, meaning the companion is not a giant exoplanet, even though a planetary-like formation origin can go some way to describing the distribution of benchmark binaries currently known. We show how PZ Tel B compares to other currently known age and metallicity benchmark systems and try to empirically test the effects of dust opacity as a function of metallicity on the near-infrared colours of brown dwarfs. Current models suggest that in the near-infrared observations are more sensitive to low-mass companions orbiting more metal rich stars. We also look for trends between infrared photometry and metallicity amongst a growing population of substellar benchmark objects, and identify the need for more data in mass-age-metallicity parameter space. Title: High-Resolution Spectroscopy of the Cool R CrB Star Candidates V1983 Cyg and V2074 Cyg Authors: Smirnova, O.; Začs, L.; Pavlenko, Y. V. Bibcode: 2011ASPC..445..177S Altcode: Preliminary results of high-resolution optical spectral analysis of two carbon-rich long-term variables, V1983 Cyg and V2047 Cyg, are presented. The stars were suspected to be cool R CrB variables according to their photometric light curves, although our spectroscopic study suggests that both stars are more similar to ordinary N-type carbon stars. For V1983 Cyg, possible absorption in the Balmer lines is detected. Title: Theory of azimuthal surface waves propagating in non-uniform waveguides Authors: Girka, V. O.; Girka, I. O.; Girka, A. V.; Pavlenko, I. V. Bibcode: 2011JPlPh..77..493G Altcode: This paper is devoted to the theory of surface waves propagating across axis of symmetry in non-uniform cylindrical metal waveguides with plasma filling. The presented results are devoted to: first, studying an influence of plasma density non-uniformity on the features of these waves; second, studying an influence of an external magnetic fields' non-uniformity on their dispersion properties; third, studying possibility to sustain gas discharge by propagation of these waves under different operating regimes. The problems have been solved both analytically and numerically. Plasma particles are described in the framework of hydrodynamics; fields of the studied waves are determined by a set of Maxwell equations. Analytical research of the obtained equations is carried out by the method of successive approximation; adequacy of such approach is proved here as well. Numerical evaluations of the possibilities to observe experimentally the phenomena, which accompany propagation of these waves, are carried out. Title: Spectroscopic Analysis of Cool Galactic R CrB Star Candidates Authors: Smirnova, O.; Zavcs, L.; Pavlenko, Y. V.; Kaminsky, B. Bibcode: 2011IAUS..280P.340S Altcode: The results of optical spectra analysis of two carbon-rich long-period variables V1983 Cyg and V2047 Cyg are presented. The stars were suspected to be cool R CrB variables candidates according to the photometric light curves. We compared the spectroscopic properties of the selected stars with those of DY Per and ordinary carbon stars to check their possible connection to cool RCBs. Also the spectral synthesis technique was used for analysis of the obtained high-resolution spectra, dominated by strong absorption features of carbon-bearing molecules. Our spectroscopic study suggests that both stars are more similar to ordinary N-type carbon stars than to DY Per star. For V1983 Cyg star possible absorption in Balmer lines is detected. Title: Infrared Mn I laboratory oscillator strengths for the study of late type stars and ultracool dwarfs Authors: Blackwell-Whitehead, R.; Pavlenko, Y. V.; Nave, G.; Pickering, J. C.; Jones, H. R. A.; Lyubchik, Y.; Nilsson, H. Bibcode: 2011A&A...525A..44B Altcode:
Aims: The aim of our new laboratory measurements is to measure accurate absolute oscillator strengths for neutral manganese transitions in the infrared needed for the study of late-type stars and ultracool dwarfs.
Methods: Branching fractions have been measured by high resolution Fourier transform spectroscopy and combined with radiative level lifetimes in the literature to yield oscillator strengths.
Results: We present experimental oscillator strengths for 20 Mn I transitions in the wavelength range 3216 to 13 997 Å, 15 of which are in the infrared. The transitions at 12 899 Å and 12 975 Å are observed as strong features in the spectra of late-type stars and ultracool dwarfs. We have fitted our calculated spectra to the observed Mn I lines in spectra of late-type stars. Using the new experimentally measured Mn I log(gf) values together with existing data for Mn I hyperfine structure splitting factors we determined the manganese abundance to be log N(Mn) = -6.65 ± 0.05 in the atmosphere of the Sun, log N(Mn) = 6.95 ± 0.20 in the atmosphere of Arcturus, and log N(Mn) = -6.70 ± 0.20 in the atmosphere of M 9.5 dwarf 2MASSW 0140026+270150. Title: Spectral Investigations of CM Dra Authors: Kuznetsov, M. K.; Pavlenko, Y. V.; Pinfield, D.; Jones, H. Bibcode: 2010OAP....23...74K Altcode: We present an analysis of a high resolution (R=47000) echelle spectra of the low-mass eclipsing binary CM Draconis, which were obtained on the 4.2-m William Herschel Telescope. Spectra were obtained for various phases of the orbit. There are some difficulties in echelle spectra processing of cool stars, since it is hard to get energy distribution in a large scale in such spectra. We proposed an efficient method for making the continuum of spectrum of cool stars. We refined the parameters (effective temperature, rotational velocity and metallicity) of the components of the system CM Dra using the method of stellar atmospheres. The data that we obtained are in good agreement with the results obtained by other authors. It is indicate on efficiency of our technique. The errors of temperature and metallicity determinations is about 100 K and 0.3 dex respectively. Title: Line Identification And Equivalent Width Measurements Of Atomic Lines In Spectra Of 40 Late M Dwarfs Authors: Deshpande, Rohit; Martin, E. L.; Montgomery, M. M.; Lyubchik, Y.; Zapatero Osorio, M. R.; Rodler, F.; del Burgo, C.; Pavlenko, Y. Bibcode: 2010AAS...21560604D Altcode: 2010BAAS...36R1130D We present preliminary results of line identification and equivalent width measurements in spectra of late M Dwarfs. We obtained 3.5 nights on Keck NASA time to collect high resolution (R 20,000) near-infrared (J-band) spectra using the NIRSPEC instrument on the Keck II telescope. Our sample consists of 40 nearby (distance < 20 pc) late M dwarfs (spectral type M5 - M9.5). Using VALD database we identified new atomic lines and verified them by comparing our results to those obtained through models of synthetic spectra. We obtained equivalent width of new and previously observed atomic lines. Our results of existing atomic lines compare well with those from Cushing et al. 2005. We observe a linearly increasing trend in equivalent widths of strong lines such as K I l while a decreasing trend is found in weakening lines like Na I. Title: Rotational Velocities for M Dwarfs Authors: Jenkins, J. S.; Ramsey, L. W.; Jones, H. R. A.; Pavlenko, Y.; Gallardo, J.; Barnes, J. R.; Pinfield, D. J. Bibcode: 2009ApJ...704..975J Altcode: 2009arXiv0908.4092J We present spectroscopic rotation velocities (v sin i) for 56 M dwarf stars using high-resolution Hobby-Eberly Telescope High Resolution Spectrograph red spectroscopy. In addition, we have also determined photometric effective temperatures, masses, and metallicities ([Fe/H]) for some stars observed here and in the literature where we could acquire accurate parallax measurements and relevant photometry. We have increased the number of known v sin i values for mid M stars by around 80% and can confirm a weakly increasing rotation velocity with decreasing effective temperature. Our sample of v sin is peak at low velocities (~3 km s-1). We find a change in the rotational velocity distribution between early M and late M stars, which is likely due to the changing field topology between partially and fully convective stars. There is also a possible further change in the rotational distribution toward the late M dwarfs where dust begins to play a role in the stellar atmospheres. We also link v sin i to age and show how it can be used to provide mid-M star age limits. When all literature velocities for M dwarfs are added to our sample, there are 198 with v sin i <= 10 km s-1 and 124 in the mid-to-late M star regime (M3.0-M9.5) where measuring precision optical radial velocities is difficult. In addition, we also search the spectra for any significant Hα emission or absorption. Forty three percent were found to exhibit such emission and could represent young, active objects with high levels of radial-velocity noise. We acquired two epochs of spectra for the star GJ1253 spread by almost one month and the Hα profile changed from showing no clear signs of emission, to exhibiting a clear emission peak. Four stars in our sample appear to be low-mass binaries (GJ1080, GJ3129, Gl802, and LHS3080), with both GJ3129 and Gl802 exhibiting double Hα emission features. The tables presented here will aid any future M star planet search target selection to extract stars with low v sin i.

Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen. Title: Model Atmospheres and Spectra of Peculiar Stars Authors: Pavlenko, Y. V.; Evans, A.; Duerbeck, H. W.; Geballe, T.; Yakovina, L.; Kaminsky, B.; Kerr, T. Bibcode: 2008ASPC..401..124P Altcode: 2009ASPC..401..124P The method and results of the computation of the model atmospheres and spectral energy distributions of chemically peculiar stars are discussed. The models and spectra are computed with special consideration of the particular problems encountered for peculiar and hydrogen deficient stars in the later stages of evolution. We present some computed model atmospheres and fits to observed spectra of Sakurai's object, V838 Mon, and RS Oph. Title: Fifteen new T dwarfs discovered in the UKIDSS Large Area Survey Authors: Pinfield, D. J.; Burningham, B.; Tamura, M.; Leggett, S. K.; Lodieu, N.; Lucas, P. W.; Mortlock, D. J.; Warren, S. J.; Homeier, D.; Ishii, M.; Deacon, N. R.; McMahon, R. G.; Hewett, P. C.; Osori, M. R. Zapatero; Martin, E. L.; Jones, H. R. A.; Venemans, B. P.; Day-Jones, A. C.; Dobbie, P. D.; Folkes, S. L.; Dye, S.; Allard, F.; Baraffe, I.; Barrado Y Navascués, D.; Casewell, S. L.; Chiu, K.; Chabrier, G.; Clarke, F.; Hodgkin, S. T.; Magazzù, A.; McCaughrean, M. J.; Nakajima, T.; Pavlenko, Y.; Tinney, C. G. Bibcode: 2008MNRAS.390..304P Altcode: 2008arXiv0806.0294P We present the discovery of 15 new T2.5-T7.5 dwarfs (with estimated distances ~24-93pc), identified in the first three main data releases of the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey. This brings the total number of T dwarfs discovered in the Large Area Survey (LAS) (to date) to 28. These discoveries are confirmed by near-infrared spectroscopy, from which we derive spectral types on the unified scheme of Burgasser et al. Seven of the new T dwarfs have spectral types of T2.5-T4.5, five have spectral types of T5-T5.5, one is a T6.5p and two are T7-7.5. We assess spectral morphology and colours to identify T dwarfs in our sample that may have non-typical physical properties (by comparison to solar neighbourhood populations), and find that three of these new T dwarfs may have unusual metallicity, two may have low surface gravity, and one may have high surface gravity. The colours of the full sample of LAS T dwarfs show a possible trend to bluer Y - J with decreasing effective temperature, and some interesting colour changes in J - H and z - J (deserving further investigation) beyond T8. The LAS T dwarf sample from the first and second main data releases show good evidence for a good level of completion to J = 19. By accounting for the main sources of incompleteness (selection, follow-up and spatial) as well as the effects of unresolved binarity, Malmquist and Eddington bias, we estimate that there are 17 +/- 4 >= T 4 dwarfs in the J <= 19 volume of the LAS second data release. This value is most consistent with theoretical predictions if the substellar mass function exponent α (dN/dm ~ m-α) lies between -1.0 and 0. This is consistent with the latest 2-Micron All Sky Survey (2MASS)/Sloan Digital Sky Survey (SDSS) constraint (which is based on lower number statistics) and is significantly lower than the α ~ 1.0 suggested by L dwarf field populations, which is possibly a result of the lower mass range probed by the T dwarf class. Title: Model Atmospheres and Spectra for Cool Hydrogen-Deficient Stars and Peculiar Giants Authors: Pavlenko, Y. V. Bibcode: 2008ASPC..391...65P Altcode: New model atmospheres, spectra and spectral energy distributions of hydrogen-deficient chemically peculiar stars are presented. The methods used in the computation of these models are discussed, with special consideration given to the treatment of opacity. Some of the model atmospheres have been computed for R CrB stars with different H/He ratios and carbon abundances. In order to test these models the observed spectra of Sakurai's object and some carbon-rich giants are fit with the newly computed spectral energy distributions. Title: Metallicities and activities of southern stars Authors: Jenkins, J. S.; Jones, H. R. A.; Pavlenko, Y.; Pinfield, D. J.; Barnes, J. R.; Lyubchik, Y. Bibcode: 2008A&A...485..571J Altcode: 2008arXiv0804.1128J Aims: We present the results from high-resolution spectroscopic measurements to determine metallicities and activities of bright stars in the southern hemisphere.
Methods: We measured the iron abundances ([Fe/H]'s) and chromospheric emission indices (log h{R}'{HK}) of 353 solar-type stars with V = 7.5-9.5. [Fe/H] abundances are determined using a custom χ2 fitting procedure within a large grid of Kurucz model atmospheres. The chromospheric activities were determined by measuring the amount of emission in the cores of the strong Caii HK lines.
Results: Our comparison of the metallicity sample to other [Fe/H] determinations was found to agree at the ±0.05 dex level for spectroscopic values and at the ±0.1 dex level for photometric values. The distribution of chromospheric activities is described by a bimodal distribution, agreeing with the conclusions from other works. Also an analysis of Maunder minimum status was attempted, and it was found that 6 ± 4 stars in the sample could be in a Maunder minimum phase of their evolution and hence the Sun should only spend a few per cent of its main sequence lifetime in Maunder minimum.

Based on observations made with the ESO telescopes at the La Silla Paranal observatory under programme ID's 076.C-0578(B) and 077.C-0192(A). Table 4 is 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/485/571 Title: VizieR Online Data Catalog: Metallicities & activities of southern stars (Jenkins+, 2008) Authors: Jenkins, J. S.; Jones, H. R. A.; Pavlenko, Y.; Pinfield, D. J.; Barnes, J. R.; Lyubchik, Y. Bibcode: 2008yCat..34850571J Altcode: This table comprises a list of stellar metallicities and activities for a number of solar-type stars in the southern hemisphere using high-resolution (R~46000) spectra acquired at the ESO-MPI 2.2m telescope and the instrument FEROS. The stars all have B-V colours in the range 0.5-0.9, V magnitudes between 7.5-9.5 and were selected from the Hipparcos catalogue (Perryman et al., 1997, Cat. ). The chromospheric activities along with their photon counting errors are shown, and were extracted by comparing the flux in triangular bandpasses centred in the cores of the Calcium II H and K lines (wavelengths of 3933.664{AA} and 3968.470{AA}) against the flux in two square bandpass regions centred on the continuum at either side of these lines (wavelengths of 3891{AA} and 4001{AA}). These values have been calibrated onto the Mt. Wilson system of measurements (Duncan et al., 1991, Cat. ) and then converted to the commonly used logRhk system (Noyes et al. 1984ApJ...287..769N) to remove the photospheric component of the flux. The metallicities shown in column 6, were measured by comparing a grid of synthetic spectra (WITA6; Pavlenko et al., 1995A&A...303..807P) to a number of mostly weak and unblended FeI lines at this spectral resolution. The internal errors were determined by fitting the Chi-squared parabola and after comparison with other works these values were found to agree to <0.1dex or 0.05dex with other high-resolution spectral abundances (e.g. Valenti & Fischer, 2005, Cat. ). The tail of objects with really high errors were mainly lower S/N spectra due to changing weather patterns.

(1 data file). Title: Spectral analysis of high resolution near-infrared spectra of ultra cool dwarfs Authors: Lyubchik, Y.; Jones, H. R. A.; Pavlenko, Y. V.; Martin, E.; McLean, I. S.; Prato, L.; Barber, R. J.; Tennyson, J. Bibcode: 2007A&A...473..257L Altcode: 2007arXiv0708.2676L Aims:We present an analysis of high resolution spectra in the J band of five ultra cool dwarfs from M6 to L0.
Methods: We make use of a new ab initio water vapour line list and existing line lists of FeH and CrH for modelling the observations.
Results: We find a good fit for the Mn I 12 899.76 Å line. This feature is one of the few for which we have a reliable oscillator strength. Other atomic features are present but most of the observed features are FeH and H2O lines. While we are uncertain about the quality of many of the atomic line parameters, the FeH and CrH line lists predict a number of features which are not apparent in our observed spectra. We infer that the main limiting factor in our spectral analysis is the FeH and CrH molecular spectra. Title: Eight new T4.5-T7.5 dwarfs discovered in the UKIDSS Large Area Survey Data Release 1 Authors: Lodieu, N.; Pinfield, D. J.; Leggett, S. K.; Jameson, R. F.; Mortlock, D. J.; Warren, S. J.; Burningham, B.; Lucas, P. W.; Chiu, K.; Liu, M. C.; Venemans, B. P.; McMahon, R. G.; Allard, F.; Baraffe, I.; Barrado y Navascués, D.; Carraro, G.; Casewell, S. L.; Chabrier, G.; Chappelle, R. J.; Clarke, F.; Day-Jones, A. C.; Deacon, N. R.; Dobbie, P. D.; Folkes, S. L.; Hambly, N. C.; Hewett, P. C.; Hodgkin, S. T.; Jones, H. R. A.; Kendall, T. R.; Magazzù, A.; Martín, E. L.; McCaughrean, M. J.; Nakajima, T.; Pavlenko, Y.; Tamura, M.; Tinney, C. G.; Zapatero Osorio, M. R. Bibcode: 2007MNRAS.379.1423L Altcode: 2007MNRAS.tmp..609L; 2007arXiv0705.3727L We present eight new T4.5-T7.5 dwarfs identified in the UKIRT (United Kingdom Infrared Telescope) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) Data Release 1 (DR1). In addition we have recovered the T4.5 dwarf SDSSJ020742.91+000056.2 and the T8.5 dwarf ULASJ003402.77-005206.7. Photometric candidates were picked up in two-colour diagrams over 190deg2 (DR1) and selected in at least two filters. All candidates exhibit near-infrared spectra with strong methane and water absorption bands characteristic of T dwarfs and the derived spectral types follow the unified scheme of Burgasser et al.. We have found six new T4.5-T5.5 dwarfs, one T7 dwarf, one T7.5 dwarf and recovered a T4.5 dwarf and a T8.5 dwarf. We provide distance estimates which lie in the 15-85pc range; the T7.5 and T8.5 dwarfs are probably within 25pc of the Sun. We conclude with a discussion of the number of T dwarfs expected after completion of the LAS, comparing these initial results to theoretical simulations.

Based on observations made with the United Kingdom Infrared Telescope, operated by the Joint Astronomy Centre on behalf of the UK Particle Physics and Astronomy Research Council.

E-mail: nlodieu@iac.es ‡

Alfred P. Sloan Research Fellow. Title: Two T dwarfs from the UKIDSS early data release Authors: Kendall, T. R.; Tamura, M.; Tinney, C. G.; Martín, E. L.; Ishii, M.; Pinfield, D. J.; Lucas, P. W.; Jones, H. R. A.; Leggett, S. K.; Dye, S.; Hewett, P. C.; Allard, F.; Baraffe, I.; Barrado Y Navascués, D.; Carraro, G.; Casewell, S. L.; Chabrier, G.; Chappelle, R. J.; Clarke, F.; Day-Jones, A.; Deacon, N.; Dobbie, P. D.; Folkes, S.; Hambly, N. C.; Hodgkin, S. T.; Nakajima, T.; Jameson, R. F.; Lodieu, N.; Magazzù, A.; McCaughrean, M. J.; Pavlenko, Y. V.; Tadashi, N.; Zapatero Osorio, M. R. Bibcode: 2007A&A...466.1059K Altcode: 2007astro.ph..2534K Context: We report on the first ultracool dwarf discoveries from the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey Early Data Release (LAS EDR), in particular the discovery of T dwarfs which are fainter and more distant than those found using the 2MASS and SDSS surveys.
Aims: We aim to show that our methodologies for searching the ~27 deg2 of the LAS EDR are successful for finding both L and T dwarfs via cross-correlation with the Sloan Digital Sky Survey (SDSS) DR4 release. While the area searched so far is small, the numbers of objects found shows great promise for near-future releases of the LAS and great potential for finding large numbers of such dwarfs.
Methods: Ultracool dwarfs are selected by combinations of their YJH(K) UKIDSS colours and SDSS DR4 z-J and i-z colours, or, lower limits on these red optical/infrared colours in the case of DR4 dropouts. After passing visual inspection tests, candidates have been followed up by methane imaging and spectroscopy at 4 m and 8 m-class facilities.
Results: Our main result is the discovery following CH4 imaging and spectroscopy of a T4.5 dwarf, ULAS J 1452+0655, lying ~80 pc distant. A further T dwarf candidate, ULAS J 1301+0023, has very similar CH4 colours but has not yet been confirmed spectroscopically. We also report on the identification of a brighter L0 dwarf, and on the selection of a list of LAS objects designed to probe for T-like dwarfs to the survey J-band limit.
Conclusions: Our findings indicate that the combination of the UKIDSS LAS and SDSS surveys provide an excellent tool for identifying L and T dwarfs down to much fainter limits than previously possible. Our discovery of one confirmed and one probable T dwarf in the EDR is consistent with expectations from the previously measured T dwarf density on the sky. Title: Modelling the Spectrum and SED of V838 Mon Authors: Pavlenko, Y.; Kaminsky, B.; Lyubchik, Y.; Yakovina, L. Bibcode: 2007ASPC..363..225P Altcode: 2006astro.ph..9604P We model the spectra and spectral energy distribution of V838 Mon which were observed in February, March, and November, 2002. Theoretical spectra are calculated using the classical model atmospheres taking into account absorption of atomic and molecular lines. By fitting the observed spectra we determine the physical parameters of the atmosphere of V838 Mon. These parameters are determined to be {Teff } = 5330 ± 300 K, 5540 ± 270 K, 4960 ± 190 K, and 2000 ± 200 K for February 25, March 2, March 26, and November 6, respectively. Title: Experimental TiI oscillator strengths and their application to cool star analysis Authors: Blackwell-Whitehead, R. J.; Lundberg, H.; Nave, G.; Pickering, J. C.; Jones, H. R. A.; Lyubchik, Y.; Pavlenko, Y. V.; Viti, S. Bibcode: 2006MNRAS.373.1603B Altcode: 2006astro.ph.12656B; 2006MNRAS.tmp.1308B We report experimental oscillator strengths for 88 TiI transitions covering the wavelength range 465-3892 nm, 67 of which had no previous experimental values. Radiative lifetimes for 13 energy levels, including the low energy levels 3d2(3F) 4s4p (3P) z 5D°j, have been measured using time-resolved laser-induced fluorescence. Intensity-calibrated TiI spectra have been measured using Fourier transform spectroscopy to determine branching fractions for the decay channels of these levels. The branching fractions are combined with the radiative lifetimes to yield absolute transition probabilities and oscillator strengths. Our measurements include 50 transitions in the previously unobserved infrared region λ > 1.0μm, a region of particular interest to the analysis of cool stars and brown dwarfs. Title: Theoretical modelling of optical and IR spectra of brown dwarfs and ultracool dwarfs Authors: Pavlenko, Y. V. Bibcode: 2005AN....326..934P Altcode: The current state of theoretical modelling of the spectra of cool dwarfs and ultracool objects are discussed. Fits of synthetical spectral energy distributions (SEDs) in the optical and IR spectral regions to observed spectra show problems of theoretical modelling. Problems of interpretation of observed spectra are more obvious for the case of L and T dwarfs. Still even for late-M dwarfs the situation is far from being perfect. Some examples of the fine analysis of the spectra of ultracool dwarfs are presented. Title: VizieR Online Data Catalog: Linelist of HCN and HNC (Harris+, 2006) Authors: Harris, G. J.; Tennyson, J.; Kaminskiy, B.; Pavlenko, Y. V.; Jones, H. R. A. Bibcode: 2005yCat.6121....0H Altcode: We present an energy level list which contains the ab initio energies and exact quantum numbers from HPT, together with lab determined energies and assigned approximate quantum numbers where available. A new HCN/HNC linelist is presented. Lab determined energy levels were used to compute accurate line frequencies, where available. Where lab data is not available frequencies are computed from ab initio energy levels. The linelist is truncated at a minimum frequency of 3*10-28^cm/mol at T=3000K. Resulting in a linelist of 38 million lines, which accounts for 99.99% of the opacity of the full linelist at 3000K. The file has been compressed using bzip2. The data is sorted into increasing frequency order. A FORTRAN code is supplied to convert the Einstein A coefficients of HPT and the new energy level list into a usable linelist.

(3 data files). Title: Temperatures in the atmopshere of the cool component of CH Cygni Authors: Jurdana-Sepic, R.; Kotnik-Karuza, D.; Majlinger, Z.; Pavlenko, Y. V. Bibcode: 2004ASPC..318..371J Altcode: 2004ssrc.conf..371J We have investigated the temperatures in the atmosphere of the cool component of CH Cygni by use of highly resolved optical and near infrared spectra taken in a short epoch of the 1998-2000 active phase. TiO absorption bands belonging to α, γ, γ', β, δ, φ and ɛ band systems with partly resolved rotational structure have been studied and vibrational temperatures belonging to γ' and φ system were obtained from the relative intensities of vibrational band heads. In order to determine the effective temperature we used model atmospheres appropriate for M giants and computed synthetic spectra by the line-to-line approach. Results are discussed in view of the previously determined rotational temperature. Title: Atomic lines in infrared spectra for ultracool dwarfs Authors: Lyubchik, Y.; Jones, H. R. A.; Pavlenko, Y. V.; Viti, S.; Pickering, J. C.; Blackwell-Whitehead, R. Bibcode: 2004A&A...416..655L Altcode: 2003astro.ph.12578L We provide a set of atomic lines which are suitable for the description of ultracool dwarf spectra from 10 000 to 25 000 Å. This atomic linelist was made using both synthetic spectra calculations and existing atlases of infrared spectra of Arcturus and Sunspot umbra. We present plots which show the comparison of synthetic spectra and observed Arcturus and Sunspot umbral spectra for all atomic lines likely to be observable in high resolution infrared spectra.

Figure 1 is only available in electronic form at http://www.edpsciences.org

Tables 1 and 2 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/416/655 Title: Draco 461, an intrinsic carbon star in a metal poor stellar population: 3rd dredge up and mixing Authors: Domínguez, I.; Abia, C.; Straniero, O. Cristallo, S.; Pavlenko, Y. V. Bibcode: 2004MmSAI..75..601D Altcode: In July 2003 we observed the first Li-rich carbon star in a dwarf spheroidal galaxy. We compute stellar models for AGB stars and, by comparing them to the available photometric and spectroscopic data, conclude that D461 is an intrinsic carbon star, more massive and younger than the dominant stellar population of Draco. Title: VizieR Online Data Catalog: Atomic lines in IR spectra for ultracool dwarfs (Lyubchik+, 2004) Authors: Lyubchik, Y.; Jones, H. R. A.; Pavlenko, Y. V.; Viti, S.; Pickering, J. C.; Blackwell-Whitehead, R. Bibcode: 2004yCat..34160655L Altcode: Table 1 contains all identified lines with central intensities deeper than 0.8 of residual flux using "ultracool dwarf model" identifications.

Table 2 investigates the sensitivity of priority 1 lines identified in Table 1 to temperature, gravity and metallicity.

We compute some synthetic spectra for ultracool objects varying parameters of Teff, log g and metallicity to show the sensitivity of the central intensities of identified lines to these parameters. For our computations we chose the minimal step in model atmospheres grid: {Delta}Teff=100K, {Delta}logg=0.5, {Delta}[M/H]=-0.5. STeff shows the dependence of residual fluxes on effective temperature. For comparison a 2100/5.0/0.0 synthetic spectrum was used. One can see that only a few lines show strong temperature dependence for {Delta}=100K.

The NextGen 2000/4.5/0.0 model was used with 2000/5.0/0.0 to test gravity sensitivity. The dependence for {Delta}(log g)=0.5 is also relatively weak for most lines.

The NextGen model atmospheres 2000/5.0/-0.5 and 2000/5.0/0.0 to test metallicity sensitivity. The metallicity dependence is relatively high for all lines.

(2 data files). Title: A Comparison of Water Vapour Line Lists Authors: Jones, H. R. A.; Pavlenko, Y.; Viti, S.; Tennyson, J. Bibcode: 2003csss...12..899J Altcode: M dwarf spectra, at wavelengths beyond 1.35 μm, are dominated by water vapour yet terrestrial water vapour makes it notoriously difficult to make accurate measurement from ground-based observations. We have used the short wavelength spectrometer on the Infrared Space Observatory to obtain the 2.5--3.0 μm region. The observations show a good match with synthetic spectra based on the Partridge & Schwenke (1997) line list though not with the SCAN (Jorgensen et al. 2001) line list. Nonetheless, the Partridge & Schwenke calculations for water vapour lines still need to be extended to higher energy levels with good convergence for reliable modelling of hot water vapour. Then water bands can assume their natural role as the primary tool for the spectroscopic analysis of M stars. Title: Model Atmospheres and SEDs of Chemically Peculiar Stars Authors: Pavlenko, Y. V. Bibcode: 2003IAUS..210P.A16P Altcode: 2002astro.ph..9022P Procedure and results of computations of stellar model atmospheres and spectral energy distributions are discussed. Model atmospheres of some chemically peculiar stars are computed taking into account detailed information about their abundances: -- R CrB-like stars of Teff $\sim$ 7000 K, -- Sakurai's object (V4334 Sgr) of 4000 $<$ \Tef $<$ 7000 K -- Przybylski's star of Teff $\sim$ 6500 K. We show that our self-consistent approach provides a unique possibility to investigate the temporal changes of physical parameters of chemically peculiar stars. Some problems of computation of model atmospheres of M and C-giants are also considered. Title: Stellar Abundance Patterns. What is the Possible Level of Completeness Today? Authors: Gopka, V.; Yushchenko, A.; Musaev, F.; Galazutdinov, G.; Kim, C.; Shavrina, A.; Pavlenko, Y.; Polosukhina, N.; North, P. Bibcode: 2003IAUS..210P..E5G Altcode: 2003astro.ph..8339G We discuss the way of increasing of the number of chemical elements, investigated in stellar spectra. We can reach it by using spectrum synthesis method, new atomic data and observation of stellar spectra with resolution comparable to solar spectral atlases. We show two examples of this kind researches. The first is the implementation of new atomic data to well known Przybylski's star. We show that the number of spectral lines, which can be identificated in the spectrum of this star can be significantly higher. The second example is the investigation of zeta Cyg. We found the abundances of 51 elements in the atmosphere of this mild barium star. Title: Carbon monoxide bands in M dwarfs Authors: Pavlenko, Y. V.; Jones, H. R. A. Bibcode: 2002A&A...396..967P Altcode: 2002astro.ph.10017P We compare the observational and theoretical spectra of the Delta v = 2 CO bands in a range of M dwarfs. We investigate the dependence of theoretical spectra on effective temperatures as well as carbon abundance. In general we find that the synthetic CO bands fit the observed data extremely well and are excellent diagnostics. In particular the synthetic spectra reasonably match observations and the best fit temperatures are similar to those found by empirical methods. We also examine the 12C/13C isotopic ratio. We find that fundamental 13CO bands around 2.345 and 2.375 mu m are good discriminators for the 12C/13C ratio in M dwarfs. The 2.375 mu m band is more useful because it doesn't suffer such serious contamination by water vapour transitions. Our current dataset does not quite have the wavelength coverage to perform a reliable determination of the 12C/13C ratio in M dwarfs. For this we recommend observing the region 2.31-2.40 mu m at a resolution of better than 1000. Alternatively the observational problems of contamination by water vapour at 2.345 mu m maybe solved by observing at resolutions of around 50 000. We also investigated the possibility of using the Delta v = 1 CO bands around 4.5 mu m. We find that the contamination due to water vapour is even more of a problem at these wavelengths. Title: Models of infrared spectra of Sakurai's Object (V4334 Sgr) in 1997 Authors: Pavlenko, Y. V.; Geballe, T. R. Bibcode: 2002A&A...390..621P Altcode: 2002astro.ph..5528P Theoretical spectral energy distributions computed for a grid of hydrogen-deficient and carbon-rich model atmospheres have been compared with the observed infrared (1-2.5 mu m) spectra of V4334 Sgr (Sakurai's Object) on 1997 April 21 and July 13. The comparison yields an effective temperature of Teff = 5500 +/- 200 K for the April date and Teff = 5250 +/- 200 K for July. The observed spectra are well fitted by Asplund et al. (\cite{Asplund99}) abundances, except that the carbon abundance is higher by 0.3 dex. Hot dust produces significant excess continuum at the long wavelength ends of the 1997 spectra. Based on observations obtained at the United Kingdom Infrared Telescope (UKIRT), which is operated by the Joint Astronomy Centre on behalf of the U. K. Particle Physics and Astronomy Research Council. Title: Formation of the Optical Spectra of L Dwarfs Authors: Pavlenko, Y. Bibcode: 2001udns.conf...33P Altcode: No abstract at ADS Title: About Use of Quantum Effects and Fundamental Physical Constants for Elaboration of the Measurement Standards in the Field of Electronic Measurements Authors: Niemeyer, J.; Pavlenko, Y.; Anikin, V.; Kolbasin, A.; Seredniy, V. Bibcode: 2001pems.conf..341N Altcode: No abstract at ADS Title: Formation of the Optical Spectra of the Coolest M- and L-dwarfs and Lithium Abundances in their Atmospheres Authors: Pavlenko, Y. V. Bibcode: 2000IAUS..198..454P Altcode: 2000astro.ph..2144P Theoretical aspects of modeling of spectra of late M- and L-dwarfs are discussed. We show, that the processes of formation of spectra of M- and L-dwarfs are basically different. Instead of the case of M-dwarfs, atoms of Ti and V should be depleted into grains in the atmospheres of L-dwarfs. Overall shape of the L-dwarf spectra is governed by the K I + Na I resonance line wings of the huge strength. To fit lithium lines observed in spectra of the coolest dwarfs we used two additional suggestions: a) there are some EXTRA depletions of molecular species absorbed in the optical spectra of L-dwarfs; b) there may be (a few?) additional (``dusty''?) opacity sources in their atmospheres. Problems of lithium line formation and the ``natural'' limitation of their use for the ``lithium test'' for the case of L-dwarfs are considered. Title: The formation of lithium lines in the atmospheres of super Li-rich AGB stars Authors: Abia, C.; Pavlenko, Y.; de Laverny, P. Bibcode: 1999A&A...351..273A Altcode: 1999astro.ph..4420A The formation of lithium lines in the atmosphere of C-rich giants is discussed. LTE and NLTE approximations are used to model lithium lines in the spectra of super Li-rich AGB stars. The system of equations of the statistical balance of neutral Li in plane-parallel model atmospheres is solved for a 20-level atom model. JOLA and line-by-line models of molecular absorption are used to compute synthetic spectra as well as the opacity in the frequencies of bound-bound and bound-free transitions of the lithium lines. Curves of growth and synthetic spectra are computed in LTE and NLTE for several model atmospheres of different {T_eff} and C/O ratios for four lithium absorptions, namely: the lambda 4603, lambda 6104, lambda 6708 and lambda 8126 Å Li I lines. The sensitivity of NLTE effects on {T_eff} and the C/O ratio is discussed. We found that NLTE mainly affects the resonance line doublet (lambda6708 ) while the impact of NLTE effects on the lithium subordinate lines, formed in the inner regions of C-rich giant atmospheres, is rather weak. Therefore the use of these lines is recommended for Li determination in AGB stars. However, in no case can we properly account for the formation of Li lines in AGB stars until sphericity, velocity stratifications, dust, chromospheres and other related phenomena, which are in fact present in AGB star atmospheres, are considered. Our results are used to derive Li abundances in three super-Li rich C-stars taking into account NLTE effects. Finally, the net Li yield from this class of stars into the interstellar medium is reconsidered. Title: The Lithium Lines Formation in Brown Dwarf Atmospheres: Molecules, Chromospheres, NLTE Authors: Pavlenko, Y. V. Bibcode: 1998ASPC..134..416P Altcode: 1998bdep.conf..416P No abstract at ADS Title: Ultraviolet NH bands as indicators of nitrogen abundance in the atmospheres of cool stars. Authors: Yakovina, L. A.; Pavlenko, Y. V. Bibcode: 1998KPCB...14..195Y Altcode: Nitrogen abundance indicators were selected for spectral resolutions of 0.0025 nm and 0.02 nm in the NH band region at λ336 nm. For this purpose a list of atomic lines from LOWLINES, DAT (CD-ROM No. 1 in Kurucz's 1993 database) and lists of molecular lines from CD-ROM No. 18 were tested and corrected using the spectrum of the Sun as a star. The effect of line list completeness on nitrogen abundance estimates is examined. Title: New and accurate Li abundance determinations in super Li-rich AGB stars Authors: Abia, C.; de Laverny, P.; Pavlenko, Y. Bibcode: 1998IAUS..191P.101A Altcode: Super lithium-rich AGB stars constitute the sole observational evidence of a stellar production of lithium. Abundance determinations report values as high as Li/H ~10^{-7} in their atmospheres (i.e. more than 10-100 times the cosmic abundance), therefore these stars might represent an important source of lithium in the galaxies. However most of these abundance analyses are based on the study of the resonance line of LiI 6708 Angstroms which usually is very strong or near saturation even in AGB stars with normal lithium abundances. Here we have used high-resolution and high signal-to-noise ratio spectra of three well known super Li-rich carbon stars (WZ Cas, WX Cyg and IY Hya) to derive LTE/N-LTE lithium abundances using two other accessible less-intense Li lines at 6103 and 8126 Angstroms for the first time in AGB stars. We show that N-LTE effects are very important for the resonance line. Furthermore, the core of the 6708 Angstroms line forms very high in the atmosphere of AGB stars where the structure of the atmosphere is almost unknown. That excludes the use of this line for realistic Li abundance determinations in AGB stars. On the contrary, we found that N-LTE effects are weak for the two other lines. Although it is saturated, the subordinate Li line at 8126 Angstroms is recommended to derive abundances in Li-rich AGB stars. Title: Common envelope evolution and Li in V471 Tauri. Authors: Martin, E. L.; Pavlenko, Y.; Rebolo, R. Bibcode: 1997A&A...326..731M Altcode: We have observed the spectral regions around the LiI resonance 670.8nm and subordinate 610.4nm lines of V471 Tau. This is an eclipsing post common-envelope (CE) binary system. A revision of several independent measurements of the parallax and proper motion of V471 Tau allow us to argue that this system is indeed a Hyades cluster member by examining and rejecting earlier, flawed results. Using spectral synthesis and taking into account NLTE effects, we have derived a photospheric Li abundance of log N(Li)=2.35+/-0.25 for the K dwarf, which is a factor >100 higher than single Hyades members of the same mass. We argue that two mechanisms are responsible for this: a) Accretion of a substantial amount of Li-rich material onto the K dwarf during CE evolution inside the giant precursor of the white dwarf. Recently, a number of Li-rich giants have been observed and they appear to undergo large mass-loss. We speculate that CE evolution could actually explain the properties of these giants as well. b) Reduced Li depletion in the K dwarf due to sustained fast rotation in a short-period tidally-locked orbit. This process accounts for the preservation of Li after CE evolution has ceased. Title: Formation of lithium lines in very cool dwarfs. Authors: Pavlenko, Y. V.; Rebolo, R.; Martin, E. L.; Garcia Lopez, R. J. Bibcode: 1995A&A...303..807P Altcode: We present LTE and NLTE results on the formation of LiI lines (λ6103, λ6708, and λ8126) in the atmospheres of solar metallicity dwarfs with effective temperatures in the range 5500K to 2000K. NLTE effects are governed by overionization of Li and by the interlocking effects of energy levels. For stars with T_eff_>=4000K, we confirm previous findings by Magazzu et al. (1992). NLTE corrections can lower the LTE Li abundances derived from strong LiIλ6708 lines by up to 0.5 dex. Our computations using model atmospheres with T_eff_ between 3000K and 2000K show that prominent LiI lines are formed. We give a set of line profiles, which support the feasability of the Li test for brown dwarfs. The ionization-dissociation equilibrium for Li species was carefully considered. NLTE effects on the LiI lines of very cool dwarfs are found to be small, implying corrections to the LTE Li abundances lower than 0.1 dex. Several numerical tests have been carried out to estimate the effects of chromosphere-like structures on the formation of LiI lines. Our preliminary results suggest that in the presence of very strong chromospheres, the line strengths are reduced. Title: Li I Lines in POP II Dwarf Spectra: NLTE Effects Authors: Pavlenko, Y. V. Bibcode: 1995lea..conf..324P Altcode: No abstract at ADS Title: Interpretations of stellar spectra: NLTE effects Authors: Pavlenko, Y. V. Bibcode: 1995MmSAI..66..441P Altcode: No abstract at ADS Title: Interpretations of stellar spectra: NLTE effects Authors: Pavlenko, Y. V. Bibcode: 1995HiA....10..453P Altcode: No abstract at ADS Title: The Behaviour of the Lithium Abundance Along the Pre-Main Sequence Authors: Magazzú, A.; Martín, E. L.; Rebolo, R.; García Lopez, R. J.; Pavlenko, Y. V. Bibcode: 1995lea..conf..260M Altcode: No abstract at ADS Title: The Statistical Equilibrium of Lithium in the Atmospheres of Dwarfs with Various Metallicities Authors: Pavlenko, Y. V. Bibcode: 1994AZh....71..600P Altcode: No abstract at ADS Title: Beryllium abundances in unevolved metal deficient stars. Authors: Rebolo, R.; Garcia Lopez, R. J.; Martin, E. L.; Beckman, J. E.; McKeith, C. D.; Webb, J. K.; Pavlenko, Y. V. Bibcode: 1993oee..conf..149R Altcode: No abstract at ADS Title: Beryllium and Lithium abundances in stars with a range of metallicities Authors: Garcia Lopez, R. J.; Martin, E. L.; Rebolo, R.; Beckman, J. E.; McKeith, C. D.; Webb, J. K.; Pavlenko, Y. V. Bibcode: 1993ASPC...40..180G Altcode: 1993IAUCo.137..180G; 1993ist..proc..180G No abstract at ADS Title: Observational patterns of lithium depletion in pre-main sequence stars Authors: Martín, E. L.; Rebolo, R.; Garcia Lopez, R. J.; Magazzu, A.; Pavlenko, Y. V. Bibcode: 1993ASPC...40..165M Altcode: 1993ist..proc..165M; 1993IAUCo.137..165M No abstract at ADS Title: Nonlte Effects and Strong Lii Lines in the Spectra of the K Giants HD9746 and HD112127 Authors: Pavlenko, Y. V. Bibcode: 1992SvA....36..605P Altcode: No abstract at ADS Title: Lithium Abundances in Classical and Weak T Tauri Stars Authors: Magazzu, Antonio; Rebolo, Rafael; Pavlenko, Iakov V. Bibcode: 1992ApJ...392..159M Altcode: A study on the lithium abundance in 36 T Tauri stars (mass range 0.4-2.25 solar masses), partly based on high-dispersion spectra taken with the Isaac Newton Telescope, is presented. A study of non-LTE effects in the formation of the lithium double in T Tauri stars and derived corrections to the abundances in the LTE in the range 1.0-4.0 log N(Li) is presented. Tor T(eff) of 400-4500 K, a significant upward correction to the LTE abundance (about 0.3-0.6 dex) is found. For T(eff) close to 500 K, smaller corrections (about 0.2 dex), and for log N(Li) greater than about 3, downward corrections (about 0.1 dex) are found. The initial value of the lithium abundance in T Tauri stars is estimated at 3.2 +/- 0.1, which is in close agreement with the accepted present cosmic abundance. Title: Statistical Equilibrium and the Lii 670.766-NM and 670.791-NM Absorption Lines in the Spectrum of Red Giants - Results Authors: Pavlenko, Y. V. Bibcode: 1991SvA....35..623P Altcode: No abstract at ADS Title: The statistical equilibrium and the 670.776- and 670.791-nm absorption lines of Li I in red-giant spectra - Methodology Authors: Pavlenko, Y. V. Bibcode: 1991AZh....68..776P Altcode: A method for calculating the statistical equilibrium for lithium in the atmospheres of red giants without LTE is analyzed. The cool-atmosphere opacity circulation method (absorption mean) is investigated. The analysis makes it possible to determine the role played by free-bound transitions from different levels in establishing the lithium ionization balance in the atmospheres of late stars. Title: Statistical Equilibrium and the 670.776-NM and 670.791-NM Lii Absorption Lines in the Spectrum of Red Giants - Procedure Authors: Pavlenko, Y. V. Bibcode: 1991SvA....35..384P Altcode: No abstract at ADS Title: Atmosphere of the K2III-STAR Alpha-Arietis Authors: Berdyugina, S. V.; Boyarchuk, M. E.; Pavlenko, Y. V.; Savanov, I. S.; Shavrina, A. V. Bibcode: 1991SvA....35..387B Altcode: No abstract at ADS Title: Determination of C N and O Abundances in the Atmospheres of Late Type Stars - Extreme Value Problem Authors: Pavlenko, Y. V. Bibcode: 1991SvA....35..212P Altcode: No abstract at ADS Title: The determination of C, N, and O abundances in late-type star atmospheres - Extremum problem Authors: Pavlenko, Y. V. Bibcode: 1991AZh....68..431P Altcode: The possibility of determining carbon, nitrogen, and oxygen abundances through the extremum problem treatment is discussed. The minimized functional consists of differences between observed and calculated parameters of atomic and molecular absorption lines or their blends. A brief description of the procedure and C, N, and O abundance data for the atmosphere of a K giant are presented. Title: Li C N and O Abundances and the 12/C/13/C Isotope Ratio in the Atmospheres of the K Giants 39-CYGNI and Alpha-Arietis Authors: Boyarchuk, M. E.; Pavlenko, Y. V.; Shavrina, A. V. Bibcode: 1991SvA....35..143B Altcode: No abstract at ADS Title: Spectral Features in the Circumstellar Envelope of the Close Binary System V367-CYGNI Authors: Menchenkova, E. V.; Pavlenko, Y. V. Bibcode: 1990SvA....34..489M Altcode: No abstract at ADS Title: The determination of physical parameters of the atmosphere of the primary star of the system V367 Cygni with the method of atmosphere models. Authors: Menchenkova, E. V.; Pavlenko, Y. V. Bibcode: 1989AZh....66..194M Altcode: No abstract at ADS Title: Solution of the NLTE Problem for MGI in Atmosphere of M Giants with Chromosphere - Part One - Menzel Coefficients Authors: Pavlenko, Y. V. Bibcode: 1988Afz....28..163P Altcode: Results of a solution of the NLTE problem for magnesium in the atmosphere of a red giant M2 (Teff = 3800K, log g = 1.5) are discussed. An empirical model chromosphere was used. The over-ionization of magnesium in the atmosphere of the M2 giant takes place only in the region of the temperature minimum. In contrast, the number of Mg+ ions in the chromosphere decreased compared with LTE. Title: The Over Ionization of Metals in Atmospheres of M Giants Authors: Pavlenko, Y. V. Bibcode: 1983ATsir1267....6P Altcode: No abstract at ADS Title: The Curve of Growth and Radiation Diffusion in the Case of a Hydrogen Multilevel Atom in Prominences Authors: Yakovkin, N. A.; Zeldina, M. Y.; Pavlenko, Y. V. Bibcode: 1980BSolD..12...89Y Altcode: No abstract at ADS Title: Diffusion of Hydrogen Radiation in Prominences Authors: Yakovkin, N. A.; Zeldina, M. Y.; Pavlenko, Y. V. Bibcode: 1979SvA....23..585Y Altcode: No abstract at ADS