J/AZh/83/265ivo://CDS.VizieR/J/AZh/83/265CDSKlochkova V.G.Panchuk V.E.Tavolganskaya N.S.Zhao G.2007-04-01T07:43:18Z2007-04-01T07:41:47ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frstellar-atmospheresspectroscopychemical-abundancesBased on high-resolution spectra we revealed variability of the optical spectrum of the cool star identified with the IR source IRAS 20508+2011. Over the five years of our observations, the radial velocity derived from photospheric absorption lines varied in the interval V_r_=15-30km/s. In the same time, the H(alpha) profile varied from an intense bell-shaped emission line with a small absorption to 2-peaked emission with a central absorption feature below the continuum level. At all but one epoch, the positions of the metallic photospheric lines were systematically shifted relative to the H(alpha) emission: Delta V_r_=V_r_(met)-V_r_(Halpha,emis)~-23km/s. The NaD doublet lines shown a complex profile with broad (half-width about 120km/s) emission and photospheric absorption, as well as an interstellar component. We used model atmospheres to determine the physical parameters and chemical composition of the star's atmosphere: Teff=4800K, logg=1.5, Vt=4.0km/s and metallicity [Fe/H]=-0.36. We detected overabundances of oxygen [O/Fe]=+1.79 (with the ratio [C/O]~-0.9), and alpha-process elements, as well as a deficit of heavy metals. The totality of the parameters suggests that the optical component of IRAS 20508+2011 is an "O-rich" AGB star with luminosity M_v_~-3mag that is close to its evolution transition to the post-AGB stage.2006AZh....83..265Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AZh/83/265CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AZh/83/265https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AZh/83/265http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AZh/83/265https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AZh/83/265https://vizier.iucaa.in/viz-bin/votable?-source=J/AZh/83/265http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AZh/83/265GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AZh/83/265/table3Identification of lines and their intensities in spectrum s25309 of IRAS 20508+2011, along with the derived elemental abundancesLambdaWavelength expressed in Angstroem ({AA})0.1nmem.wlfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIonIon name and ionisation stagemeta.id;phys.atmol.ionStage;phys.atmol.ionizationcharEPExcitation potential of the lower leveleVphys.atmol.excitation;phys.atmol.levelfloatloggfOscillator strength (loggf)phys.atmol.oscStrengthfloatEWEquivalent width, in m{AA}0.1pmspect.line.eqWidthintlog(eps(X))Chemical composition log(epsilon(X)) (log(epsilon(H))=12.0)phys.abundfloat