J/MNRAS/477/2276ivo://CDS.VizieR/J/MNRAS/477/2276doi:10.26093/cds/vizier.74772276CDSKovtyukh V.Yegorova I.Andrievsky S.Korotin S.Saviane I.,Lemasle B.Chekhonadskikh F.Belik S.2024-08-18T20:19:05Z2021-06-28T14:06:07ZCDS support team

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

cds-question@unistra.frvariable-starschemical-abundancesThe chemical composition of 28 Population II Cepheids and one RR Lyrae variable has been studied using high-resolution spectra. The chemical composition of W Vir variable stars (with periods longer than 8 d) is typical for the halo and thick disc stars. However, the chemical composition of BL Her variables (with periods of 0.8-4 d) is drastically different, although it does not differ essentially from that of the stars belonging to globular clusters. In particular, the sodium overabundance ([Na/Fe]~=0.4) is reported for most of these stars, and the Na-O anticorrelation is also possible. The evolutionary tracks for BL Her variables (with a progenitor mass value of 0.8 solar masses) indicate that mostly helium-overabundant stars (Y=0.30-0.35) can fall into the instability strip region. We suppose that it is the helium overabundance that accounts not only for the existence of BL Her variable stars but also for the observed abnormalities in the chemical composition of this small group of pulsating variables.2018MNRAS.477.2276Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/477/2276CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/477/2276https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/477/2276http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/477/2276https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/477/2276https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/477/2276http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/477/2276GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/477/2276/table1 (Details of observations and stellar parameters for 29 stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/477/2276/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/477/2276/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/477/2276/table1?GETtext/xml+votable180.050000true285.07012-10.44339640.0055555555555555566/8584 9356 12685 14739 25833 25842 25869 28721 28743 28745 28768-28769 28793 28970 29583 29860 30225 30927 32170 36705 42088 42855 42948 43309 44176 44786 45720 48024 48880https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/477/2276?format=asciidefaultJ/MNRAS/477/2276/table1Details of observations and stellar parameters for 29 starsSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAbundindicates abundances in tables 3 and 4meta.ref.urlcharStarStar namemeta.id;meta.maincharprimaryn_Star[a] Note on Star (1)meta.notecharPerPerioddtime.perioddoubleTelTelescopemeta.id;instr.telcharJD? Julian date (JD-2400000)dtime.epochdoublenullableExptime? Exposure timestime.duration;obs.exposureintnullablePhase? Phasetime.phasefloatnullableTeff? Effective temperatureKphys.temperature.effectiveintnullablelogg? Surface gravitylog(cm.s**-2)phys.gravityfloatnullableVt? Microturbulent velocitykm/sphys.velocfloatnullable[Fe/H]? Metallicityphys.abund.ZfloatnullableRemRemarksmeta.notechar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/MNRAS/477/2276/abundRelative to Fe abundances in T2C (tables 2 and 3)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarStar namemeta.id;meta.maincharPerPerioddtime.perioddouble[C/Fe]? Abundance [C/Fe]phys.abundfloatnullable[N/Fe]? Abundance [N/Fe]phys.abundfloatnullable[O/Fe]? Abundance [O/Fe]phys.abundfloatnullable[Na/Fe]? Abundance [Na/Fe]phys.abundfloatnullable[Mg/Fe]? Abundance [Mg/Fe]phys.abundfloatnullable[Al/Fe]? Abundance [Al/Fe]phys.abundfloatnullable[Si/Fe]? Abundance [Si/Fe]phys.abundfloatnullable[S/Fe]? Abundance [S/Fe]phys.abundfloatnullable[Ca/Fe]? Abundance [Ca/Fe]phys.abundfloatnullable[Sc/Fe]? Abundance [Sc/Fe]phys.abundfloatnullable[Ti/Fe]? Abundance [Ti/Fe]phys.abundfloatnullable[V/Fe]? Abundance [V/Fe]phys.abundfloatnullable[Cr/Fe]? Abundance [Cr/Fe]phys.abundfloatnullable[Mn/Fe]? Abundance [Mn/Fe]phys.abundfloatnullable[Fe/H]Metallicityphys.abund.Zfloat[Co/Fe]? Abundance [Co/Fe]phys.abundfloatnullable[Ni/Fe]? Abundance [Ni/Fe]phys.abundfloatnullable[Cu/Fe]? Abundance [Cu/Fe]phys.abundfloatnullable[Zn/Fe]? Abundance [Zn/Fe]phys.abundfloatnullable[Y/Fe]? Abundance [Y/Fe]phys.abundfloatnullable[Zr/Fe]? Abundance [Zr/Fe]phys.abundfloatnullable[Ba/Fe]? Abundance [Ba/Fe]phys.abundfloatnullable[La/Fe]? Abundance [La/Fe]phys.abundfloatnullable[Ce/Fe]? Abundance [Ce/Fe]phys.abundfloatnullable[Nd/Fe]? Abundance [Nd/Fe]phys.abundfloatnullable[Sm/Fe]? Abundance [Sm/Fe]phys.abundfloatnullable[Eu/Fe]? Abundance [Eu/Fe]phys.abundfloatnullable