Type II Cepheids abundances

DOI

The 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.

Cone search capability for table J/MNRAS/477/2276/table1 (Details of observations and stellar parameters for 29 stars)

Identifier
DOI http://doi.org/10.26093/cds/vizier.74772276
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/MNRAS/477/2276
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/477/2276
Related Identifier https://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/477/2276
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/J/MNRAS/477/2276
Provenance
Creator Kovtyukh V.; Yegorova I.; Andrievsky S.; Korotin S.; Saviane I.,Lemasle B.; Chekhonadskikh F.; Belik S.
Publisher CDS
Publication Year 2021
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Representation
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Interdisciplinary Astronomy; Natural Sciences; Physics; Stellar Astronomy