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The Dynamical Mass and Evolutionary Status of the Type II Cepheid in the Eclipsing Binary System OGLE-LMC-T2CEP-211 with a Double-ring Disk

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dc.abstract.enWe present the analysis of a peculiar W Virginis (pWVir) type II Cepheid, OGLE-LMC-T2CEP-211 (P <SUB>puls</SUB> = 9.393 days), in a double-lined binary system (P <SUB>orb</SUB> = 242 days), which shed light on virtually unknown evolutionary status and structure of pWVir stars. The dynamical mass of the Cepheid (first ever for a type II Cepheid) is 0.64 ± 0.02 M <SUB>⊙</SUB>, and the radius R = 25.1 ± 0.3 R <SUB>⊙</SUB>. The companion is a massive (5.67 M <SUB>⊙</SUB>) main-sequence star obscured by a disk. Such a configuration suggests a mass transfer in the system history. We found that originally the system ({P}<SUB>orb</SUB>}<SUP>init</SUP>} = 12 days) was composed of 3.5 and 2.8 M <SUB>⊙</SUB> stars, with the current Cepheid being more massive. The system age is now ˜200 Myr, and the Cepheid is almost completely stripped of hydrogen, with helium mass of ˜92% of the total mass. It finished transferring the mass 2.5 Myr ago and is evolving toward lower temperatures passing through the instability strip. Comparison with observations indicates a reasonable 2.7 × 10<SUP>-8</SUP> M <SUB>⊙</SUB> yr<SUP>-1</SUP> mass loss from the Cepheid. The companion is most probably a Be main-sequence star with T = 22,000 K and R = 2.5 R <SUB>⊙</SUB>. Our results yield a good agreement with a pulsation theory model for a hydrogen-deficient pulsator, confirming the described evolutionary scenario. We detected a two-ring disk (R <SUB>disk</SUB> ˜ 116 R <SUB>⊙</SUB>) and a shell (R <SUB>shell</SUB> ˜ 9 R <SUB>⊙</SUB>) around the companion, which is probably a combination of the matter from the past mass transfer, the mass being lost by the Cepheid owing to wind and pulsations, and a decretion disk around a rapidly rotating secondary. Our study, together with observational properties of pWVir stars, suggests that the majority of them are products of a similar binary evolution interaction.
dc.affiliationUniwersytet Warszawski
dc.contributor.authorPilecki, Bogumił
dc.contributor.authorDervișoğlu, Ahmet
dc.contributor.authorGieren, Wolfgang
dc.contributor.authorSmolec, Radosław
dc.contributor.authorSoszyński, Igor
dc.contributor.authorPietrzyński, Grzegorz
dc.contributor.authorThompson, Ian B.
dc.contributor.authorTaormina, Mónica
dc.date.accessioned2024-01-26T10:10:44Z
dc.date.available2024-01-26T10:10:44Z
dc.date.copyright2018-10-15
dc.date.issued2018
dc.description.accesstimeBEFORE_PUBLICATION
dc.description.financeNie dotyczy
dc.description.number1
dc.description.versionORIGINAL_AUTHOR
dc.description.volume868
dc.identifier.doi10.3847/1538-4357/AAE68F
dc.identifier.issn0004-637X
dc.identifier.urihttps://repozytorium.uw.edu.pl//handle/item/122131
dc.identifier.weblinkhttp://adsabs.harvard.edu/abs/2018ApJ...868...30P
dc.languageeng
dc.pbn.affiliationastronomy
dc.relation.ispartofAstrophysical Journal
dc.relation.pages30
dc.rightsOther
dc.sciencecloudnosend
dc.titleThe Dynamical Mass and Evolutionary Status of the Type II Cepheid in the Eclipsing Binary System OGLE-LMC-T2CEP-211 with a Double-ring Disk
dc.typeJournalArticle
dspace.entity.typePublication