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dc.contributor.authorCatalan, Silvia
dc.contributor.authorRibas, I.
dc.contributor.authorIsern, J.
dc.contributor.authorGarcia-Berro, E.
dc.date.accessioned2011-12-20T11:01:03Z
dc.date.available2011-12-20T11:01:03Z
dc.date.issued2008-01
dc.identifier.citationCatalan , S , Ribas , I , Isern , J & Garcia-Berro , E 2008 , ' WD0433+270: an old Hyades stream member or an Fe-core white dwarf? ' , Astronomy and Astrophysics , vol. 477 , no. 3 , pp. 901-906 . https://doi.org/10.1051/0004-6361:20078230
dc.identifier.issn0004-6361
dc.identifier.otherPURE: 493669
dc.identifier.otherPURE UUID: 89d6f25b-28e7-474b-b449-33eab86da120
dc.identifier.otherWOS: 000252131000025
dc.identifier.otherScopus: 38049146533
dc.identifier.urihttp://hdl.handle.net/2299/7394
dc.description.abstractContext. G39-27/289 is a common proper-motion pair formed by a white dwarf (WD0433+270) and a main-sequence star (BD+26 730) that apparently has been classified as a member of the Hyades open cluster. Previous studies of the white dwarf component yielded a cooling time of similar to 4 Gyr. Although it has not been pointed out before explicitly, this result is 6 times greater than the age of the Hyades cluster, giving rise to an apparent conflict between the physics of white dwarfs and cluster main-sequence fitting. Aims. We investigate whether this system belongs to the Hyades cluster and, accordingly, give a plausible explanation for the nature of the white dwarf member. Methods. We have performed and analyzed spectroscopic observations to better characterize these objects, and used their kinematic properties to evaluate their membership in the Hyades. Then, different mass-radius relations and cooling sequences for different core compositions (He, C/O, O/Ne and Fe) were employed to infer the mass and cooling time of the white dwarf. Results. From kinematic and chemical composition considerations, we believe that the system was a former member of the Hyades cluster and therefore has an evolutionary link with it. However, the evidence is not conclusive. With regards to the nature of the white dwarf component, we find that two core compositions -C/O and Fe - are compatible with the observed effective temperature and radius. These compositions yield very different cooling times of similar to 4 Gyr and similar to 1 Gyr, respectively. Conclusions. We distinguish two possible scenarios. If the pair does not belong to the Hyades cluster but only to the Hyades stream, this would indicate that such a stream contains rather old objects and is definitely not coeval with the cluster. This has interesting consequences for Galactic dynamics. However, our favored scenario is that of a white dwarf with a rather exotic Fe core, having a cooling time compatible with the Hyades age. This is a tantalizing result that would have implications for the thermonuclear explosion of white dwarfs and explosion theories of degenerate nuclei.en
dc.format.extent6
dc.language.isoeng
dc.relation.ispartofAstronomy and Astrophysics
dc.rightsOpen
dc.subjectstars : evolution
dc.subjectstars : white dwarfs
dc.subjectGalaxy : open clusters and associations : individual : WD0433+270
dc.subjectstars : kinematics
dc.subjectMASS-RADIUS RELATIONS
dc.subjectOPEN-CLUSTER
dc.subjectSOLAR NEIGHBORHOOD
dc.subjectSTARS
dc.subjectHIPPARCOS
dc.subjectBINARIES
dc.subjectAGE
dc.subjectEVOLUTION
dc.subjectCOLORS
dc.subjectPARAMETERS
dc.titleWD0433+270: an old Hyades stream member or an Fe-core white dwarf?en
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.contributor.institutionScience & Technology Research Institute
dc.contributor.institutionCentre for Astrophysics Research
dc.description.statusPeer reviewed
dc.relation.schoolSchool of Physics, Astronomy and Mathematics
dc.description.versiontypeFinal Accepted Version
dcterms.dateAccepted2008-01
rioxxterms.versionAM
rioxxterms.versionofrecordhttps://doi.org/10.1051/0004-6361:20078230
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue
herts.rights.accesstypeOpen


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