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dc.contributor.authorFerguson, D.H.
dc.contributor.authorLiebert, J.
dc.contributor.authorHaas, S.
dc.contributor.authorNapiwotzki, R.
dc.contributor.authorJames, T.A.
dc.date.accessioned2007-12-17T09:58:00Z
dc.date.available2007-12-17T09:58:00Z
dc.date.issued1999
dc.identifier.citationFerguson , D H , Liebert , J , Haas , S , Napiwotzki , R & James , T A 1999 , ' Masses and Other Parameters of the PostCommon Envelope Binary BE Ursae Majoris ' , The Astrophysical Journal , vol. 518 , pp. 866-872 .
dc.identifier.issn0004-637X
dc.identifier.otherPURE: 168855
dc.identifier.otherPURE UUID: 95b485f6-9c00-4812-90f2-3141a0d6a99a
dc.identifier.otherdspace: 2299/1230
dc.identifier.otherScopus: 0033587238
dc.identifier.urihttp://hdl.handle.net/2299/1230
dc.descriptionOriginal article can be found at: http://www.journals.uchicago.edu/ApJ/--Copyright American Astronomical Society
dc.description.abstractThe binary star BE Ursae Majoris is recently emerged from the common envelope phase; indeed, the hot sdO/DAO component is the central star of the associated planetary nebula. As such, BE UMa represents an important test case of stellar evolution theory. Using the Hubble Space Telescope (HST ) Goddard High Resolution Spectrograph (GHRS), we measured the radial velocity amplitude of the He II j1640 absorption line from the sdO/DAO component of this eclipsing system. Combining our results with those of Crampton, Cowley, & Hutchings, we determine stellar masses in units of solar mass as follows : for the sdO, the mass is 0.70^0.07, and that of the secondary star is 0.36^0.07, where we report the 1 p value for all errors. The separation between the component stars is 7.5 R and _^0.5 R_ is insensitive to small changes in inclination angle due to the near edge-on viewing angle of 84¡^1¡. Using these values, we modeled the eclipse light curve. Our results matched observed UBV R light curves of Wood and coworkers only if the modeled secondary star radius of 0.72 R has nearly _^0.05 R_ double the radius expected from the main-sequence mass-radius relation. The secondary star has thus not yet relaxed to thermal equilibrium since the common envelope phase ended D104 yr ago. Using the j1640 absorption-line proÐle and the surrounding continuum, we also were able to constrain the sdO helium abundance as log nHe\[1.1^0.2 and log nFe\1. Our results support the sdO/DAO log gD6.5 surface gravity and TeffD100,000 K values of Liebert et al. and are consistent with the post- AGB evolutionary track. Our best estimate of the distance to the BE UMa system is 2000 pc.en
dc.language.isoeng
dc.relation.ispartofThe Astrophysical Journal
dc.rightsOpen
dc.titleMasses and Other Parameters of the PostCommon Envelope Binary BE Ursae Majorisen
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.description.statusPeer reviewed
dc.relation.schoolSchool of Physics, Astronomy and Mathematics
dcterms.dateAccepted1999
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue
herts.rights.accesstypeOpen


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