[alpha] Centauri AB

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dc.creator Guenther, David B.
dc.creator Demarque, P.
dc.date.accessioned 2015-02-03T19:11:37Z
dc.date.available 2015-02-03T19:11:37Z
dc.date.issued 2000-03
dc.identifier.issn 0004-637X
dc.identifier.issn 1538-4357
dc.identifier.uri http://library2.smu.ca/xmlui/handle/01/25940
dc.description Publisher's version/PDF en_CA
dc.description.abstract Detailed models of [alpha] Centauri A and B based on the Hipparcos, Yale, and Soderhjelm parallaxes are compared. The consequences of the uncertainty in mass, luminosity, surface temperature, and composition on the structure and the p-mode pulsation spectrum of the models are presented. All of the models were constructed using the most current stellar structure physics available to us, including helium and heavy-element diffusion, OPAL (Lawrence Livermore Opacity Library) equation of state, and OPAL and Alexander opacities. Self-consistent models of [alpha] Cen A and B that satisfy the observational constraints have an initial helium mass fraction Y[subscript ZAMS] = ~0.28. The age of the system depends critically on whether or not [alpha] Cen A has a convective core. If it does (our best model), then [alpha] Cen AB is ~7.6 Gyr old, and if it does not, then the binary system is ~6.8 Gyr old. Both ages and Y[subscript ZAMS] are accurate to [plus or minus] ~10% owing to observational uncertainties. The Galactic enrichment parameter ([delta]Y /[delta]Z) for our best model pair is less than 1. Pulsation analyses of our best models yield an average large and small spacing of 101 [plus or minus] 3 [microhertz] and 4.6 [plus or minus] 0.4 [microhertz], respectively, for [alpha] Cen A, and 173 [plus or minus] 6 [microhertz] and 15 [plus or minus] 1 [microhertz] for [alpha] Cen B. Some methodologies that use p-mode frequency observations to constrain the system further are outlined. We include a simple test to determine whether or not [alpha] Cen A has a convective core and introduce a method to use the small frequency spacing to determine the age of system, overcoming the limitation that it is also sensitive to composition. en_CA
dc.language.iso en en_CA
dc.publisher American Astronomical Society en_CA
dc.relation.uri http://doi.org/10.1086/308446
dc.rights Article is made available in accordance with the publisher’s policy and is subject to copyright law. Please refer to the publisher’s site. Any re-use of this article is to be in accordance with the publisher’s copyright policy. This posting is in no way granting any permission for re-use to the reader/user.
dc.subject.lcsh Alpha Centauri
dc.subject.lcsh Double stars
dc.subject.lcsh Stars -- Structure
dc.subject.lcsh Stellar oscillations
dc.title [alpha] Centauri AB en_CA
dc.type Text en_CA
dcterms.bibliographicCitation Astrophysical Journal 531, 503-520. (2000) en_CA


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Article is made available in accordance with the publisher’s policy and is subject to copyright law. Please refer to the publisher’s site. Any re-use of this article is to be in accordance with the publisher’s copyright policy. This posting is in no way granting any permission for re-use to the reader/user.
 
Published Version: http://doi.org/10.1086/308446
 
 

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