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.description.provenance |
Submitted by Janine Mills (janine.mills@smu.ca) on 2015-02-03T19:11:37Z
No. of bitstreams: 1
Guenther_David_B_article_2000.pdf: 913173 bytes, checksum: 58e68733ddebf200cfdbf315c69a2e8b (MD5) |
en |
dc.description.provenance |
Made available in DSpace on 2015-02-03T19:11:37Z (GMT). No. of bitstreams: 1
Guenther_David_B_article_2000.pdf: 913173 bytes, checksum: 58e68733ddebf200cfdbf315c69a2e8b (MD5)
Previous issue date: 2000-03 |
en |
dc.language.iso |
en |
en_CA |
dc.publisher |
American Astronomical Society |
en_CA |
dc.relation.uri |
http://doi.org/10.1086/308446 |
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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. |
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dc.subject.lcsh |
Alpha Centauri |
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dc.subject.lcsh |
Double stars |
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dc.subject.lcsh |
Stars -- Structure |
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dc.subject.lcsh |
Stellar oscillations |
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dc.title |
[alpha] Centauri AB |
en_CA |
dc.type |
Text |
en_CA |
dcterms.bibliographicCitation |
Astrophysical Journal 531, 503-520. (2000) |
en_CA |
Copyright statement:
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.