Time-dependent diffusion in pulsating white dwarf stars: Asteroseismology of G117-B15A

We study the structural characteristic of the variable DA white dwarf G117-B15A by applying the methods of asteroseismology. For such a purpose, we construct white dwarf evolutionary models considering a detailed and up-to-date physical description as well as several processes responsible for the oc...

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Detalles Bibliográficos
Autores principales: Benvenuto, Omar Gustavo, Córsico, Alejandro Hugo, Althaus, Leandro Gabriel, Serenelli, Aldo Marcelo
Formato: Articulo
Lenguaje:Inglés
Publicado: 2002
Materias:
Ciencias Astronómicas
Stars: evolution
Stars: individual: G117-B15A
Stars: interiors
Stars: oscillations
White dwarfs
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/84613
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-84613
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Astronómicas
Stars: evolution
Stars: individual: G117-B15A
Stars: interiors
Stars: oscillations
White dwarfs
spellingShingle Ciencias Astronómicas
Stars: evolution
Stars: individual: G117-B15A
Stars: interiors
Stars: oscillations
White dwarfs
Benvenuto, Omar Gustavo
Córsico, Alejandro Hugo
Althaus, Leandro Gabriel
Serenelli, Aldo Marcelo
Time-dependent diffusion in pulsating white dwarf stars: Asteroseismology of G117-B15A
topic_facet Ciencias Astronómicas
Stars: evolution
Stars: individual: G117-B15A
Stars: interiors
Stars: oscillations
White dwarfs
description We study the structural characteristic of the variable DA white dwarf G117-B15A by applying the methods of asteroseismology. For such a purpose, we construct white dwarf evolutionary models considering a detailed and up-to-date physical description as well as several processes responsible for the occurrence of element diffusion. We have considered several thicknesses for the outermost hydrogen layer, whereas for the inner helium-, carbon- and oxygen-rich layers we considered realistic profiles predicted by calculations of the white dwarf progenitor evolution. The stellar masses we have analysed cover the mass range of 0.50 ≤ M⁎/M⊙ ≤ 0.60. The evolution of each of the considered model sequences was followed down to very low effective temperatures; in particular, from 12 500 K on we computed the dipolar, linear, adiabatic oscillations with radial order k = 1,..., 4. We find that asteroseismological results are not univocal regarding mode identification for the case of G117-B15A. However, our asteroseismological results are compatible with spectroscopic data only if the observed periods of 215.2, 271.0 and 304.4 s are due to dipolar modes with k = 2, 3, 4, respectively. Our calculations indicate that the best fit to the observed period pattern of G117-B15A corresponds to a DA white dwarf structure with a stellar mass of 0.525 M⊙, with a hydrogen mass fraction log(M<SUB>H</SUB>/M⁎) ≳ -3.83 at an effective temperature T<SUB>eff</SUB> ≈ 11 800 K. The value of the stellar mass is consistent with that obtained spectroscopically by Koester & Allard.
format Articulo
Articulo
author Benvenuto, Omar Gustavo
Córsico, Alejandro Hugo
Althaus, Leandro Gabriel
Serenelli, Aldo Marcelo
author_facet Benvenuto, Omar Gustavo
Córsico, Alejandro Hugo
Althaus, Leandro Gabriel
Serenelli, Aldo Marcelo
author_sort Benvenuto, Omar Gustavo
title Time-dependent diffusion in pulsating white dwarf stars: Asteroseismology of G117-B15A
title_short Time-dependent diffusion in pulsating white dwarf stars: Asteroseismology of G117-B15A
title_full Time-dependent diffusion in pulsating white dwarf stars: Asteroseismology of G117-B15A
title_fullStr Time-dependent diffusion in pulsating white dwarf stars: Asteroseismology of G117-B15A
title_full_unstemmed Time-dependent diffusion in pulsating white dwarf stars: Asteroseismology of G117-B15A
title_sort time-dependent diffusion in pulsating white dwarf stars: asteroseismology of g117-b15a
publishDate 2002
url http://sedici.unlp.edu.ar/handle/10915/84613
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AT althausleandrogabriel timedependentdiffusioninpulsatingwhitedwarfstarsasteroseismologyofg117b15a
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bdutipo_str Repositorios
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