On the possible existence of short-period g-mode instabilities powered by nuclear-burning shells in post-asymptotic giant branch H-deficient (PG1159-TYPE) stars

We present a pulsational stability analysis of hot post-asymptotic giant branch (AGB) H-deficient pre-white dwarf stars with active He-burning shells. The stellar models employed are state-of-the-art equilibrium structures representative of PG1159 stars derived from the complete evolution of the pro...

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Detalles Bibliográficos
Autores principales: Córsico, Alejandro Hugo, Althaus, Leandro Gabriel, Miller Bertolami, Marcelo Miguel, González Pérez, J. M., Kepler, S. O.
Formato: Articulo
Lenguaje:Inglés
Publicado: 2009
Materias:
Ciencias Astronómicas
Stars: Interiors
Stars: Oscillations
Stars: individual (VV 47)
Stars: evolution
White dwarfs
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/82770
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-82770
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: Interiors
Stars: Oscillations
Stars: individual (VV 47)
Stars: evolution
White dwarfs
spellingShingle Ciencias Astronómicas
Stars: Interiors
Stars: Oscillations
Stars: individual (VV 47)
Stars: evolution
White dwarfs
Córsico, Alejandro Hugo
Althaus, Leandro Gabriel
Miller Bertolami, Marcelo Miguel
González Pérez, J. M.
Kepler, S. O.
On the possible existence of short-period g-mode instabilities powered by nuclear-burning shells in post-asymptotic giant branch H-deficient (PG1159-TYPE) stars
topic_facet Ciencias Astronómicas
Stars: Interiors
Stars: Oscillations
Stars: individual (VV 47)
Stars: evolution
White dwarfs
description We present a pulsational stability analysis of hot post-asymptotic giant branch (AGB) H-deficient pre-white dwarf stars with active He-burning shells. The stellar models employed are state-of-the-art equilibrium structures representative of PG1159 stars derived from the complete evolution of the progenitor stars, through the thermally pulsing AGB phase and born-again episode. On the basis of fully nonadiabatic pulsation computations, we confirmed theoretical evidence for the existence of a separate PG1159 instability strip in the log T<SUB>eff</SUB>-log g diagram characterized by short-period g-modes excited by the ε-mechanism. This instability strip partially overlaps the already known GW Vir instability strip of intermediate/long-period g-modes destabilized by the classical κ-mechanism acting on the partial ionization of C and/or O in the envelope of PG1159 stars. We found that PG1159 stars characterized by thick He-rich envelopes and located inside this overlapping region could exhibit both short and intermediate/long periods simultaneously. As a natural application of our results, we study the particular case of VV 47, a pulsating planetary nebula nucleus (PG1159 type) that is particularly interesting because it has been reported to exhibit a rich and complex pulsation spectrum including a series of unusually short pulsation periods. We found that the long periods exhibited by VV 47 can be readily explained by the classical κ-mechanism, while the observed short-period branch below ≈300 s could correspond to modes triggered by the He-burning shell through the ε-mechanism, although more observational work is needed to confirm the reality of these short-period modes. Were the existence of short-period g-modes in this star convincingly confirmed by future observations, VV 47 could be the first known pulsating star in which both the κ-mechanism and the ε-mechanism of mode driving are simultaneously operating.
format Articulo
Articulo
author Córsico, Alejandro Hugo
Althaus, Leandro Gabriel
Miller Bertolami, Marcelo Miguel
González Pérez, J. M.
Kepler, S. O.
author_facet Córsico, Alejandro Hugo
Althaus, Leandro Gabriel
Miller Bertolami, Marcelo Miguel
González Pérez, J. M.
Kepler, S. O.
author_sort Córsico, Alejandro Hugo
title On the possible existence of short-period g-mode instabilities powered by nuclear-burning shells in post-asymptotic giant branch H-deficient (PG1159-TYPE) stars
title_short On the possible existence of short-period g-mode instabilities powered by nuclear-burning shells in post-asymptotic giant branch H-deficient (PG1159-TYPE) stars
title_full On the possible existence of short-period g-mode instabilities powered by nuclear-burning shells in post-asymptotic giant branch H-deficient (PG1159-TYPE) stars
title_fullStr On the possible existence of short-period g-mode instabilities powered by nuclear-burning shells in post-asymptotic giant branch H-deficient (PG1159-TYPE) stars
title_full_unstemmed On the possible existence of short-period g-mode instabilities powered by nuclear-burning shells in post-asymptotic giant branch H-deficient (PG1159-TYPE) stars
title_sort on the possible existence of short-period g-mode instabilities powered by nuclear-burning shells in post-asymptotic giant branch h-deficient (pg1159-type) stars
publishDate 2009
url http://sedici.unlp.edu.ar/handle/10915/82770
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