Modeling He-rich subdwarfs through the hot-flasher scenario

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We present 1D numerical simulations aimed at studying the hot-flasher scenario for the formation of He-rich subdwarf stars. Sequences were calculated for a wide range of metallicities and physical assumptions, such as the stellar mass at the moment of the helium core flash. This allows us to study t...

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Detalles Bibliográficos
Autores principales: Miller Bertolami, Marcelo Miguel, Althaus, Leandro Gabriel, Unglaub, K., Weiss, A.
Formato: Articulo
Lenguaje:Inglés
Publicado: 2008
Materias:
Ciencias Astronómicas
Stars: evolution
Stars: horizontal-branch
Stars: mass-loss
Stars: subdwarfs
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/84831
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-84831
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: horizontal-branch
Stars: mass-loss
Stars: subdwarfs
spellingShingle Ciencias Astronómicas
Stars: evolution
Stars: horizontal-branch
Stars: mass-loss
Stars: subdwarfs
Miller Bertolami, Marcelo Miguel
Althaus, Leandro Gabriel
Unglaub, K.
Weiss, A.
Modeling He-rich subdwarfs through the hot-flasher scenario
topic_facet Ciencias Astronómicas
Stars: evolution
Stars: horizontal-branch
Stars: mass-loss
Stars: subdwarfs
description We present 1D numerical simulations aimed at studying the hot-flasher scenario for the formation of He-rich subdwarf stars. Sequences were calculated for a wide range of metallicities and physical assumptions, such as the stellar mass at the moment of the helium core flash. This allows us to study the two previously proposed flavors of the hot-flasher scenario ("deep" and "shallow" mixing cases) and to identify a third transition type. Our sequences are calculated by solving simultaneously the mixing and burning equations within a diffusive convection picture, and in the context of standard mixing length theory. We are able to follow chemical evolution during deep-mixing events in which hydrogen is burned violently, and therefore able to present a homogeneous set of abundances for different metallicities and varieties of hot-flashers. We extend the scope of our work by analyzing the effects of non-standard assumptions, such as the effect of chemical gradients, extra-mixing at convective boundaries, possible reduction in convective velocities, or the interplay between difussion and mass loss. Particular emphasis is placed on the predicted surface properties of the models. We find that the hot-flasher scenario is a viable explanation for the formation and surface properties of He-sdO stars. Our results also show that, during the early He-core burning stage, element diffusion may produce the transformation of (post hot-flasher) He-rich atmospheres into He-deficient ones. If this is so, then we find that He-sdO stars should be the progenitors of some of the hottest sdB stars.
format Articulo
Articulo
author Miller Bertolami, Marcelo Miguel
Althaus, Leandro Gabriel
Unglaub, K.
Weiss, A.
author_facet Miller Bertolami, Marcelo Miguel
Althaus, Leandro Gabriel
Unglaub, K.
Weiss, A.
author_sort Miller Bertolami, Marcelo Miguel
title Modeling He-rich subdwarfs through the hot-flasher scenario
title_short Modeling He-rich subdwarfs through the hot-flasher scenario
title_full Modeling He-rich subdwarfs through the hot-flasher scenario
title_fullStr Modeling He-rich subdwarfs through the hot-flasher scenario
title_full_unstemmed Modeling He-rich subdwarfs through the hot-flasher scenario
title_sort modeling he-rich subdwarfs through the hot-flasher scenario
publishDate 2008
url http://sedici.unlp.edu.ar/handle/10915/84831
work_keys_str_mv AT millerbertolamimarcelomiguel modelingherichsubdwarfsthroughthehotflasherscenario
AT althausleandrogabriel modelingherichsubdwarfsthroughthehotflasherscenario
AT unglaubk modelingherichsubdwarfsthroughthehotflasherscenario
AT weissa modelingherichsubdwarfsthroughthehotflasherscenario
bdutipo_str Repositorios
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