Low-mass, helium-enriched PG1159 stars: A possible evolutionary origin and implications for their pulsational stability properties

Autores
Althaus, Leandro Gabriel; Córsico, Alejandro Hugo; Miller Bertolami, Marcelo Miguel
Año de publicación
2007
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Aims, We examine a recently-proposed evolutionary scenario that could explain the existence of the low-mass, helium-enriched PG 1159 stars. We focus in particular on studying the pulsational stability properties of the evolutionary models predicted by such a scenario. Methods. We assess the overstability of pulsation g-modes of stellar models as evolution proceeds in the PG 1159 domain. Stellar models are extracted from the full evolution of a 1-M⊙ model star that experiences its first thermal pulse as a late thermal pulse (LTP) after leaving the AGB. The evolutionary stages corresponding to the born-again episode and the subsequent helium sub-flashes are taken into account in detail. Results. Under reasonable assumptions of mass-loss rate, the evolutionary scenario reproduces the high helium abundances observed in some PG 1159 stars. We find that, despite the high helium abundance in the driving layers, a narrow region exists in the log Teff - log g diagram for which the helium-enriched PG 1159 sequence exhibits unstable pulsation modes with periods in the range 500 to 1600 s. In particular, the nonpulsating helium-enriched PG 1159 star, MCT 0130-1937, is located outside the theoretical instability domain. Our results suggest that MCT 0130-1937 is a real non-pulsating star and that the lack of pulsations should not be attributed to unfavorable geometry. Conclusions. Our study hints at a consistent picture between the evolutionary scenario that could explain the existence of heliumenriched PG 1159 stars and the nonvariable nature of MCT 0130-1937. We also present theoretical support for the unusually high helium abundance observed in the nonpulsating PG 1159 star HS 1517+7403. We suggest that HS 1517+7403 could be a transition object linking the low-mass helium-rich O(He) stars with the helium-enriched PG 1159 stars via the evolutionary connection K1-27 →HS 1517+7403 → MCT 0130-1937.
Facultad de Ciencias Astronómicas y Geofísicas
Instituto de Astrofísica de La Plata
Materia
Ciencias Astronómicas
Stars: abundances
Stars: AGB and post-AGB
Stars: evolution
Stars: interiors
Stars: variables: general
White dwarfs
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by-nc-sa/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/83336

id SEDICI_043e85ed05962b07fe5d054fd505eb0b
oai_identifier_str oai:sedici.unlp.edu.ar:10915/83336
network_acronym_str SEDICI
repository_id_str 1329
network_name_str SEDICI (UNLP)
spelling Low-mass, helium-enriched PG1159 stars: A possible evolutionary origin and implications for their pulsational stability propertiesAlthaus, Leandro GabrielCórsico, Alejandro HugoMiller Bertolami, Marcelo MiguelCiencias AstronómicasStars: abundancesStars: AGB and post-AGBStars: evolutionStars: interiorsStars: variables: generalWhite dwarfsAims, We examine a recently-proposed evolutionary scenario that could explain the existence of the low-mass, helium-enriched PG 1159 stars. We focus in particular on studying the pulsational stability properties of the evolutionary models predicted by such a scenario. Methods. We assess the overstability of pulsation g-modes of stellar models as evolution proceeds in the PG 1159 domain. Stellar models are extracted from the full evolution of a 1-M⊙ model star that experiences its first thermal pulse as a late thermal pulse (LTP) after leaving the AGB. The evolutionary stages corresponding to the born-again episode and the subsequent helium sub-flashes are taken into account in detail. Results. Under reasonable assumptions of mass-loss rate, the evolutionary scenario reproduces the high helium abundances observed in some PG 1159 stars. We find that, despite the high helium abundance in the driving layers, a narrow region exists in the log T<SUB>eff</SUB> - log g diagram for which the helium-enriched PG 1159 sequence exhibits unstable pulsation modes with periods in the range 500 to 1600 s. In particular, the nonpulsating helium-enriched PG 1159 star, MCT 0130-1937, is located outside the theoretical instability domain. Our results suggest that MCT 0130-1937 is a real non-pulsating star and that the lack of pulsations should not be attributed to unfavorable geometry. Conclusions. Our study hints at a consistent picture between the evolutionary scenario that could explain the existence of heliumenriched PG 1159 stars and the nonvariable nature of MCT 0130-1937. We also present theoretical support for the unusually high helium abundance observed in the nonpulsating PG 1159 star HS 1517+7403. We suggest that HS 1517+7403 could be a transition object linking the low-mass helium-rich O(He) stars with the helium-enriched PG 1159 stars via the evolutionary connection K1-27 →HS 1517+7403 → MCT 0130-1937.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plata2007info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdf1175-1180http://sedici.unlp.edu.ar/handle/10915/83336enginfo:eu-repo/semantics/altIdentifier/issn/0004-6361info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361:20066887info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by-nc-sa/4.0/Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-09-29T11:15:41Zoai:sedici.unlp.edu.ar:10915/83336Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-29 11:15:42.16SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Low-mass, helium-enriched PG1159 stars: A possible evolutionary origin and implications for their pulsational stability properties
title Low-mass, helium-enriched PG1159 stars: A possible evolutionary origin and implications for their pulsational stability properties
spellingShingle Low-mass, helium-enriched PG1159 stars: A possible evolutionary origin and implications for their pulsational stability properties
Althaus, Leandro Gabriel
Ciencias Astronómicas
Stars: abundances
Stars: AGB and post-AGB
Stars: evolution
Stars: interiors
Stars: variables: general
White dwarfs
title_short Low-mass, helium-enriched PG1159 stars: A possible evolutionary origin and implications for their pulsational stability properties
title_full Low-mass, helium-enriched PG1159 stars: A possible evolutionary origin and implications for their pulsational stability properties
title_fullStr Low-mass, helium-enriched PG1159 stars: A possible evolutionary origin and implications for their pulsational stability properties
title_full_unstemmed Low-mass, helium-enriched PG1159 stars: A possible evolutionary origin and implications for their pulsational stability properties
title_sort Low-mass, helium-enriched PG1159 stars: A possible evolutionary origin and implications for their pulsational stability properties
dc.creator.none.fl_str_mv Althaus, Leandro Gabriel
Córsico, Alejandro Hugo
Miller Bertolami, Marcelo Miguel
author Althaus, Leandro Gabriel
author_facet Althaus, Leandro Gabriel
Córsico, Alejandro Hugo
Miller Bertolami, Marcelo Miguel
author_role author
author2 Córsico, Alejandro Hugo
Miller Bertolami, Marcelo Miguel
author2_role author
author
dc.subject.none.fl_str_mv Ciencias Astronómicas
Stars: abundances
Stars: AGB and post-AGB
Stars: evolution
Stars: interiors
Stars: variables: general
White dwarfs
topic Ciencias Astronómicas
Stars: abundances
Stars: AGB and post-AGB
Stars: evolution
Stars: interiors
Stars: variables: general
White dwarfs
dc.description.none.fl_txt_mv Aims, We examine a recently-proposed evolutionary scenario that could explain the existence of the low-mass, helium-enriched PG 1159 stars. We focus in particular on studying the pulsational stability properties of the evolutionary models predicted by such a scenario. Methods. We assess the overstability of pulsation g-modes of stellar models as evolution proceeds in the PG 1159 domain. Stellar models are extracted from the full evolution of a 1-M⊙ model star that experiences its first thermal pulse as a late thermal pulse (LTP) after leaving the AGB. The evolutionary stages corresponding to the born-again episode and the subsequent helium sub-flashes are taken into account in detail. Results. Under reasonable assumptions of mass-loss rate, the evolutionary scenario reproduces the high helium abundances observed in some PG 1159 stars. We find that, despite the high helium abundance in the driving layers, a narrow region exists in the log T<SUB>eff</SUB> - log g diagram for which the helium-enriched PG 1159 sequence exhibits unstable pulsation modes with periods in the range 500 to 1600 s. In particular, the nonpulsating helium-enriched PG 1159 star, MCT 0130-1937, is located outside the theoretical instability domain. Our results suggest that MCT 0130-1937 is a real non-pulsating star and that the lack of pulsations should not be attributed to unfavorable geometry. Conclusions. Our study hints at a consistent picture between the evolutionary scenario that could explain the existence of heliumenriched PG 1159 stars and the nonvariable nature of MCT 0130-1937. We also present theoretical support for the unusually high helium abundance observed in the nonpulsating PG 1159 star HS 1517+7403. We suggest that HS 1517+7403 could be a transition object linking the low-mass helium-rich O(He) stars with the helium-enriched PG 1159 stars via the evolutionary connection K1-27 →HS 1517+7403 → MCT 0130-1937.
Facultad de Ciencias Astronómicas y Geofísicas
Instituto de Astrofísica de La Plata
description Aims, We examine a recently-proposed evolutionary scenario that could explain the existence of the low-mass, helium-enriched PG 1159 stars. We focus in particular on studying the pulsational stability properties of the evolutionary models predicted by such a scenario. Methods. We assess the overstability of pulsation g-modes of stellar models as evolution proceeds in the PG 1159 domain. Stellar models are extracted from the full evolution of a 1-M⊙ model star that experiences its first thermal pulse as a late thermal pulse (LTP) after leaving the AGB. The evolutionary stages corresponding to the born-again episode and the subsequent helium sub-flashes are taken into account in detail. Results. Under reasonable assumptions of mass-loss rate, the evolutionary scenario reproduces the high helium abundances observed in some PG 1159 stars. We find that, despite the high helium abundance in the driving layers, a narrow region exists in the log T<SUB>eff</SUB> - log g diagram for which the helium-enriched PG 1159 sequence exhibits unstable pulsation modes with periods in the range 500 to 1600 s. In particular, the nonpulsating helium-enriched PG 1159 star, MCT 0130-1937, is located outside the theoretical instability domain. Our results suggest that MCT 0130-1937 is a real non-pulsating star and that the lack of pulsations should not be attributed to unfavorable geometry. Conclusions. Our study hints at a consistent picture between the evolutionary scenario that could explain the existence of heliumenriched PG 1159 stars and the nonvariable nature of MCT 0130-1937. We also present theoretical support for the unusually high helium abundance observed in the nonpulsating PG 1159 star HS 1517+7403. We suggest that HS 1517+7403 could be a transition object linking the low-mass helium-rich O(He) stars with the helium-enriched PG 1159 stars via the evolutionary connection K1-27 →HS 1517+7403 → MCT 0130-1937.
publishDate 2007
dc.date.none.fl_str_mv 2007
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
Articulo
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info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://sedici.unlp.edu.ar/handle/10915/83336
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dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/issn/0004-6361
info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361:20066887
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-sa/4.0/
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
eu_rights_str_mv openAccess
rights_invalid_str_mv http://creativecommons.org/licenses/by-nc-sa/4.0/
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
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instname:Universidad Nacional de La Plata
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instacron_str UNLP
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repository.name.fl_str_mv SEDICI (UNLP) - Universidad Nacional de La Plata
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