Further Observations and Analysis of the Rapidly Pulsating Subdwarf B Star EC 20117-4014

Detalhes bibliográficos
Autor(a) principal: Lopes, I
Data de Publicação: 2006
Outros Autores: Randall, S.K.
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10174/5692
https://doi.org/10.1086/505634
Resumo: We present the results of further observations and the subsequent analysis of the rapidly pulsating subdwarf B star EC 20117-4014. Despite our efforts, the only pulsations detected were those already reported by O'Donoghue et al., at 137.3, 142.1, and 157.4 s. We attempted a detailed asteroseismological analysis by thoroughly exploring the four-dimensional parameter space defining our equilibrium stellar structures [Teff, logg, M*, logq(H)] in search of models that could account precisely for the three observed periodicities. We were able to isolate just two potential families of optimal models, one of which is to be preferred on the basis of the period fit achieved and the surface gravity inferred. To proceed, we used external constraints on the effective temperature from published independent optical spectroscopy. Unfortunately, the contamination of the optical spectrum of EC 20117-4014 made it hard to quantify the uncertainties on the estimated spectroscopic temperature of ~34,800 K, and consequently, we adopted the conservative point of view that the true value would lie somewhere in the rather broad interval 32,800-36,800 K. Despite this limitation, leading to less accurate estimates of structural parameters than has been possible before for isolated pulsating EC 14026 stars, we still find that our asteroseismological exercise has been quite fruitful. Indeed, on the basis of our current models, we find that EC 20117-4014 would have a (logarithmic) surface gravity in the range 5.848-5.864 dex, a total mass in the range 0.50-0.59 Msolar, and a (logarithmic) fractional mass of its H envelope in the interval from -4.10 to -4.25 dex. From these primary parameters, we obtained useful estimates of secondary quantities such as the radius, the luminosity, the absolute visual magnitude, and the distance.
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spelling Further Observations and Analysis of the Rapidly Pulsating Subdwarf B Star EC 20117-4014StarsoscillationsWe present the results of further observations and the subsequent analysis of the rapidly pulsating subdwarf B star EC 20117-4014. Despite our efforts, the only pulsations detected were those already reported by O'Donoghue et al., at 137.3, 142.1, and 157.4 s. We attempted a detailed asteroseismological analysis by thoroughly exploring the four-dimensional parameter space defining our equilibrium stellar structures [Teff, logg, M*, logq(H)] in search of models that could account precisely for the three observed periodicities. We were able to isolate just two potential families of optimal models, one of which is to be preferred on the basis of the period fit achieved and the surface gravity inferred. To proceed, we used external constraints on the effective temperature from published independent optical spectroscopy. Unfortunately, the contamination of the optical spectrum of EC 20117-4014 made it hard to quantify the uncertainties on the estimated spectroscopic temperature of ~34,800 K, and consequently, we adopted the conservative point of view that the true value would lie somewhere in the rather broad interval 32,800-36,800 K. Despite this limitation, leading to less accurate estimates of structural parameters than has been possible before for isolated pulsating EC 14026 stars, we still find that our asteroseismological exercise has been quite fruitful. Indeed, on the basis of our current models, we find that EC 20117-4014 would have a (logarithmic) surface gravity in the range 5.848-5.864 dex, a total mass in the range 0.50-0.59 Msolar, and a (logarithmic) fractional mass of its H envelope in the interval from -4.10 to -4.25 dex. From these primary parameters, we obtained useful estimates of secondary quantities such as the radius, the luminosity, the absolute visual magnitude, and the distance.2012-11-16T15:54:23Z2012-11-162006-09-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articlehttp://hdl.handle.net/10174/5692http://hdl.handle.net/10174/5692https://doi.org/10.1086/505634engilopes@uevora.ptnd343Lopes, IRandall, S.K.info:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2024-01-03T18:44:38Zoai:dspace.uevora.pt:10174/5692Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T01:00:40.062155Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Further Observations and Analysis of the Rapidly Pulsating Subdwarf B Star EC 20117-4014
title Further Observations and Analysis of the Rapidly Pulsating Subdwarf B Star EC 20117-4014
spellingShingle Further Observations and Analysis of the Rapidly Pulsating Subdwarf B Star EC 20117-4014
Lopes, I
Stars
oscillations
title_short Further Observations and Analysis of the Rapidly Pulsating Subdwarf B Star EC 20117-4014
title_full Further Observations and Analysis of the Rapidly Pulsating Subdwarf B Star EC 20117-4014
title_fullStr Further Observations and Analysis of the Rapidly Pulsating Subdwarf B Star EC 20117-4014
title_full_unstemmed Further Observations and Analysis of the Rapidly Pulsating Subdwarf B Star EC 20117-4014
title_sort Further Observations and Analysis of the Rapidly Pulsating Subdwarf B Star EC 20117-4014
author Lopes, I
author_facet Lopes, I
Randall, S.K.
author_role author
author2 Randall, S.K.
author2_role author
dc.contributor.author.fl_str_mv Lopes, I
Randall, S.K.
dc.subject.por.fl_str_mv Stars
oscillations
topic Stars
oscillations
description We present the results of further observations and the subsequent analysis of the rapidly pulsating subdwarf B star EC 20117-4014. Despite our efforts, the only pulsations detected were those already reported by O'Donoghue et al., at 137.3, 142.1, and 157.4 s. We attempted a detailed asteroseismological analysis by thoroughly exploring the four-dimensional parameter space defining our equilibrium stellar structures [Teff, logg, M*, logq(H)] in search of models that could account precisely for the three observed periodicities. We were able to isolate just two potential families of optimal models, one of which is to be preferred on the basis of the period fit achieved and the surface gravity inferred. To proceed, we used external constraints on the effective temperature from published independent optical spectroscopy. Unfortunately, the contamination of the optical spectrum of EC 20117-4014 made it hard to quantify the uncertainties on the estimated spectroscopic temperature of ~34,800 K, and consequently, we adopted the conservative point of view that the true value would lie somewhere in the rather broad interval 32,800-36,800 K. Despite this limitation, leading to less accurate estimates of structural parameters than has been possible before for isolated pulsating EC 14026 stars, we still find that our asteroseismological exercise has been quite fruitful. Indeed, on the basis of our current models, we find that EC 20117-4014 would have a (logarithmic) surface gravity in the range 5.848-5.864 dex, a total mass in the range 0.50-0.59 Msolar, and a (logarithmic) fractional mass of its H envelope in the interval from -4.10 to -4.25 dex. From these primary parameters, we obtained useful estimates of secondary quantities such as the radius, the luminosity, the absolute visual magnitude, and the distance.
publishDate 2006
dc.date.none.fl_str_mv 2006-09-01T00:00:00Z
2012-11-16T15:54:23Z
2012-11-16
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dc.identifier.uri.fl_str_mv http://hdl.handle.net/10174/5692
http://hdl.handle.net/10174/5692
https://doi.org/10.1086/505634
url http://hdl.handle.net/10174/5692
https://doi.org/10.1086/505634
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343
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