The “Mass Discrepancy” for Massive Stars: Tests of Models Using Spectroscopic Binaries

Stellar evolutionary models are often used to infer a star's mass via its luminosity, but empirical checks on the accuracy of the theoretical mass-luminosity relation for very massive stars have been lacking. This is of particular concern given that modern atmosphere models yield systematically...

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Detalles Bibliográficos
Autores principales: Burkholder, Valorie, Massey, Philip, Morrell, Nidia Irene
Formato: Articulo
Lenguaje:Inglés
Publicado: 1997
Materias:
Astronomía
binaries: spectroscopic
stars: early-type
stars: evolution
stars: fundamental parameters
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/140829
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-140829
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Astronomía
binaries: spectroscopic
stars: early-type
stars: evolution
stars: fundamental parameters
spellingShingle Astronomía
binaries: spectroscopic
stars: early-type
stars: evolution
stars: fundamental parameters
Burkholder, Valorie
Massey, Philip
Morrell, Nidia Irene
The “Mass Discrepancy” for Massive Stars: Tests of Models Using Spectroscopic Binaries
topic_facet Astronomía
binaries: spectroscopic
stars: early-type
stars: evolution
stars: fundamental parameters
description Stellar evolutionary models are often used to infer a star's mass via its luminosity, but empirical checks on the accuracy of the theoretical mass-luminosity relation for very massive stars have been lacking. This is of particular concern given that modern atmosphere models yield systematically smaller masses for massive stars than do evolutionary models, with the discrepancy being a factor of 2 for Of stars. We attempt to resolve this mass discrepancy by obtaining new, high-resolution optical data on seven early-type spectroscopic binaries: V453 Cyg, HD 191201, V382 Cyg, Y Cyg, HD 206267, DH Cep, and AH Cep. Our study produces improved spectral subtypes for the components of these systems, which are crucial for evaluating their luminosities and locations in the H-R diagram. Our radial velocity study utilizes a measuring method that explicitly accounts for the effects of pair blending. We combine our new orbit solutions with existing data on inclinations and distances when available to compare the orbital masses with evolutionary models, and we find good agreement in all cases where the stars are noninteracting. (The components of V382 Cyg and DH Cep fill their Roche lobes, and in both cases we find masses substantially lower than the masses inferred from evolutionary tracks, suggesting that significant material has been lost rather than transferred. We confirm that this same trend exists for other systems drawn from the literature.) Our own data extends to only 15 M☉, although photometric inclination determinations for HD 191201 and HD 206267 should prove possible and will provide examples of higher mass systems. We briefly discuss suitable systems from the literature and conclude that orbit solutions provide good agreement with the evolutionary models to 25 M☉. Beyond this, most known binaries either fill their Roche lobes or have other complications. We also discuss five systems for which our improved data and analysis failed to yield acceptable orbit solutions: EO Aur, IU Aur, V640 Mon (Plaskett's star), LY Aur, and 29 UW CMa all remained intractable, despite improved data.
format Articulo
Articulo
author Burkholder, Valorie
Massey, Philip
Morrell, Nidia Irene
author_facet Burkholder, Valorie
Massey, Philip
Morrell, Nidia Irene
author_sort Burkholder, Valorie
title The “Mass Discrepancy” for Massive Stars: Tests of Models Using Spectroscopic Binaries
title_short The “Mass Discrepancy” for Massive Stars: Tests of Models Using Spectroscopic Binaries
title_full The “Mass Discrepancy” for Massive Stars: Tests of Models Using Spectroscopic Binaries
title_fullStr The “Mass Discrepancy” for Massive Stars: Tests of Models Using Spectroscopic Binaries
title_full_unstemmed The “Mass Discrepancy” for Massive Stars: Tests of Models Using Spectroscopic Binaries
title_sort “mass discrepancy” for massive stars: tests of models using spectroscopic binaries
publishDate 1997
url http://sedici.unlp.edu.ar/handle/10915/140829
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