Godart, M.; Simón-Díaz, S.; Herrero, A.; Dupret, M. A.; Grötsch-Noels, A.; Salmon, S. J. A. J.; Ventura, P.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 597, id.A23, 13 pp.
Fecha de publicación:
1
2017
Revista
Número de citas
22
Número de citas referidas
20
Descripción
Context. Asteroseismology is a powerful tool to access the internal
structure of stars. Apart from the important impact of theoretical
developments, progress in this field has been commonly associated with
the analysis of time-resolved observations. Recently, the so-called
macroturbulent broadening has been proposed as a complementary and less
expensive way - in terms of observational time - to investigate
pulsations in massive stars. Aims: We assess to what extent this
ubiquitous non-rotational broadening component which shapes the line
profiles of O stars and B supergiants is a spectroscopic signature of
pulsation modes driven by a heat mechanism. Methods: We compute
stellar main-sequence and post-main-sequence models from 3 to 70
M⊙ with the ATON stellar evolution code, and determine
the instability domains for heat-driven modes for degrees ℓ = 1-20
using the adiabatic and non-adiabatic codes LOSC and MAD. We use the
observational material compiled in the framework of the IACOB project to
investigate possible correlations between the single snapshot
line-broadening properties of a sample of ≈260 O and B-type stars and
their location inside or outside the various predicted instability
domains. Results: We present an homogeneous prediction for the
non-radial instability domains of massive stars for degree ℓ up to
20. We provide a global picture of what to expect from an observational
point of view in terms of the frequency range of excited modes, and we
investigate the behavior of the instabilities with respect to stellar
evolution and the degree of the mode. Furthermore, our pulsational
stability analysis, once compared to the empirical results, indicates
that stellar oscillations originated by a heat mechanism cannot explain
alone the occurrence of the large non-rotational line-broadening
component commonly detected in the O star and B supergiant domain.
Based on observations made with the Nordic Optical Telescope, operated
by NOTSA, and the Mercator Telescope, operated by the Flemish Community,
both at the Observatorio del Roque de los Muchachos (La Palma, Spain) of
the Instituto de Astrofísica de Canarias.
Proyectos relacionados
Proyecto IACOB: Una Nueva Era en el Estudio de Estrellas OB Galácticas
Massive stars has been many times claimed as Cosmic Engines and Gifts of Nature for the study of the Universe, from the Solar neighbourhood to the large-z Universe. The complete understanding of the physical properties and evolution of massive stars (and their interplay with the ISM) is crucial for many fields of Astrophysics and, ultimately, to
Sergio
Simón Díaz