Simón-Díaz, S.; Godart, M.; Castro, N.; Herrero, A.; Aerts, C.; Puls, J.; Telting, J.; Grassitelli, L.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 597, id.A22, 17 pp.
Fecha de publicación:
1
2017
Revista
Número de citas
112
Número de citas referidas
103
Descripción
Context. The term macroturbulent broadening is commonly used to refer to
a certain type of non-rotational broadening affecting the spectral line
profiles of O- and B-type stars. It has been proposed to be a
spectroscopic signature of the presence of stellar oscillations;
however, we still lack a definitive confirmation of this hypothesis. Aims: We aim to provide new empirical clues about macroturbulent
spectral line broadening in O- and B-type stars to evaluate its physical
origin. Methods: We used high-resolution spectra of 430 stars
with spectral types in the range O4 - B9 (all luminosity classes)
compiled in the framework of the IACOB project. We characterized the
line broadening of adequate diagnostic metal lines using a combined
Fourier transform and goodness-of-fit technique. We performed a
quantitative spectroscopic analysis of the whole sample using automatic
tools coupled with a huge grid of fastwind models to determine their
effective temperatures and gravities. We also incorporated quantitative
information about line asymmetries into our observational description of
the characteristics of the line profiles, and performed a comparison of
the shape and type of line-profile variability found in a small sample
of O stars and B supergiants with still undefined pulsational properties
and B main-sequence stars with variable line profiles owing to a
well-identified type of stellar oscillations or to the presence of spots
in the stellar surface. Results: We present a homogeneous and
statistically significant overview of the (single snapshot)
line-broadening properties of stars in the whole O and B star domain. We
find empirical evidence of the existence of various types of
non-rotational broadening agents acting in the realm of massive stars.
Even though all these additional sources of line-broadening could be
quoted and quantified as a macroturbulent broadening from a practical
point of view, their physical origin can be different. Contrarily to the
early- to late-B dwarfs and giants, which present a mixture of cases in
terms of line-profile shape and variability, the whole O-type and B
supergiant domain (or, roughly speaking, stars with MZAMS
≳ 15 M⊙) is fully dominated by stars with a
remarkable non-rotational broadening component and very similar profiles
(including type of variability). We provide some examples illustrating
how this observational dataset can be used to evaluate scenarios aimed
at explaining the existence of sources of non-rotational broadening in
massive stars.
Full Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/597/A22
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