Grassitelli, L.; Fossati, L.; Simón-Diáz, S.; Langer, N.; Castro, N.; Sanyal, D.
Bibliographical reference
The Astrophysical Journal Letters, Volume 808, Issue 1, article id. L31, 6 pp. (2015).
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7
2015
Citations
48
Refereed citations
41
Description
The major mass fraction of the envelope of hot luminous stars is
radiatively stable. However, the partial ionization of hydrogen, helium,
and iron gives rise to extended sub-surface convection zones in all of
them. In this work, we investigate the effect of the pressure induced by
the turbulent motion in these zones based on the mixing-length theory,
and we search for observable consequences. We find that the turbulent
pressure fraction can amount up to ∼ 5% in OB supergiants and up to
∼ 30% in cooler supergiants. The resulting structural changes are,
however, not significantly affecting the evolutionary tracks compared to
previous calculations. Instead, a comparison of macroturbulent
velocities derived from high-quality spectra of OB stars with the
turbulent pressure fraction obtained in corresponding stellar models
reveals a strong correlation between these two quantities. We discuss a
possible physical connection and conclude that turbulent pressure
fluctuations may drive high-order oscillations, which—as
conjectured earlier—manifest themselves as macroturbulence in the
photospheres of hot luminous stars.
Related projects
The IACOB project: A new Era in the Study of Galactic OB Stars
IACOB is an ambitious long-term project whose main scientific goal is to provide an unprecedented empirical overview of the main physical properties of Galactic massive O- and B-type stars which can be used as definitive anchor point for our theories of stellar atmospheres, winds, interiors and evolution of massive stars
Sergio
Simón Díaz