Bibcode
Grassitelli, L.; Fossati, L.; Langer, N.; Simón-Díaz, S.; Castro, N.; Sanyal, D.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 593, id.A14, 8 pp.
Fecha de publicación:
8
2016
Revista
Número de citas
15
Número de citas referidas
13
Descripción
Macroturbulence, introduced as a fudge to reproduce the width and shape
of stellar absorption lines, reflects gas motions in stellar
atmospheres. While in cool stars, it is thought to be caused by
convection zones immediately beneath the stellar surface, the origin of
macroturbulence in hot stars is still under discussion. Recent works
established a correlation between the turbulent-to-total pressure ratio
inside the envelope of stellar models and the macroturbulent velocities
observed in corresponding Galactic stars. To probe this connection
further, we evaluated the turbulent pressure that arises in the envelope
convective zones of stellar models in the mass range 1-125
M⊙ based on the mixing-length theory and computed for
metallicities of the Large and Small Magellanic Cloud. We find that the
turbulent pressure contributions in models with these metallicities
located in the hot high-luminosity part of the Hertzsprung-Russel (HR)
diagram is lower than in similar models with solar metallicity, whereas
the turbulent pressure in low-metallicity models populating the cool
part of the HR-diagram is not reduced. Based on our models, we find that
the currently available observations of hot massive stars in the
Magellanic Clouds appear to support a connection between macroturbulence
and the turbulent pressure in stellar envelopes. Multidimensional
simulations of sub-surface convection zones and a larger number of
high-quality observations are necessary to test this idea more
rigorously.