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 Msun 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.Comment: Accepted A&A, 8 p
