  During their main sequence evolution, massive stars can develop convective
regions very close to their surface. These regions are caused by an opacity
peak associated with iron ionization. Cantiello et al. (2009) found a possible
connection between the presence of sub-photospheric convective motions and
small scale stochastic velocities in the photosphere of early-type stars. This
supports a physical mechanism where microturbulence is caused by waves that are
triggered by subsurface convection zones. They further suggest that clumping in
the inner parts of the winds of OB stars could be related to subsurface
convection, and that the convective layers may also be responsible for
stochastic excitation of non-radial pulsations. Furthermore, magnetic fields
produced in the iron convection zone could appear at the surface of such
massive stars. Therefore subsurface convection could be responsible for the
occurrence of observable phenomena such as line profile variability and
discrete absorption components. These phenomena have been observed for decades,
but still evade a clear theoretical explanation. Here we present preliminary
results from 3D MHD simulations of such subsurface convection.

Solar and Stellar Astrophysics;Earth and Planetary Astrophysics