Friday 16 April 2010
to 14:30 at
122:026 (House 12)
Matteo Cantiello (University of Bonn)
During their main sequence evolution, massive stars can develop convective
regions very close to their surface.
These regions are caused by opacity peaks associated with iron ionization.
We studied the possible observational signatures of such subsurface
convection. We 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.
We further suggest that clumping in the inner parts of the winds of OB stars
could be caused by the same mechanism, and that magnetic fields produced in
the iron convection zone could appear at the surface of such massive stars.
This way 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.
We want to attempt MHD simulations of such subsurface convection zones using
the Pencil Code, for which we discuss possible computational setups.