3D simulations of M star atmosphere velocities and their influenceon molecular FeH lines

摘要

Our aim is to characterize the T_(eff)- and log g-dependence of the velocity fields and express them in terms of micro- and macro-turbulent velocities in the one dimensional sense. We present a direct comparison between 3D hydrodynamical velocity fields and1D turbulent velocities. The velocity fields strongly affect the line shapes of FeH, and it is our goal to give a rough estimate of thelog g and Teff parameter range in which 3D spectral synthesis is necessary and where 1D synthesis suffices. We want to distinguishbetween the velocity-broadening from convective motion and the rotational- or Zeeman-broadening in M-type stars we are planningto measure. For the latter, FeH lines are an important indicator.