Observation andmodelling of main sequence stellar chromospheres VI . H α and Ca II line observations ? of M 1 dwarfs and comparison with models

We compare hydrogen and calcium line calculations for dM1 (Teff=3500K) stellar chromospheres with high resolution observations of a selected sample of stars with the same spectral type ((R-I)K=0.875±0.05). We bring evidence that grids of uniform model atmospheres in the plane-parallel and hydrostatic equilibrium approximations can reproduce the average… (More)