## Building reliable models of M dwarf chromospheres: the impact of the usual assumptions
^{1} Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5,
I-50155 Firenze, Italy^{2} Instituto de Astronomía y Física del
Espacio, CC 67, Suc. 28, 1428-Buenos Aires, R. Argentina
We study different approximations usually made to simplify the
calculation of chromospheric models of M dwarf stars. The
approximations we discuss in details are: the assumption that the
minority species are in LTE, the omission of the contribution of
numerous atomic and molecular lines ( We consider a "cold" chromospheric model corresponding to a low activity dM star and a "hot" one corresponding to a very active dMe star. We find that the assumptions under study affect more strongly the cold than the hot model. In particular the approximation of Complete Frequency Redistribution in the line, through the statistical equilibrium and ionization equilibrium equation, changes the electron density in the high chromosphere and strongly affects other line profiles.
## Contents© European Southern Observatory (ESO) 1998 Online publication: July 7, 1998 |