A study of M dwarfs. I. Preliminary model atmospheres.

A sequence of model atmospheres for early M dwarfs is presented. The models contain opacity distribution functions for the most prominent molecular bands in M dwarfs, H2O and TiO. A mixing-length theory of convection is included, and a test on one model shows no dependence of the emergent flux on the mixing-length to scale height ratio. The emergent fluxes are tabulated for comparison with observations. Fair agreement is evident, but the inclusion of atomic line blanketing seems necessary before a discrepancy in the optical continuum gradient can be remedied.