Solution to the problem of the DA white dwarf log g distribution... (P.-E. Tremblay et al.)

Vol. 531In section 1. Letters to the Editor

Solution to the problem of the surface gravity distribution of cool DA white dwarfs from improved 3D model atmospheres

Deriving parameters of hydrogen-rich DA white dwarfs from Balmer line fitting is a well-established technique. A longstanding problem in this field is an apparent increase in the mean surface gravity (translating into higher masses) for white dwarfs cooler than about 12000K. Several authors have argued that this effect must be an artifact. The present publication shows that shortcomings of the standard 1D treatment of convection in model atmospheres are responsible. The authors calculate model atmospheres with a full 3D hydrodynamical treatment of convection and compare them to 1D results. It is shown that the differences found agree well with the observed discrepancy.