Improved View of Hydrogen-Rich Atmosphere White Dwarfs

Pier-Emmanuel Tremblay

White dwarfs with hydrogen-rich atmospheres are the most abundant of all degenerate objects. Their atmospheres are thought to be relatively simple, with a pure composition due to the gravitational settling, and we rely on them as spectroscopic standards. Nevertheless, a great deal of work has been done in the recent years to increase the accuracy of their model spectra. Most notably, we improved the macrophysics aspect of the models by using for the first time 3D radiation-hydrodynamics instead of the standard 1D models for the treatment of convective motions. It will be shown that these 3D simulations now reach the level of accuracy to be the main theoretical tool in spectroscopic analyzes of cool white dwarfs. Furthermore, we demonstrate that our improved model spectra provide a much better characterization of the mass distribution of white dwarfs.