“The high-mass problem in cool white dwarfs: an old obstacle now seen with 3D radiationhydrodynamics”

Conferenciant: Dr. Pier-Emmanuel Tremblay. (LSW, Heidelberg)

Lloc: Seminari del DAM (Dept. Astronomia i Meteorologia, planta 7)
Dia: Dimecres, 28 de març de 2012
Hora: 12:00 hores

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 can be used as spectroscopic standards. However, at cool effective temperatures (cooling age > 1 Gyr), a problem observed for the last 20 years is an unexpected 20% increase of the mean mass. We have recently improved our knowledge of these cool objects, with high-resolution observations to constrain the abundances of elements other than hydrogen, and with a better account of the non-ideal gas microphysics. Finally, we improved the macrophysics aspect of the models by using 3D radiation-hydrodynamics instead of the standard 1D models for the treatment of convective motions.
This new generation of pure hydrogen models with small atmospheric convective zones could serve as a benchmark to study pulsation-convection interactions (in ZZ Ceti pulsating white dwarfs) and the influence of magnetic fields.

Josep Manel Carrasco (carrascoarrobaam.ub.es)