New simulations of accreting DA white dwarfs: infering accretion rates from the surface contamination
A non negligible fraction of white dwarf stars show the presence of heavy elements in their atmospheres. The most accepted explanation for this contamination is the accretion of material coming from tidally disrupted planetesimals, which form a debris disk around the star. We provide a grid of models for hydrogen rich white dwarfs accreting heavy material. We sweep a 3D parameter space involving different effective temperatures, envelope's hydrogen content and accretion rates. The grid is appropriate for determining accretion rates in white dwarfs showing the presence of heavy elements. Full evolutionary calculations of accreting white dwarfs were computed including all relevant physical processes, particularly the fingering (thermohaline) convection, a process neglected in most previous works, that has to be considered to obtain realistic estimations. Accretion is treated as a continuous process and bulk Earth composition is assumed for the accreted material. We obtain final (stationary or near stationary) and reliable abundances for a grid of models representing hydrogen rich white dwarfs of different effective temperatures and hydrogen contents, submitted to various accretion rates. Our results provide realistic estimates of accretion rates to be used for further studies on evolved planetary systems.