Applications of

Radiative Transfer

to stellar and planetary atmospheres
Tenerife, Spain - 13-17 Nov. 2017

Poster abstract details

First 3D simulations of pure-helium atmosphere white dwarfs
Elena Cukanovaite and Pier-Emmanuel Tremblay


Most stars in the universe will end their lives as white dwarfs, and as such, they are important for studies of stellar evolution, for instance, measuring the ages of stellar populations. To do this, we require the fundamental parameters of white dwarfs themselves, which in turn necessitates a good understanding of their interiors and atmospheres. Synthetic spectra calculated from model atmospheres can be used to directly extract effective temperatures and surface gravities ($\log{g}$) of white dwarfs, and indirectly determine their masses, cooling ages, radii and other useful parameters. Until recently, 1D atmosphere modelling has been used. In this poster, we present the first 3D hydrodynamical models of pure-helium atmosphere (DB) white dwarfs. We discuss our preliminary results, focusing on the so-called 'high-$\log{g}$ problem', where surface gravities derived from 1D spectral models deviate significantly from evolutionary model predictions at low temperatures. It has been suggested that this discrepancy is a consequence of imperfect implementation of line broadening by neutral helium and not due to problems with 1D modelling. However, we have found that this discrepancy can be resolved in part by 3D modelling of DB atmospheres.