Abstract
White dwarfs with hydrogen-rich atmospheres (DA) are the most abundant of all degenerate objects. In recent years work has been dedicated to increase the accuracy of their model atmospheres. Most notably, convective motions are now treated with 3D radiation-hydrodynamics instead of the standard mixing-length theory. We present and describe selected 3D model atmospheres close and within the instability strip of the pulsating ZZ Ceti white dwarfs. Our 3D simulations depend only weakly on numerical parameters and compared to 1D models, they provide more realistic determinations of the depth of the convective zone. The 3D structures can then be adopted as input for asteroseismology.
Highlights
The multidimensional treatment of convective motions in pure-hydrogen atmosphere dwarfs with hydrogen-rich atmospheres (DA) white dwarfs was pioneered by the works of the Kiel group [1,2,3]
The main objective was to look at the 3D effects on the predicted Balmer profiles, and to determine whether the 3D models could solve the long-standing high-log g problem in which the 1D models suggest that cool DA white dwarfs (Teff < 13, 000 K) have surface gravities that are much higher than those of hot DA white dwarfs [8,9,10]
We presented the properties of four CO5BOLD 3D radiation-hydrodynamics model atmospheres, characteristic of DA white dwarfs close to or within the ZZ Ceti instability strip (13,000 < Teff (K) < 11,500)
Summary
The multidimensional treatment of convective motions in pure-hydrogen atmosphere DA white dwarfs was pioneered by the works of the Kiel group [1,2,3] These studies with 2D radiation-hydrodynamics (RHD) models have reported important information about the physical size of the convective flows, the extend of convective overshoot and the RHD effects on the mean spectra. We show that our 3D simulations could be used as input to derive asteroseismic properties for these objects that do not depend on the mixing-length parameterization.
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