Query : 2013A&A...559A.104T

2013A&A...559A.104T - Astronomy and Astrophysics, volume 559A, 104-104 (2013/11-1)

Spectroscopic analysis of DA white dwarfs with 3D model atmospheres.


Abstract (from CDS):

We present the first grid of mean three-dimensional (3D) spectra for pure-hydrogen (DA) white dwarfs based on 3D model atmospheres. We use CO5BOLD radiation-hydrodynamics 3D simulations instead of the mixing-length theory for the treatment of convection. The simulations cover the effective temperature range of 6000<Teff(K)<15000 and the surface gravity range of 7<logg<9 where the large majority of DAs with a convective atmosphere are located. We rely on horizontally averaged 3D structures (over constant Rosseland optical depth) to compute <3D> spectra. It is demonstrated that our <3D> spectra can be smoothly connected to their 1D counterparts at higher and lower Teff where the 3D effects are small. Analytical functions are provided in order to convert spectroscopically determined 1D effective temperatures and surface gravities to 3D atmospheric parameters. We apply our improved models to well studied spectroscopic data sets from the Sloan Digital Sky Survey and the White Dwarf Catalog. We confirm that the so-called high-logg problem is not present when employing <3D> spectra and that the issue was caused by inaccuracies in the 1D mixing-length approach. The white dwarfs with a radiative and a convective atmosphere have derived mean masses that are the same within ∼0.01M, in much better agreement with our understanding of stellar evolution. Furthermore, the 3D atmospheric parameters are in better agreement with independent Teff and logg values from photometric and parallax measurements.

Abstract Copyright:

Journal keyword(s): convection - hydrodynamics - line: profiles - stars: atmospheres - white dwarfs

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 V* ZZ Cet WD* 01 36 13.6153974672 -11 20 32.632874601   14.328 14.16 14.4   DA4.0 287 0
2 EC 10532-2903 WD* 10 55 39.9534896952 -29 19 52.681005552   15.52 15.38 14.9   DA4.7 19 0
3 LAWD 94 WD* 23 54 01.0726392457 -33 16 31.078214643   14.6 13.56     DA5.7 57 0

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