Issue |
A&A
Volume 559, November 2013
|
|
---|---|---|
Article Number | A104 | |
Number of page(s) | 23 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361/201322318 | |
Published online | 21 November 2013 |
Spectroscopic analysis of DA white dwarfs with 3D model atmospheres⋆
1
Zentrum für Astronomie der Universität Heidelberg,
Landessternwarte, Königstuhl 12,
69117
Heidelberg,
Germany
e-mail: ptremblay@lsw.uni-heidelberg.de; hludwig@lsw.uni-heidelberg.de
2
Leibniz-Institut für Astrophysik Potsdam,
An der Sternwarte
16, 14482
Potsdam,
Germany
e-mail:
msteffen@aip.de
3
Centre de Recherche Astrophysique de Lyon, UMR 5574 CNRS,
Université de Lyon, École Normale
Supérieure de Lyon, 46 allée d’Italie, 69364
Lyon Cedex 07,
France
e-mail:
Bernd.Freytag@ens-lyon.fr
Received:
18
July
2013
Accepted:
28
August
2013
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) < 15 000 and the surface gravity range of 7 < log g < 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-log g 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 ~0.01 M⊙, in much better agreement with our understanding of stellar evolution. Furthermore, the 3D atmospheric parameters are in better agreement with independent Teff and log g values from photometric and parallax measurements.
Key words: convection / hydrodynamics / line: profiles / stars: atmospheres / white dwarfs
Appendices are only available in electronic form at http://www.aanda.org
© ESO, 2013
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.