EDP Sciences
Free Access
Volume 394, Number 2, November I 2002
Page(s) 647 - 651
Section Stellar atmospheres
DOI https://doi.org/10.1051/0004-6361:20021141

A&A 394, 647-651 (2002)
DOI: 10.1051/0004-6361:20021141

Quasi-molecular lines in Lyman wings of cool DA white dwarfs

Application to ${\it FUSE}$ observations of G $\,$231-40
G. Hébrard1, N. F. Allard1, 2, I. Hubeny3, S. Lacour4, 1, R. Ferlet1 and A. Vidal-Madjar1

1  Institut d'Astrophysique de Paris, CNRS, 98 ${\rm bis}$ boulevard Arago, 75014 Paris, France
2  Observatoire de Paris-Meudon, LERMA, 92195 Meudon Principal Cedex, France
3  NOAO, 950 North Cherry Avenue, Tucson, AZ 85726, USA
4  Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA

(Received 3 April 2002 / Accepted 5 August 2002 )

We present new theoretical calculations of the total line profiles of Lyman  $\alpha$ and Lyman  $\beta$ which include perturbations by both neutral hydrogen and protons and all possible quasi-molecular states of H 2 and H 2+. They are used to improve theoretical modeling of synthetic spectra for cool DA white dwarfs. We compare them with FUSEobservation of G $\,$231-40. The appearance of the line wings between Lyman  $\alpha$ and Lyman  $\beta$ is shown to be sensitive to the relative abundance of hydrogen ions and neutral atoms, and thereby to provide a temperature diagnostic for stellar atmospheres and laboratory plasmas.

Key words: line: profiles -- radiation mechanisms: general -- stars: atmospheres -- stars: individual: G231-40 -- white dwarfs -- ultraviolet: stars

Offprint request: G. Hébrard, hebrard@iap.fr

© ESO 2002

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.