AAS 201st Meeting, January, 2003
Session 119. White Dwarfs
Poster, Thursday, January 9, 2003, 9:20am-4:00pm, Exhibit Hall AB

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[119.05] Quasi-molecular satellites of Lyman lines observed in the spectra of white dwarfs

G. Hébrard, N. F. Allard (Institut d'Astrophysique de Paris), P. Chayer, J. Dupuis, J. W. Kruk (Johns Hopkins University), J. Kielkopf (University of Louisville)

Quasi-molecular satellites are absorption features due to transitions that take place during close collisions of the radiating hydrogen atom with a perturbing atom or proton. These spectral features, which are present in the red wings of the Lyman series lines, provide an important source of opacity in the hydrogen-rich atmospheres of white dwarfs.

We present new theoretical calculations of the total line profiles of Lyman~\alpha, Lyman~\beta, and Lyman~\gamma. These calculations include perturbations by both neutral hydrogen and protons, and all possible quasi-molecular states of H2 and H2+. These new line absorption profiles improve significantly the model atmospheres of cool hydrogen-rich white dwarfs. We show these improvements by comparing these line profiles to new FUSE spectra of white dwarfs, and to archival HUT, ORFEUS, and HST data.

This work is based on data obtained by the NASA-CNES-CSA FUSE mission operated by the Johns Hopkins University. Financial support to U.S. participants has been provided by NASA contract NAS5-32985. French participants are supported by CNES.

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