• H–He collision-induced satellite in the Lyman-α profile of DBA white dwarf stars

Journal Article
Hubeny, NF Allard, JF Kielkopf, S Xu, G Guillon, B Mehnen, Roberto Linguerri, Muneerah Mogren Al Mogren, Majdi Hochlaf, Ivan . 2020
Publication Work Type
Magazine \ Newspaper
Monthly Notices of the Royal Astronomical Society
Volume Number
Conference Date
Publication Abstract

The spectra of helium-dominated white dwarf stars with hydrogen in their atmosphere present a distinctive broad feature centered around 1160 Å in the blue wing of the Lyman-α line. It is extremely apparent in WD 1425+540 recently observed with HST COS. With new theoretical line profiles based on ab initio atomic interaction potentials we show that this feature is a signature of a collision-induced satellite due to an asymptotically forbidden transition. This quasi-molecular spectral satellite is crucial to understanding the asymmetrical shape of Lyman-α seen in this and other white dwarf spectra. Our previous work predicting this absorption feature was limited by molecular potentials that were not adequate to follow the atomic interactions with spectroscopic precision to the asymptotic limit of large separation. A new set of potential energy curves and electronic dipole transition moments for the lowest electronic