Quasi-Molecular Satellites of Lyβ in the Spectrum of the DA White Dwarf Wolf 1346

We present new FUV/UV observations of the DA white dwarf Wolf 1346 obtainedwith the Hopkins Ultraviolet Telescope. The atmospheric parameters of thisobject are estimated from a fit of model atmospheres to several optical spectrato be Teff = 20000 K, log g = 7.90. From the optical spectrum this star is anormal DA without any indications for chemical elements other than hydrogen.The hydrogen line L beta, however, shows a very unusual shape, with a steep redwing and two absorption features on this wing. The shape is reminiscent of theeffects of quasi-molecular line broadening, as observed in L alpha in cooler DAwhite dwarfs. We show that this is indeed the correct explanation, byidentifying 4 quasi-molecular satellites caused through perturbations by the H+ion (H2+ quasi-molecule). The steep red wing is caused by the exponentialdecline of the line profile beyond the satellite most distant from the linecenter at 1078 A.Comment: 11 pages Latex with aaspp4 style, 4 postscript figures, as compressed tar file, ApJ Letters, in pres