We report the detection of As V resonance lines observed in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectra of three hot DA white dwarfs: G191-B2B, WD0621-376, and WD2211-495. The stars have effective temperatures ranging from 60,000 K to 64,000 K and are among the most metal-rich white dwarfs known. We measured the arsenic abundances not only in these stars, but also in three DO stars in which As has been detected before: HD149499B, HZ21, and RE0503-289. The arsenic abundances observed in the DA stars are very similar. This suggests that radiative levitation may be the mechanism that supports arsenic. The arsenic abundance in HZ21 is significantly lower than that observed in HD149499B, even though the stars have similar atmospheric parameters. An additional mechanism may be at play in the atmospheres of these two DO stars.
P. Chayer, J. Dupuis and J. Kruk
Thu, 11 Dec 14
Comments: 5 pages, 2 figures, 19th European White Dwarf Workshop in Montreal