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Paper: New Observations of the Mysterious Metal-Polluted White Dwarf GD 394
Volume: 509, 20th European Workshop on White Dwarfs (EuroWD16)
Page: 107
Authors: Wilson, D. J.; Gänsicke, B. T.; Koester, D.; Holberg, J.; Burleigh, M. R.; Belardi, C..
Abstract: GD394 is a hot, extremely metal-polluted white dwarf. EUVE observations in the early 1990s revealed a 1.15 day periodicity with a 25 percent amplitude. This was hypothesised to be due to an accretion spot on the white dwarf, rotating into and out of view on the white dwarf spin period. We have obtained phase-resolved HST/STIS high-resolution FUV spectra of GD394 that sample the entire spin period. The spectra contain dozens of strong metal absorption lines, which we use to test the hypothesis of a rotating spot. No variation is seen in the STIS spectra, nor between them and a 1992 GHRS spectrum. Furthermore, archive SuperWASP observations do not show the optical variability predicted by the spot hypothesis. The STIS spectra also show mysterious C IV lines that may be an indicator of circumstellar material.
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