AAS 195th Meeting, January 2000
Session 6. Early Results from the FUSE Mission
Display, Wednesday, January 12, 2000, 9:20am-6:30pm, Grand Hall

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[6.19] FUSE Observations of the Hot DA White Dwarf GD 394

P. Chayer (UVIC/JHU), J.W. Kruk (JHU), P. Barrett (STScI), FUSE Science Team

We present far-ultraviolet observations of the hot hydrogen-rich white dwarf GD 394, performed with the Far Ultraviolet Spectroscopic Explorer (FUSE). The resulting spectrum, which covers 910--1180 Å\ at a resolution of ~0.1 Å, was obtained by using the large (30\times30 arcsecond) slit. The spectrum reveals the presence of numerous photospheric \ion{Si}{3} and \ion{Si}{4} features. The equivalent widths of these lines range from 15 to 85 mÅ. Based on preliminary analysis, we observed the possible presence of photospheric phosphorus; if confirmed by subsequent analysis, this represents the first detection of a heavy element other than silicon in the spectrum of GD 394. The non-detection of photospheric \ion{C}{3} \lambda 1176, \ion{N}{3} \lambda 991, and \ion{S}{4} \lambda 1070 puts stringent upper limits on the abundances of these elements. These upper limits provide a good test of the diffusion theory. They also add a constraint to the models derived from the ROSAT and EUVE observations of GD 394. In addition, we report the detection of interstellar features along the line of sight of this hot star.

We acknowledge financial support from UVIC, the CSA Space Science Program, and NASA contract NAS5-32985.

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