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G.J. Peters (University of Southern California), B.-G. Andersson, T.B. Ake, R. Sankrit (The Johns Hopkins University)
A survey of Algol binaries at random phases is currently being carried through with the FUSE spacecraft as part of the FUSE survey and supplemental program. A similar survey program was undertaken in FUSE Cycle~3. Both programs have produced multiple observations of 12 Algol systems with periods ranging from 1.2 - 37 d and include direct-impact and disk systems. We report highlights from the data acquired so far. The absence of O~VI absorption in the systems observed to date allows us to place upper limits on its column density and the temperature of the High Temperature Accretion Region, HTAR (~100,000~K) confirmed in some Algols from earlier IUE data. In the case of RY~Per, this demonstrates that the HTAR plasma component is distinct from the O~VI-emitting polar plasma discovered in a FUSE observation taken during totality (Peters & Polidan, 2004, Astron. Nachr., 325, 225). A 6.5 ks observation of the direct-impact Algol U~Cep revealed the presence of an apparent accretion hot spot centered near phase 0.94, where the gas stream impacts the mass gainer's photosphere at a steep angle. During the course of the observation, which took place over a duration of 0.25 d, the FUV flux steadily rose before leveling off at an elevated value. Since the flux had returned to its normal value at the beginning of an observation 1.5 d later (\phi~0.28), we can place an upper limit on the size of the hot spot. The authors appreciate support from NASA grants NAG5-12253, NNG04GL17G, and NAS5-32985.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.