HEAD 2000, November 2000
Session 22. Accreting X-Ray Pulsars
Display, Wednesday, November 8, 2000, 8:00am-6:00pm, Bora Bora Ballroom

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[22.05] Probing the circumstellar environment of X Per and A0535+262 - implications for X-ray behaviour

N.J. Haigh (Dept. of Physics and Astronomy, University of Southampton, England), P.D. Roche (Dept. of Physics and Astronomy, University of Leicester, England), M.J. Coe (Dept. of Physics and Astronomy, University of Southampton, England), A.E. Tarasov (Crimean Astrophysical Observatory, Nauchny, Crimea, 334413 Ukraine), V.M. Lyuty (Sternberg Astronomical Institute, Universiteskii pr. 13, Moscow, 119899 Russia), J.S. Clark (Astronomy Centre, CPES, University of Sussex, Brighton, England)

We present 10 years of high resolution optical spectroscopy and multicolour photometry of the Be stars X Per and HDE 245770, counterparts to the X-ray pulsars 4U0352+30 and A0535+26. The X Per data reveals the presence of multiple disc structures; discrete inner discs form at orbital radii scarcely greater than that of the photosphere, before propagating outwards. There are suggestions of similar structure in the data for A0535+262. We explore the links between such unusual disc behaviour and the recent disc-loss events in both systems.

The accretion-driven X-ray flux of these systems, particularly the occurrence or otherwise of periastron passage outbursts, is hard to understand without some knowledge of conditions in appropriate regions of the disc. The observable disc behaviour is placed in the context of both the X-ray flux (in particular "mini-flares" in X Per and major outbursts in A0535+262) and photometry, in an attempt to form a coherent picture of the behaviour of these systems.

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