Low level optical and X-ray activity in A0538-66

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Session 48 -- Degenerate Stars and Pulsars
Display presentation, Thursday, June 15, 1995, 9:20am - 4:00pm

[48.07] Low level optical and X-ray activity in A0538-66

R.H.D. Corbet, A.P. Smale (NASA GSFC/USRA), P.A. Charles, K.A. Southwell (Oxford University)

We present ASCA observations made in February 1995 around the time of a predicted outburst from the 16.65 day period recurrent transient A0538-66 together with simultaneous optical photometry. Optical spectroscopy was also obtained near a predicted outburst approximately two months earlier. We find that A0538-66 is active, both in X-rays and optically, although at a much lower level than during the largest super-Eddington outbursts that have been seen in the past. The optical spectra show variable Balmer emission but not the strong HeII 4686\AA\ emission that accompanies large outbursts.

We consider X-ray production processes that may produce the observed behavior. In particular accretion onto the magnetosphere rather than the surface of a neutron star is discussed.

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