The August 1993 outburst of the black hole candidate GRO J0422+32 *
A.J. Castro-Tirado 1,
J.L. Ortiz 2 and
J. Gallego 3
Received 29 October 1996 / Accepted 2 December 1996
One year after the X-ray outburst, the optical counterpart of the black hole candidate GRO J0422+32 underwent an unexpected one-month outburst beginning on 10 August 1993. CCD photometry was obtained for the optical counterpart with the 1.5-m telescope at Calar Alto on 6 consecutive nigths since the onset of this event, never seen before in other transients belonging to the black-hole class. Two spectra were also taken with the 2.2-m telescope on 14 August. We suggest the Mass Transfer Instability model as possible explanation of the event on the basis of the observational facts presented here.
Key words: X-ray: bursts; stars stars: GRO J0422+32 instabilities accretion disks
* Based on observations collected at the German-Spanish Astronomical Center, Calar Alto, Spain, operated jointly by the Max-Planck-Institut fur Astronomie (MPIA), Heidelberg, and the Spanish National Commission for Astronomy.
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© European Southern Observatory (ESO) 1997
Online publication: June 5, 1998