Hercules X-1 Extended Low State
W. Coburn, D. E. Gruber, W. A. Heindl, M. R. Pelling, R. E. Rothschild
R. Staubert, P. Risse, J. Wilms, I. Kreykenbohm
Recently a failed high state turn-on in the 35d cycle of Her X-1,
which is thought to be caused by the precession of a tilted
accretion disk, was observed with the RXTE. This has been seen
only twice before; in 1983 and again 1993. We present timing and
spectral results of this latest extended low obtained 1999 April
26. Pulsations were observed in the 2-20keV band but with a small
pulse fraction. Preliminary spectral analysis indicates 70%
absorbed emission (NH = 7×1023) with the
remainder unabsorbed. This is consistent with a swelling of the
accretion disk causing the extended low.
File translated from TEX by TTH, version 2.32.
On 16 Jul 1999, 09:19.