Binary modulation and transient periodic variations in X-ray emission from the AM Her binary H 0139 - 68

A detailed timing analysis of HEAO-1 and Einstein satellite soft X-ray data on the AM Her-type binary H 0139 - 68 indicates that the X-ray flux is modulated at the 113.6363-min period of its optical counterpart, and that the X-ray source shows high and low states. Transient X-ray pulsations with a period of about 275 sec are noted in the Imaging Proportional Counter (IPC) data during the high state, and the rapid X-ray flickering observed in the IPC light curve is characterized by an average e-folding autocorrelation time of about 10-20 sec. The present optical and X-ray data preclude the presence of an accretion disk in the primary system.