EXOSAT observations of GH 2215^-086 : detection of the X-ray pulse period

Abstract

A 2.8 hr observation of the intermediate polar H2215 - 086 using the Exosat Medium Energy experiment has revealed a strong, quasi-sinusoidal modulation of the hard X-ray flux with a period (20.65 + or - 0.32 min) consistent with, and in phase with, that of the large amplitude optical variations. The detection of this hard X-ray modulation confirms that the optical pulse period represents the white dwarf rotation period in this system. The X-ray spectrum observed is consistent with a hard X-ray source of less than about 4 keV with substantial low energy absorption implying a column density of less than about 7 x 10 to the 22nd per sq cm. At an assumed distance of 500 pc the 2-10 keV X-ray luminosity of H2215 - 086 is about 3.0 x 10 to the 32nd ergs per sec.