EXOSAT observations of the iron line in CEN X-3

Abstract

Properties of the iron line in Cen X-3 have been studied, using the gas scintillation proportional counter onboard EXOSAT. The iron line energy is seen to be constant (kT = 6.59 +/- 0.06 keV) over orbital and pulse periods. On the other hand the iron line intensity is seen to vary with both periods. The pulse period variations are sinusoidal, but the orbital period variations are more complex. These variations can be explained assuming that the iron line emission comes from, at least, two different emitting regions; the Alfven sphere and the primary's atmosphere. The pulse period variations are produced at the Alfven sphere and the orbital period variations at the primary's atmosphere.