Search Publications

Circinus X-1 revisited: fast-timing properties in relation to spectral state.

van Paradijs, J.; van der Klis, M.; Lewin, W. H. G. +2 more

We have studied the X-ray spectral and fast-timing variations of Cir X-1 by performing a homogenous analysis of all EXOSAT ME data on this source using X-ray hardness-intensity diagrams (HIDs), colour-colour diagrams (CDs), and power spectra. Cir X-1 exhibits a wide range of power spectral shapes and a large variety in X-ray spectral shapes. At di…

A comparison between the Hercules X-1 pre-eclipse and anomalous dips.

Parmar, A. N.; Reynolds, A. P.

We report the properties of three pre-eclipse and two anomalous dips from Hercules X-1 using data from the EXOSAT Observatory. The anomalous dips are shorter, lasting ~1hr compared to lower limits of ~3hr for the pre-eclipse dips, and shallower, never resulting in more than 91+/-4% of the 2-17keV flux being obscured, compared to the pre-eclipse di…

EXOSAT observations of the ultra-soft X-ray binary 4U 1957+11.

Stella, L.; Israel, G. L.; Ricci, D.

We present results from the analysis of the two EXOSAT observations of the low mass X-ray binary (LMXRB) 4U 1957+11. The 1-20keV spectrum of the source is best fitted by a power law model with exponential cutoff, that provides an approximation of a thermal Comptonisation spectrum. The cutoff energy (~2keV), as well as the X-ray colours, are interm…