DW Cancri in X-rays

DW Cancri : a magnetic VY Scl star with an orbital period of 86 minutes

We present the first time-resolved spectroscopic study of the cataclysmic variable DWCancri. We have determined an orbital period of 86.10 ± 0.05min, which places the system very close to the observed minimum period of hydrogen-rich cataclysmic variables. This invalidates previous speculations of DW Cnc being either a permanent superhumper below the period minimum or a nova-like variable with a...

Subject headings: galaxies: general—galaxies: spiral—X-rays: general—X-rays: galaxies—X-rays: ISM

We present results from the analysis of deep ROSAT HRI and PSPC observations of the spiral galaxy M81. The inferred total (0.5–2 keV band) luminosity of M81 is ∼ 3×10 ergs s, excluding the contribution from identified interlopers found within the D25 ellipse. The nucleus of the galaxy alone accounts for about 65% of this luminosity. The rest is due to 26 other X-ray sources (contributing ∼ 10%)...

Symbiotic stars in X-rays

Until recently, symbiotic binary systems in which a white dwarf accretes from a red giant were thought to be mainly a soft X-ray population. Here we describe the detection with the X-ray Telescope (XRT) on the Swift satellite of 9 white dwarf symbiotics that were not previously known to be X-ray sources and one that was previously detected as a supersoft X-ray source. The 9 new X-ray detections...

Blazars in hard X–rays

Although blazars are thought to emit most of their luminosity in the γ–ray band, there are subclasses of them very prominent in hard X–rays. These are the best candidates to be studied by Simbol–X. They are at the extremes of the blazar sequence, having very small or very high jet powers. The former are the class of TeV emitting BL Lacs, whose synchrotron emission often peaks at tens of keV or ...

X-Rays in Military Surgery