Some Recent Observations of Supernova Remnants Emitting X-Rays
Proceedings of the Royal Society A
There are currently believed to be 13 X-ray sources which can be fairly confidently identified with galactic supernova remnants. All of these sources are thought to be at reasonably small distances, thus supporting the view th at absorption in the interstellar medium prevents us from seeing the more distant galactic remnants with the level of sensitivity currently avail able from soft X-ray instrumentation. Of the older remnants, the Cygnus Loop and Puppis-A are discussed in the light of recent
... the light of recent observations. Several mapping experiments show th a t the Cygnus Loop exhibits a shell-like structure in X-rays, though with considerable fine structure. From these experiments, it is still not clear how uniform is the temperature over the X-ray emitting region. In addi tion, results from a crystal spectrometer are described which imply th a t the temperature may be higher than had been previously determined from proportional counter observations. Results from observations of Puppis-A are presented. These imply th a t two distinct temperatures exist in this source. I t is argued th a t this may represent the interaction of the expand ing shock front with a relatively dense interstellar cloud. The sources W 44 and y-Cygni supernova rem nant are discussed and it is suggested th at these may now be regarded as members of the class of confirmed X-ray emitting supernova remnants. Finally, an optical coronal line observation of the remnant N49 in the L.M.C. is considered, and it is suggested that this source is a likely candidate to be detected as the first X-ray emitting supernova remnant outside the galaxy.