X-ray Evolution of SN 1987A

The X-ray observations of SN 1987A over the previous 20 years have seen the emergence of soft X-rays from the interaction of the explosion shock wave with the ambient medium. This shock wave is now interacting strongly with the inner ring and might have passed already the highest density regions. The emission can be described by thermal models with temperatures of ∼0.28 keV and ∼2.8+0.7 −1.0 keV, with perhaps some but little change over time. High resolution spectroscopy reveals a large variety of shock velocities ranging from a few hundred to many thousand km s−1. Relative to the elemental abundances prevailing in the LMC the inner ring shows an overabundance of Si and S compared to the lighter elements and Fe, which suggests that the ring consists of highly processed matter dredged up in a binary merger event well before the explosion. The Xray lightcurves between 0.5–2 keV and 3–10 keV differ significantly in slope, with the latter being much flatter but very similar to the radio light curve.