SOME IMPLICATIONS OF X-RAY DATA FROM OLD SUPERNOVA-REMNANTS

Several old supernova remnants emit soft X-rays. With certain assumptions, and using a standard adiabatic shock-wave model, values for the initial blast energy of a supernova and the age of its remnant may be estimated. These parameters are evaluated using the most recently available X-ray and radio results for four old supernova remnants. The data imply high ratios of initial blast energy to interstellar density and comparatively young ages for the remnants. These conclusions, while at variance with some earlier estimates based on optical and radio data, support the results of a statistical analysis of the most recent catalogue of radio remnants. Predicted X-ray fluxes for other supernova remnants lying within 6 kpc of the Sun are presented as a guide to future observational programmes. © Royal Astronomical Society.