Soft X-ray spectrum and structure of the supernova remnant G65.2+5.7

The HEAO 1 low energy detectors have observed the supernova remnant G65.2+5.7 in the energy range 0.2-2.5 keV. A strong, extended source of X-ray emission is observed coincident with the eastern side of the optical filamentary structure. The characteristic temperature of the emission is in the range 2-3.8 x 10 to the 6th K, and evidence is found for line emission at about 0.8 keV in the X-ray spectrum. These observations imply a shock velocity (425 km/s) and age (about 20,000 yr) that markedly disagree with the estimates from optical and radio observations.