2002ApJ...580L.125K

Chandra observations of M31 allow the first spatially resolved X-ray image of a supernova remnant (SNR) in an external spiral galaxy. CXOM31 J004327.7+411829 is a slightly elongated ring-shaped object with a diameter of ∼11" (42 pc). In addition, the X-ray image hints that the chemical composition of the SNR is spatial dependent. The X-ray spectrum of the SNR can be well fitted with a Raymond-Smith model or a nonequilibrium ionization model. Depending on the spectral model, the 0.3-7 keV luminosity is between 3.2x10³⁶ and 4.5x10³⁷ ergs.s^–1. The age of the SNR is estimated to be 3210-22,300 yr, and the number density of ambient gas is ∼0.003-0.3 cm^–3. This suggests that the local interstellar medium around the SNR is low.