An ASCA study of the high-luminosity supernova remnant G349.7+0.2

We present ASCA observations of supernova remnant (SNR) G349.7+0.2. The remnant has irregular shell morphology and is interacting with a molecular cloud, evident from the presence of OH (1720 MHz) masers and shocked molecular gas. The X-ray morphology is consistent with that at radio wavelengths, with a distinct enhancement in the south. The X-ray emission from the SNR is well described by a model of a thermal plasma that has yet to reach ionization equilibrium. The hydrogen column of ∼6.0 × 10²² cm ^-2 is consistent with the large distance to the remnant of ∼22 kpc estimated from the maser velocities. We derive an X-ray luminosity of L _x(0.5-10.0 keV) = 1.8 × 10³⁷d₂₂ ² ergs s^-1, which makes G349.7+0.2 one of the most X-ray luminous shell-type SNRs known in the Galaxy. The age of the remnant is estimated to be ∼2800 yr. The ambient density and pressure conditions appear similar to those inferred for luminous compact SNRs found in starburst regions of other galaxies and provide support for the notion that these may be the result of SNR evolution in the vicinity of dense molecular clouds.