Supernova Remnants in the Magellanic Clouds. I. The Colliding Remnants DEM L316

The Large Magellanic Cloud (LMC) supernova remnant (SNR) DEM L316 is of considerable interest, as it shows two overlapping shells at radio and optical wavelengths. This morphology suggests that DEM L316 is in fact two SNRs, which may or may not be spatially connected. We have observed the DEM L316 remnants at optical, radio, and X-ray wavelengths in order to address the question of whether the SNRs are interacting, and if so, whether a tunnel might have formed between the remnants, allowing them to equilibrate. Besides the connecting shell morphologies at optical and radio wavelengths, our observations show enhanced [O III] emission at the juncture between the shells, enhanced X-ray emission from one shell at that juncture, and a change in the structure of the magnetic field near the interaction region. These factors strongly imply that the two remnants are indeed colliding. In addition, we have done a detailed study on the physical properties of the remnants, including an examination of thermal and kinetic energies and of the balance of thermal and magnetic pressures.