Radio Properties of Three Young Supernova Remnants in the Large Magellanic Cloud

Radio images of N132D, N103B, and 0519-690 have been made with the Australia Telescope. These three prominent young SNRs in the LMC have significantly different optical properties: N132D is oxygen rich and probably had a massive progenitor similar to Cas A; N103B, on the edge of a massive H II region complex, was probably also from a massive star; on the other hand, isolated, Balmer-dominated 0519-690 was probably from a low-mass Type Ia supernova. All three remnants show the characteristic shell structure with some clumpiness. Although the polarimetric data are not complete for all three, the results are compatible with a small net radial orientation of the magnetic fields in these young remnants. We suggest that N132D is older and probably somewhat more energetic and/or massive than Cas A. N103B appears to be a younger version of N132D, while 0519-690 is less luminous and not unlike the remnants of low-mass supernovae seen in the Milky Way.