THE RADIO STRUCTURE OF SUPERNOVA REMNANT 0540-693

We present an Australia Telescope Compact Array multifrequency study of the supernova remnant 0540 693 which is the youngest known remnant, after SN 1987A, in the Large Magellanic Cloud. The radio observations reveal that it consists of a central synchrotron nebula of diameter 1.4 pc which is powered by the 50 ms pulsar PSR B0540-69, and a nearly circular low-surface brightness annulus of diameter 17.5 pc. The central nebula has a flatter spectrum than the annular emission and is the radio counterpart of the synchrotron nebula previously detected at optical and X-ray wavelengths. Its properties are very similar to those of the Crab Nebula. The annular emission is similar to other young supernova remnant shells and is generated b the interaction of the supernova ejecta with the circumstellar medium.