A HIGH-RESOLUTION RADIO IMAGE OF A YOUNG SUPERNOVA

Supernovae in our own Galaxy are so rare that images of their remnants 1 can show only the late aftermath of an explosion that occurred anything from a few hundred to several tens of thousands of years ago. Young supernovae are seen frequently in other galaxies, but because they are more distant, it has not been possible until now to obtain high-resolution images that would reveal details of the explosion and the immediate development of the ejected material. Here we present a very-long-baseline interferometric (VLBI) radio image of the bright supernova 1986J, which occurred in the galaxy NGC891 at a distance of approximately 12 Mpc. No detailed image of any supernova or remnant has been obtained before so soon after the explosion. Our image shows a shell of emission with jet-like protrusions. Their analysis should advance our understanding of the dynamics of the expanding debris, the dissipation of energy into the surrounding circumstellar medium, and the evolution of the supernova into the remnant.