DISCOVERY OF EXPLOSION FRAGMENTS OUTSIDE THE VELA SUPERNOVA REMNANT SHOCK-WAVE BOUNDARY

THE nearby (500 pc) Vela supernova remnant has presented several puzzles. Its true shape has been difficult to determine(1), and as a result it has never been clear whether the pulsar seen in that part of the sky resulted from same explosion that created the remnant(2). Here we present an X-ray image of the Vela supernova remnant which shows that the pulsar is close to the centre, and therefore most probably resulted from the same explosion. We see six extended X-ray features outside the blast-wave front, which apparently originated close to the pulsar. We propose that these features result from the passage through the surrounding medium of fragments formed by instabilities during the collapse and subsequent explosion of the progenitor star.