V E L A   &   C H A M A E L E O N

Between 10,000 and 15,000 years ago, an extremely massive O or B-type star exploded as a supernova in the constellation Vela, about 250 parsecs (800 light years) away (Cha et al. 1999). See this older discussion and a more recent one. The shells of gas that it threw off still linger within about 15 parsecs (50 light years) of the source, as shown this image of the shock wave, which is about 30 parsecs in diameter. At the center of the gaseous filaments are the remains of the blown-out star, now compressed into a dense and tiny pulsar rotating 10 times per second.