E0102-72 is the remnant of a star that exploded in a nearby galaxy known as the Small Magellanic Cloud. The galaxy is approximately 190,000 light years from Earth, so we see the remnant as it was about 190,000 years ago, around a thousand years after the explosion occurred
The star exploded outward at speeds in excess of 20 million kilometers per hr (12 million mph) and collided with surrounding gas. This collision produced two shock waves, or cosmic sonic booms one traveling outward, and the other rebounding back into the material ejected by the explosion.
The radio image was made using the Australia Telescope Compact Array. The radio waves are due to extremely high-energy electrons spiraling around magnetic field lines in the gas and trace the outward moving shock wave.
The Chandra X-ray image, shown in blue, shows gas that has been heated to millions of degrees Celsius by the rebounding, or reverse shock wave. The X-ray data show that this gas is rich in oxygen and neon. These elements were created by nuclear reactions inside the star and hurled into space by the supernova.
The Hubble Space Telescope optical image shows dense clumps of oxygen gas that have cooled to about 30,000 degree Celsius.
Image : NASA CXC SAO, NASA HST, CSIRO ATNF ATCA