Images: X-rays document death of a star

NASA released an image Monday of the death of an enormous star with a mass 150 times larger than the sun. They say it is the brightest, most powerful supernova ever observed. The SN 2006gy supernova occurred 240 million light-years away. It was studied using the NASA's Chandra X-ray Observatory, which was launched into orbit in 1999, as well as earthbound optical telescopes.

One theory of SN 2006gy held that a white dwarf not much larger than the sun had exploded in a hydrogen-rich region. But were that the case, the supernova would have been 1,000 times brighter than what Chandra observed, NASA said. With data collected from Chandra, astronomers now know the supernova is simply the result of a massive star exploding. This is significant because it gives astronomers clues as to how early stars, which were much bigger than those seen today, may have died.

The supernova also has them looking with interest at a star closer to home. SN 2006gy expelled a large amount of mass before it exploded. Scientists report a similar "mass exodus" from Eta Carinae, a huge star in our own galaxy. That observation leads some to believe Eta Carinae may be on the brink of exploding in a supernova. Such an occurrence would be visible from Earth during both day and night, and could be the "best star-show in the history of modern civilization," Mario Livio of the Space Telescope Science Institute in Baltimore told NASA.

Chandra, which NASA calls the most sophisticated X-ray observatory ever built, allows scientists to see new detail in high-energy areas that can appear too bright and blurry when studied with other types of instruments. The top portion of this graphic is an artist's illustration of what SN 2006gy might have looked like up close. The bottom left panel is an infrared image from the Lick Observatory of the galaxy SN 2006gy is in. The dim green spot is the center of that galaxy, and the bright blue spot is the supernova. The panel on the right shows the same objects viewed by Chandra.