Probing New Stellar Explosion Image 1
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Probing New Stellar Explosion (Image 1)

November 10, 2011
The star Eta Carinae as it may have appeared before its 1843 eruption--a hot, blue supergiant surrounded by an older shell of gas that was ejected in a previous outburst about 1,000 years ago. This image is part of a sequence showing an artist's conception of the expanding blast wave from Eta Carinae's 1843 eruption, an explosive, huge outburst that created the well-known, two-lobed "Homunculus" nebula (a slow-moving shell of gas and dust) and the fast shock wave that propagates ahead it. In this sequence of images, as time passes, we see both the faster shock wave and the denser Homunculus expand and fill the interior of the old shell. Eventually, the faster blast wave begins to catch up with and overtake parts of the older shell, producing a bright fireworks display that heats the older shell (the collision of the two is generating X-rays (orange) that have been observed by an orbiting observatory). Scientists have long wondered what caused Eta Carinae's outburst ever since the star was observed brightening immensely in 1843. But astronomers using the Gemini South and the Blanco Telescopes in Chile have observed faint but extremely fast material indicative of a powerful shock wave having been produced by the event, and suggesting that the cause was an actual explosion deep in the star, rather than a surface eruption caused by the stellar wind. The research, which was led by Nathan Smith of the University of California, Berkeley, and supported in part by the National Science Foundation and NASA, shows that the famous nebulosity around the star contains extremely fast-moving filaments of material not observed before and that cannot be explained by current theories.

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