For years, astronomers have relied on a variety of supernova called a Type Ia. These titanic explosions were thought to produced a consistent brightness. Using that "standard candle," astronomers could calculate a supernova's distance from Earth and also track the acceleration of the universe caused by the mysterious force called dark energy. Now, the discovery of two supernova remnants in a nearby galaxy calls the consistency of Type Ia explosions into question.
Supernovae occur when stars with big enough masses--at least 1.4 times that of the sun--have exhausted the supply of fuel that powers the thermonuclear fusion reactions in their cores. When the reactions stop, the stars can no longer push outward against the inexorable effects of gravity. In an instant, they collapse into tiny versions of their former selves, and the recoil from that abrupt and violent process produces the supernovae, which expel huge amounts of matter outward at hypersonic speeds. Up to now, astronomers have identified four types of supernova, including Type Ia.
Now a team from several universities using NASA's orbiting Chandra X-ray Observatory and the European Space Agency's XMM-Newton spacecraft say they have discovered supernova remnants that harbor the usual products of Type Ia explosions but are considerably brighter and contain much more hot gas than normal.
After studying x-ray observations of the remnant clouds, the astronomers concluded that the stars exploded when they were only 100 million years old, instead of the 1 billion to 1.5 billion years old for a typical star producing a Type Ia. One possible explanation, is that both stars grew up in a dense star-forming area and therefore could pull in a great deal of matter easily and quickly. That might have caused them to grow prematurely massive and trigger the supernovae.
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posted by Shaun A. Saunders
Supernovae occur when stars with big enough masses--at least 1.4 times that of the sun--have exhausted the supply of fuel that powers the thermonuclear fusion reactions in their cores. When the reactions stop, the stars can no longer push outward against the inexorable effects of gravity. In an instant, they collapse into tiny versions of their former selves, and the recoil from that abrupt and violent process produces the supernovae, which expel huge amounts of matter outward at hypersonic speeds. Up to now, astronomers have identified four types of supernova, including Type Ia.
Now a team from several universities using NASA's orbiting Chandra X-ray Observatory and the European Space Agency's XMM-Newton spacecraft say they have discovered supernova remnants that harbor the usual products of Type Ia explosions but are considerably brighter and contain much more hot gas than normal.
After studying x-ray observations of the remnant clouds, the astronomers concluded that the stars exploded when they were only 100 million years old, instead of the 1 billion to 1.5 billion years old for a typical star producing a Type Ia. One possible explanation, is that both stars grew up in a dense star-forming area and therefore could pull in a great deal of matter easily and quickly. That might have caused them to grow prematurely massive and trigger the supernovae.
Please click on the article title to read more and click here for more information on SuperNova
posted by Shaun A. Saunders
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