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Friday, January 8, 2010

Matter/anti-matter explosion observed

University of Notre Dame astronomer Peter Garnavich and his colleagues have discovered a matter/anti-matter explosion. The exploding star, Y-155, was one of many found by the Essence project (Equation of State: SupErNovae trace Cosmic Expansion), a search for supernovae. The rest, being ordinary supernovae, paled in comparison.

Stars that are larger than 8 times the size of our sun will eventually either collapse into a supernova or a black hole. However, there seems to be a sweet spot for objects 150 to 300 times the mass of the sun where anti-matter particles can be formed. These stars can then blow up spectacularly. Y-155 was about 200 times the mass of the sun, the perfect size for a runaway anti-matter explosion.

Y-155 actually exploded 7 billion years ago. Because of the enormous distances involved (we are just now seeing the light from that explosion), the explosion appears quite faint. As Garnavich puts it:

“In our images, Y-155 appeared a million times fainter than the unaided human eye can detect, but that is because of its enormous distance. If Y-155 had exploded in the Milky Way it would have knocked our socks off.”

Such matter/anti-matter explosions were first hypothesized 40 years ago, but have only recently been observed.

A supernova, as seen by the Hubble telescope.