Axions

StarDate: May 21, 2009

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The Sun might seem like a strange place to hunt for dark matter. The Sun is a ball of superhot gas that produces energy galore. Dark matter, on the other hand, produces no energy at all. We know it's there only because it exerts a gravitational pull on the matter that we can see. And there's a lot of it -- several times more dark matter than visible matter.

So far, no one's sure just what dark matter is. But one idea says it may consist of axions -- subatomic particles with almost no mass. If the idea's correct, enormous amounts of axions were created shortly after the Big Bang, and today they fill the universe.

Axions may also be created in the hearts of stars -- and that's where the Sun comes in.

The theory says that nuclear reactions in the Sun's core convert X-rays into axions. As they zip out into space, some of the axions may be converted back into X-rays by the Sun's powerful magnetic field. A team of astronomers is using orbiting X-ray telescopes to look for that energy, which would look different from other X-rays produced by the Sun.

Some of the axions may make it all the way to Earth's surface. A couple of teams are searching for those axions with special telescopes that use superconducting magnets to convert the axions to X-rays.

So far, the searches have turned up empty, but they're still going on. At the same time, other astronomers are searching for axions in other stars. We'll have more about that tomorrow.

Script by Damond Benningfield, Copyright 2009

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