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Flickering Crab

April 8, 2011

Just because a star is dead doesn't mean it isn't still interesting. In fact, some dead stars are a lot more interesting than the ones that are still tickin'.

Consider an object known as the Crab Nebula. It's to the upper left of the Moon this evening, along one of the "horns" of Taurus, the bull. You need a telescope to see it, though, and even then it's little more than a hazy, jagged patch of light.

That wasn't the case in the year 1054, though. That year, a dazzling star appeared at that spot: a supernova -- a giant star that blasted itself to cosmic dust.

Much of that "dust" is still around -- it forms the nebula, which is spreading out as it expands into space. And at the center of the nebula is the star's crushed core -- a neutron star. It's more massive than the Sun, yet no bigger around than a city. It spins about 30 times a second, producing a flash of energy on each spin like a cosmic lighthouse.

The neutron star generates strong "winds" of electrically charged particles. When the wind rams into the gas and dust around it, it produces shock waves, which can sometimes produce powerful flares of X-rays and gamma rays. The flares can last for days.

Scientists can't fully explain how this process works, though. So they're using several space telescopes to keep a close eye on the Crab. They hope the telescopes can catch more of the flares -- powerful events that make this dead star one of the most interesting around.

Script by Damond Benningfield, Copyright 2011


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