Speedy Star

StarDate: October 18, 2009

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The constellation Microscopium slides low across the southern sky on October evenings. It's not that much to look at -- you need to get away from city lights to see even its brightest stars. That's not a problem for astronomers, though. Their telescopes see plenty of interesting sights in the microscope.

An example is a star known as BO Microscopii. No, it doesn't smell bad -- that's just its catalog designation. But it also has a sporty nickname: Speedy Mic. That's because the star spins in a hurry -- about 70 times faster than the Sun.

Astronomers know that Speedy Mic is a little cooler than the Sun, and that it's about 150 light-years away. They also know that it's a little bigger than the Sun, and that it's quite young -- less than one percent the age of the Sun.

The star was discovered because it produces a lot of X-rays. They probably come from magnetic storms on its surface. The storms create dark "starspots" and powerful outbursts of energy. This high level of magnetic activity shows that the star spins in a hurry, which is one of the signatures of a young star.

Even so, Speedy Mic spins faster than most stars of its size and age. That might be because of a distant companion star. Early on, the stars might have been much closer together. But interactions with a third star could have pushed them farther apart -- and given BO Microscopii a "speedy" kick.

Tomorrow: A "veil" for the Seven Sisters.

Script by Damond Benningfield, Copyright 2009

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