Alpha Centauri B
Like a giant waking up after a long winter's nap, the Sun is starting to get a little more active these days. It was pretty quiet over the last year or two as it slumbered through the least-active part of its 11-year magnetic cycle. Last year, in fact, it went months without a single dark sunspot marking its surface. But it began picking up the pace late last year, as it builds toward "solar maximum" around 2012.
One of our closest stellar neighbors appears to go through a cycle that's almost identical to the Sun's.
Alpha Centauri B is just four light-years away. It's part of a triple-star system that is closer to us than any other star system.
Alpha Centauri B is a little smaller, cooler, and less massive than the Sun. It's also at least a billion years older than the Sun.
Several orbiting X-ray telescopes have kept an eye on the star over the last decade or so. The X-rays come from the star's hot outer atmosphere, which gets hotter or cooler as the star's magnetic activity gets stronger or weaker. The X-rays indicate that Alpha Centauri B has a magnetic cycle that lasts about 10 and a half years -- almost identical to the length of the solar cycle.
The X-ray observations also suggest that the star rotates once every five weeks -- about a week longer than the Sun.
So the Sun and this nearby neighbor appear to have a lot in common.
We'll talk about the smallest member of the Alpha Centauri system tomorrow.
Script by Damond Benningfield, Copyright 2009
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