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Companionable Stars

March 9, 2010

The heart of the lion -- the star Regulus -- climbs high across the sky on March nights. The bright white star is well up in the east at sunset.

The star that we see as Regulus is much hotter and brighter than the Sun. Any planet that orbits the star would have to be far away for conditions to be favorable for life. And Regulus will live a fairly short lifetime of its own, so it's not a good place to look for life-bearing worlds.

But Regulus has two smaller, fainter companions. And one of those stars could be just right for life.

The star is classified as a "K dwarf." It's a bit smaller and cooler than the Sun, so it looks orange. A study by astronomers at Villanova suggests that such stars are great places to look for habitable planets.

For one thing, such stars live long, stable lives -- tens of billions of years. That means their "habitable zones" -- the distance where the temperature is just right for liquid water -- remain stable for a long time as well, giving life plenty of time to take hold. Also, these stars don't produce a lot of explosive flares that could bathe planets with deadly radiation. And finally, there are a lot of K dwarfs around -- perhaps 5 to 10 times as many as stars like the Sun.

Although Regulus's companion isn't on the list, many other K dwarfs are targets for the planet-hunting spacecraft known as Kepler. It may detect several Earth-like planets orbiting these cool orange stars.

Script by Damond Benningfield, Copyright 2010

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