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Cygnus, the swan, is one of the prominent denizens of the summer sky. It's a large constellation that resembles a giant cross. And its brightest star, Deneb, is the most distant of the bright stars in the night sky, at a distance of about 1500 light-years.
But Cygnus is also home to a much closer star -- one that new research suggests could have habitable planets.
61 Cygni is barely visible to the unaided eye, even though it's a mere 11.4 light-years away. It's actually a binary -- two orange stars locked in orbit around each other.
Like the Sun, these stars generate their energy by converting hydrogen into helium at their centers. The stars are less massive than the Sun, though, so their centers are cooler and the nuclear reactions proceed more slowly. As a result, the stars' surfaces are cooler and dimmer than the Sun.
As such a star ages, it uses up its original hydrogen fuel. Over billions of years, these changes cause the star to expand. Because of that, astronomers can deduce the star's approximate age from its size. New measurements of the diameters of the stars of 61 Cygni find that they're about six billion years old -- a billion-and-a-half years older than the Sun.
No one yet knows whether 61 Cygni has planets. But if it does, its age means those planets have had plenty of time to develop not just life, but intelligent life. So it's possible that life-bearing worlds could exist within just a dozen light-years, orbiting the stars of 61 Cygni.
Script by Ken Croswell, Copyright 2011