Orion, the hunter, climbs majestically across the southern sky this evening. The constellation is marked by a distinctive belt of three bright stars. And south of the belt is the Orion Nebula, a cloud of gas and dust that's given birth to thousands of stars. Some of these stars have left the nest, so to speak, and moved into other constellations.
A good example currently resides in the constellation Columba, the dove, which is far to the south of Orion. The star is known as Mu Columbae. It's about the same distance from Earth as the Orion Nebula -- about 1300 light-years.
Mu Columbae is a hot, blue star that's much more powerful than the Sun. But what's most remarkable is its path through space: Mu Columbae is a "runaway" star -- it's shooting away from the Orion Nebula at high speed.
By tracking its motion back in time, astronomers deduce that Mu Columbae was in the Orion Nebula just two and a half million years ago. So the star probably was born not in Columba, but in the Orion Nebula. But it was catapulted out of the nebula at a pretty good clip. Perhaps it passed close to another massive star, whose gravity flung it away from Orion. Or perhaps it once orbited a star that exploded, hurling it southward.
Whatever the case, today Mu Columbae is 600 light-years from its birthplace in the Orion Nebula -- a vivid illustration of Orion's bounty: it's so rich that it can share some of its stellar wealth with its neighbors.
Script by Ken Croswell, Copyright 2007
For more skywatching tips, astronomy news, and much more, read StarDate magazine.