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Ophiuchus, the serpent bearer, wheels high across the south tonight. It's not that much to look at -- only a few modest stars climbing above Scorpius, the scorpion.
Yet Ophiuchus is home to one of our closest stellar neighbors: Barnard's Star. It's just six light-years away. Only the Alpha Centauri system is closer.
Unfortunately, Barnard's Star is too faint to see with the unaided eye. That's because it's a red dwarf -- known to astronomers as an M dwarf -- the smallest and faintest class of stars. Barnard's Star itself is less than one percent as bright as the Sun, and many other M dwarfs are even fainter.
Even so, astronomers at the University of Texas are searching Barnard's Star and about a hundred other M dwarfs for evidence of planets.
In particular, they're hunting for Earth-size planets in orbits that are close to their parent stars -- close enough for temperatures to be just right for liquid water -- a necessary ingredient for life.
The astronomers are using the Hobby-Eberly Telescope at McDonald Observatory to look for a small "wobble" in a star's light caused by the gravitational tug of a planet. An upgrade to the telescope and its instruments that's scheduled to begin later this year should enhance the search.
So far, the search hasn't yielded any planets in the habitable zone. But is has found several other planets, including a giant orbiting farther out from its star; more about that tomorrow.
Script by Damond Benningfield, Copyright 2011