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Red Dwarf Planets

May 24, 2011

Most of the effort in the search for planets beyond our own solar system is directed toward stars that are like the Sun. That's largely because Sun-like stars produce conditions that are the most like those here on Earth -- the only place in the universe where we know there's life.

But a few searches are looking for planets around the smallest and faintest stars of all: red dwarfs.

Red dwarfs are also the most common stars -- they probably make up about three-quarters of the stars in the galaxy, including most of our close stellar neighbors.

These nearby red dwarfs are good targets for one of the leading techniques for finding planets: looking for a slight back-and-forth "wobble" in a star's spectrum -- the pattern produced when you break the star's light into its individual wavelengths. The star moves back and forth in response to the gravity of orbiting planets.

Scientists are particularly interested in finding planets in a star's "habitable zone" -- the region where temperatures are right for liquid water. The habitable zone around a red dwarf is so close in that even a planet as small as Earth would produce a good-sized wobble in the star's spectrum.

But red dwarfs are so faint that you need a powerful telescope to study them in detail -- like the Hobby-Eberly Telescope at McDonald Observatory, which is being used for one of the largest of the red-dwarf planet searches. We'll talk about that tomorrow.


Script by Damond Benningfield, Copyright 2011


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