In the Zone
Most astronomers don’t pay a lot of attention to the stars known as red dwarfs. They’re the smallest and faintest stars known, and they don’t change much, so they don’t have a lot of sex appeal. But when it comes to the hunt for habitable planets, these cool stars are a hot topic.
To support life as we know it, a planet must be small and rocky, like Earth. And it must be at the right distance from its star to have liquid water on its surface.
But finding such planets is difficult. The techniques that astronomers use to reveal Earth-like planets in Earth-like orbits take a lot of time, and the indications of such planets are small and hard to detect.
Since red dwarfs are so small, though, they offer advantages in the planet-hunting derby. For one thing, the signature of an Earth-like planet that orbits a red dwarf is much larger. And for another, such a planet would be quite close to the parent star, so each orbit would take only a few weeks or months, which also makes detection easier.
And there are a lot more red dwarfs than other types of stars. In fact, red dwarfs account for at least three-quarters of all the stars in the entire galaxy. So that gives astronomers a lot of targets.
Searches of the three closest red dwarfs - Proxima Centauri, Barnard’s Star, and Wolf 359 - have yet to discover any planets at all, much less planets in the “habitable zone.” Yet the searches continue - for comfortable worlds around feeble stars.
Script by Damond Benningfield, Copyright 2013
For more skywatching tips, astronomy news, and much more, read StarDate magazine.