Red dwarfs are known for being small, cool, dim stars, but some astronomers believe planets around these stellar bodies may also be the best place to find alien life. Researchers are studying 20,000 of these diminutive stellar bodies in an effort to find extraterrestrials.
The search for extraterrestrial intelligence (SETI) Institute is undertaking a massive study of the dim stars, which are plentiful through the galaxy.
Astronomers typically study stars much like our sun in an effort to detect alien civilizations. The traditional thought is that life is most likely to form in planetary families similar to that in our own solar system. This new study is seeking evidence of life on planets orbiting dim red dwarf stars, which were previously ignored up to this time. Stars of this type are the most common variety in the galaxy, meaning life around one of these stars is likely to be closer than a civilization discovered around a sun-like star.
"Significantly, three-fourths of all stars are red dwarfs. That means that if you observe a finite set of them – say the nearest twenty thousand – then on average they will be at only half the distance of the nearest twenty thousand sun-like stars" said Seth Shostak, an astronomer at the SETI Institute.
Life is most likely to form on planets within the so-called "habitable zone" around their parent stars, where temperatures are able to sustain liquid water. Because red dwarfs are significantly cooler than our sun, the habitable zones around their bodies are much thinner, and closer to the star, than seen in our own solar system.
Because planets would need to be so close to red dwarf to prevent water from freezing, they would likely be in gravitational lock with their stars, with one side always facing toward the stellar body. This would likely result in a situation where one hemisphere of such a planet would experience perpetual scorching heat, while the dark side remains in a deep freeze. Many astronomers believe such conditions make these planets unlikely to support life. However, oceans and atmospheres on these worlds may mitigate temperature extremes, causing much of the planet to be habitable.
The total lifetime of stars is determined solely by their mass, and red dwarfs live far longer than stars like our sun. This means planets around red dwarfs may have far more time for life to form, making these targets even more attractive for SETI researchers.
