New study suggests that there should be billions of habitable alien planets around the faint red stars of our galaxy.
The findings are based on a survey of 102 stars in a class called red dwarfs. Red dwarfs are fainter, cooler, less massive and longer-lived than the sun, and are thought to make up about 80 percent of the stars in our galaxy. Using the HARPS spectrograph on the 3.6-metre telescope at the European Southern Observatory’s La Silla Observatory in Chile, astronomers found nine planets slightly larger than Earth over a six-year period. These planets, called super-Earths, weigh between one and 10 times the mass of our own world, and two of the nine were discovered in the habitable zone of their parent star, where temperatures are right for liquid water to exist. Extrapolating from these findings, the researchers estimate that tens of billions of these planets are to be found in the Milky Way, and about 100 should lie in the immediate neighborhood of the sun. According to team leader Xavier Bonfils of the Observatoire des Sciences de l’Univers de Grenoble in France this new observations with HARPS mean that about 40 percent of all red dwarf stars have a super-Earth orbiting in the habitable zone where liquid water can exist on the surface of the planet. Because red dwarfs are so common, there are about 160 billion of them in the Milky Way, this leads us to the astonishing result that there are tens of billions of these planets in our galaxy alone. The two stars found inside the habitable zone were discovered around the stars Gliese 581 and Gliese 667 C. The latter planet is the second of three worlds orbiting its star, and seems to lie right in the middle of Gliese 667 C’s habitable zone. Although the planet has four times the mass of Earth, it is considered the closest twin to Earth found so far.