Two habitable super-Earths discovered around nearby stars

Two recently detected exoplanets, named GJ229Ac and GJ180d, will constitute new prime targets for the search for life.



You probably won't remember their name, but astronomers are not going to forget them. The two exoplanets that researchers at the Carnegie Institution have just discovered have remarkable characteristics. Called GJ229Ac and GJ180d, they are both of a size close to that of Earth, in other words probably rocky, and located in the habitable zone of their respective stars, that is to say capable of harboring l liquid water. These first two elements therefore make them planets theoretically suitable for the appearance of life. But that's not all…

If they deserve so much attention, it is also because they orbit around stars that are closest to our Sun. Indeed, GJ229Ac and GJ180d orbit around two red dwarfs, Gliese 229 (GJ229) and Gliese 180 (GJ180), located respectively 19 and 39 light years from us. If this may seem enormous, it is very little on an astronomical scale. Thus, the closest star to the Sun, Proxima Centauri, is already 4.2 light years away from it. On the scale of the Milky Way, which is approximately 100,000 light years wide, these potentially habitable super-Earths are therefore found in the suburbs of the solar system. For all these reasons, even if the hospitality of the planets orbiting red dwarf stars is still under discussion, it is a safe bet that GJ229Ac and GJ180d will be among the first targets of telescope observations. new generations, such as the James-Webb telescope, which is scheduled to start operating in March 2021.

While waiting for these state-of-the-art devices to look into their case, scientists already have some information on these almost neighboring worlds. The mass of GJ229Ac and that of GJ180d are equivalent to 7.9 and 7.5 times that of Earth. The first revolves around its star in 122 days and the second in 106 days. Finally, while GJ229Ac is the potentially habitable super-Earth orbiting a star which has a brown dwarf companion closest to us, GJ180d constitutes the “temperate” super-Earth whose orbit is not locked. (unlike the Moon which always presents the same face to the Earth and the majority of exoplanets orbiting red dwarfs) closest to us. A feature that further increases the chances that GJ180d can shelter life