An article being published in the journal “Monthly Notices of the Royal Astronomical Society” reports the discovery of three super-Earths in the system of the red dwarf star GJ 1061. A team of astronomers from the Red Dots collaboration made this discovery during the 2018 observation campaign thanks to a series of spectroscopic detections obtained over three months using the radial velocity method. The masses of these exoplanets are a bit higher than the Earth’s and the outermost is in ​​its system’s habitable zone, where it receives an amount of energy from its star close to what the Earth receives from the Sun.

About 12 light years from Earth, the star GJ 1061, or Gliese 1061, has a mass that is just over a tenth of the Sun’s but is much older, with an estimated age of 7 billion years. The Red Dots project is among those that aim to look for rocky planets exactly around stars of that type in what is astronomically the cosmic neighborhood. This project uses the HARPS (High Accuracy Radial velocity Planet Searcher) spectrograph at the La Silla Observatory in Chile. These are surveys that use the radial velocity method to discover traces of exoplanets and in the GJ 1061 system the detections carried out between July and September 2018 led to the discovery of three exoplanets.

The exoplanet GJ 1061 b has a mass estimated at 1.38 times the Earth’s and a year that lasts 3.2 Earth’s days. The exoplanet GJ 1061 c has a mass estimated at 1.75 times the Earth’s and a year that lasts 6.7 Earth’s days. The exoplanet GJ 1061 d has a mass estimated at 1.68 times the Earth’s and a year that lasts 13 Earth’s days and is in ​​its star system’s habitable zone. The estimated masses are the minimum ones and if they’re not seriously wrong they clearly indicate that they’re rocky exoplanets, therefore super-Earths.

The data collected leave the possibility open that there’s a fourth planet with a longer year but a longer observation baseline would be needed to try to verify it. To discover a exoplanets smaller than the Earth with a year longer than 20 Earth’s days, additional high-precision measurements with the radial velocity method would be needed. That’s why the discovered exoplanets are generally massive and very close to their stars.

The star GJ 1061 is similar to Proxima Centauri but older and this is important because red dwarfs are small but can be very active when they’re young striking their planets with powerful flares. The exoplanet GJ 1061 d has an interesting potential regarding habitability and now its star is rather quiet. The radial velocity method is indirect so there’s no way to tell if that exoplanet has an atmosphere. At least for now there’s a new confirmation that even very small stars can have various planets, the reason why some surveys in recent years are focusing on them.