An international team, led by Michaël Gillon, an astronomer at the University of Liège (STAR Research Unit), has characterized two planets that have a mass about 4 times that of the Earth, orbiting the HD219134 star. This very close star is located at "only" 20 light years of our solar system. With the help of the NASA's Spitzer Space Telescope, scientists were able to measure the masses and rays of these planets very precisely and to deduce rock-like compositions similar to the Earth’s. This makes these two planets, HD219134b and c, the closest rocky exoplanets to our system known to date. These planets, however, do not have similar characteristics to the TRAPPIST-1 system discovered, HD219134b and c are too close to their star to shelter life. Whatever this study will help us understand the formation and evolution of 'super-terrestrial' systems with short orbital periods, which appear more frequent around solar-type stars than planetary systems similar to ours. This study was the subject of an article in the journal Nature Astronomy.

Read also : Discovey of the closest rocky exoplanet

Picture : IPAC-Caltech

This sky map shows the location of the star HD 219134 (circle), host to the nearest confirmed rocky planet found to date outside of our solar system. The star lies just off the "W" shape of the constellation Cassiopeia and can be seen with the naked eye in dark skies. It actually has multiple planets, none of which are habitable.

(1) Gillon M. et al, Two massive rocky planets transiting a K-dwarf 6.5 parsecs away. Nature Astronomy, mars 2017