Using the HARPS-N instrument, the ‘planet hunter’ , from the Telescopio Nazionale Galileo at the Roque de Los Muchachos Astrophysical Observatory (La Palma, Canary Islands) and NASA’s Spitzer space telescope, an international team of astronomers has discovered the rocky planet closest to ours outside the solar system . The finding has been published in the journal Astronomy & Astrophysics .
The planet in question has been christened HD 219134b and is located about 21 light years away , in the constellation Cassiopeia. The research data reveals that its parent star, a K-type dwarf, is very similar to our Sun but somewhat cooler and also slightly smaller. According to astronomers’ calculations, its orbital period is only three days .
“It is the closest rocky planet to us that has been confirmed, which offers exciting prospects to study its atmosphere in the near future,” explains Giusi Micela, director of the Palermo Astronomical Observatory of the National Institute of Astrophysics (INAF) in Italy and co-author of the study.
The high-resolution spectrograph has the ability to measure the radial velocity of the star that houses a planet with unequaled precision; Thanks to the slight ‘rocking’ that its presence induces gravitationally on the star, it was possible to identify the mass of the planet: four and a half times the earth’s mass and with an approximate density of 6 grams per cubic centimeter. It is a super-earth, but smaller than Uranus or Neptune.
“ It is an unprecedented result. It is the closest rocky exoplanet, with characteristics very similar to those of Earth . It is an incandescent planet, not hospitable to life, but the most important thing is that we are getting closer and closer to identifying a planet analogous to Earth ”, explains Giampaolo Piotto, co-author of the study.
