A rare exoplanet smaller than Earth has been discovered orbiting one of the stars closest to the Sun, although its surface is too hot to support life, a group of researchers reported. astronomers on Tuesday.
The planet orbits Barnard’s Star, which is only six light years away, according to observations made over five years by the Very Large Telescope installed in the Chilean desert.
Astronomers look for planets that are in the “habitable zone” of their respective suns, where it is neither too hot nor too cold to prevent the existence of liquid water, which is considered an essential ingredient for life.
The newly discovered exoplanet, designated Barnard b, is outside the habitable zone.
The Barnard star is a red dwarf, much colder than the Sun, and the exoplanet orbits very close (at a distance 20 times smaller than Mercury from the Sun), which suggests a surface temperature of 125 degrees Celsius and that one year of the planet only lasts three Earth days.
“Barnard b is one of the lowest-mass exoplanets known and one of the few with a mass lower than that of Earth,” said Jonay González Hernández, a researcher at the Institute of Astrophysics of the Canary Islands in Spain.
“Although the star is approximately 2,500° C colder than our Sun, it is too hot there for liquid water to exist on the surface,” said Jonay González Hernández, researcher at the Institute of Astrophysics of the Canary Islands and lead author of the new study published in the Astronomy and Astrophysics magazine.
Barnard is located in the constellation Ophiuchus. After the three stars of the Alpha Centauri system, 4.2 light years away, it is the closest to Earth.
Astronomers detect exoplanets when they pass in front of their star, so the closer they orbit, the more opportunities there are to observe them.
The researchers also found evidence of three other possible exoplanets orbiting Barnard, but they need more observations to confirm their findings.
The discovery, along with that of two exoplanets orbiting the nearby star Proxima Centauri, “shows that our cosmic neighborhood is full of low-mass planets,” said Alejandro Suárez Mascareño, co-author of the study.
Since the 1990s, more than 5,700 planets have been discovered outside the Solar System, but few are in a habitable zone.