The Sun’s nearest single star neighbour may have an icy exoplanet orbiting it, according to a newly released study.
Researchers say the potential planet, dubbed Barnard’s Star b, is an icy super-Earth planet – which means it’s greater in mass than Earth, but significantly smaller than ice giants like Neptune.
The study estimates that the planet has a mass that’s at least 3.2 times that of Earth and an orbit that takes roughly 233 days.
Less than six light-years away from our Sun, the potential planet orbits Barnard’s Star, a well-studied low-mass red dwarf star in the Ophiuchus constellation.
Barnard’s Star is theorized to be about twice as old as our Sun, but only one-sixth the size and two per cent as luminous.
The star’s properties make it a prime target for researchers trying to find new planets, but until now searches have only had disappointing results.
This new discovery came from an investigation that saw astronomers from around the world combining more than 20 years of data on the star from seven different instruments.
What they were looking for was signs of the Doppler Effect – searching for changes in starlight caused by the gravitational pull of a planet as it orbits.
“After a very careful analysis, we are 99% confident that the planet is there,” the team’s lead scientist, Ignasi Ribas, said in a statement.
“However, we’ll continue to observe this fast-moving star to exclude possible, but improbable, natural variations of the stellar brightness which could masquerade as a planet.”
This is the first time that this approach to planet hunting has been used to find a super-Earth planet in such a wide orbit, with Barnard’s Star b orbiting about 0.4 astronomical units from the star.
The study says that the newly discovered planet exists near the star’s “snow line,” where objects receive so little sunlight that most water present would condense into ice.
As a result, researchers estimate that Barnard’s Star b has a surface temperature around minus 170 degrees Celsius, making it an unhospitable home for life as we know it.
If confirmed, the exoplanet would be the second-closest planet known beyond our solar system, and a prime target for further research.
The potential planet is an excellent candidate for directing imaging and astrometric observations because of its wide orbit, researchers say, which could give us a look at the planet’s surface.
The team says it has also found signs in the data that could suggest the activity of another more distant, planetary object, but these hints are as of yet unconfirmed.
