Astronomers have, for years, been peering at Barnard's star, one of closest star systems to Earth, looking for signs of an orbiting exoplanet.
However, for years, the search has come up empty. There have been hints of a possible hidden world here and there, but nothing was considered conclusive.
Until now. In a study published in the journal Nature, a team of researchers presented proof of an icy planet about three times the size of Earth.
Barnard's Star's Icy Wonderland
Barnard's star, because of proximity to Earth, is one of the most studied areas within the Milky Way Galaxy. It is a red dwarf located in the constellation called Ophiuchus, just below the Summer Triangle. It is only about six light-years away from Earth.
However, it took more than two decades of observation before someone found definitive evidence that an exoplanet is in orbit around Barnard's star. In a recent investigation led by Ignasi Ribas of the Institute of Space Sciences in Spain, the team used new and archival data sourced from seven instruments across the world. The data included Barnard's star's radial velocity and relative speed toward and away from Earth.
After looking at 20 years' worth of data, the team detected a planet that circles the star every 233 days, a mass at least 3.2 times that of Earth, and an orbital distance similar to that of Mercury to the Sun. Dubbed Barnard's star b, the exoplanet is situated close to its star system's snow line, which suggests that water exists in its frozen form.
The team used the method called radial velocity, which uses the Doppler shifts of a star's light to measure the tug of a nearby planet. This is the first time that astronomers used radial velocity to detect an exoplanet of this size and this far away from its host star.
Lone Planet
Ribas and colleagues reported that Barnard's star b might be alone in the area. The team ruled out the possibility of another exoplanet orbiting within the star's habitable zone — a region in which there might be liquid water where life could thrive.
Follow-up observations of the newly discovered exoplanet are currently underway.
