Astronomers have spotted an icy super-Earth right on our cosmic doorstep.
According to the European Southern Observatory (ESO), the newfound exoplanet is estimated to be at least 3.2 times more massive than Earth. However, unlike our home planet, this is a remarkably cold place, with freezing surface temperatures that plummet to minus 170 degrees Celsius (minus 275 degrees Fahrenheit).
This alien world circles a nearby — and rather famous — star known as Barnard’s Star. At just six light-years away, Barnard’s Star is the next closest star to the sun after the Alpha Centauri triple system — located only four light-years away, as previously reported by the Inquisitr.
The newly discovered world — which was given the name Barnard’s Star b — is currently classified as an exoplanet candidate. However, the team behind the discovery is “99 percent confident” that they have made a positive detection and that the exoplanet will ultimately be confirmed.
“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,” said team leader Ignasi Ribas, a researcher at the Institute of Space Studies of Catalonia and the Institute of Space Sciences in Spain.
If the alien world turns out to be real, it will become the second closest exoplanet to the sun. The nearest planet to our solar system is Proxima b, an inhospitable world orbiting the closest star in the Alpha Centauri trio — namely Proxima Centauri.
The exciting news was announced earlier today in the journal Nature and marks a major a “breakthrough” in the study of Barnard’s Star. This nearest single star to the sun has been kept under intense scrutiny for a long time in the hope that it would eventually unveil a new alien world located in its orbit.
“The biggest ‘kick’ about this discovery is the host star,” Paul Butler, study co-author and astronomer at the Carnegie Institution for Science, told CNN.
“Barnard’s Star is the ‘great white whale’ of planet hunting.”
Classified as a red dwarf, this star is twice as old as our sun and considerably smaller, weighing just one sixth of the sun’s mass. In addition, Barnard’s Star is a lot dimmer, shining with just 3 percent of the sun’s luminosity, notes Space.
One notable thing about our stellar neighbor is that it’s the fastest moving star on the night sky, as perceived from Earth. Barnard’s Star is zipping through the solar system at speeds of 310,000 miles per hour relative to the sun — constantly creeping closer and closer to us.
Some 10,000 years from now, this star will rank as the closest to our sun and will have moved within 3.8 light-years from us.
Because the star is so dim, the habitable zone around it lies a lot closer than in the case of other, brighter stars. Also known as the “Goldilocks zone,” this is the area where liquid water can pool on the surface of an orbiting planet.
According to the study, the habitable zone surrounding Barnard’s Star only stretches between 0.06 AU to 0.10 AU from the red dwarf. One AU, or astronomical unit, represents the distance between the Earth and the sun, estimated at about 93 million miles.
Meanwhile, Barnard’s Star b orbits at a distance of 0.4 AU — well outside the star’s “Goldilocks zone.” This places the exoplanet “near the snow line of Barnard’s Star,” the study authors wrote in their paper. As such, the newfound super-Earth is most likely uninhabitable — given that the snow line is a region where water no longer exists in liquid form but condenses into solid ice.
This means that the exoplanet has surface temperatures well below the freezing point — capping in at minus 275 degrees Fahrenheit, reports Phys.org.
Fun Facts About Barnard’s Star B
According to the Physics Forum, the surface temperature of Barnard’s Star b is comparable to that of Saturn. At the same time, its distance from the parent star mirrors the distance between Mercury and the sun.
Moreover, the exoplanet goes around Barnard’s Star once every 233 days — the same orbital period as that of Venus.
Unlike most exoplanet discoveries, Barnard’s Star b wasn’t detected through the transit method — which looks for dips in a star’s brightness, caused by orbiting planets as they pass in front of the star. Instead, the exoplanet was spotted via the radial velocity method — which checks for wobbles in the starlight that could be triggered by the gravity of a nearby planet.
“We used observations from seven different instruments, spanning 20 years of measurements, making this one of the largest and most extensive datasets ever used for precise radial-velocity studies,” explained Ribas.
“The combination of all data led to a total of 771 measurements — a huge amount of information!”
Although Barnard’s Star b is so big and so close, it’s actually the smallest and most distant planet ever discovered through the radial velocity method. In addition, the frozen super-Earth is the smallest exoplanet ever uncovered so close to its parent star, states astronomer Rodrigo Diaz of the University of Buenos Aires, who wasn’t involved in the study.
“Until now, only giant planets had been detected at such a distance from their stars,” Diaz writes in an accompanying article published in Nature. “The authors’ discovery of a low-mass planet near the snow line places strong constraints on formation models for this type of planet.”