Super-Earth Discovered Orbiting Closest Single Star to the Sun

Martin Kornmesser  ESO

Martin Kornmesser ESO

We've observed an alien world orbiting Barnard's Star, a tiny red dwarf that's only six light-years away, making it the second-closest known exoplanet beyond our solar system.

The only closer star system is Alpha Centauri, which consists of three stars bound together by gravity.

Among the instruments used to locate the planet were the European Southern Observatory's planet hunters, the HARPS and UVES spectrographs, which, in combination with the Doppler effect, were able to see when the planet's gravitational pull resulted in the star wobbling.

"After a very careful analysis, we are over 99 percent confident that the planet is there", said the paper's lead author Ignasi Ribas with Spain's Institute of Space Studies of Catalonia. The work drew out a quite unusual planetary candidate: a super-cold planet, about 3.2 times the mass of Earth, that circles its star every 233 days. The exoplanet has a predicted surface temperature of -170 degrees Celsius (-274 F), making it wholly incompatible for life (as we know it, anyway).

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.

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"He worked hard at improving the only technique at that time that had a prayer of finding planets, and spent decades collecting the data", Butler said. Astronomers had to combine almost 800 observations from seven different instruments, spanning 18 years' worth of archives, to trace faint variations in the spectral characteristics of starlight from Barnard's star.

"Though the super-Earth we detected is much too cold to be likely habitable, it does underscore exoplanet statistics that confirm there are more planets in the universe than there are stars, and more potentially habitable Earth-sized planets than grains of sand on all the beaches on our planet!" said Vogt. Not only as a sun attracts the planet and keeps him on the circular orbit, the planet's mass, "crazy", the sun. Spotting planets at a huge distance is still important, and every new planet researchers are able to detect adds to our knowledge of the universe and nature itself, but majority are so distant that we'll likely never actually visit them.

Barnard's Star's biggest claim to fame is the rate at which it is tearing across the night sky.

During the course of their study, Smithsonian notes, researchers found faint evidence of another planet, which would be Barnard's Star c.

The researchers used the radial velocity method during the observations that led to the discovery of Barnard's star b.

He added: "Difficult detections such as this one warrant confirmation by independent methods and research groups. a signal for the planet might be detectable in astrometric data - precision measurements of stellar positions - from the Gaia space observatory that are expected to be released in the 2020s".

Barnard's star is one of the least active known red dwarfs.

"Tantalisingly, super-Earths like Barnard's Star b probably sustain geothermal activity for longer than their lower mass counterparts". Teams of semi-professional astronomers coordinated by the American Association of Variable Star Observers also contributed to the detection.

Their measurements suggested that Barnard's Star is approaching and moving away from us at about walking speed - and it is best explained by a planet, Barnard's star b, orbiting it.

"Now, we have nearly 800 measurements that we're publishing", Ribas said.

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