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Trending Science: Astronomers discover icy planet in orbit around one of the closest stars to the sun

An international team of scientists has found evidence that suggests a large, rocky world may be orbiting a nearby star.
Trending Science: Astronomers discover icy planet in orbit around one of the closest stars to the sun
For years, astronomers have been gazing at Barnard’s star looking for signs of a planet orbiting stars beyond our solar system known as an exoplanet. After Proxima Centauri, Barnard’s star is the second-closest red dwarf star to the solar system at 48 trillion km from Earth. Time and again, their search has been fruitless. Just some tantalising hints of a possible hidden world exist, but nothing conclusive – until now.

A study published in the journal ‘Nature’ presents proof of a frozen planet with a mass about three times the size of Earth and six light years away from the sun. The planet, dubbed Barnard’s star b, has a surface temperature of around – 170 °C. It’s thought to be a super-Earth, a term used to describe a group of planets much larger than Earth but smaller than the large gas planets like Neptune and Uranus.

Barnard’s star has a new planetary companion

“After a very careful analysis, we are 99 percent confident that the planet is there,” lead author and astronomer at Barcelona’s Institute of Space Studies of Catalonia Ignasi Ribas told ‘Reuters’. “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.”

To discover the planet, the team exploited about 20 years’ worth of measurements and observations from 7 high-precision instruments mounted on telescopes around the world. Data included Barnard’s star’s radial velocity and relative speed towards and away from Earth.

The researchers employed the radial velocity method. This is the first time that astronomers used this technique to uncover an exoplanet of this size and this far away from its host star. They detected that this super-Earth circles the star every 233 days, and is situated close to its star system’s snow line, a boundary suggesting that water exists only in its frozen form.

Barnard’s star b’s size or composition isn’t known yet. Speaking to the ‘BBC’, co-lead scientist of the team Dr Guillem Anglada-Escudé described it as “possibly a mostly rocky planet with a massive atmosphere. It’s probably very rich in volatiles like water, hydrogen, carbon dioxide - things like this. Many of them are frozen on the surface.” The Queen Mary University of London astronomer added: “The closest analogue we may have in the Solar System might be the moon of Saturn called Titan, which also has a very thick atmosphere and is made of hydrocarbons. It has rain and lakes made of methane.”

Given Barnard’s star b’s distance from its star, it’s unlikely that there are any signs of life. However, a massive atmosphere could potentially warm the planet, making conditions more hospitable.

The newly discovered exoplanet is giving us a glimpse into planetary formation and evolution. More observations are currently underway. Where one exoplanet lurks, more usually follow. Nearly 4 000 have already been discovered. Could there be other smaller worlds orbiting Barnard’s star?

Source: Based on media reports

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