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Sunday 18 August 2019

Newly discovered planet thought to have 'mild', habitable atmosphere

An artist’s impression of the planet Ross 128b, with its red dwarf parent star in the background. Photo: PA
An artist’s impression of the planet Ross 128b, with its red dwarf parent star in the background. Photo: PA

John von Radowitz

A newly discovered planet orbiting a nearby star could be the closest world to Earth providing a comfortable home for life.

The Earth-sized planet, named Ross 128b, is just 11 light years away and thought to have a "mild" climate with temperatures ranging between an icy -60C and balmy 20C.

That could mean it has oceans and lakes in which life may have evolved. But the best news for any plants or animals living on Ross 128b is the planet's peaceful parent star.

Like many other exoplanets, it orbits close to a dim and cool "red dwarf" at a distance 20 times less than that between the sun and Earth. Red dwarfs have tightly bound "habitable zones" - the narrow temperature belts where surface water can exist as a liquid - but are also prone to deadly eruptions of ultraviolet radiation and X-rays.

Habitable zone planets around most red dwarfs are likely to be severely irradiated, causing many scientists to doubt that life could survive on them. However, Ross 128b's star is much less volatile than typical red dwarfs. The planet's surface receives only 1.38 times more radiation than the Earth, scientists believe.

Conditions on what is technically the closest habitable zone exoplanet to Earth, Proxima Centauri b, are likely to be far less pleasant. Its parent Proxima Centauri is also a red dwarf and part of the Alpha Centauri triple star system, just over four light years from Earth. The star unleashes bursts of radiation and "solar wind" particles powerful enough to strip the atmosphere from a nearby planet.

Astronomer Dr Xavier Bonfils, from the University of Grenoble, France, who led the European team behind the discovery, said: "It seems that Ross 128 is a much quieter star, and so its planets may be the closest known comfortable abode for possible life."

Irish Independent

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