Cold dust detected around Earth's nearest star

Astronomers at Chile's Atacama Large Millimeter/submillimeter Array (ALMA) observatory have discovered cold dust around the closest star to Earth, indicating an elaborate planetary system, says a report.

Proxima Centauri is a faint red dwarf lying just four light-years away in the southern constellation of Centaurus (The Centaur), orbited by the Earth-sized temperate world Proxima b that was discovered in 2016, and the closest planet to the Solar System.

The new observations reveal emission from clouds of cold cosmic dust surrounding the star, which presents a glow that could be coming from a region between one to four times as far from Proxima Centauri as the Earth is from the Sun, the astronomers led by Guillem Anglada, from the Instituto de Astrofisica de Andalucia (CSIC), at Granada in Spain, said in a statement.

The dust lies in a belt that extends a few hundred million kilometres from Proxima Centauri. It has a total mass of about one hundredth of the Earth's mass and is estimated to have a temperature of about minus 230 degrees Celsius, as cold as that of the Kuiper Belt in the outer Solar System.

In addition, the ALMA data also hinted at the presence of an even cooler dust belt about ten times further out, indicating the presence of an elaborate planetary system.

"The dust around Proxima is important because, following the discovery of the terrestrial planet Proxima b, it's the first indication of the presence of an elaborate planetary system, and not just a single planet, around the star closest to our Sun," Anglada said.

If confirmed, the nature of an outer belt is intriguing, given its very cold environment far from a star that is cooler and fainter than the Sun.

Both belts are much further from Proxima Centauri than the planet Proxima b, which orbits at just four million kilometres from its parent star, the report noted.

"This result suggests that Proxima Centauri may have a multiple planet system with a rich history of interactions that resulted in the formation of a dust belt," Anglada explained.

--IANS

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