ALMA detects cold dust around Earth’s nearest stellar neighbor (research)

Proxima Centauri is already known to have one Earth-sized world around it, and now astronomers have detected dust belts that could be an indication of more.

Scientists from the ALMA Observatory in Chile have found cold dust around Proxima Centauri—the closest star to the Sun—in a region between one to four times as far from Proxima Centauri as the Earth is from the Sun.

The discovery indicates that there may be an even cooler outer dust belt and an undiscovered elaborate planetary system beyond Proxima Centauri.

Proxima Centauri is a faint red dwarf lying just four-light years away in the southern constellation of Centaurus. It is orbited by Proxima b—an Earth-sized temperate world discovered in 2016 and considered the closest planet to our solar 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,” Guillem Anglada, from the Instituto de Astrofísica de Andalucía (CSIC), Granada, Spain, said in a statement.

Dust belts are the remains of material— including rock and ice— that did not form into larger bodies like planets. The particles in the belt vary in size, from minuscule dust grain that are smaller than a millimeter across, to asteroid-like bodies that are several kilometers in diameter.

The dust that appears in the belt extend a few hundred million kilometers from the star and has a total mass of about one hundredth of the Earth’s mass.

The scientists estimate that the belt has a temperature of about -230 degrees Celsius and the data hints that another belt of even colder dust may be present about 10 times further out.

“The 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 said. “Further study may also provide information that might point to the locations of as yet unidentified additional planets.”

Co-author Pedro Amado, also from the Instituto de Astrofísica de Andalucía, explained the plan to build on these observations.

“These first results show that ALMA can detect dust structures orbiting around Proxima,” Amado said in a statement. “Further observations will give us a more detailed picture of Proxima’s planetary system.

“In combination with the study of protoplanetary discs around young stars, many of the details of the processes that led to the formation of the Earth and the Solar System about 4,600 million years ago will be unveiled,” he added.

The British Journal Editors and Wire Services

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