Gigantic solar flare detected on the surface of Proxima Centauri

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An artist impression of a Proxima Centauri flare, modeled after the glowing hot gas loops observed in the largest solar flares. The exoplanet Proxima b is shown in the foreground. Proxima b orbits its star 20 times closer than the Earth orbits around the Sun. A eruption 10 times larger than a major solar flare would bombard Proxima b with 4000 times more radiation than Earth receives from a typical solar flare. Credit: Roberto Molar Candanosa / Carnegie Institute for Science, NASA / SDO, NASA / JPL

A team of astronomers led by Meredith MacGregor and Alycia Weinberger of the Carnegie Institution for Science (USA) announced last March the detection of a massive stellar eruption. The explosion of energy radiation took place on the surface of the nearest star of our own Sun, Proxima Centauri. But this discovery raises new questions about Proxima b, which orbits around Proxima Centauri at 4.23 light-years from Earth, and more particularly on the livability of this neighbor exoplanetary.
The observation, made last year by the Atacama Large Millimeter/submillimeter Array, or ALMA, a radio telescope composed of 66 antennas, would have revealed here an eruption 10 times brighter than the most important ones observed on the Sun at similar wave lengths. “March 24, 2017 was not an ordinary day for Proxima,” notes Meredith MacGregor. First preceded by a first small eruption, the celestial event would have increased the brightness of Proxima Centauri by 1000 times for 10 seconds. As a whole, the event lasted less than two minutes, on the 10 hours of observation recorded between January and March of last year.

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The brightness of Proxima Centauri observed by ALMA on March 24, 2017. The massive solar flare is represented in red.At its peak, the torch would have multiplied the brightness of Proxima Centauri by 1,000. Credit: Meredith MacGregor.

And concerning Proxima b? “It is very likely that she was bombarded by high energy radiation during this flash of light,” says the researcher, adding that it was already known that Proxima Centauri had regular explosion, but usually smaller.

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“Over the billions of years since the formation of Proxima b, eruptions like this one could have evaporated any atmosphere or ocean and sterilized the surface.” If this was the case, then life on Proxima b seems very compromised.

The study was published in The Astrophysical Journal.

Carl Frantz

Polyglot, humanitarian, Carl was born in Germany but raised in the USA. He writes mostly on tech, science and culture.