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Credit: ESA/Hubble & NASA

Proxima Centauri is the star closest to our sun, a red dwarf that is a mere four light years away. An exoplanet circling may be in what scientists have called the “habitable zone,” a distance just far enough to potentially support life.

But the star was caught blasting out a huge flare of such force that is made the star 1,000 times brighter than normal. The flare would likely wipe out any life on the exoplanet Proxima b orbiting the star, write the scientists in the journal Astrophysical Journal Letters.

“Over the billions of years since Proxima b formed, flares like this one could have evaporated any atmosphere or ocean and sterilized the surface, suggesting that habitability may involve more than just being the right distance from the host star to have liquid water,” said Meredith MacGregor, an astronomer with the Carnegie Institution for Science, and lead author.

The astronomers observed Proxima Centauri for about 10 hours total between January and March 2017, using Atacam Large Millimeter/submillimeter Array, or ALMA, the radio-telescope facility in the deserts of northern Chile.

The flare was noticed here on Earth on March 24, 2017. It lasted about one minute. But the star’s light became 1,000 brighter than normal – and was 10 times larger than anything our sun emits, according to the light measurements.

“It’s likely that Proxima b was blasted by high energy radiation during this flare,” said MacGregor.

Proxima b had been considered to be in the “habitable zone,” a distance away from its star to potentially host water and life. But the new findings have cast doubt on whether that is possible, the scientists said.

“There is now no reason to think that there is a substantial amount of dust around Proxima Cen – nor is there any information yet that indicates the star has a rich planetary system like ours,” said Alycia Weinberger, co-lead author, also of the Carnegie Institution for Science.

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