A massive flare from the sun's closest neighbour sets new records.

◆Scientists have discovered the largest flare ever seen from Proxima Centauri, the sun's nearest neighbour.

◆The University of Colorado Boulder led the study, which was published in The Astrophysical Journal Letters .The University of Colorado Boulder led the study, which could further influence the search for life outside Earth's solar system.

◆A violent flare erupts from the star Proxima Centauri, according to an artist's rendering. (S. Dagnello/NRAO)

CU Proxima Centauri is a tiny but powerful star, astrophysicist Meredith MacGregor of Boulder explained. It's just four light-years out from our own sun, just more than 20 trillion miles away, and it's home to at least two planets, one of which may resemble Earth. It is also known as a "red dwarf."It's also a "red dwarf," which refers to a kind of star that's extremely small and faint.

◆The mass of Proxima Centauri is around one-eighth that of our own sun. But don't be fooled by that.

◆MacGregor and her collaborators used nine telescopes on the ground and in space to observe Proxima Centauri for 40 hours in their recent research. They got a surprise in the process: Proxima Centauri expelled a flare, or a burst of radiation that starts near a star's surface, that was one of the most powerful ever seen anywhere in the galaxy.

◆"In ultraviolet wavelengths, the star went from average to 14,000 times brighter in a matter of seconds," said MacGregor, an assistant professor at CU Boulder's Center for Astrophysics and Space Astronomy (CASA) and Department of Astrophysical and Planetary Sciences (APS).

◆The results of the team point to new physics that can alter how scientists think about stellar flares. They're also bad news for any squishy organism brave enough to survive by the exploding star.

◆"It would have to be very different from everything on Earth if there was life on the planet closest to Proxima Centauri," MacGregor said. "On this world, a human would have a hard time."

◆Stars that are still involved

Scientists have been looking for life outside Earth's solar system for a long time. For starters, Proxima Centauri is close by. It also has one planet, called Proxima Centauri b, that is located in the "habitable zone"—a area around a star with the right temperature range for sustaining liquid water on a planet's surface.

 ◆But, as MacGregor pointed out, there's a catch: Red giants, which make up the majority of the galaxy's stars, are also exceptionally active.

 ◆"We've observed a couple of exoplanets around these forms of stars so far," she said. "However, they are significantly more powerful than our sun. They flare up a lot more often and with a lot more intensity."

◆To figure out how many Proxima Centauri bursts, she and her colleagues pulled off more of an astrophysics coup: Over the course of several months in 2019, they pointed nine main instruments at the star for 40 hours. The Hubble Space Telescope, the Atacama Large Millimeter Array (ALMA), and NASA's Transiting Exoplanet Survey Satellite were among the instruments used (TESS). There are five of them.

Crispy world

◆One of the most detailed anatomies of a flare from any star in the galaxy was obtained using this method.

◆The occurrence took place on May 1, 2019 and lasted just 7 seconds. Although it didn't emit any visible light, it did produce a massive amount of ultraviolet and microwave, or "millimetre," radiation.

 ◆"We didn't know stars could flare in the millimetre range in the past, so this is the first time we've been looking for millimetre flares," MacGregor said.

◆According to MacGregor, those millimetre signals could aid researchers in learning more about how stars produce flares. These blasts of energy are thought to occur as magnetic fields surrounding a star's surface curl, according to scientists.

◆The detected flare was approximately 100 times more intense than any equivalent flare seen from the sun on Earth. Such energies can deplete a planet's atmosphere over time, exposing life forms to lethal radiation.

◆That kind of flare may not be uncommon on Proxima Centauri. In addition to the significant increase in May of this year,