A gigantic glow from the sun’s nearest neighbor breaks records

Scientists have seen the largest solar flare ever seen from the sun’s closest neighbor, the star Proxima Centauri.

The research, which appears today in The Astrophysical Journal Letters, was led by the University of Colorado Boulder and could help shape the hunt for life beyond Earth’s solar system.

CU Boulder astrophysicist Meredith MacGregor explained that Proxima Centauri is a small but mighty star. It is located just four light years or more than 20 trillion miles from our own sun and is home to at least two planets, one of which is similar to Earth. It is also a red dwarf, the name for a class of stars that are unusually small and faint.

Proxima Centauri has about one-eighth the mass of our own sun. But don’t let that fool you.

In their new study, MacGregor and her colleagues observed Proxima Centauri for 40 hours with nine ground and space telescopes. In the process, they got a surprise: Proxima Centauri emitted a burst, or a burst of radiation starting near the surface of a star, which is considered one of the most violent seen anywhere in the galaxy.

“The star went from normal to 14,000 times brighter when observed in ultraviolet wavelengths in seconds,” said MacGregor, an assistant professor at the Center for Astrophysics and Space Astronomy (CASA) and Department of Astrophysical and Planetary Sciences (APS). ) at CU Boulder.

The team’s findings hint at new physics that could change the way scientists think about stellar eruptions. Nor do they bode well for a soft organism brave enough to live near the fleeting star.

“If there were life on the planet closest to Proxima Centauri, it would have to look very different from anything on Earth,” MacGregor said. “A human on this planet would have a bad time.”

Active stars

The star has long been a target for scientists hoping to find life outside of Earth’s solar system. For starters, Proxima Centauri is nearby. It also houses one planet, called Proxima Centauri b, which is located in what researchers call the habitable zone – an area around a star with the correct temperature range to accommodate liquid water on a planet’s surface.

But there’s a twist, MacGregor said: Red dwarfs, considered the most abundant stars in the galaxy, are also extraordinarily vibrant.

“Many of the exoplanets we have found so far are in the vicinity of stars like this,” she said. ‘But the catch is that they are much more active than our sun. They flicker much more often and more intensely. ‘

To see how much Proxima Centauri flares up, she and her colleagues did what is approaching an astrophysics coup d’état: they aimed nine different instruments at the star for 40 hours over the course of several months in 2019. Those eyes included the Hubble . Space Telescope, the Atacama Large Millimeter Array (ALMA) and NASA’s Transiting Exoplanet Survey Satellite (TESS). Five of them recorded Proxima Centauri’s enormous flash of light and captured the event while it produced a wide spectrum of radiation.

“It’s the first time we’ve ever had such multi-wavelength coverage of a stellar burst,” MacGregor said. “You’re usually lucky if you can get two instruments.”

Crispy planet

The technique yielded one of the most in-depth anatomies of a solar flare from a star in the galaxy.

The event in question was observed on May 1, 2019 and lasted only 7 seconds. Although it didn’t produce much visible light, it generated a huge wave of ultraviolet as well as radio or ‘millimeter’ radiation.

“In the past, we didn’t know stars could shine in the millimeter range, so this is the first time we’ve looked for millimeter flames,” MacGregor said.

Those millimeter signals, MacGregor added, could help researchers gather more information about how stars generate flares. Currently, scientists suspect that these bursts of energy occur when magnetic fields near a star’s surface rotate and refract with explosive consequences.

In total, the light flash observed was about 100 times more powerful than any comparable flash of light seen from Earth’s sun. Over time, such energy can clear a planet’s atmosphere and even expose life forms to deadly radiation.

That type of eruption may not be rare in Proxima Centauri. In addition to the big boom in May 2019, the researchers recorded many other flares during the 40 hours they spent looking at the star.

“The planets of Proxima Centauri are hit by something like this not once in a century, but at least once a day, if not several times a day,” MacGregor said.

The findings suggest there may be more surprises in store for the sun’s closest companion.

“There will probably be more weird kinds of torches that demonstrate different kinds of physics that we haven’t thought about before,” MacGregor said.