Proxima Centauri’s ferocious flare
Intense outburst on the Sun’s nearest star is bad news for its orbiting planet
One of the most powerful flares ever seen has erupted from our neighbouring star, Proxima Centauri. A new paper revealed the flare was 100 times more powerful than anything ever seen ejecting from our own Sun and would have ravaged the atmosphere of the star’s planet.
The flare was first observed coming from the red dwarf star on 1 May 2019. It lasted just seven seconds. Though it didn’t release a huge amount of visible light, it created massive amounts of ultraviolet, radio and millimetre radiation.
“The star went from normal to 14,000 times brighter when seen in ultraviolet wavelengths over the span of a few seconds,” says Meredith MacGregor from the University of Colorado, Boulder, who headed up the study. “In the past we didn’t know that stars could flare in the millimetre range, so this is the first time we have gone looking for millimetre flares.”
To get the full picture of the flare across the electromagnetic spectrum, MacGregor’s team spent several months observing Proxima Centauri for a total of 40 hours, using nine different telescopes including the Hubble Space Telescope, the Atacama Large Millimetre Array and NASA’s Transiting Exoplanet Survey.
“It’s the first time we’ve ever had this kind of multi-wavelength coverage of a stellar flare,” says MacGregor. “Usually you’re lucky if you can get two instruments.”
During these observations, the astronomers observed many other, smaller flares being ejected from the star.
While this was good news for the astronomers trying to understand the physics behind the mega-flare on 1 May, it was less good news for the star’s planet, Proxima Centauri b. The planet lies in the star’s habitable zone, meaning it has the right temperature range for liquid water to persist on the surface and could potentially host life as we know it. Unfortunately, the constant bombardment by radiation from these flares would strip away the planet’s atmosphere, making it much less likely life could survive there.
“If there was life on the planet nearest to Proxima Centauri, it would have to look very different than anything on Earth,” says MacGregor. “A human being on this planet would have a bad time.” www.colorado.edu