Two years ago, our star’s next door neighbor – Proxima Centauri – got a little emotional. It happens from time to time, only this time, the small red star really let go. A storm of fury that breaks its previous records, outdoing anything our own Sun could manage by magnitudes.
Sure, we were eavesdropping, but it’s all in the name of science. Besides, we now have some galactic gossip we’re dying to share – this was not your typical solar eruption.
As far as neighbors go, you could do worse than Proxima Centauri. At a mere 4 light-years (just over 30 trillion kilometers) over the back fence, it’s close enough to keep an eye on without being prone to blowing up in a life-destroying cataclysm.
That doesn’t mean it’s quiet. Like most hot-tempered red dwarf stars, Proxima Centauri vents its rage every now and then in a brilliant display of radiation, spilling streams of plasma and light out into its system with a manic snapping and rejoining of its magnetic fields.
This is bad news for its host of innermost planets, which periodically cop a roasting that makes it unlikely that any complex organic chemistry on the surface would have remained intact long enough to spark into life.
But for us, watching these outbursts from a safe distance gives insight into the mechanisms of stellar physics. In 2019, astronomers trained nine telescopes around the globe on Proxima Centauri for a marathon 40-hour session.
They weren’t planning on missing any details – using telescopes such as the Australian Square Kilometre Array Pathfinder, the Atacama Large Millimeter/submillimeter Array, and the Transiting Exoplanet Survey Satellite, they listened in on multiple frequencies, from radio to X-ray.
“It’s the first time we’ve ever had this kind of multi-wavelength coverage of a stellar flare,” says astrophysicist Meredith MacGregor from University of Colorado Boulder.
“Usually, you’re lucky if you can get two instruments.”
And oh boy, they weren’t disappointed. Not only did five of their instruments catch sight of the largest flare to be observed in the Proxima Centauri system to date, the signature of the eruption was strange enough to suggest they had an entirely new kind of solar event on their hands.
Back in 2016, astronomers caught a similar superflare, one that could be seen without telescopes.
Though technically bigger, becoming 14,000 times brighter over the span of a few seconds, this more recent activity was largely in the form of wavelengths we can’t see, such as in the ultraviolet and radio parts of the spectrum.
Finding such a strong surge in the radio zone of millimeter range waves was completely unexpected, making this flare really worth paying attention to.
“In the past, we didn’t know that stars could flare in the millimeter range, so this is the first time we have gone looking for millimeter flares,” says MacGregor.
The timing and energies of the different wavelengths of light in the flare provide astrophysicists with a novel look into the mechanisms behind flare production, adding details to our models.
Knowing that solar flares emit in this part of the spectrum means researchers will be more inclined to train a greater range of instruments on variable stars in the future in the hopes of catching a stray whisper of radiation they missed before.
“There will probably be even more weird types of flares that demonstrate different types of physics that we haven’t thought about before,” says MacGregor.
This won’t be the last tantrum we’ll see Proxima Centauri have, and probably not even the biggest. While this unusual eruption was the largest of the flares seen during the 40-hour window of observations, it wasn’t the only one the researchers saw.
In fact, our tiny neighbor could be in a near constant rage, unleashing its hostility at least once a day. Maybe more.
At least its temper isn’t as bad as AD Leonis, another angry red dwarf in our neighborhood. Now there’s some gossip.
This research was published in The Astrophysical Journal Letters.
