In a nearby binary system, flares are erupting from the surface of a red dwarf star. These flares caught the attention of the Burst Alert Telescope (BAT) on NASA's Swift satellite. After detecting the strong bursts of radiation, the satellite repositioned itself for better observation of the red dwarf star.
These flares are 10,000 times stronger and more intense than any flare ever recorded on our sun.
"We used to think major flaring episodes from red dwarfs lasted no more than a day, but Swift detected at least seven powerful eruptions over a period of about two weeks," says astrophysicist Stephen Drake at NASA's Goddard Space Flight Center. "This was a very complex event."
The red dwarf star in question exists in a binary system called DG Canum Venaticorum (DG CVn) around 60 light-years away from the Earth. Both of its stars are red dwarfs have masses about one-third of our sun's. Because they are so close to each other, though, Swift doesn't know exactly which star the flares were coming from.
But there is still no denial that these bursts were happening. Swift picked up the first flare on April 23. After that, it notified other astronomers of this rare event.
"For about three minutes after the BAT trigger, the superflare's X-ray brightness was greater than the combined luminosity of both stars at all wavelengths under normal conditions," says Adam Kowalski, also from NASA's Goddard Space Flight Center. "Flares this large from red dwarfs are exceedingly rare."
The red dwarf star, however, didn't stop there. Three hours after the first burst, another flare erupted, almost as strong as the initial one.
The flares continued for the next 11 days, although each became weaker than the last, much like aftershocks that often follow an earthquake. The activity eventually died down after about 20 days, when Swift's measurements reported a normal level of X-ray emissions from that region of space.
It's slightly baffling that a star so much smaller than our sun could emit such powerful bursts, but scientists explain that this happened due to the star's spin.This particular star rotates 30 times faster than our sun. Faster spins amplify the magnetic field around the star, which results in more intense flares coming off its surface.
The red dwarf star in DG CVn is probably relatively young at about 30 million years old. Because of this, it could help us understand the early life of stars. NASA's Swift is now keeping a steady eye on it for further activity.
