Astronomers have spotted a monstrous stellar flare coming from a baby star 685 light-years away that’s estimated to be 10,000 times larger than any such event emitted by our sun.
Experts say the stellar ‘tantrum’ could provide a window into the birth of potentially habitable exoplanets, revealing how huge events shake up the material orbiting distant stars.
The M-type star is just 2 million years old, meaning it has yet to reach the size at which it will remain for most of its life.
The flare was seen coming from a star called NGTS J121939.5-355557. It was spotted by researchers using the Next-Generation Transit Survey (NGTS) telescope array in Chile.
Though M-type stars are known to have ultra-strong magnetic fields, typically preventing this type of outburst, the researchers say the rare event spotted in the recent study likely occurs about every three years.
‘This is normally a star that shows little activity and stays a constant brightness,’ said University of Warwick Ph.D. student James Jackman.
‘Then, on this one particular night, we saw it suddenly grow seven times brighter than normal for a few hours, which is pretty extreme. And then after that it goes back to normal.
‘We see these types of flares on the Sun, but no-where near as big as this,’ the researcher says.
‘On our Sun, you can do incredibly detailed studies on this kind of activity. It’s difficult to extend that understanding to other stars because the data we need hasn’t been available until now.’
According to the team, the star is what’s known as a pre-main sequence star, meaning it’s still in the early stages of its lifecycle.
‘This is an incredibly young star, only about 2 million years old,’ Jackman says.
‘You’d call it a baby – it’s going to live for ten of billions of years, so it’s in the first one percent of its lifetime.
‘Even though it’s much cooler than our Sun by about 2000 degrees it is roughly the same size, but pretty large for an M star.
‘This is because it’s still being formed from gas in the disc and contracting and cooling until it reaches the main sequence, staying at a certain radius and luminosity for billions of years.
‘Finding out these kinds of details has only been possible thanks to the Gaia mission that began earlier this year.’
The researchers say X-rays from huge stellar flares such as this may influence the formation of calcium-aluminium-rich grains called chondrules.
These arise in the star’s protoplanetary disc, and eventually come together to be asteroids and ultimately, planets.
‘A massive flare like this could be advantageous for planet formation, or it could be disruptive,’ says Professor Peter Wheatley.
‘This particular star won’t have formed its planets yet so this type of flare activity is something that astronomers will need to take into account when considering planet formation.
‘There’s a discussion at the moment around whether flares are a good or bad thing for life on orbiting habitable planets, because they output a large amount of UV radiation.
‘That could cause biological damage to surface organisms and damage their DNA.
‘On the other hand, UV radiation is required for various chemical reactions to start life and that’s not typically provided in great enough quantity by these types of stars.
‘These flares could potentially kickstart these reactions.’