As for the stars, SDSSJ013333 looks like the quiet child in school that no one remembers. Small, weak and unimaginable, it doesn’t gain much attention. That’s until he gets very angry.
A few days before the end of 2018, the Xinglong Observatory’s Ground Angle Ground Camera (GWAC) alerted researchers to an explosion of light that deserves attention.
After reaching its peak in less than a minute, the entire event – a solar flare called GWAC 181229A – lasted several hours. But given where it came from, it would be one worth considering for record books.
A brief tour of the star catalogs quickly revealed SDSSJ013333, which was spinning on its own about 490 light-years away, so dark and distant astronomers had difficulty determining exactly how far it really was. Not a star you would expect something so bright to explode.
SDSSJ013333 belongs to a category of stellar objects called ultra-cool dwarfs. Usually, about a third of the mass of our own Sun, they have an effective temperature that is only half as warm and a slow-burning furnace that can last hundreds of billions of years.
But while ultra-cool dwarfs might take things slow, from time to time their magnetic fields get caught and reconnected in ways that see them erupt with huge bursts of radiation and plasma.
We’re not even talking about a little frying. Due to the brilliance of many such emissions, these missiles can only be described as super.
Usually, the surfaces are the work of young people, especially the slightly warmer red dwarfs. One of a red dwarf was caught by a team of Japanese researchers last year, measuring about 20 times stronger than anything seen coming out of our Sun.
But the flame produced by the ultra-cool SDSSJ013333 left a break that would be the most embarrassing.
Usually measured in a unit of energy called erg (from an ancient Greek word for work, ergon), a typical flare could take out around 10 ^ 30 erg. Surfaces can reach up to about 10 ^ 36 erg.
Astronomers have estimated that SDSSJ013333 released just over 10 ^ 34 energy ergs; a crazy effort for such a cold-hearted star and probably among the greatest ever recorded for one of its special class.
In other words, the flame briefly made the star 10,000 times brighter, taking its magnitude from just over 24 to a dazzling 15. Not something we would see with the naked eye, but bright enough to a good telescope to be able to capture.
The researchers made their results available on the pre-published arXiv database for public review, where we can read their approach while awaiting peer review.
As remarkable as the event is, only in the context of other flames can we learn how ultra-cool dwarfs form and develop – representing about 15% of all stellar objects in our corner of the galaxy.
“Due to the wide field of view and the high cadence of the survey, GWAC is very suitable for detecting white light. In fact, so far we’ve detected more than 130 white lights flhas an amplitude greater than 0.8 mag “, the team reports.
“It is expected that more GWAC units will operate in the next two years, aiming to increase the detection rate of high-amplitude stellar flames by simultaneously monitoring over 5,000 square degrees.
There’s a lot of space. But we will have to cast a wide net to see what else is hidden in our galaxy.
Having solid evidence of what these stars are capable of producing can help astronomers better understand the physics that are flipping beneath their surface.
It also has implications for the possibility of life around these stars.
An ultra-cool dwarf who has become famous in recent years is TRAPPIST-1. Found surrounded by an extended family of exoplanets – some of which are in an area that could wet them with liquid water – it was once speculated as a hot spot for future alien hunters.
That was until astronomers figured out how often TRAPPIST-1 could bake its tiny world baby in a high-energy solar wind sterilizer tsunami.
Similarly, if SDSSJ013333 had hosted an alien paradise before, there is little chance of finding much there.
This research was published on arXiv.org.