Scientists Spot the First Dormant Black Hole Outside the Milky Way
Hiya!
Black holes are one of the many mysteries in our universe. Actually, they’re more like a mystery wrapped in a puzzle with a multiverse of enigmas woven throughout. In other words, we know very little about them, and we have no idea how much we don’t know, which means we also don’t know how much we do know. But, what we think we know tickles and bends our minds in new ways as we attempt to make sense of their bizarre nature.
There are a few things we’re pretty sure of, though. Black holes have enormously dense masses with a gravitational pull so strong that not even light escapes. We’re also convinced that most black holes are formed when massive stars die and that they come in various sizes. But not all of them behave the way we expect. Some aren’t active. In fact, you could call them dormant.
How Many Kinds of Black Holes Are There?
There are a few different black holes, though NASA states three classifications – Steller, Intermediate, and Supermassive. Gotta hand it to them for the self-explanatory and easy-to-remember names.
Stellar black holes are the smallest and results from the violent death of a colossal star called a supernova. This explosion is so bright that it can outshine an entire galaxy for a week. What’s left is a small dense core, which, if it’s large enough, will collapse to form a Stellar black hole.
(Side note: Our sun isn’t big enough to become a black hole. Instead, it’ll gradually grow dimmer as it loses fuel until eventually fading away completely.)
Super Massive black holes are typically found near the center of a galaxy – like Sagittarius A* in the middle of the Milky Way — and as the name suggests, they’re supermassive. Whereas, as I’m sure you can guess, Intermediate black holes fall somewhere in the middle.
Experts don’t know how either Supermassiveor Intermediate black holes become so large, but there are plenty of ideas. In fact, a recent article in Big Think claims to have finally solved the mystery of how the first supermassive black hole formed.
I used to think black holes were the same regardless of size, but have since learned my assumption is wrong. Some black holes, it appears, are dormant. Unlike the black holes we’re familiar with, these ones aren’t actively pulling mass toward them or swallowing everything in their sight.
Instead, they float harmlessly without interacting with their surroundings or a care in the world. There are definitely more astrophysicists who want to learn about dormant black holes, but so far, their lack of activity appears to be connected to binary star systems.
Binary Star Systems and Dormant Black Holes
A binary star system is when two stars orbit each other. Dormant black holes are believed to be the result of when one of the stars in a binary system dies before the other. The new black hole can’t escape the gravity of the remaining star, but its dormancy means it isn’t devouring its counterpart either. The black hole sticks nearby, stuck in orbit with the star’s gravity until it too eventually dies.
Interestingly, many scientists now think most stars are part of a binary system. The binary orbits could even allow the stars to travel over 10,000 light years apart, which also makes them hard to identify. Sagittarius A*, the supermassive black hole in the center of the Milky Way, is thought to be mostly dormant. Which is theoretically why we aren’t catapulting toward it at alarming speeds. This also suggests Sagittarius A* may have a very-much-alive-binary star twin it’s orbiting somewhere in the universe.
New Finding
But as of July 2022, a large team of scientists led by Tomer Shenar, working at the European Southern Observatory (ESO) in Chile, spotted a dormant black hole called VFTS 243 using the perfectly named Very Large Telescope (VLT). It’s the first dormant black hole discovered outside the Milky Way galaxy. The team published their findings in Nature Astrology, though ESO provides a free version too.
Specifically, VFTS 243 is in the Large Magellanic Cloud, one of our galactic neighbors, and visible to those lucky to be in the Southern Hemisphere. The Large Magellanic Cloud is thought to have at least 30 billion stars, which makes it ideal for studying because we have a better perspective and a more complete image.
Sort of like how it’s easier to assess your appearance when observing your reflection in a mirror rather than looking directly down, which distorts your perspective.
According to the study, it took nearly six years and searching nearly 1,000 stars in the Tarantula Nebula area of the Large Magellanic Cloud to find VFTS 243.
Ironically, some researchers, particularly Shenar, are well known for debunking several supposed black hole discoveries, but now they’ve located one themselves. “For the first time, our team got together to report on a black hole discovery instead of rejecting one.” Shenar joked in an article by the ESO about the find.
Perspective Shift
Dormant black holes open a whole gaggle of new questions in my mind. What happens when the dormant black hole’s binary partner star eventually dies too? Do they combine to form an Intermediate black hole? Does the star’s death snap the black hole awake and activate its gravitational pull? Perhaps the star will become its own black hole, and the two become binary black holes, destined to orbit each other in darkness as in light.
I dunno, but regardless, learning about the celestial relationships between binary star systems and black holes, especially the dormant ones, paints everything happening in outer space differently in my mind. I always thought of the universe as a snapshot where time stands still, and I suppose it is — but not at the same time.
Now I see the entire universe is more interconnected than I thought. Black holes, stars, and planets aren’t just haphazardly scattered around the universe. They have relationships with each other going back millions or billions of years. I can almost anthropize them. Shenar appears to also. I’ll end by sharing with you what Shenar told Popular Mechanics about how he now views VFTS 243.
“In my mind’s eye, I imagine what a turbulent life this star has experienced: it was born less massive than it currently is, in an orbit of a few days around a more massive star (now the black hole), accreted mass from it, had to suffer powerful radiation and direct impact of outflows from the nearby star.
“And then, it saw its companion star, only a few stellar radii away, fading from existence into a black hole. And it sits there, a blue widow, quietly and peacefully, orbiting the remnant of its past companion. And it looks like a normal star, and you’d never guess that it’s been through all of that. I find this inspiring.”
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