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At a little less than 8000 light-years from Earth is a monster: a black hole that actively eats its companion.
This pair of stars – one dead, the other dying – called V 404 Cygni. The black hole was formed a long time ago, when an extremely massive star exploded. The core has collapsed, leaving behind a black hole of a mass nine times greater than that of our Sun. The other star is more like the Sun, although a lower and colder mass, but it is nearing the end of its life and has started to swell to become a red giant. It is a subgiant at this moment, of a diameter several times greater than that of the Sun.
The star revolves around the black hole in about 6.5 days. They are so close together that the gravity of the black hole draws the material from the sub-giant. However, this question does not fall directly into the black hole, as the orbital movement of objects gives it a fairly decent lateral velocity. Instead, this material spirals around the black hole, forming a disc of material around it called accretion disk.
Materials close to the black hole move incredibly fast, at a speed close to that of light, while materials move more slowly into orbit. While the slower material in the disc rubs against the faster displacement, the friction is so important that it heats the disc at a temperature of several degrees and that it radiantly radiates on the electromagnetic spectrum, X-ray radio waves.
The material in the disc also generates a powerful magnetic field, which winds like a tornado around the black hole. It is so powerful that it can extract matter from the disc and blow it into twin beams perpendicular to the disc; this substance cries away from the black hole at a fraction of the speed of light. Sometimes the material of the accretion disk that feeds these beams is a hiccup, and you get a bigger drop of ejected material, which becomes very bright and then fades over time.
If your mind is still not crushed by the colossal power of this system, well, we still have not done it. Because astronomers have now determined that the direction of the jets changes, moving several degrees in just a few seconds. hours. Why? Because the black hole literally drags the fabric of space-time around him.
Black holes are of course known for their intense gravity, which can apply tremendous force to the materials around them. However, everything that happens with gravity distorts space-time – that's what gravity is, a breach in the structure of space and time – and if that object also turns, it shoots space-time, wrapping it around him. This is another strange result of general relativity.
Think of it as a bowl containing honey. If you put a ball in the honey and turn it, it will cause the honey with it because of the friction. Objects very close to the ball move faster than objects further away. The same thing happens with an object rotating in space; the space closest to the object will be moved with the spin. This is called the Lens-Thirring effect, or more familiarly, and more colorful. slide the frame.
The spinning Earth does this to space around it, but the effect is minimal as the Earth is of such a low mass. But a black hole has a huge gravity and the effect can be deep enough around it.
When the black hole of the V404 Cygni turns, he drags some space with him. But here's the really weird part (and we've set a bar high enough for weird here): the black hole does not turn up and down with respect to the accretion disk, and that affects the way the material flows very close to the black hole.
The black hole is inclined compared to the orbit of the subgiant star around him. The material from the other star remains in the orbital plane of the two objects as it approaches the black hole, but as it gets closer, it feels the effect of sliding the frame and squeezes it. The content located near the black hole wants to place it in the plane of the equator of the black hole, so that the disc deforms several degrees very closely.
When you apply a force to a rotating object (such as a material in the disc), it starts to precede – it looks like the rotation of the rotating plate, due to friction with the surface on which it rotates. The axis of the material that rotates around the black hole flickers, forming a circle in the sky. The Earth does so because of the gravity of the Moon and its axis slowly wobbles every 26,000 years or so. The forces in the black hole and the sliding of the frame are so huge, however, that the disk of material near the black hole precedes. every two hours. This means that the direction in which the jets of material moving to the outside moves also makes a complete circuit once every 2.6 hours at most.
That's what astronomers have seen! They used very long basic interferometry (essentially combining the power of radio telescopes from around the world to create a virtual Earth-size telescope) to observe the blurring of materials in black hole jets and literally see the jets rock in the space of a few hours, sending pieces of material in one direction, then in another. The jets oscillated about 36 ° in both directions as they whirled, sending material in different directions.
A good question however remains: Why is the black hole inclined with respect to the accretion disk? It is possible that when it formed in the center of the supernova billions of years ago, the huge explosion was a little out of the way. This asymmetry can create a pretty big blow in the heart of the star. Thus, when it collapsed to form the black hole, it reversed by about 18 °. Now, as and when, the jets gush like a garden sprinkler, thus swinging this 36 ° (18 ° in one direction and 18 ° in the other).
Yeah. I know. Trust me, it's hard for anyone to think on these scales.
But not impossible. That's what scientists do.
Yet there is nothing in this story that destroys the spirit. Black holes, distorted space-time, temperatures that vaporize matter, exploding blobs at a large fraction of the speed of light, virtual telescopes the size of planets, titanic explosions and literal stripping of a star at the 39; another.
But what I like in all this – in addition to the impressive reality – is that we can understand that. The Universe is a very strange place, with things so outside of our concept of normal that without science, it would seem magical. But that's the beauty of science: it helps us understand these things, and what seemed like a fantasy just becomes what the cosmos does.
And what it does is no less amazing because of that. I say it's even more amazing, because now we can see the mechanisms behind these things, and discover how they work.
There is still mystery, fear and beauty … and on top of that, we can add comprehension.
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