https://www.eso.org/public/videos/eso1825e/ - time lapse of a 20 year period.
The black hole in question is a supermassive black hole, named Sagittarius A* (the asterisk means it is a radio source that is excited and it is pronounced "star"). The black hole is a area of space that is approximately the size of the orbit of Mercury, but packs in nearly 4.3 million solar masses. And yes, that means pretty much what it says, imagine 4.3 million suns jammed inside the orbit of Mercury. Though for a supermassive black hole, its quite small. Compare it to the black hole in the center of the M87 galaxy (the one that famously had its portrait taken a few years ago), which has 6.5 billion solar masses. Yes, that's a billion, with a B. But of course, space being completely bonkers, even that is pretty small, if you compared it to TON 618, it is estimated to be 40.7 billion solar masses.
But anyway, enough about holes in the sky. I want to mention one of the stars that are whizzing around our beloved Sagittarius A, the very imaginatively named S2 star. The star is a main sequence star with a mass of about 14 solar masses. Nothing special there. Where things get interesting is its orbit around Sgt A. Its apoapsis (furthest point in the orbit) is 1800 AU (Astronomical Unit, translates to the distance between the earth and the sun), in kilometers that would be around 270 billion kilometers, a distance that would take about 10 days for light to travel. To put that into some sort of frame, the Voyager space probes, that have recently crossed to the outside of our solar system, are less than 1 light day away.
At its closest, or at its periapsis, S2 is as close as 120 AU, 18 billion kilometers, or around 17 light hours. Lets compare that to the orbit of Pluto, which varies between 30 and 49 AU.
So, highly eccentric orbit then. So far, all good. Big numbers, but so what?
Where things get interesting is its orbital period. While Pluto takes a leisurely 248 years to do one lap around the sun, S2 does it in 16 years. That makes it one of the fastest things we've observed in orbit around another object. Pluto hasn't done even half a lap around its period, since the day we discovered it. S2 has done managed to do 6 laps around Sgt A* in the same time.
At its fastest, it reaches up to 7,650 km/s. I would like to point out, that this is kilometers per second. If you turn that into kilometers per hour, you'd have generational debt, until your bloodline dies, from the speeding ticket the Finnish police would give you, since you'd be going at 27.5 million km/h. This translates to about 2.5% of the speed of light. The fastest human made object is the Parker Solar Probe, that reached 692,000 km/h, 0.064% of speed of light, during its dive to touch the sun.
But if you were to orbit S2, or somehow standing on it and not die from the heat, radiation and gravity, you wouldn't notice the speed. Since you'd be in your own local little bubble just going about your business. Sure, the night sky would change more rapidly than on earth, but other than that, you wouldn't really feel much. Other than the intense radiation of the environment, tidal forces from going near the black hole, you know, minor stuff like that.
So, anyway. Why should anyone care about a star going fast? Well, if you don't think that's cool as fuck, I don't want to be your friend. But more importantly, the observations have been used to further confirm the theories of Einstein and black hole theories.
https://www.aanda.org/articles/aa/full_ ... 13-20.html
https://www.mpg.de/14692117/detection-o ... of-star-s2
https://www.eso.org/public/news/eso0226/
https://www.aanda.org/articles/aa/pdf/2 ... 718-18.pdf