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posted by Fnord666 on Monday August 17 2020, @07:50AM   Printer-friendly
from the pushing-the-speed-limit dept.

Fastest star ever seen is moving at 8% the speed of light:

In the center of our galaxy, hundreds of stars closely orbit a supermassive black hole. Most of these stars have large enough orbits that their motion is described by Newtonian gravity and Kepler's laws of motion. But a few orbit so closely that their orbits can only be accurately described by Einstein's theory of general relativity. The star with the smallest orbit is known as S62. Its closest approach to the black hole has it moving more than 8% of light speed.

[...] For years, S2 was thought to be the closest star to SgrA*, but then S62 was discovered. As a team recently discovered, it's a star about twice as massive as the sun that orbits the black hole every 10 years. By their calculations, at the closest approach, its speed approaches 8% of the speed of light. That's so fast that time dilation comes into play. An hour at S62 would last about 100 Earth minutes.

Because of its proximity to SgrA*, S62 doesn't follow a Keplerian orbit. Rather than being a simple ellipse, it follows a spirograph motion by which its orbit precesses about 10 degrees with each cycle. This kind of relativistic precession was first observed with the orbit of Mercury, but only as a small effect.

Journal Reference:
Florian Peißker, Andreas Eckart, and Marzieh Parsa. S62 on a 9.9 yr Orbit around SgrA* - IOPscience, The Astrophysical Journal (2020) (DOI: 10.3847/1538-4357/ab5afd)


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  • (Score: 2) by FatPhil on Tuesday August 18 2020, @06:58PM

    by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Tuesday August 18 2020, @06:58PM (#1038461) Homepage
    Unfortunately the existence of a nett average CMB drift hasn't provided us with anything more than another thing to shrug our shoulders at and say "oh, that's interesting, I guess". It could be, and is, called a rest frame, but there's no useful thing that we know of that's actually in that frame, so it's just an abstract concept. If you want to be positive, and not an old grump like me, you could say "but it's like the Greenwich Meridian, now we have a universal reference", but meh - it's still pretty arbitrary, it has led us to no new conclusions and insights apart from its own value. Now you've got a velocity you can subtract from every other velocity. Congratulations. I hope you really enjoy subtraction.

    Yes, I have been reading Sabine Hossenfelder's blog all day, how did you guess?
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