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upstart writes:

8,000 kilometers per second: Star with the shortest orbital period around black hole discovered:

Researchers at the University of Cologne and Masaryk University in Brno (Czech Republic) have discovered the fastest known star, which travels around a black hole in record time. The star, S4716, orbits Sagittarius A*, the black hole in the center of our Milky Way, in four years and reaches a speed of around 8,000 kilometers per second. S4716 comes as close as 100 AU (astronomical unit) to the black hole—a small distance by astronomical standards. One AU corresponds to 149,597,870 kilometers. The study has been published in The Astrophysical Journal.

[...] By means of continuously refining methods of analysis, together with observations covering almost twenty years, the scientist now identified without a doubt a star that travels around the central supermassive black hole in just four years. A total of five telescopes observed the star, with four of these five being combined into one large telescope to allow even more accurate and detailed observations. "For a star to be in a stable orbit so close and fast in the vicinity of a supermassive black hole was completely unexpected and marks the limit that can be observed with traditional telescopes," said Peissker.

Journal Reference:
Florian Peißker, Andreas Eckart, Michal Zajaček, and Silke Britzen. Observation of S4716—a Star with a 4 yr Orbit around Sgr A* - IOPscience, [open access] The Astrophysical Journal (DOI: 10.3847/1538-4357/ac752f)

Original Submission