Researchers from the University of Cologne and Masaryk University in Brno (Czech Republic) have discovered the fastest known star, traveling around a black hole in record time. The star S4716 orbits Sagittarius A*, the black hole at the center of our Milky Way, in four years, reaching a speed of about 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 is equivalent to 149,597,870 kilometers. The study is published in The Astrophysical Journal†
Near the black hole at the center of our galaxy is a densely packed cluster of stars† This cluster, called the S-cluster, is home to more than a hundred stars that differ in their brightness and mass. S stars move very fast. “A prominent member, S2, acts like a large person sitting in front of you in a movie theater: it blocks your view of what’s important,” says Dr. Florian Peissker, lead author of the new study. “The view of the center of our galaxy is therefore often obscured by S2. In short moments, however, we can observe the vicinity of the central black hole.”
Through continued refinement of analytical methods, along with observations spanning nearly two decades, the scientist now undoubtedly identified a star that travels around the central supermassive black hole in just four years. A total of five telescopes have observed the star, four of which have been combined into one large telescope to enable even more accurate and detailed observations. “Having a star in a stable orbit so close and fast to a supermassive black hole was completely unexpected and marks the limit that can be observed with traditional telescopes,” Peissker said.
In addition, the discovery sheds new light on the origin and evolution of the orbits of fast-moving stars at the heart of the Milky Way. “The short, compact orbit of S4716 is quite puzzling,” said Michael Zajaček, an astrophysicist at Masaryk University in Brno who was involved in the study. “Stars cannot form as easily near the black hole. S4716 had to move inward, for example by approaching other stars and objects in the S cluster, causing its track shrink significantly.”
Florian Peißker et al, Observation of S4716 – a star orbiting 4 years around Sgr A*, The Astrophysical Journal (2022). DOI: 10.3847/1538-4357/ac752f
Provided by Universität zu Köln
Quote: 8,000 kilometers per second: star with shortest orbital black hole discovered (2022, July 5) recovered on July 5, 2022 from https://phys.org/news/2022-07-kilometers-star-shortest-orbital-period .html
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