The fastest known star: 8,000 kilometers per second

Researchers from 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 star, the black hole at the center of our Milky Way, in four years and reaches a speed of about 8,000 kilometers per second.

S4716 comes within 100 AU (Earth-Sun distances) of the black hole, a small distance by astronomical standards. The study has been published in The Astrophysical Journal. In the vicinity of the black hole at the center of our galaxy is a densely populated star cluster.

This cluster, called cluster S, hosts more than a hundred stars that differ in their brightness and mass. S stars move particularly fast. “A prominent member, S2, behaves like a large person sitting across from you in a movie theater: It blocks your view of what’s important,” said Dr. Florian Peissker, lead author of the new study. “The view towards the center of our galaxy is therefore often obscured by S2.

However, in a few moments we can observe the surroundings of the central black hole.” Through continuous refinement of analysis methods, coupled with observations spanning nearly twenty years, the scientist now unequivocally identified a star traveling around the black hole. central supermassive black in just four years.

A total of five telescopes observed the star, and four of these five were combined into one large telescope to enable even more precise and detailed observations. “For a star to be in a stable orbit so close and so fast in the vicinity of a supermassive black hole was completely unexpected and marks the limit of what can be observed with traditional telescopes,” Peissker said in a statement.

Furthermore, the discovery sheds new light on the origin and evolution of the orbit of the fast-moving stars at the heart of the Milky Way. “S4716’s short-period compact orbit is quite puzzling,” said Michael Zajacek, an astrophysicist at Masaryk University in Brno, who was involved in the study.

“Stars can’t form so easily near the black hole. S4716 had to move inwards, for example by approaching other stars and objects in the S cluster, causing its orbit to shrink significantly.”