Researchers at the University of Cologne and Masaryk University in Brno have found the fastest known star, which roams around a black hole in record time. The star, S4716, revolves around Sagittarius A*, the black hole in the heart of our Milky Way, in four years and attains a speed of roughly 8,000 kilometers per second. S4716 appears as near as 100 AU to the black hole. This is considered a small distance by astronomical standards. One AU is about 149,597,870 kilometers. The research has been published in The Astrophysical Journal.
In the proximity of the black hole at the heart of our galaxy exists a compact cluster of stars. This cluster, named S cluster, is home to well over a hundred stars that vary in their brightness and mass. S stars move significantly fast. “One prominent member, S2, behaves like a large person sitting in front of you in a movie theater: it blocks your view of what’s important,” announced Dr.
Florian Peissker, lead author of the new study. “The view into the center of our galaxy is therefore often obscured by S2. However, in brief moments we can observe the surroundings of the central black hole.”
The finding also sheds new light on the origin and expansion of the orbit of fast-moving stars at the center of the Milky Way. “The short-period, compact orbit of S4716 is quite puzzling,” Michael Zajaček said. He is an astrophysicist at Masaryk University in Brno who was there during the research. “Stars cannot form so easily near the black hole. S4716 had to move inwards, for example by approaching other stars and objects in the S cluster, which caused its orbit to shrink significantly.”