Astronomers have discovered the fastest star in the known universe
The fastest star in the known universe orbits the Sagittarius A black hole in the center of the Milky Way, which is about 26,000 light-years from the Sun.
The star, called S4716, is part of a cluster of over 100 stars known for the extremely fast way in which it moves, but its speed seems simply dizzying: in a second it travels 8,000 kilometers.
At the center of our galaxy, the Milky Way, is this massive black hole, Sagittarius A, a true gravitational monster, which is surrounded by a swarm of stars, called the S Swarm, which orbits around it at high speed. First identified in 1996, these S stars can be characterized at speeds of up to several thousand kilometers per second, some of them moving in very strange orbits.
After observing S4716 for almost 20 years, scientists have determined that this star moves around the supermassive black hole – which has a diameter of 23.5 million kilometers – in just four years, at a speed of 8,000 kilometers per second. It took five telescopes to observe the star, four of which were combined into a single larger telescope to allow for more accurate and detailed observations.
The S4716 is up to 100 astronomical units (AU) close to the black hole, a distance considered short by astronomical standards. An AU has almost 150 million kilometers. The S4716’s short-range orbit continues to amaze scientists.
“Stars cannot form easily near a black hole. S4716 had to move inward, for example approaching other stars and objects in cluster S, which caused a significant reduction in its orbit,” said Michael Zajaček, an astrophysicist at Masaryk University in Brno, Czech Republic. , which contributed to the study.
“It was completely unexpected for a star to be in a stable orbit, so close and fast, in the vicinity of a supermassive black hole and marks the limit to how far observations can be made with traditional telescopes,” said Florian Peissker, lead author of the new study, which was published in The Astrophysical Journal.