A newly discovered star, now designated S4716, is traveling at the breathtaking speed of 5,000 miles (8,000 km) per second around the black hole at the center of our galaxy, the Milky Way, Space.com reported.
The vast expanse of our universe means astronomers are always finding something they’ve never seen before. Earlier this week, astronomers spotted two bus-sized asteroids heading towards Earth, which will pass at distances of just a quarter of what separates the Moon from us.
Besides asteroids, our galaxy is also of particular interest to astronomers looking for signs that other planets harbor life. However, right in the center of the Milky Way there is a supermassive black hole which has been dubbed Sagittarius A* or Sgr A* and S4716 is orbiting this black hole at a breakneck pace.
What we know about S4716
From observations so far, we know that at 5,000 miles (8,000 km) per second or 18 million miles (29 million km) per hour, S4716 is the fastest star in orbit. around Sgr A*. It completes an orbit around the 14.6 million (23.5 million km) diameter black hole in just four years.
S4716 is part of a dense group of other stars that also orbit Sgr A* that astronomers call the S cluster. All of the stars in this cluster move at high speeds but vary in mass and brightness. Another star in this cluster, known as S2, is better known and is much larger than S4716.
However, S2’s orbit around the black hole takes 16 years and it comes within 11 billion miles (18 billion km) of Sgr A*. By comparison, S4716 is 9.2 billion miles (150 million km) closer to the black hole, about 100 times the distance between Earth and the Sun.
Finding a star so close to a black hole could change our understanding of the evolution of our galaxy and its fast-moving stars. “The compact, short-period orbit of S4716 is quite puzzling,” said Michael Zajaček, an astrophysicist at Masaryk University in a statement. “Stars cannot form so easily near the black hole. S4716 must have moved inward, such as approaching other stars and objects in the S cluster, which significantly reduced its orbit.”
How did astronomers spot the fastest star?
Although S2 helped us to understand more details about Sgr A*, it has drawbacks. “S2 behaves like a big person sitting in front of you in a movie theater — it blocks your view of what’s important. The view towards the center of our galaxy is therefore often obscured by S2,” said Florian Peissker, astrophysicist at the University of Cologne, who participated in this research, in a press release.
Peissker and his team used data from five telescopes, NIR2 and OSIRIS, at the Keck Observatory in Hawaii, and the Very Large Telescopes SINFONI, NACO and GRAVITY and refined their analytical techniques over more than two decades to confirm the orbital period. of S4716. “For a star to be in such a close and fast stable orbit near a supermassive black hole was completely unexpected,” Peissker added.
The research has been published in The Astrophysical Journal.
Continued monitoring of the Galactic Center and Sgr A*, the central supermassive black hole, is yielding startling and unexpected findings. This goes hand in hand with the technical evolution of terrestrial and space telescopes and instruments, but also with the progression of image filtering techniques such as the Lucy-Richardson algorithm. As we continue to plot the S cluster members near Sgr A* on their expected trajectory around the supermassive black hole, we present the discovery of a new stellar source, which we call S4716. The newly discovered star orbits Sgr A* in about 4.0 years and can be detected with NIRC2 (Keck), OSIRIS (Keck), SINFONI (VLT), NACO (VLT), and GRAVITY (VLTI). With a periapse distance of about 100 au, S4716 shows an equivalent distance to Sgr A* as S4711. These fast-moving stars undergo similar dynamical evolution, since S4711–S4716 share comparable orbital properties. We will further relate the recent discovery of a faint new star called S300 to the data presented here. Additionally, we observed a blend-star event with S4716 and another newly identified S-star S148 in 2017