An international group of scientists has discovered a binary star that is orbiting close to Sagittarius A*, which is the supermassive black hole located at the heart of our galaxy. This marks the first instance of finding a pair of stars near a supermassive black hole. This breakthrough enhances our knowledge of how stars can survive in extreme gravitational conditions and may lead to the future discovery of planets in the vicinity of Sagittarius A*.
An international group of scientists has discovered a binary star located near Sagittarius A*, the supermassive black hole at the center of our galaxy. This is the first time a pair of stars has been observed in proximity to a supermassive black hole. This finding, derived from data gathered by the European Southern Observatory’s Very Large Telescope (ESO’s VLT), improves our understanding of how stars can endure in extreme gravitational environments and might open the door for the discovery of planets near Sagittarius A*.
“Black holes are not as destructive as we previously believed,” states Florian Peißker, a researcher from the University of Cologne, Germany, and the lead author of the newly published study in Nature Communications. While binary stars—pairs of stars that orbit each other—are quite common throughout the Universe, they had never been identified near a supermassive black hole, where strong gravitational forces could destabilize stellar systems.
This recent finding illustrates that some binary star systems can manage to exist, even when faced with destructive forces. The newly identified binary star, referred to as D9, has been observed at a remarkable time: it is estimated to be just 2.7 million years old, and the significant gravitational influence of the nearby black hole is expected to lead to its merger into a single star in only one million years—an incredibly short period for such a young system.
“This gives us only a fleeting opportunity to observe such a binary system within cosmic timelines—and we did it!” remarks co-author Emma Bordier, another researcher from the University of Cologne and a former student at ESO.
For many years, it was thought that the extreme environment surrounding a supermassive black hole hindered the formation of new stars. However, several young stars have been discovered close to Sagittarius A*, challenging this belief. The identification of the young binary star now indicates that even star pairs are capable of forming under these harsh conditions. “The D9 system shows evident signs of gas and dust around the stars, indicating that it might be an exceptionally young stellar system that likely formed in the vicinity of the supermassive black hole,” explains co-author Michal Zajaček, a researcher at Masaryk University in Czechia and at the University of Cologne.
The newly identified binary star was located within a dense collection of stars and other cosmic objects orbiting Sagittarius A*, known as the S cluster. Most intriguing within this cluster are the G objects, which seem to act like stars yet appear as clouds composed of gas and dust.
During their investigations of these enigmatic G objects, the team discovered an unexpected pattern in D9. The data acquired using the VLT’s ERIS instrument, along with historical data from the SINFONI instrument, revealed repetitive changes in the star’s velocity, confirming that D9 is actually made up of two stars orbiting one another. “I initially questioned the accuracy of my analysis,” says Peißker, “but spanning approximately 15 years, the spectroscopic pattern clearly indicated that this detection is indeed the first binary star seen within the S cluster.”
The findings provide new insights into the potential identities of the mysterious G objects. The team suggests that these phenomena could be a mix of binary stars that have yet to merge, along with residual material from stars that have already combined.
The exact nature of many objects orbiting Sagittarius A*, as well as the mechanisms behind their formation so close to the supermassive black hole, continues to elude clear understanding. However, improvements such as the planned GRAVITY+ upgrade to the VLT Interferometer and the METIS instrument on the Extremely Large Telescope (ELT), currently being built in Chile, have the potential to shed light on these mysteries. Both instruments will enable more detailed observations of the Galactic center, helping to clarify the characteristics of known objects and likely leading to the discovery of additional binary stars and youthful systems. “Our discovery opens the door to the possibility of planets existing around these young stars. It seems realistic that finding planets in the Galactic center is merely a matter of time,” Peißker concludes.
