Reviewed by Lexie CornerDec 18 2024
An international team of researchers has identified a binary star system orbiting near Sagittarius A*, the supermassive black hole at the center of the Milky Way galaxy. This is the first documented discovery of a stellar pair in close proximity to a supermassive black hole. The study was published in Nature Communications.
Location of binary star D9 in the Milky Way. Image Credit: European Southern Observatory
The discovery, made using data from the European Southern Observatory’s Very Large Telescope (ESO’s VLT), provides valuable insight into how stars can survive in environments with intense gravitational forces. It could also enable the detection of planets near Sagittarius A*.
Black holes are not as destructive as we thought.
Florian Peißker, Study Lead Author and Researcher, University of Cologne
Binary stars are systems of two stars that orbit around a common center of mass. They are common throughout the universe, but they have not previously been observed near a supermassive black hole, where intense gravitational forces can destabilize stellar systems.
This discovery shows that some binary stars can temporarily persist even in extreme environments. The newly identified binary star, named D9, is estimated to be just 2.7 million years old. However, the strong gravitational pull of the nearby black hole is expected to cause the pair to merge into a single star within about one million years—a relatively short lifespan for a system of this kind.
This provides only a brief window on cosmic timescales to observe such a binary system — and we succeeded!
Emma Bordier, Study Co-Author and Researcher, University of Cologne
Emma Bordier is a former student at ESO.
For many years, scientists believed that the extreme conditions near a supermassive black hole would prevent new stars from forming. However, the identification of several young stars near Sagittarius A* has challenged this view. The discovery of a young binary star further suggests that even stellar pairs can form and exist, albeit briefly, in such harsh environments.
The D9 system shows clear signs of the presence of gas and dust around the stars, which suggests that it could be a very young stellar system that must have formed in the vicinity of the supermassive black hole.
Michal Zajaček, Study Co-Author and Researcher, Masaryk University
Michal Zajaček is also associated with the University of Cologne.
The newly discovered binary star was found within the dense cluster of stars and other objects orbiting Sagittarius A*, known as the S cluster. One of the most intriguing features of this cluster is the presence of G objects, which resemble stars but behave like clouds of gas and dust.
While studying these G objects, the team identified an unusual pattern in the star D9. Data collected with the VLT’s ERIS instrument, along with archival data from the SINFONI instrument, revealed periodic changes in D9’s velocity. These changes indicated that D9 is actually a binary system, consisting of two stars orbiting a common center of mass.
“I thought that my analysis was wrong,” Peißker adds, “but the spectroscopic pattern covered about 15 years, and it was clear this detection is indeed the first binary observed in the S cluster.”
The findings offer new perspectives on the mysterious G objects. The team proposes that these objects could include binary stars that have not yet merged, as well as material remnants from stars that have already merged.
The precise nature of many objects near Sagittarius A*, and the mechanisms by which they form in such close proximity to the supermassive black hole, remain uncertain. However, upcoming advancements like the GRAVITY+ upgrade to the VLT Interferometer and the METIS instrument on the ESO’s Extremely Large Telescope (ELT), currently under construction in Chile, promise to shed light on these mysteries. These state-of-the-art tools will enable more detailed observations of the Galactic center, likely clarifying the nature of known objects and potentially identifying additional binary stars and young stellar systems.
“Our discovery lets us speculate about the presence of planets since these are often formed around young stars. It seems plausible that the detection of planets in the Galactic center is just a matter of time,” concludes Peißker.
Journal Reference:
Peißker, F., et al. (2024) A binary system in the S cluster close to the supermassive black hole Sagittarius A*. Nature Communications. doi.org/10.1038/s41467-024-54748-3.