First binary star found near a supermassive black hole

Dec. 17 () –

An international team has detected a binary star orbiting near Sagittarius A star, the supermassive black hole located in the center of our galaxy.

It is the first time that a stellar pair has been found in the vicinity of a supermassive black hole. The discovery, based on data collected by the European Southern Observatory’s (ESO) Very Large Telescope (VLT), helps understand how stars survive in environments with extreme gravity, and could pave the way for the detection of planets close to Sagittarius A staraccording to the authors of the study.

“Black holes are not as destructive as we thought,” declares in a statement Florian Peisker, researcher at the University of Cologne and lead author of the study published in Nature Communications. Binary stars, pairs of stars that orbit each other, are very common in the universe, but have never before been detected near a supermassive black hole, where intense gravity can make star systems unstable.

This new discovery shows that some binary systems can briefly thrive even under such adverse conditions. D9, as the newly discovered binary star is called, was detected just in time: estimated to be only 2.7 million years oldand the strong gravitational pull of the nearby black hole will likely cause it to merge into a single star within just a million years, a very small time frame for such a young system.

“This provides only a small window, on cosmic time scales, to observe such a binary system, and we succeeded!” explains co-author Emma Bordier, also a researcher at the University of Cologne and former student in THAT.

For many years, the scientific community also thought that the extreme environment near a supermassive black hole prevented new stars from forming nearby. Several young stars that are located very close to Sagittarius A star have refuted this assumption. The discovery of the young binary star now shows that Even in these harsh conditions, stellar couples can form. “The D9 system shows clear signs of the presence of gas and dust around the stars, suggesting that it could be a very young star system that must have formed in the vicinity of the supermassive black hole,” explains co-author Michal Zajacek, researcher from Masaryk University (Czech Republic) and the University of Cologne.

The newly discovered binary system was found in a dense cluster of stars and other objects orbiting Sagittarius A starcalled cluster S. The most enigmatic thing about this cluster are the G objects, which behave like stars but look like clouds of gas and dust.

While observing these mysterious objects, the team found a surprising pattern in D9. Data obtained with the VLT’s ERIS instrument, combined with archival data from the SINFONI instrument, revealed recurring variations in the star’s velocity, indicating that D9 was actually two stars orbiting each other. “I thought my analysis was wrong,” Peisker declares, “but the spectroscopic pattern spanned about 15 years, and it was clear that this detection is, in fact, the first binary system observed in the S cluster.”

THERE MAY BE PLANETS

The results shed new light on what the mysterious G objects could be. The team proposes that they could actually be a combination of binary stars that have not yet merged and leftover material from already merged stars.

The precise nature of many of the objects orbiting the Sagittarius A star, as well as how they could have formed so close to the supermassive black hole, remains a mystery. But this could soon change thanks to the upgrade of GRAVITY+, installed on the VLT interferometer, and the METIS instrument, on ESO’s Extremely Large Telescope (ELT), which is being built in Chile. Both facilities will allow the team to carry out even more detailed observations of the galactic center, revealing the nature of known objects and, undoubtedly, discovering more binary stars and young systems.

“Our discovery allows us to speculate about the presence of planets, since they often form around young stars. It seems plausible that the detection of planets in the galactic center is only a matter of time“concludes Peisker.