D9 binary star orbiting Sagittarius A. Image: © ESO/F. Peißker et al., S. Guisard
The discovery of D9 disproves previously held opinions on the strength of black holes.
In a first-of-its-kind discovery, a binary star has been found orbiting close to the supermassive black hole at the centre of our galaxy.
The discovery, based on data collected by the European Southern Observatory’s (ESO) Very Large Telescope, will help scientists understand how stars survive in environments with extreme gravity and could pave the way for scientists to detect planets close to the black hole, the international team behind the discovery said.
Binary stars are a pair of stars orbiting each other. Although they are very common in the universe, they have never been found near a supermassive black hole before, where intense gravity can make stellar systems unstable.
According to the team, this new discovery shows that some binaries can “briefly thrive, even under destructive conditions”.
“Black holes are not as destructive as we thought,” said Dr Florian Peißker, a researcher at the University of Cologne, and lead author of the study published yesterday (17 December) in Nature Communications.
The newly discovered binary, named D9, is estimated to be 2.7m years old, and might merge into a single star within 1m years due to the strong gravitational force of Sagittarius A – the supermassive blackhole at the centre of the Milky Way galaxy – researchers said, providing them a brief window on the cosmic timescale to observe this system.
It was previously thought that the extreme environment surrounding a supermassive black hole prevented new stars from forming there. However, the discovery of several young stars and yesterday’s announcement of a binary star disprove previously held assumptions.
“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,” said the study’s co-author Dr Michal Zajaček, a researcher at Masaryk University in Czechia and the University of Cologne.
“I thought that my analysis was wrong,” Peißker said, “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 ‘S cluster’ refers to the dense cluster of stars and other celestial bodies orbiting Sagittarius A. The cluster includes ‘G objects,’ or celestial bodies that behave like stars, but look like gas and dust.
Although the precise nature of many of the objects orbiting Sagittarius A remain concealed, the new discovery shines more light on what the G objects could be, which – according to the researchers – could be among a combination of binary stars that have not yet merged.
“It seems plausible that the detection of planets in the galactic centre is just a matter of time,” said Peißker.
Earlier this year, MIT and Caltech scientists found a “black hole triple,” for the first time – two objects orbiting a black hole, leading them to speculate that the black hole in question was formed through a more gentle process contrary to previously held beliefs on the celestial phenomenon’s formation.
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