Astronomers have made a groundbreaking discovery by finding a binary star system orbiting the supermassive black hole, Sagittarius A*, at the heart of the Milky Way galaxy. Led by Florian Peißker from the University of Cologne, Germany, the team identified the system, known as D9, using the European Southern Observatory’s Very Large Telescope. This discovery, published in Nature Communications, is significant not only for its rarity but also for its role in solving the cosmic mystery behind hypervelocity stars—those hurtling through space at speeds exceeding 1,000 kilometers per second.

A binary star system consists of two stars orbiting each other. Most stars in the Milky Way are single stars, but about a third belong to binary or multiple star systems. The discovery of a binary system around a supermassive black hole had been predicted but never confirmed until now. Astronomers observed the light from the stars using the Doppler effect, which revealed the characteristic wobble indicating that the stars are in orbit around each other.

The discovery sheds light on how black holes interact with nearby stars, potentially ejecting them into hypervelocity trajectories. This phenomenon likely explains the origin of hypervelocity stars that have been observed speeding through our galaxy. The team estimated that the binary stars are about 2.7 million years old and were not originally formed in the extreme environment near the black hole, suggesting they wandered into the region and adapted to the complex gravitational interactions over time.

This discovery offers crucial evidence for the theory that hypervelocity stars originate from binary systems near supermassive black holes. By studying the interactions in such systems, astronomers can better understand how these fast-moving stars are created and ejected from the galactic centre.