The Gaia Black Hole 3 binary system (voice - music)

This video describes the binary system of Gaia Black Hole 3 or Gaia BH3.

The Gaia space observatory, operated by the European Space Agency (ESA), uncovered a remarkable find within the constellation Aquila. Initially, Gaia detected what seemed to be a solitary, ageing giant star in that celestial region. During the validation process, which covers over 5.5 years of observations, a remarkable discovery has come to light. The data hinted at the existence of a massive, unseen companion.

The peculiar movement of the observed star diverged significantly from what's anticipated for a solitary stellar system, leading scientists to infer the presence of a black hole as the most plausible explanation. Through rigorous analysis, researchers determined that this black hole, dubbed Gaia BH3, boasts an astonishing mass roughly 33 times that of our Sun, making it the most massive of its kind originating from a star within our galaxy known today.

This celestial pair exhibits a captivating orbital interplay. The giant star and the black hole engage in a gravitational duet, circling a shared centre of mass approximately every 11.6 years. At their closest encounter, they approach each other to a mere 4.5 astronomical units (equivalent to the distance between the Sun and Jupiter), while at their farthest, they stretch nearly 29 astronomical units apart, resembling the gap between the Sun and Neptune.

Additionally, the chemical composition of the observed star offers valuable insights into its evolutionary journey. Its scarcity of heavy elements beyond hydrogen and helium suggests a distinctive origin and developmental path.

Unlike the majority of stars in the Milky Way, which orbit within the Galactic plane, Gaia BH3 travels on a retrograde trajectory, opposite to the galactic flow and bringing it also far away from the Galactic plane in millions of years. Furthermore, it is part of a group of stars in the Galactic halo, which is believed to have been accreted by our own Galaxy more than 8 billion years ago.

This groundbreaking discovery not only illuminates the mechanisms behind the formation and progression of massive black holes but also serves to validate theoretical models in stellar astrophysics. It marks a significant milestone in our understanding of black holes, with the promise of further revelations as the Gaia mission continues to collect and process data.