They found the most massive stellar black hole in the Milky Way – DW – 04/17/2024

A team of astronomers has discovered the most massive stellar black hole in the Milky Way, with a mass 33 times that of the Sun, the European Southern Observatory (ESO) reported on Tuesday (15/04/2024)..

The black hole was discovered in data from the Gaia mission, a space observatory of the European Space Agency (ESA), which is surveying the sky from Earth orbit to create the largest and most accurate 3D map of Via Dairy yet.

Data from ESO’s Extremely Large Telescope and other ground-based observatories was used to test the black hole’s mass, which was found to be 33 times the mass of the Sun.

The discovery was made possible because the black hole causes a strange “oscillating” motion of the companion star orbiting it.

Stellar black holes form from the collapse of massive stars, and those discovered in the Milky Way are on average about 10 times more massive than the Sun.

Even the next most massive stellar black hole known in our galaxy, Cygnus X-1, is only 21 solar masses, making this new observation exceptional.

Very close to Earth

ESO also highlighted that, surprisingly, this black hole is also very close to Earth, just 2,000 light years away in the constellation Aquila, and is the second closest known black hole.

Called Gaia BH3 or BH3 for short, it was discovered when the team analyzed Gaia observations in preparation for a new data release.

“No one expected to find a large mass black hole lurking nearby that had not yet been discovered,” said Pasquale Panuzzo, a member of the Gaia collaboration and an astronomer at the Paris Observatory, part of the French National Center for Scientific Research. (CNRS).

“You make such a discovery once in your research career,” he emphasized.

The astronomical community has previously discovered similar massive black holes outside our galaxy and theorized that they may form from the collapse of stars whose chemistry contains very few elements heavier than hydrogen and helium.

These metal-poor stars are thought to lose less mass during their lives and therefore have more material left over to form high-mass black holes after they die.

But until now there has been no evidence directly linking metal-poor stars to high-mass black holes.

Pairs of stars tend to have similar compositions, meaning companion BH3 contains important clues about the star that collapsed to form this exceptional black hole, ESO explains.

This companion was a very metal-poor star, indicating that the star that collapsed to form BH3 was also metal-poor, as predicted.

A LITTLE (EFE, ESO)