By Jim Leffman via SWNS
Astronomers have discovered the most massive stellar black hole in our galaxy – 33 times the mass of our Sun.
The hole known as Gaia BH3 hailed a ‘once in a lifetime’ discovery, is 2,000 light years away but the second closest black hole to Earth.
Most stellar black holes caused when a star collapses in on itself, are about ten times the Sun’s mass, with the largest in the Milky Way previously known to be 21 times as big.
Gaia collaboration member Pasquale Panuzzo, an astronomer at the Observatoire de Paris, part of France’s National Centre for Scientific Research (CNRS) said: “No one was expecting to find a high-mass black hole lurking nearby, undetected so far.
“This is the kind of discovery you make once in your research life.”
Lurking in the constellation Aquila, it was found while the team was reviewing Gaia’s observations in preparation for an upcoming data release.
It was spotted in data from the European Space Agency’s Gaia mission because it imposes an odd ‘wobbling’ motion on the companion star orbiting it
Data from the European Southern Observatory’s Very Large Telescope (ESO’s VLT) and other ground-based observatories were used to verify the mass of the black hole as an “exceptional” 33 times that of the Sun.
Study co-author Elisabetta Caffau, also a Gaia collaboration member from the CNRS Observatoire de Paris said: “We took the exceptional step of publishing this paper based on preliminary data ahead of the forthcoming Gaia release because of the unique nature of the discovery.”
Making the data available early in the journal Astronomy & Astrophysics will let other astronomers start studying this black hole right now, without waiting for the full data release, planned for late 2025 at the earliest.
As well as stellar black holes coming from the collapse of stars there are supermassive black holes with colossal masses that scientists do not know how they form.
Sagittarius A*, the supermassive black hole at the Milky Way’s center, has about four million times the mass of the Sun.
The find also solves a mystery as to why similar stellar black holes outside our galaxy are so big.
The theory was that stars with very few elements heavier than hydrogen and helium in their chemical composition, or metal-poor stars, lose less mass over time so are larger when they collapse.
Stars in pairs tend to have similar compositions, meaning that BH3’s companion holds important clues about the star that collapsed to form this exceptional black hole.
Data showed that the companion was a very metal-poor star, indicating that the star that collapsed to form BH3 was also metal-poor — just as predicted.
