Scientists discover the largest stellar black hole of the Milky Way

A European team of astronomers has discovered the largest stellar black hole of the Milky Way. The black hole is more than 30 times heavier than our sun and it is located in the Aquila Constellation, approximately 2000 light years from Earth. The astronomers made their discovery by chance while preparing the fourth data release of ESA's Gaia mission, which follows the movements of billions of stars in the Milky Way. The black hole was noticed because it produces a strange ‘wobbling motion’ in the star that orbits it. Data from the Very Large Telescope (VLT) of the European Southern Observatory (ESO) have been used to confirm the mass of the black hole. The scientists involved from the Netherlands include Anthony Brown, Amina Helmi and Eduardo Balbinot.

Text: Nederlandse Onderzoekschool voor Astronomie (NOVA)

Amina Helmi (University of Groningen) is involved in the discovery as a member of the Data Processing and Analysis Consortium of Gaia and because of her expertise on old stars and star streams. ‘We were able to discover the black hole thanks to the star that orbits around it. The star, and the black hole, appear to come from a group of stars that were captured by our Milky Way and previously discovered by my own research group. Coincidentally, I had been looking at this group of stars for some time. And now it turns out that there is a black hole there, which is very special. We have never seen a star stream with a black hole before.’

Eduardo Balbinot (University of Groningen and Leiden University) is also a member of the Data Processing and Analysis Consortium of Gaia, and specializes in preparing and processing large amounts of data on stars. Like Helmi, he is looking for star stream that got caught up in our Milky Way over the course of billions of years. ‘We hope, thanks to new spectroscopic observations, to soon know more about the origin of the star stream and about the black hole. And I assume many telescopes will now be focused on the star and the black hole.’

Anthony Brown (Leiden University) is head of the Data Processing and Analysis Consortium of Gaia. He leads the preparation of data releases. ‘The fourth data release is scheduled for late 2025. We often come across unusual things when preparing the data, but this is so surprising that we are coming out with it now. We want to make sure that scientists across the world can investigate this particular black hole in more detail as soon as possible.’

Read more:

• ESO's press release
• Discovery of a dormant 33 solar-mass black hole in pre-release Gaia astrometry. Door: Gaia Collaboration, P. Panuzzo, et al. In: Astronomy & Astrophysics, 16 april 2024 [original | preprint (pdf)]

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The Netherlands Research School for Astronomy (NOVA) is a partnership between the astronomical institutes of the universities of Amsterdam, Groningen, Leiden, and Nijmegen. The mission of the NOVA top research school is to conduct pioneering astronomical research, train young astronomers at the highest international level, and share new discoveries with society. The NOVA laboratories specialize in building state-of-the-art optical/infrared and submillimetre instruments for the largest telescopes on Earth.