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Black holes · a heavy one

Gaia BH3: the heaviest black hole of its kind in the Milky Way

Gaia BH3, a black shadow with a thin bright ring, drawn in Exo-View

Gaia BH3 is a black hole of 33 Suns, 1,940 light-years away in the constellation Aquila, the second nearest known and the heaviest of its kind, made by a star, in our galaxy. It was found in 2024, when the European Gaia telescope noticed an ancient star swinging round something invisible every eleven and a half years.

Fly to Gaia BH3See Gaia BH1
Distance
About 1,940 light-years
Mass
About 33 Suns
Companion
An old giant star, LS II +14 13, going round it every 11.6 years
Kind
Dormant black hole: no disc, no X-rays
Found
In 2024, in data from the Gaia satellite

Why it is so heavy

Stars that formed early in the history of the galaxy had very few heavy elements, and such stars lose less of their mass in winds as they age. That leaves more mass behind to collapse into a black hole. The star that orbits Gaia BH3 is itself almost pure hydrogen and helium, as the first stars were, which suggests that the black hole formed from a star of that kind.

A neighbour of the first Gaia find

Gaia BH3 was spotted in a check of the data that was being prepared for the next big release, and the team announced it early, because it was so unusual. Like Gaia BH1, it is quiet: it is only seen by its pull on its star. Its companion belongs to a stream of stars, the remains of a small cluster that was pulled apart by the Milky Way long ago.

In Exo-View

The button below flies from the Sun to Gaia BH3. With no disc to draw, the hole is a black shadow with a thin ring of bent starlight. It is enlarged for the eye, and the plate says so.

Fly to Gaia BH3See Gaia BH1

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