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Black holes · the nearest

Gaia BH1: the nearest known black hole

Gaia BH1, a black shadow with a thin bright ring, on a dark sky, drawn in Exo-View

Gaia BH1 is the nearest black hole known, 1,560 light-years away in the constellation Ophiuchus, less than half the distance of the one before it. It is nine times the Sun's mass and is silent: nothing is falling into it, so it gives off no X-rays at all. It was found in 2022 only because of the star it pulls about.

Fly to Gaia BH1See the Milky Way
Distance
1,560 light-years
Mass
About 9.3 Suns
Companion
A Sun-like star, going round it every 185 days
Orbit
About 1.4 AU across, between the Earth's distance from the Sun and Mars's
Kind
Dormant black hole: no disc, no X-rays
Found
By the Gaia satellite, announced in 2022

Found by a wobble

Gaia, the European space telescope, measured the positions of nearly two billion stars so exactly that it could see one of them tracing a small oval on the sky every half year. Something unseen, nine times as heavy as the Sun, was pulling it. The star is much like the Sun, so the object cannot be another star: it would shine. A black hole is what is left.

Quiet black holes

Most known stellar-mass black holes were found because they are feeding on a close companion and glow in X-rays. Gaia BH1 and its companion are far enough apart that nothing flows. Such quiet holes are thought to be common, and are only found by their pull: in 2024 Gaia added Gaia BH3, 33 Suns and 1,940 light-years away, the heaviest of its kind in the Milky Way.

In Exo-View

The key below flies from the Sun to Gaia BH1. With no disc to draw, the hole is a black shadow with a thin ring of bent starlight, and its companion circles it on its true, stretched orbit. The shadow is enlarged for the eye, and the plate says so.

Fly to Gaia BH1See the Milky Way

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