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Regions where gravity overwhelms even light.
The compact object of Cygnus X-1 — the first widely accepted black hole. A bright X-ray source in Cygnus discovered in 1964, it is a stellar-mass black hole of roughly twenty-one solar masses pulling gas from its blue-supergiant donor star (HD 226868). It was the subject of a famous bet between Stephen Hawking and Kip Thorne, which Hawking conceded in 1990.
The supermassive black hole at the heart of galaxy M87, the first black hole ever directly imaged, in 2019.
The supermassive black hole at the center of the Milky Way, imaged by the Event Horizon Telescope in 2022.
A stellar-mass black hole of about nine solar masses in a binary system in Cygnus, and one of the nearest black holes with a precisely measured distance from radio parallax. Normally quiet, it erupted in a dramatic X-ray and radio outburst in June 2015 — a nearby microquasar caught devouring gas from its companion.