什么是Stellar-Mass Black Hole？
A stellar-mass black hole is what a massive star becomes when its core collapses and nothing is left to stop it. Between roughly 3 and 150 solar masses of material falls inside its own event horizon — a surface from which not even light can escape. There are probably a hundred million of them in the Milky Way.
The formation is a failure of resistance. Electron degeneracy pressure holds up a white dwarf; neutron degeneracy and the strong force hold up a neutron star. Past about 2.3 solar masses of collapsed core, no known force wins, and the material falls inward indefinitely. What is left behind is not matter at all in any useful sense but geometry: a region of spacetime curved so steeply that every future-pointing path leads inward.
The event horizon is not a wall. It is a boundary defined by where escape velocity reaches the speed of light, and for a 10-solar-mass black hole it lies about 30 kilometres from the centre. Nothing special happens locally when you cross it; you simply lose the option of turning around. Outside it, at 1.5 times the horizon radius, sits the photon sphere, where light can orbit — which is why the rendered model shows a razor-thin bright ring hugging the shadow.
This model is a real ray-trace, not an artistic impression: light paths are integrated through curved spacetime, so the accretion disk behind the hole is bent up and over the shadow, background stars smear into Einstein rings, and the approaching side of the disk is brightened by relativistic Doppler beaming. Cygnus X-1, discovered in 1964 and the subject of a famous bet between Stephen Hawking and Kip Thorne, was the first object widely accepted as one of these.