{"dataset":{"slug":"compact-objects","title":"Black Holes & Neutron Stars","description":"The compact objects in the graph — black holes (Sgr A*, M87*, Cygnus X-1, V404 Cygni) and neutron stars (the Crab, Vela, first and most-massive pulsars). The physics of these end-states of gravity — the ergosphere, photon sphere, ISCO, jets, neutron degeneracy, the pulsar mechanism and the equation of state — is modelled alongside as reused cosmology, stellar-physics and object-class concepts. Only well-established astrophysics; nothing fabricated.","version":"1.0.0","lastGenerated":"2026-06-29","license":"CC BY-SA 4.0","entityCount":8,"sources":["nasa","eso"]},"entities":[{"id":"black_hole:cygnus-x-1","name":"Cygnus X-1 (black hole)","type":"black_hole","domain":"science","description":"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.","entryPath":"/compact-objects/cygnus-x-1"},{"id":"black_hole:m87-star","name":"M87*","type":"black_hole","domain":"science","description":"The supermassive black hole at the heart of galaxy M87, the first black hole ever directly imaged, in 2019.","entryPath":""},{"id":"neutron_star:psr-b1919-21","name":"PSR B1919+21","type":"neutron_star","domain":"science","description":"The first pulsar ever discovered, found by Jocelyn Bell Burnell and Antony Hewish in 1967 as a startlingly regular radio signal once labelled 'LGM-1' for Little Green Men. Its 1.337-second pulses opened the study of neutron stars; the discovery is commemorated on the cover of Joy Division's album Unknown Pleasures.","entryPath":"/compact-objects/psr-b1919-21"},{"id":"neutron_star:psr-j0740-6620","name":"PSR J0740+6620","type":"neutron_star","domain":"science","description":"One of the most massive neutron stars known, at about 2.08 solar masses, weighed through the Shapiro delay of its pulses. Its radius has been measured by NASA's NICER X-ray telescope, and together the mass and radius are among the tightest constraints on the neutron-star equation of state and how dense matter behaves.","entryPath":"/compact-objects/psr-j0740-6620"},{"id":"black_hole:sagittarius-a-star","name":"Sagittarius A*","type":"black_hole","domain":"science","description":"The supermassive black hole at the center of the Milky Way, imaged by the Event Horizon Telescope in 2022.","entryPath":""},{"id":"neutron_star:crab-pulsar","name":"The Crab Pulsar","type":"neutron_star","domain":"science","description":"The young neutron star at the heart of the Crab Nebula, formed in the supernova recorded by observers in 1054. It spins about thirty times a second and is the archetypal rotation-powered pulsar, its wind lighting up the surrounding nebula across the spectrum, from radio to gamma rays.","entryPath":"/compact-objects/crab-pulsar"},{"id":"neutron_star:vela-pulsar","name":"The Vela Pulsar","type":"neutron_star","domain":"science","description":"A young, bright pulsar in the Vela supernova remnant, spinning about eleven times a second. It is the classic glitching pulsar — famous for sudden small speed-ups in its rotation that reveal the superfluid interior of a neutron star — and one of the brightest gamma-ray sources in the sky.","entryPath":"/compact-objects/vela-pulsar"},{"id":"black_hole:v404-cygni","name":"V404 Cygni","type":"black_hole","domain":"science","description":"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.","entryPath":"/compact-objects/v404-cygni"}]}