Cygnus X-1


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Cygnus X-1

An intense galactic X-ray source and the first to yield good observational evidence for the existence of a black hole of stellar mass. Identification of Cygnus X-1 in 1971 with the luminous supergiant star HDE 226868 was followed by the discovery of a 5.6-day binary period. Analysis of the optical observations showed the mass of the ‘unseen’ companion star (the X-ray source) to lie in the range 6–15 solar masses, well above the limit allowed for a neutron star (≤ 3 solar masses) or white dwarf (≤ 1.4 solar masses). Support for the view that Cygnus X-1 involves gas accretion from the optical supergiant onto a black hole is provided by the rapid (millisecond) and irregular variability of the X-ray emission.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006

Cygnus X-1

[′sig·nəs ‚eks ′wən]
(astrophysics)
A source of x-rays whose intensity varies in an irregular manner, associated with a weak variable radio source and a ninth-magnitude spectroscopic binary star, designated HDE226868, that consists of a blue supergiant and an invisible companion, which may be a black hole. Abbreviated Cyg X-1.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Lightman also shares his experiences studying for a doctorate in astrophysics at the California Institute of Technology He recalls the excitement when Cygnus X-1 (the first black hole) was discovered in the early 1970s.
Designated as the first-ever black hole to be discovered in the universe, the void of Cygnus X-1 weighs nearly as much as 15 suns.
In an international collaboration between Japan and Sweden, scientists clarified how gravity affects the shape of matter near the black hole in binary system Cygnus X-1. Their findings, which were published in Nature Astronomy this month, may help scientists further understand the physics of strong gravity and the evolution of black holes and galaxies.
Sep 23-Oct 23 LIBRA CYGNUS X-1 is rising in your sign this week, as Venus is in the declension.
Gamma Rays "Energetic radiation from Cygnus X-1 has given astronomers new hints about the nature of this enigmatic object, which lies in the Milky Way some 8,000 light-years from us.
Studies of radio emissions from Cygnus X-1 support claims that it is a black hole (9/23/72, p.
Over three decades ago, Stephen Hawking placed - and eventually lost - a bet against the existence of a black hole in Cygnus X-1.
In 1971 an X-ray-detecting satellite found irregular changes in an X-ray source in the constellation of Cygnus, a source that had been named Cygnus X-1. Such irregular changes might be the result of matter circling a black hole in varying concentrations.
Jul 23-Aug 23 LEO CYGNUS X-1 is rising in your sign this week as Venus is in the declension.
Hawking also broke into the office of another CalTech physicist, Kip Thorne, in order to covertly concede that the mysterious celestial object Cygnus X-1 was a black hole.
Backyard telescope users seeking to spot a stellar-mass black hole, or the next closest thing, have one good option: Cygnus X-1, which is locked in a close, 5.6-day orbit with a 9th-magnitude blue-giant star visible halfway down the Northern Cross.