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.

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.
References in periodicals archive ?
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.
Studies of radio emissions from Cygnus X-1 support claims that it is a black hole (9/23/72, p.
Using several telescopes, both ground-based and in orbit, the scientists unraveled longstanding mysteries about the object called Cygnus X-1, a famous binary-star system discovered to be strongly emitting X-rays nearly a half-century ago.
Over three decades ago, Stephen Hawking placed - and eventually lost - a bet against the existence of a black hole in Cygnus X-1.
The Swift team tested the BAT by observing Cygnus X-1, a well-known bright source that produces gamma rays in our galaxy.
They concluded that the object must, be a black hole, and they named it Cygnus X-1.
Using several telescopes, both ground-based and in orbit, the scientists unravelled longstanding mysteries about the object called Cygnus X-1, a famous binary-star system discovered to be strongly emitting X-rays nearly a half-century ago.
Analyzing a trove of data collected nearly a decade ago by the Hubble Space Telescope, astronomers observed what seems to be the last gasp emitted by gaseous material spiraling into Cygnus X-1, a suspected black hole 6,000 light-years from Earth.
Charles calls the findings the most definitive case yet for a black hole, surpassing previous evidence that other X-ray-emitting binary stars in the Milky Way -- Cygnus X-1 and A0620-00 -- harbor black holes.
7-2942, is only slightly less luminous than Cygnus X-1, a black-hole candidate and the brightest known gamma-ray emitter in the sky.
In the gamma-ray range, this object is only slightly less luminous than Cygnus X-1, the brightest known gamma-ray source in the galaxy.