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Cygnus X-1 (abbreviated Cyg X-1) [11] is a galactic X-ray source in the constellation Cygnus and was the first such source widely accepted to be a black hole. [12] [13] It was discovered in 1964 during a rocket flight and is one of the strongest X-ray sources detectable from Earth, producing a peak X-ray flux density of 2.3 × 10 −23 W/(m 2 ⋅Hz) (2.3 × 10 3 jansky).
Betty Louise Turtle (née Webster [also Webster in published works]) (20 May 1941 - 29 September 1990) was an Australian astronomer and physicist.In 1971, with her colleague Paul Murdin, she identified the powerful X-ray source Cygnus X-1 as the first clear candidate for a black hole.
Cygnus X-1 belongs to a massive X-ray binary system; this system, about 6,000 light-years away, includes a blue variable supergiant cataloged as HDE 226868, whose orbit is about 0.2 AU. A strong stellar wind from this star transfers large amounts of matter to an accretion disk surrounding its companion, the X-ray source. [9]
They measured the Doppler shift to find that HDE226868 was a binary star with an orbit of 5.6 days orbiting an invisible partner, presumably the source of the X-rays, and which they calculated to be certainly more than 2.5 and probably more than six solar masses. Such a star cannot be a white dwarf or neutron star and they assumed this body to ...
Bolton observed the star HDE 226868 independently of the work by Louise Webster and Paul Murdin, at the Royal Greenwich Observatory, who could not prove that star was Cygnus X-1's optical companion. The high dispersion of the 74-inch (1.9 m) telescope's spectrograph, combined with the 74-inch (1.9 m) aperture was adequate to prove the star was ...
Cygnus-X is a massive star formation region located in the constellation of Cygnus at a distance from the Sun of 1.4 kiloparsecs (4,600 light years). As it is located behind the Cygnus Rift and its light is heavily absorbed by the Milky Way 's interstellar dust , it is better studied in other wavelengths of the electromagnetic spectrum that ...
ξ Cygni (Latinised as Xi Cygni) is a spectroscopic binary star in the constellation Cygnus, made up of a K-type supergiant star (primary) and an A-type star (secondary). Its apparent magnitude is 3.73, making it readily visible to the naked eye , and it is located around 350 parsecs (1,100 ly) away.
61 Cygni / ˈ s ɪ ɡ n i / is a binary star system in the constellation Cygnus, consisting of a pair of K-type dwarf stars that orbit each other in a period of about 659 years. Of apparent magnitude 5.20 and 6.05, respectively, they can be seen with binoculars in city skies or with the naked eye in rural areas without light pollution.