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Cygnus X-3A luminous X-ray binary source with an unusually short (4.8 hour) binary period. The short period suggests that the system consists of a neutron star and a low-mass companion. Recent infrared spectra show strong helium emission lines as for a Wolf-Rayet companion star. The sinusoidal X-ray light curve is interpreted as being due to scattering of X-rays from the (unseen) central source by a hot dense wind driven off the companion star. Cygnus X-3 occasionally produces strong sometimes violent radio flares, first observed in 1972, between which it shows variable radio emission with a dominant component having a periodicity of 4.8 hours, similar to the X-ray period. Extremely high energy (>1015 eV) gamma rays have also been detected, though not recently. These observations make Cygnus X-3 a unique source. It is postulated that the unusual properties may arise from very rapid rotation of the neutron star embedded in the dense wind of its companion star.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
Cygnus X-3[′sig·nəs ‚eks ′thrē]
A variable source of x-rays, with a period of 4.8 hours, associated with a variable radio source that flared up to enormous levels in September 1972 with no observed increase in x-ray emission. Abbreviated Cyg X-3.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.