Binary star system in which two massive stars emit powerful stellar winds
A colliding-wind binary is a binary star system in which the two members are massive stars that emit powerful, radiatively-driven stellar winds. The location where these two winds collide produces a strong shock front that can cause radio, X-ray and possibly synchrotron radiation emission.[1] Wind compression in the bow shock region between the two stellar winds allows dust formation. When this dust streams away from the orbiting pair, it can form a pinwheel nebula of spiraling dust. Such pinwheels have been observed in the Quintuplet Cluster.[2]
A composite optical/x-ray image of Eta Carinae and its surrounding nebula taken by the Chandra X-ray Observatory and the Hubble Space Telescope. The blue inner part of the nebula is optical emission, powered by the collision of winds from Eta Carinae and its unseen companion.[3] Credit: Chandra Science Center and NASA.
The archetype of such a colliding-wind binary system is WR 140 (HD 193793), which consists of a 20 solar mass (M☉) Wolf-Rayet star orbiting about a 50 M☉, spectral classO4–5 main sequence star every 7.9 years. The high orbital eccentricity of the pair allows astronomers to observe changes in the colliding wind region as their separation varies.[4][5] Another prominent example of a colliding-wind binary is thought to be Eta Carinae, one of the most luminous objects in the Milky Way galaxy.[6] The first colliding-wind binary to be detected in the X-ray band outside
the Milky Way galaxy was HD 5980, located in the Small Magellanic Cloud.[7]
^Volpi, Delia; Blomme, Ronny; De Becker, Michael; Rauw, Gregor (December 2010). "Non-thermal radio emission from colliding-wind binaries: modelling Cyg OB2 No. 8A and No. 9". Proceedings of the International Astronomical Union. 6: 638–639. arXiv:1012.3403. Bibcode:2011IAUS..272..638V. doi:10.1017/S1743921311011689. S2CID7269006.
^Dougherty, S. M.; Trenton, V.; Beasley, A. J. (November 2010). "The orbit and distance of WR140". Bulletin de la Société Royale des Sciences de Liège. 80: 658. arXiv:1011.0779. Bibcode:2011BSRSL..80..658D.
