Colliding-Wind Binary

A colliding-wind binary ( German translation double star with colliding stellar winds ) is an interacting binary consisting of two stars early, their stellar winds collide at high speeds and in the collision zone radio , X-rays and gamma rays produce.

Early stars of the spectral type O and Wolf-Rayet stars produce stellar winds with speeds of several 1000 km / s and mass loss rates of up to 10 ⁻³ solar masses per year. If two such stars are in a close binary star system with orbital times of no more than a few 10 days, a shock front forms between them in which the particles of the stellar winds are slowed down and heated to temperatures of up to 10 ⁸ K. The resulting braking and thermal radiation reaches luminosity of 10 ³² to 10 ³⁴ erg / s in the X-ray range .

The X-ray radiation is variable due to the inhomogeneous structure of the stellar wind, the varying line of sight to the observer during orbit and the fluctuating distance between the stars in elliptical orbits. Colliding wind binaries are not counted among the X-ray binary stars , since the radiated energy is not obtained from the acceleration in a gravitational field .

In addition to thermal radiation in the area of radio and X-ray radiation, signs of non-thermal emissions have also been discovered in colliding wind binaries . The gamma radiation is definitely of a non-thermal nature and could result from electron-positron pair generation with subsequent acceleration of the particles in the magnetic field in the wind collision zone. Pion decay and Compton scattering could be other sources of gamma radiation .

Most of the radio radiation is likely to be generated by synchrotron radiation .

Examples

V444 Cygni
Gamma ² Velorum
WR 140
Eta Carinae

literature

M. De Becker, F. Raucq: Catalog of particle-accelerating colliding-wind binaries . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1308.3149v1 (English).
M. Werner, O. Reimer, A. Reimer, K. Egberts: Fermi-LAT upper limits on gamma-ray emission from colliding wind binaries . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1308.2573v1 (English).
Astrid Lamberts, Guillaume Dubus, Sebastien Fromang, Geoffroy Lesur: Colliding wind binaries and gamma-ray binaries: relativistic version of the RAMSES code . In: Astrophysics. Solar and Stellar Astrophysics . 2012, arxiv : 1212.4142v1 (English).
Marc Gagne, Garrett Fehon, Michael Savoy, Carlos Cartagena, David H. Cohen, Stanley P. Owocki: An X-ray Survey of Colliding Wind Binaries . In: Astrophysics. Solar and Stellar Astrophysics . 2012, arxiv : 1205.3510v2 (English).