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Schematic View of SS433

Schematic View of SS433. Rotation axis. 15.10 COMPACT X-RAY SOURCES AND STELLAR EVOLUTION.

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Schematic View of SS433

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  1. Schematic View of SS433 Rotation axis PHYS3010 - STELLAR EVOLUTION

  2. PHYS3010 - STELLAR EVOLUTION

  3. 15.10 COMPACT X-RAY SOURCES AND STELLAR EVOLUTION From the available observational evidence it appears that X-ray binary sources are a natural product of stellar evolution. The next page illustrates a possible scenario in which one stage is an x-ray emitting black hole binary object. Period changes are caused by mass transfer and supernovae explosions. Clearly since a very wide range of starting masses and separations are possible for the two stars there will be an enormous variety of such scenarios possible, with many different end products. • Initially two main sequence stars , the 20 M0 star exhausts its H core first (~ 6 x 106 y) • The envelope expands and the star fills its Roche lobe and spills via an accretion disk onto other star over a period of 2 x 104 y. • A 20.6 M0star is formed after ~ 5 x 105 y and becomes H burning at a rate according to this higher mass. The primary is now a ~5.4 M0 He burning star. • The He burning primary completes core burning in ~ 6 x 105 y, then proceeds to core C, O, Si burning and undergoes a supernova explosion. 3.4 M0 of the mantle is is expelled leaving the ~2 M0 core to implode to a either a neutron star or a black hole. Although the supernova explosion does not disrupt the binary the mass loss and the recoil momentum do change the period and eccentricity of the orbit. • The binary now consists of the compact object and the 20.6 M0 star. It is a detached binary system with eccentric orbits which will circularise by tidal interactions within several million years. • The secondary is a main sequence O or B type star. After completing its H burning phase its envelope expands and it becomes a blue supergiant For period of about 4 x 104 years the star loses matter in the form of a stellar wind driven by the high radiation pressure. The compact object accretes matter and becomes an x-ray source in the mould of Cygnus X-1. • After this period the expanding blue supergiant fills its Roche lobe and a new phase of mass exchange takes place. An accretion disk forms around the compact object. Most of the x-radiation produced will be absorbed by the dense accreting material and the only x-rays likely to escape will be those emitted normal to the plane of the accretion disk. The rate of accretion will be limited by the Eddington luminosity limit. During this phase the compact object is likely to gradually grow in terms of mass. Taken from Astrophysics I (Bowers and Deeming) P 326. PHYS3010 - STELLAR EVOLUTION

  4. STAGES IN THE EVOLUTION OF A MASSIVE CLOSE BINARY SYSTEM PHYS3010 - STELLAR EVOLUTION

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