Schematic View of SS433

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Schematic View of SS433
Rotation axis
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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 M0 star 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.
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STAGES IN THE EVOLUTION OF A MASSIVE CLOSE BINARY
SYSTEM