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Stability of a Collisional Galactic Disk

Published online by Cambridge University Press:  25 May 2016

E. Griv*
Affiliation:
Department of Physics, Ben-Gurion University, Israel

Extract

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Until recently, only collisionless models have been investigated in the kinetic treatment of stellar disk stability (e.g., Fridman and Polyachenko [1984]). This is due to the fact that the frequency of ordinary binary stellar gravitational (elastic) encounters in the Galaxy is much smaller than the variation of the gravitational field for the process being studied. However, in the pioneering paper Spitzer and Schwarzschild (1951) proposed a different kind of encounter: interaction of stars with gas clouds of the interstellar medium having a mass of rougly 106 M⊙. In recent years this hypothesis was partially confirmed by observations: it was discovered in the Galaxy a few thousand giant molecular clouds of mass Mc ≥ 105 M⊙. Other evidence of dynamical relaxation of the star–cloud disk in the solar neighborhood was found by Grivnev and Fridman (1990); the time of relaxation was estimated equal to τ = (2 – 4) × 109 years. Hence the study of collisional star–cloud system is not only of academic interest – on the time span t ≥ 109 years an actual galaxy may be a collisional ensemble of stars and clouds.

Type
Chapter 6: How are we to Understand the Large Scale Structure of the ISM?
Copyright
Copyright © Kluwer 1996 

References

Bhatnagar, P.L., Gross, E.P. and Krook, M. (1954) Phys. Rev. , 94, p. 511 Google Scholar
Fridman, A.M. and Polyachenko, V.L. (1984) Physics of Gravitating Systems , Vols. 1 and 2, Springer-Verlag, New York Google Scholar
Grivnev, E.M. and Fridman, A.M. (1990) Soviet Astron. , 34, p. 10 Google Scholar
Spitzer, L. and Schwarzschild, M. (1951) Astrophys. J. , 114, p. 385.Google Scholar