Astrophysics and Space Science

, Volume 194, Issue 2, pp 245–250 | Cite as

Changes in binding energy of interacting galaxies

  • M. Narasimha Rao
  • K. S. V. S. Narasimhan


It is shown that the fractional increase in binding energy of a galaxy in a fast collision with another galaxy of the same size can be well represented by the formula
$$\xi _2 = 3({G \mathord{\left/ {\vphantom {G {M_2 \bar R}}} \right. \kern-\nulldelimiterspace} {M_2 \bar R}}) ({{M_1 } \mathord{\left/ {\vphantom {{M_1 } {V_p }}} \right. \kern-\nulldelimiterspace} {V_p }})^2 e^{ - p/\bar R} = \xi _1 ({{M_1 } \mathord{\left/ {\vphantom {{M_1 } {M_2 }}} \right. \kern-\nulldelimiterspace} {M_2 }})^3 ,$$
whereM1,M2 are the masses of the perturber and the perturbed galaxy, respectively,V p is the relative velocity of the perturber at minimum separationp, and\(\bar R\) is the dynamical radius of either galaxy.


Binding Energy Relative Velocity Fractional Increase Fast Collision Dynamical Radius 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Aguilar, A. and White, S. D. M.: 1985,Astrophys. J. 295, 374.Google Scholar
  2. Ahmed, F.: 1979,Astrophys. Space Sci. 60, 493.Google Scholar
  3. Alladin, S. M.: 1965,Astrophys. J. 141, 768.Google Scholar
  4. Alladin, S. M. and Narasimhan, K. S. V. S.: 1982,Phys. Reports 92, 339.Google Scholar
  5. Binney, J. and Tremaine, S.: 1987,Galactic Dynamics, Princeton University Press, Princeton.Google Scholar
  6. Dekel, A., Lecar, M. and Shaham, J.: 1980,Astrophys. J. 241, 946.Google Scholar
  7. Knobloch, E.: 1976,Astrophys. J. 209, 411.Google Scholar
  8. Navarro, J. F. and Mosconi, M. B.: 1989,Astrophys. J. 336, 669.Google Scholar
  9. Richstone, D. O.: 1975,Astrophys. J. 200, 535.Google Scholar
  10. Roos, N. and Norman, C. A.: 1979,Astron. Astrophys. 76, 75.Google Scholar
  11. Sastry, K. S. and Alladin, S. M.: 1970,Astrophys. Space Sci. 7, 261.Google Scholar
  12. Spitzer, L.: 1958,Astrophys. J. 127, 7.Google Scholar
  13. Toomre, A.: 1977, in B. M. Tinsley and R. B. Larson (eds.),The Evolution of Galaxies and Stellar Populations, Yale University Observatory, p. 401.Google Scholar
  14. Zafarullah, S. N., Narasimhan, K. S. V. S., and Shankara Sastry, K.: 1983,Bull. Astron. Soc. India 11, 145.Google Scholar

Copyright information

© Kluwer Academic Publishers 1992

Authors and Affiliations

  • M. Narasimha Rao
    • 1
  • K. S. V. S. Narasimhan
    • 1
  1. 1.Centre of Advanced Study in AstronomyOsmania UniversityHyderabadIndia

Personalised recommendations