On the hidden mass

          J.B. Baillon and M. Mizony
          Institut Girard Desargues*


We describe a method to calculate the mass-distribution within galaxies
given the form of the rotational velocity curve. The approach is based
upon the explicit solution of an n-body problem.
We proceed to deduce the decreasing exponential law for the surface
density and, by fitting with observed data, we calculate the galactic
mass, a galactic radius and make inferences regarding hidden mass.
For the Milky Way, the model implies the absence of significant hidden
mass near the sun.

*U.R.A. 746, Bat. 101, Université Lyon 1, 69622 Villeurbanne
Cedex
e-mail: baillon@jonas.univ.lyon1.fr,mizony@jonas.univ.lyon1.fr