Dissipative Collapse of a Spherical Cluster of Gas Clouds
  With a view to understand the galaxy/star formation scenario, we investigate the dissipative collapse of a spherical cluster of gas clouds with an isotropic velocity distribution. The time scale for collapse to one tenth radius is studied as a function of the collision time in the system. The scalar virial equation is used to investigate the evolution of the size of the cluster. This is supplemented with an evolution equation for the random kinetic energy. The above system is numerically solved and the results analyzed. For large values of the collision time we find that the time scale for collapse is proportional to the collision time as expected. However for large values of the dissipation, i.e. for small collision times, the collapse time shows a nonlinear dependence on the collision time. 
K.Indulekha, G.V.Vijayagovindan (Mahatma Gandhi University) and   S.Ramadurai (Tata Institute of Fundamental Research)