The effect of external tidal field on life-time of star clusters in collisional and collision-less codes

The results of several performed N-body simulations using a collisionless N-body code named NMODY are reported here which aim at studying the evolution and life-time of star clusters under influence of an external tidal field. The code does not include stellar evolution, two body relaxation, and external tidal field as well. Having added the external tidal field to the code, we simulated our model clusters which are moving in circular orbits, in different galactocentric distances with various half-mass radius and initial mass around the Galaxy. Thereafter the results are compared with those of claimed by collisional code Nbody6. As the relaxation plays a main role in evolution of collisional systems, the main focus is to study how using an either collisional or collisionless code, changes the life-time of clusters. Finally the obtained relations between life-time of globular clusters with their initial half-mass radius are presented which numerically and virtually examine the strength of evolutionary mechanisms of globular clusters.