The gain of internal energy of a star cluster caused by the tidal attraction of our Galaxy is examined. Expressions are derived which include the effects of a two-body orbit and internal motions of the cluster. These formulae are compared with previous results based on (i) uniform rectilinear motion and (ii) neglect of internal motions induced by cluster gravitation(i.e., impulsive approximation), and it is found that these simplifying assumptions generally introduce significant uncertainties.

ABSTRACT
Ⅰ. INTRODUCTION
Ⅱ. EQUATIONS OF MOTION
Ⅲ. RATE OF ENERGY INCREASE ON THE IMPULSIVE APPROXIMATION
Ⅳ. SLOW TIDAL ENERGY TANSFER
Ⅴ. SUMMARY AND CONSLUSIONS

• See-Woo Lee(Dept. of Earth Sciences, Kyungpook National University)
• Herbert J. Rood(Van Vleck Observatory, Wesleyan University)