We introduce the star cluster evolution code Evolve Me A Cluster of StarS ( EMACSS ) , a simple yet physically motivated computational model that describes the evolution of some fundamental properties of star clusters in static tidal fields .
We base our prescription upon the flow of energy within the cluster , which is a constant fraction of the total energy per half-mass relaxation time .
According to Hénon ’ s predictions , this flow is independent of the precise mechanisms for energy production within the core , and therefore does not require a complete description of the many-body interactions therein .
For a cluster of equal-mass stars , we thence use dynamical theory and analytic descriptions of escape mechanisms to construct a series of coupled differential equations expressing the time-evolution of cluster mass and radius .
These equations are numerically solved using a 4th order Runge-Kutta integration kernel , and the results bench-marked against a database of direct N -body simulations .
We use simulations containing a modest initial number of stars ( 1024 \leq N \leq 65536 ) , and point-mass tidal fields of various strengths .
Our prescription is publicly available , and reproduces the N -body results to within \sim 10 \% accuracy for the entire post-collapse evolution of star clusters .