Monte Carlo Simulations of Star Clusters - IV. Calibration of the Monte Carlo Code and Comparison with Observations for the Open Cluster M67

TL;DR

This paper details the calibration of a Monte Carlo code for star cluster evolution, incorporating binary and single star evolution, and compares simulation results with N-body models and observations of the open cluster M67.

Contribution

It introduces a calibrated Monte Carlo method that accurately models star cluster evolution, matching N-body simulations and observational data for M67.

Findings

Good agreement with N-body simulations for cluster parameters

Successful modeling of binary, white dwarf, and blue straggler populations

Reasonably matches observational data despite statistical fluctuations

Abstract

We outline the steps needed in order to incorporate the evolution of single and binary stars into a particular Monte Carlo code for the dynamical evolution of a star cluster. We calibrate the results against N-body simulations, and present models for the evolution of the old open cluster M67 (which has been studied thoroughly in the literature with N-body techniques). The calibration is done by choosing appropriate free code parameters. We describe in particular the evolution of the binary, white dwarf and blue straggler populations, though not all channels for blue straggler formation are represented yet in our simulations. Calibrated Monte Carlo runs show good agreement with results of N-body simulations not only for global cluster parameters, but also for e.g. binary fraction, luminosity function and surface brightness. Comparison of Monte Carlo simulations with observational data for M67 shows that is possible to get reasonably good agreement between them. Unfortunately, because of the large statistical fluctuations of the numerical data and uncertainties in the observational data the inferred conclusions about the cluster initial conditions are not firm.