Monte Carlo Simulations of Globular Cluster Evolution. V. Binary Stellar Evolution

TL;DR

This paper presents a Monte Carlo simulation study of globular cluster evolution, incorporating detailed stellar and binary evolution, and compares the results with observations and direct N-body simulations.

Contribution

The study introduces an updated Monte Carlo code with integrated stellar evolution, validated against N-body simulations, and explores the impact of stellar evolution on cluster dynamics.

Findings

Stellar evolution significantly affects cluster mass loss and energy dynamics.

Simulated cluster properties align well with observed Galactic globular clusters.

Stellar evolution prolongs the core contraction phase before binary burning stabilizes the cluster.

Abstract

We study the dynamical evolution of globular clusters containing primordial binaries, including full single and binary stellar evolution using our Monte Carlo cluster evolution code updated with an adaptation of the single and binary stellar evolution codes SSE/BSE from Hurley et. al (2000, 2002). We describe the modifications we have made to the code. We present several test calculations and comparisons with existing studies to illustrate the validity of the code. We show that our code finds very good agreement with direct N-body simulations including primordial binaries and stellar evolution. We find significant differences in the evolution of the global properties of the simulated clusters using stellar evolution compared to simulations without any stellar evolution. In particular, we find that the mass loss from stellar evolution acts as a significant energy production channel simply by reducing the total gravitational binding energy and can significantly prolong the initial core contraction phase before reaching the binary-burning quasi steady state of the cluster evolution as noticed in Paper IV. We simulate a large grid of clusters varying the initial cluster mass, binary fraction, and concentration and compare properties of the simulated clusters with those of the observed Galactic globular clusters (GGCs). We find that our simulated cluster properties agree well with the observed GGC properties. We explore in some detail qualitatively different clusters in different phases of their evolution, and construct synthetic Hertzprung-Russell diagrams for these clusters.