MOCCA: Global properties of tidally filling and underfilling globular star clusters with multiple stellar populations

TL;DR

This study uses extensive simulations to analyze how initial conditions influence the evolution of multiple stellar populations in globular clusters, aligning model outcomes with observed properties of Milky Way clusters.

Contribution

It expands previous research by exploring a broad range of initial conditions and their effects on present-day globular cluster properties, providing new constraints on initial parameters.

Findings

Models with initially tidally filling or slightly underfilling FG best match observed ratios and sizes.

Simulations show initial SG fractions around 0.25 are consistent with observations.

Retaining initial SG fractions depends on initial tidal filling status.

Abstract

We explore the evolution of various properties of multiple-population globular clusters (GCs) for a broad range of initial conditions. We simulated over 200 GC models using the MOCCA Monte Carlo code and find that present-day properties (core and half-light radii, ratio of the number of second-generation (SG) stars to the total number of stars, NSG/NTOT) of these models cover the observed values of these quantities for Milky Way GCs. Starting with a relatively small value of the SG fraction (NSG/NTOT ~ 0.25) and a SG system concentrated in the inner regions of the cluster, we find, in agreement with previous studies, that systems in which the first-generation (FG) is initially tidally filling or slightly tidally underfilling best reproduce the observed ratios of NSG/NTOT and have values of the core and half-light radii typical of those of many Galactic globular clusters. Models in which the FG is initially tidally underfilling retain values of NSG/NTOT close to their initial values. These simulations expand previous investigations and serve to further constrain the viable range of initial parameters and better understand their influence on present-day GC properties. The results of this investigation also provide the basis for our future survey aimed at building specific models to reproduce the observed trends (or lack thereof) between the properties of multiple stellar populations and other clusters properties.