MOCCA code for star cluster simulations - I. Blue Stragglers, first results

TL;DR

This paper introduces MOCCA, an advanced, fast simulation code for star clusters that accurately tracks Blue Straggler Stars (BSS) formation and evolution, enabling detailed comparison with observations.

Contribution

The paper presents the MOCCA code, combining Monte Carlo methods with Fewbody for precise dynamical interactions, and demonstrates its capability to simulate BSS properties in star clusters.

Findings

MOCCA accurately follows BSS evolution in star clusters.

BSS formation channels influence their properties and distributions.

Initial and final BSS positions show bimodal distribution patterns.

Abstract

We introduce an improved code for simulations of star clusters, called MOCCA. It combines the Monte Carlo method for star cluster evolution and the Fewbody code to perform scattering experiments. The Fewbody was added in order to track more precisely dynamical interactions between objects which can lead to creations of various exotic objects observed in the star clusters, like Blue Stragglers Stars (BSS). The MOCCA code is currently one of the most advanced codes for simulating real size star clusters. It follows the star cluster evolution closely to N-body codes but is much faster. We show that the MOCCA code is able to follow the evolution of BSS with details. It is a suitable tool to perform full scale evolution of real star clusters and detail comparison with observations of exotic star cluster objects like BSS. This paper is the first one of the series of papers about properties of BSS in star clusters. This type of stars is particularly interesting today, because by studying them one can get important constrains on a link between the stellar and dynamical evolution of star clusters. We discuss here first results concerning BSS for an arbitrary chosen test model. We investigate properties of BSS which characterize different channels of formation like masses, semi-major axes, eccentricities, and orbital periods. We show how BSS from different channels change their types, and discuss initial and final positions of BSS, their bimodal distribution in the star cluster, lifetimes and more.