MOCCA code for star cluster simulations - V. Initial globular cluster conditions influence on blue stragglers

Abstract

The paper presents an analysis of properties of populations of blue stragglers (BSs) in evolving globular clusters, based on numerical simulations done with the MOCCA code for various initial globular clusters conditions. We find that various populations of BSs strongly depend on the initial semi-major axes distributions. With a significant number of compact binaries, the number of evolutionary BSs can be also significant. In turn, for semi-major axes distributions preferring binaries with wider orbits, dynamical BSs are the dominant ones. Their formation scenario is very distinct: for wide binaries the number of dynamical interactions is significantly larger. Most interactions are weak and increase only slightly the eccentricities. However, due to a large number of such interactions, the eccentricities of a number of binaries finally get so large that the stars collide. We study how larger initial clusters' concentrations influence the BSs. Besides the expected increase of the number of dynamically created BSs (for denser GCs the probabilities of strong dynamical interactions and collisions are higher), we find that the number of the evolutionary BSs is not affected even by very high initial concentrations. This has a very important implication on observations - it supports the theory that the evolutionary BSs are the result of the unperturbed evolution of the primordial binaries. In addition, the paper presents the evolution of the ratio between the number of BSs in binaries and as single stars R_B/S. For a vast diversity of models, the ratio R_B/S approaches the value ~0.4. Additionally, we identified two subgroups which differ in the initial semi-major axes distributions. The first group starts with a high ratio R_B/S, it decreases with time and settles around 0.4. The second group starts with lower values of the ratio R_B/S ... . (etc., abstract continues)

submitted to MNRAS, comments are welcome

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Cited by in corpus (13)

• A stellar census in globular clusters with MUSE: Binaries in NGC 3201
• MOCCA-SURVEY database I. Accreting white dwarf binary systems in globular clusters -- I. cataclysmic variables -- present-day population
• MOCCA: Dynamics and evolution of binary stars of multiple stellar populations in tidally filling and underfilling globular star clusters
• Spatial mixing of binary stars in multiple-population globular clusters
• Small-N collisional dynamics III: The battle for the realm of not-so-small-N
• MOCCA-SURVEY database I. Accreting white dwarf binary systems in globular clusters -- II. Cataclysmic variables -- progenitors and population at birth
• Blue Stragglers and Friends: Initial Evolutionary Pathways in Close Low-Mass Binaries: Literature Review
• Fast Multipole Methods for $N$-body Simulations of Collisional Star Systems
• Binary properties of the globular cluster 47 Tuc (NGC 104). A dearth of short-period binaries
• Small-N collisional dynamics IV: Order in the realm of not-so-small-N
• A binary-related origin mediated by environmental conditions for blue straggler stars
• Blue straggler stars beyond the Milky Way. II. A binary origin for blue straggler stars in Magellanic Cloud clusters
• Blue straggler stars beyond the Milky Way. III. Detection of evolved blue straggler candidates in Large Magellanic Cloud clusters