Gravitational interactions between globular and open clusters: an introduction

TL;DR

This paper explores the potential gravitational interactions between globular and open clusters, suggesting such interactions are more common than previously thought and can influence cluster formation and destruction.

Contribution

It provides theoretical and observational evidence that globular and open clusters frequently interact through gravitational forces, challenging previous assumptions of their independence.

Findings

Globular clusters can trigger open cluster formation via interactions.

Interactions can lead to the destruction or erosion of globular clusters.

Monte Carlo simulations support the high frequency of these interactions.

Abstract

Historically, it has been assumed that globular and open clusters never interact. However, recent evidence suggests that: globular clusters passing through the disk may be able to perturb giant molecular clouds (GMCs) triggering formation of open clusters and some old open clusters may be linked to accreted globulars. Here, we further explore the existence of possible dynamical connections between globular and open clusters, and realize that the most obvious link must be in the form of gravitational interactions. If open clusters are born out of GMCs, they have to move in similar orbits. If we accept that globulars can interact with GMCs, triggering star formation, it follows that globular and open clusters must also interact. Consistently, theoretical arguments as well as observational evidence, show that globular and open clusters certainly are interacting populations and their interactions are far more common than usually thought, especially for objects part of the bulge/disk. Monte Carlo calculations confirm that conclusion. Globular clusters seem capable of not only inducing formation of open clusters but, more often, their demise. Relatively frequent high speed cluster encounters or cluster harassment may also cause, on the long-term, slow erosion and tidal truncation on the globulars involved. The disputed object FSR 1767 (2MASS-GC04) may be, statistically speaking, the best example of an ongoing interaction.