The impact of the galactic environment on the dynamical evolution of long-lived open star clusters in the Latte suite of Feedback In Realistic Environment simulations

Wiggins, Alessa

Item

The impact of the galactic environment on the dynamical evolution of long-lived open star clusters in the Latte suite of Feedback In Realistic Environment simulations

Wiggins, Alessa

Date

2025-07-28

Abstract

Open clusters serve as powerful tracers of the Milky Way's chemical and dynamical evolution. Because their member stars share common ages and chemical abundances, they provide insight into when and where stars formed in the Galactic disk, as well as how stars migrate and are dynamically heated over time. In this thesis, we use high-resolution cosmological zoom-in simulations from the FIRE-2 Latte suite (m12i, m12f, and m12m) to study the formation, evolution, and survivability of long-lived open clusters in realistic, Milky Way-like environments. We present a catalog of 128 gravitationally bound star clusters older than 1 Gyr that survive to present day (z=0). By tracking these clusters from their formation through cosmic time, we examine how local conditions, such as gas density, star formation environment, and proximity to giant molecular clouds, affect whether a cluster survives or is disrupted. We find that long-lived clusters tend to live in relatively low-density, kinematically quiet regions of the disk, and that these environments help shield clusters from disruption. Despite forming in dynamic disks that include spiral arms, gas flows, and satellite interactions, these clusters avoid disruption for billions of years. We also analyze the dynamical histories of these survivors to understand how processes like radial migration (both disk heating and cold torquing) shape their present-day orbits. In the second part of the thesis, we focus on one extreme case study: a cluster nicknamed BOB, which serves as an analog to the old, metal-rich, and distant Milky Way open cluster Berkeley 20. This simulated cluster resides ~6 kpc from the galaxy's center and reaches vertical heights of several kiloparsecs. We trace the orbital and environmental history, identifying key perturbative episodes, including interactive with a gas cloud that prompts an outward migration event and a substantial interaction with an LMC mass satellite that causes significant orbit modification. This case study demonstrates how rare open clusters with unusual orbits may arise naturally as a consequence of the larger cosmological context. Together, this work provides a comprehensive view of the processes that govern open cluster survival and orbital evolution in realistic galactic environments.