The Effects of Orbital Inclination on the Scale Size and Evolution of Tidally Filling Star Clusters

TL;DR

This study uses N-body simulations to explore how orbital inclination and eccentricity influence the size, mass loss, and evolution of tidally filling star clusters in a Milky Way-like galaxy, revealing inclination-dependent effects.

Contribution

It provides new insights into how orbital inclination affects star cluster evolution, especially regarding mass loss and size, considering different galactic orbital parameters.

Findings

Inclined clusters at small Rgc have higher mass loss rates.

Tidal heating and disk shocking influence star removal from clusters.

Inclination effects diminish with increasing orbital eccentricity.

Abstract

We have performed N-body simulations of tidally filling star clusters with a range of orbits in a Milky Way-like potential to study the effects of orbital inclination and eccentricity on their structure and evolution. At small galactocentric distances Rgc, a non-zero inclination results in increased mass loss rates. Tidal heating and disk shocking, the latter sometimes consisting of two shocking events as the cluster moves towards and away from the disk, help remove stars from the cluster. Clusters with inclined orbits at large Rgc have decreased mass loss rates than the non-inclined case, since the strength the disk potential decreases with Rgc. Clusters with inclined and eccentric orbits experience increased tidal heating due to a constantly changing potential, weaker disk shocks since passages occur at higher Rgc, and an additional tidal shock at perigalacticon. The effects of orbital inclination decrease with orbital eccentricity, as a highly eccentric cluster spends the majority of its lifetime at a large Rgc. The limiting radii of clusters with inclined orbits are best represented by the rt of the cluster when at its maximum height above the disk, where the cluster spends the majority of its lifetime and the rate of change in rt is a minimum. Conversely, the effective radius is independent of inclination in all cases.