Rediscovering the Tidal Tails of NGC 288 with Gaia DR2

TL;DR

This study combines Gaia DR2 data and N-body simulations to identify and analyze tidal tails around the globular cluster NGC 288, providing evidence for their existence and characteristics.

Contribution

It demonstrates the presence of tidal tails around NGC 288 by comparing Gaia observations with N-body simulations, revealing their structure and dynamics.

Findings

Tidal tails are aligned with the cluster's orbit.

Observed proper motions match simulation predictions.

Tidal tails are diffuse and bipolar in structure.

Abstract

NGC 288 is a Galactic globular cluster having observed extra tidal structure, without confirmed tidal tails. $Gaia$ DR2 provides photometric and astrometric data for many of the stars in NGC 288 and its extra tidal structure. To compare with $Gaia$ data, we simulate an $N$-body model of a star cluster with the same orbit as NGC 288 in a Milky Way potential. The simulation shows that the cluster forms tidal tails that are compressed along the cluster's orbit when it is at apocentre and are expected to be a diffuse bipolar structure. In this letter, we present a comparison between the simulation and observations from $Gaia$ DR2. We find that both the simulation and the observations share comparable trends in the position on the sky and proper motions of the extra-tidal stars, supporting the presence of tidal tails around NGC 288.