The Quintuplet Cluster: Extended Structure and Tidal Radius

The Quintuplet star clusteris one of only three known young ($ 10^4$ M$_\odot$) clusters within $\sim100$ pc of the Galactic Center. In order to explore star clusterformation and evolution in this extreme environment, we analyze the Quintuplet's dynamical structure. Using the HST WFC3-IR instrument, we take astrometric and photometric observations of the Quintupletcovering a $120''\times120''$ field-of-view, which is $19$ times larger than those of previous proper motionstudies of the Quintuplet. We generate a catalog of the Quintupletregion with multi-band, near-infrared photometry, proper motions, and cluster membership probabilities for $10,543$ stars. We present the radial density profile of $715$ candidate Quintuplet clustermembers with $M\gtrsim4.7$ M$_\odot$ out to $3.2$ pc from the cluster center. A $3\sigma$ lower limit of $3$ pc is placed on the tidal radius, indicating the lack of a tidal truncation within this radius range. Only weak evidence for mass segregationis found, in contrast to the strong mass segregationfound in the Arches cluster, a second and slightly younger massive cluster near the Galactic Center. It is possible that tidal stripping hampers a mass segregationsignature, though we find no evidence of spatial asymmetry. Assuming that the Arches and Quintupletformed with comparable extent, our measurement of the Quintuplet's comparatively large core radius of $0.62^{+0.10}_{-0.10}$ pc provides strong empirical evidence that young massive clusters in the Galactic Centerdissolve on a several Myr timescale.