On the physical size of the Milky Way globular cluster NGC 7089 (M 2)

A.E PIATTI

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2022 vol. 514 p. 4982 - 4988

0035-8711

We study the outer regions of the Milky Way globular cluster NGC 7089 based onnew Dark Energy Camera (DECam) observations. The resulting background cleaned stellar density  profile reveals the existence of an extended envelope.We confirm previous results that cluster stars are found out to ~ 1deg from thecluster´s centre, which is nearly three times the value of the most robust tidal radii estimations. We also used results from direct N-body simulationsin order to compare with the observations.  We found a fairly good agreementbetween the observed and numerically generated stellar density profiles. Because of the existence of gaps and substructures along globular cluster tidal tails, we closely examined the structure of the outer cluster region beyond the Jacobi radius. We extended the analysis to a sample of 35 globular clusters, 20 of them with observed tidal tails. We found that if the stellar density profile follows a power law ~ r**(-alpha), the alpha slope correlates with the globular cluster present mass, in the sense that, the more massive the globular cluster the smaller the alpha value. This trend is not found in globular clusters without observed tidal tails. The origin of such a phenomenon could be related, among otherreasons, to the proposed so-called potential escapers or to the formation of globular clusters within dark matter mini-haloes