DECam photometry reveals extra-tidal stars around the Milky Way globular cluster NGC 6864 (M75)

A.E PIATTI

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2022 vol. 509 p. 3709 - 3716

0035-8711

Globular clusters are prone to lose stars while moving around the Milky Way. Thesestars escape the clusters and are distributed throughout extended envelopes or tidaltails. However, such extra-tidal structures are not observed in all globular clusters,and yet there is no structural or dynamical parameters that can predict their presenceor absence. NGC 6864 is an outer halo globular cluster with reported no observedtidal tails. We used Dark Energy Camera (DECam) photometry reaching ∼ 4 magunderneath its main sequence turnoff to confidently detect an extra-tidal envelope, andstellar debris spread across the cluster outskirts. These features emerged once robustfield star filtering techniques were applied to the fainter end of the observed clustermain sequence. NGC 6864 is associated to the Gaia-Enceladus dwarf galaxy, amongothers 28 globular clusters. Up-to-date, nearly 64% of them have been targeted lookingfor tidal tails and most of them have been confirmed to exhibit tidal tails. Thus, thepresent outcomes allow us to speculate on the possibility that Gaia-Enceladus globularclusters share a common pattern of mass loss by tidal disruption.