Signatures of tidal disruption in the Milky Way globular cluster NGC 6981 (M72)

PIATTI, ANDRÉS E.; MESTRE, MARTÍN F.; CARBALLO-BELLO, JULIO A.; CARPINTERO, DANIEL D.; NAVARRETE, CAMILA; MORA, MARCELO D.; CENZANO, CAROLINA

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2021 vol. 646 p. 176 - 183

0004-6361

We study the outer regions of the MilkyWay globular cluster NGC6981 from publicly available BV photometry and new Dark Energy Camera (DECam) observations, both reaching nearly 4 mag below the cluster main sequence (MS) turno. While the BV data sets reveal the present of extra-tidal features, the much larger field of view of DECam observations allowed us in addition to identify a thin trailing tail and scattered extra-tidal debris. The tidal tail is nearly oriented along the direction to the Milky Way center. These cluster structural features arise from stellar density maps built using MS stars, particularly those fainter. The stars employed in constructing the density maps are those that kept unsubtracted from a cleaning procedure aimed at decontaminating the used cluster MS region from the presence of field stars. We also performed N-body simulations in order to help us to un understand the spatial distribution of the extra-tidal debris. The outcomes, that successfully reproduce the present cluster position, velocity, mass, core and tidal radii, reveal the presence of a long trailing and leading tails mostly parallel to the direction of the cluster velocity vector. We found that the cluster has lost most of its mass by tidal disruption during its perigalactic passages, that lasted nearly 20 Myr each. Hence, a gap of scaping stars near the cluster is expected from our N-body simulations, which in turns means thar stronger tidal tails could be found out by exploring much larger areas around NGC6891.