Discovery of tidal tails around the distant globular cluster Palomar 14

TL;DR

This paper reports the discovery of tidal tails around the distant globular cluster Palomar 14, indicating ongoing mass loss likely due to tidal stripping, with implications for its orbit and origin.

Contribution

First detection of tidal tails around Palomar 14, revealing its extended structure and providing insights into its dynamical history and origin.

Findings

Tidal tails are degree-long and symmetrically elongated.

Density profile shows departure from King profile at large radii.

Evidence suggests tidal stripping and specific orbital constraints.

Abstract

We report the detection of a pair of degree-long tidal tails associated with the globular cluster Palomar 14, using images obtained at the CFHT. We reveal a power-law departure from a King profile at large distances to the cluster center. The density map constructed with the optimal matched filter technique shows a nearly symmetrical and elongated distribution of stars on both sides of the cluster, forming a S-shape characteristic of mass loss. This evidence may be the telltale signature of tidal stripping in action. This, together with its large Galactocentric distance, imposes strong constraints on its orbit and/or origin: i) it must follow an external orbit confined to the peripheral region of the Galactic halo and/or ii) it formed in a satellite galaxy later accreted by the Milky Way.