FSR584 - a new globular cluster in the Galaxy?

TL;DR

This study presents evidence that FSR584 is a newly identified old, metal-poor globular cluster in the Galaxy, located about 1.4 kpc from the Sun, with structural and kinematic properties consistent with such clusters.

Contribution

The paper provides the first detailed analysis suggesting FSR584 is a globular cluster, combining photometry and proper motions to characterize its nature and properties.

Findings

FSR584 is an old, metal-poor star cluster with a well-defined turnoff.

It is located approximately 1.4 kpc from the Sun and 1 kpc outside the Solar circle.

Proper motions and photometry support its classification as a globular cluster.

Abstract

We investigate the nature of the recently catalogued star cluster candidate FSR584, which is projected in the direction of the molecular cloud W3 and may be the nearest globular cluster to the Sun. 2MASS CMDs, the stellar radial density profile, and proper motions are employed to derive fundamental and structural parameters. The CMD morphology and the radial density profile show that FSR584 is an old star cluster. With proper motions, the properties of FSR584 are consistent with a metal-poor globular cluster with a well-defined turnoff and evidence of a blue horizontal-branch. FSR584 might be a Palomar-like halo globular cluster that is moving towards the Galactic plane. The distance from the Sun is approx 1.4kpc, and it is located at approx 1kpc outside the Solar circle. The radial density profile is characterized by a core radius of rc=0.3+/-0.1 pc. However, we cannot exclude the possibility of an old open cluster. Near-infrared photometry coupled to proper motions support the scenario where FSR584 is a new globular cluster in the Galaxy. The absorption is A_V=9.2+/-0.6$, which makes it a limiting object in the optical and explains why it has so far been overlooked