# Rediscovery of the Sixth Star Cluster in the Fornax Dwarf Spheroidal Galaxy

## TL;DR

This paper confirms the existence of a sixth star cluster in the Fornax dwarf galaxy using deep imaging, revealing its properties and potential implications for understanding dark matter distribution.

## Contribution

The study provides the first definitive imaging-based confirmation of Fornax 6 as a real star cluster, clarifying its characteristics and significance.

## Key findings

- Fornax 6 is a well-resolved star cluster with significant overdensity.
- Fornax 6 has a low surface brightness and irregular shape, possibly due to tidal effects.
- Fornax 6 is likely more metal-rich than other globular clusters in the system.

## Abstract

Since first noticed by Shapley in 1939, a faint object coincident with the Fornax dwarf spheroidal has long been discussed as a possible sixth globular cluster system. However, debate has continued over whether this overdensity is a statistical artifact or a blended galaxy group. In this Letter we demonstrate, using deep DECam imaging data, that this object is well resolved into stars and is a bona fide star cluster. The stellar overdensity of this cluster is statistically significant at the level of ~ 6 - 6.7 sigma in several different photometric catalogs including Gaia. Therefore, it is highly unlikely to be caused by random fluctuation. We show that Fornax 6 is a star cluster with a peculiarly low surface brightness and irregular shape, which may indicate a strong tidal influence from its host galaxy. The Hess diagram of Fornax 6 is largely consistent with that of Fornax field stars, but it appears to be slightly bluer. However, it is still likely more metal-rich than most of the globular clusters in the system. Faint clusters like Fornax 6 that orbit and potentially get disrupted in the centers of dwarf galaxies can prove crucial for constraining the dark matter distribution in Milky Way satellites.