UKIRT follow-up observations of the old open cluster FSR0358 (Kirkpatrick1)

TL;DR

This study confirms that FSR0358 is an old (around 5 billion years) open cluster in the outer Milky Way, using deep infrared imaging and statistical analysis to characterize its properties.

Contribution

The paper presents the first detailed characterization of FSR0358 as an old open cluster, validating its status through high-resolution infrared observations and analysis.

Findings

FSR0358 is approximately 5 Gyr old.

It has a metallicity of Z=0.008.

Located 11.2 kpc from the Galactic Centre.

Abstract

We aim to characterise the properties of the stellar clusters in the Milky Way. Utilising an expectation-maximisation method we determined that the cluster FSR0358, originally discovered by J.D.Kirkpatrick, is the most likely real cluster amongst the cluster candidates from Froebrich et al.. Here we present new deep high resolution near infrared imaging of this object obtained with UKIRT. The analysis of the data reveals that FSR0358 (Kirkpatrick1) is a 5+-2Gyr old open cluster in the outer Milky Way. Its age, metallicity of Z=0.008 and distance from the Galactic Centre of 11.2kpc are typical for the known old open galactic clusters. So far six of the FSR cluster candidates have been identified as having an age above 5Gyr. This shows the significance of this catalogue in enhancing our knowledge of the oldest open clusters in the Galaxy.