Not a galaxy: IRAS 04186+5143, a new young stellar cluster in the outer Galaxy

TL;DR

This paper reports the discovery of a new young stellar cluster in the outer Galaxy, previously misidentified as a galaxy, with detailed infrared and molecular line observations confirming its nature and properties.

Contribution

The study identifies and characterizes a new young stellar cluster in the outer Galaxy using multi-wavelength data, clarifying its nature and properties.

Findings

Cluster is located at 5.5 kpc in the outer Galaxy.

Contains predominantly Class I young stellar objects.

Molecular gas mass and dust environment characterized.

Abstract

We report the discovery of a new young stellar cluster in the outer Galaxy located at the position of an IRAS PSC source that has been previously mis-identified as an external galaxy. The cluster is seen in our near-infrared imaging towards IRAS 04186+5143 and in archive Spitzer images confirming the young stellar nature of the sources detected. There is also evidence of sub-clustering seen in the spatial distributions of young stars and of gas and dust. Near- and mid-infrared photometry indicates that the stars exhibit colours compatible with reddening by interstellar and circumstellar dust and are likely to be low- and intermediate-mass YSOs with a large proportion of Class I YSOs. Ammonia and CO lines were detected, with the CO emission well centred near the position of the richest part of the cluster. The velocity of the CO and NH$_3$ lines indicates that the gas is Galactic and located at a distance of about 5.5 kpc, in the outer Galaxy. Herschel data of this region characterise the dust environment of this molecular cloud core where the young cluster is embedded. We derive masses, luminosities and temperatures of the molecular clumps where the young stars reside and discuss their evolutionary stages.