A Naive Bayes Classifier for identifying Class II YSOs

TL;DR

This paper presents a naive Bayes classifier that efficiently identifies candidate Class II Young Stellar Objects in the Galactic Plane using multi-wavelength data, achieving high accuracy and revealing potential new star clusters.

Contribution

The paper introduces a novel naive Bayes classifier for Class II YSOs that combines multiple features and demonstrates high accuracy and discovery potential in a large survey area.

Findings

Identifies 6,504 candidate Class II YSOs with 87% true positive rate.

Achieves an area under the ROC curve of approximately 0.998.

Discovers potential new star clusters or associations.

Abstract

A naive Bayes classifier for identifying Class II YSOs has been constructed and applied to a region of the Northern Galactic Plane containing 8 million sources with good quality Gaia EDR3 parallaxes. The classifier uses the five features: Gaia $G$-band variability, WISE mid-infrared excess, UKIDSS and 2MASS near-infrared excess, IGAPS H$\alpha$ excess and overluminosity with respect to the main sequence. A list of candidate Class II YSOs is obtained by choosing a posterior threshold appropriate to the task at hand, balancing the competing demands of completeness and purity. At a threshold posterior greater than 0.5 our classifier identifies 6504 candidate Class II YSOs. At this threshold we find a false positive rate around 0.02 per cent and a true positive rate of approximately 87 per cent for identifying Class II YSOs. The ROC curve rises rapidly to almost one with an area under the curve around 0.998 or better, indicating the classifier is efficient at identifying candidate Class II YSOs. Our map of these candidates shows what are potentially three previously undiscovered clusters or associations. When comparing our results to published catalogues from other young star classifiers, we find between one quarter and three quarters of high probability candidates are unique to each classifier, telling us no single classifier is finding all young stars.