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Hybrid machine learning classification of AGB stars in Gaia DR3

Kushwahaa, Tanya, Matsuura, Mikako ORCID: https://orcid.org/0000-0002-5529-5593, Wesson, Roger and Davis, Timothy ORCID: https://orcid.org/0000-0003-4932-9379 2026. Hybrid machine learning classification of AGB stars in Gaia DR3. Proceedings of the International Astronomical Union 21 , pp. 97-101. 10.1017/S1743921325104419

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Abstract

Machine learning (ML) is revolutionising the analysis of large astronomical surveys such as Gaia DR3. We present a two-step ML pipeline to classify Asymptotic Giant Branch (AGB) stars: (i) cosine similarity identifies candidate AGB stars from 140 million sources, and (ii) an XGBoost classifier which separates carbon-rich (C-rich) and oxygen-rich (O-rich) stars. Our classifier achieves ROC-AUC > 99.9%, producing a catalogue of 307,191 O-rich and 4,227 C-rich stars. Feature importance analysis shows that the sixth RP coefficient (RP6) dominates classification, underlining the critical role of Gaia red spectral features. This work demonstrates how hybrid ML approaches can efficiently identify chemically distinct stellar populations in massive survey datasets, providing opportunities for new studies of Galactic structure and stellar evolution.

Item Type: Article
Date Type: Published Online
Status: Published
Schools: Schools > Physics and Astronomy
Publisher: Cambridge University Press
Funders: EPSRC
Date of First Compliant Deposit: 13 January 2026
Date of Acceptance: 19 December 2025
Last Modified: 13 Oct 2026 11:28
URI: https://orca.cardiff.ac.uk/id/eprint/183851

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