A new method to identify subclasses among AGB stars using Gaia and 2MASS photometry

TL;DR

This paper introduces a novel multi-band photometric method combining Gaia and 2MASS data to classify and identify subclasses of AGB stars in the Large Magellanic Cloud, enhancing understanding of their properties.

Contribution

The paper presents a new diagram using Wesenheit functions that effectively distinguishes between different types and masses of AGB stars, validated by stellar population models.

Findings

Successfully discriminates O-rich and C-rich AGB stars.

Identifies low-mass, intermediate-mass, and massive O-rich giants.

Differentiates extreme C-rich stars.

Abstract

Aims: We explore the wealth of high quality photometric data provided by data release 2 of the Gaia mission for long period variables (LPVs) in the Large Magellanic Cloud. Our goal is to identify stars of various types and masses along the Asymptotic Giant Branch. Methods: For this endeavour, we developed a new multi-band approach combining Wesenheit functions W_{RP,BP-RP} and W_{K_s,J-K_s} in the Gaia BP, RP and 2MASS J, K_s spectral ranges, respectively, and use a new diagram (W_{RP,BP-RP}-W_{K_s,J-K_s}) versus K_s to distinguish between different kinds of stars in our sample of LPVs. We used stellar population synthesis models to validate our approach. Results:We demonstrate the ability of the new diagram to discriminate between O-rich and C-rich objects, and to identify low-mass, intermediate-mass and massive O-rich red giants, as well as extreme C-rich stars. Stellar evolution and population synthesis models guide the interpretation of the results, highlighting the diagnostic power of the new tool to discriminate between stellar initial masses, chemical properties and evolutionary stages.