Abstract

Contributed Talk - Plenary

Young Stellar Objects in Metal-Poor Dwarf Galaxies: JWST Studies of NGC 6822 and Sextans A

Lina Marie Gerlach, Joana Oliveira, Jacco Th. van Loon
Keele University

Dwarf galaxies in the Local Group provide powerful laboratories for studying star formation in low-metallicity environments, as they offer nearby analogues to the conditions under which massive stars formed at high redshift. In this work, I focus on NGC 6822 (∼490 kpc, ∼0.2 Z⊙) and Sextans A (∼1.32 Mpc, ∼0.07 Z⊙), which together span a range of sub-solar metallicities and host active star-forming regions. These properties make them ideal targets for probing how environment shapes the formation and early evolution of massive stars. Their low metallicities also allow me to extend resolved studies into regimes approaching those of the early Universe. I present preliminary catalogues of Young Stellar Object (YSO) candidates in both galaxies, derived from high-resolution infrared imaging obtained with the James Webb Space Telescope. In Sextans A, observations in 12 NIRCam and MIRI filters spanning 0.9–12.8 μm cover most of the star-forming disk, while in NGC 6822, eight filters spanning 1.15–21 μm provide full coverage. These datasets trace stellar, molecular, and dust emission, enabling me to identify embedded and more evolved YSOs. I initially select YSO candidates using colour–magnitude and colour–colour criteria informed by theoretical models and previous studies of Local Group galaxies. At this stage, the catalogues are based solely on photometric selection and have not yet been fully refined to remove contamination from evolved stars, background galaxies, or other sources. In subsequent analysis, I will apply visual inspection and spectral energy distribution fitting to produce robust, cleaned samples. By adopting a consistent methodology, I aim to construct matched catalogues that enable direct comparison between the two galaxies. In future work, I will analyse the spatial distribution and inferred masses of the YSO populations to quantify their contribution to global star formation rates and to assess how metallicity regulates star formation. A direct comparison between NGC 6822 and Sextans A will provide new constraints on early stellar evolution in extremely low-metallicity environments. I also plan to implement both supervised and unsupervised machine learning techniques to enable scalable and automated YSO classification in current and future JWST surveys.