Tracing neutral hydrogen in UGCA 320: A MHONGOOSE perspective on an edge-on dwarf galaxy in a group environment

Abstract We present a detailed analysis of the neutral atomic gas (H i) in the dwarf galaxy UGCA 320, observed with the MeerKAT telescope as part of the MHONGOOSE (MeerKAT H i Observations of Nearby Galactic Objects: Observing Southern Emitters) programme. In a small group consisting of three dwarf galaxies, all of which contain H i, it is the most massive. Detailed kinematic modelling shows that UGCA 320 contains a substantial amount of (kinematically) anomalous gas (≳20 %), at least ~30 % of which is likely the result of a tidal interaction with its neighbour UGCA 319. It also reveals that UGCA 320 likely harbours a star-formation driven outflow, and that ~10 % of its H i is extra-planar and has a filamentary structure. Although UGCA 320 aligns with established scaling relations from the literature, its neutral hydrogen content is notably complex – shaped by its immediate environment. This underscores the importance of deep, resolved observations and detailed kinematic analyses to capture the nuances of galaxy evolution.