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

TL;DR

This study uses MeerKAT observations to analyze the complex neutral hydrogen gas in the edge-on dwarf galaxy UGCA 320, revealing tidal interactions, outflows, and extra-planar structures influenced by its environment.

Contribution

It provides the first detailed kinematic analysis of UGCA 320's HI gas, highlighting environmental effects on its complex gas morphology and dynamics.

Findings

20% of HI is kinematically anomalous

~30% of anomalous gas likely from tidal interaction

~10% of HI is extra-planar with filamentary structure

Abstract

We present a detailed analysis of the neutral atomic gas (HI) in the dwarf galaxy UGCA 320, observed with the MeerKAT telescope as part of the MHONGOOSE (MeerKAT HI Observations of Nearby Galactic Objects: Observing Southern Emitters) programme. In a small group consisting of three dwarf galaxies, all of which contain HI, 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 HI 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.