Investigating the H  I distribution and kinematics of ESO444-G084 and [KKS2000]23: New insights from the MHONGOOSE survey

We present the neutral atomic hydrogen (H <ns0:sc>I</ns0:sc>) distribution, kinematics, mass modelling, and gravitational stability of the dwarf irregular galaxies ESO444–G084 and [KKS2000]23 using high spatial, spectral, and column density sensitivity data from the MeerKAT H <ns0:sc>I</ns0:sc> observations of nearby galactic objects: Observing Southern Emitters (MHONGOOSE) survey obtained with MeerKAT. ESO444–G084 exhibits centrally concentrated H <ns0:sc>I</ns0:sc> emission, while [KKS2000]23 has irregularly distributed high-density pockets. The total H <ns0:sc>I</ns0:sc> fluxes measured down to column density thresholds of 1019 cm−2 and 1018 cm−2 are nearly the same, suggesting that the increase in the H <ns0:sc>I</ns0:sc> diameter at lower column densities is primarily due to the larger beam size, and that no significant additional emission is detected. The total H <ns0:sc>I</ns0:sc> masses are (1.1±0.1)×108 M⊙ for ESO444–G084 and (6.1±0.3)×108 M⊙ for [KKS2000]23. We derived rotation curves using 3D kinematic modelling tools Python fully automated TiRiFiC (PyFAT) and tilted ring fitting code (TiRiFiC), which allow us to fully capture the gas kinematics. Both galaxies exhibit disk-like rotation, with ESO444–G084 showing a kinematic warp beyond ∼1.8 kpc. Its relatively fast-rising rotation curve suggests a more centrally concentrated dark matter distribution, whereas [KKS2000]23's more gradual rise indicates a more extended mass distribution. Mass modelling with an isothermal halo and stellar mass-to-light ratio $ (M/L)^{*}_{3.4\,\upmu {\mathrm {m}}} = 0.20 $ for ESO444–G084 and 0.18 for [KKS2000]23 yields physically consistent results. We further analyse disk stability using spatially resolved maps of the Toomre Q parameter and Σgas/Σcrit, linking these with recent star formation traced by hydrogen-alpha (Hα) and far-ultraviolet (FUV) emission. ESO444–G084 supports localised star formation despite global stability, while [KKS2000]23 is gravitationally unstable yet lacks strong Hα emission, suggesting that turbulence, gas depletion, or past feedback suppresses star formation. The absence of detectable inflows or outflows implies that internal processes regulate star formation. This study highlights the interplay between H <ns0:sc>I</ns0:sc> morphology, kinematics, dark matter distribution, and disk stability, demonstrating how internal mechanisms shape dwarf galaxy evolution.