2025ApJ...985...76L

In this paper, we present a comprehensive study on the properties of the interstellar medium in NGC 1222, a star-forming early-type merging galaxy that forms a triple system, using optical and far-infrared spectroscopic, and multiband photometric data. The fit to the spectral energy distribution reveals a high dust content in the galaxy, with a dust-to-stellar mass ratio of M_dust/M_⋆ ∼ 3.3 × 10^–3 that is 40-90 times larger than the mean value of local S0 galaxies. By comparing the observed optical emission line ratios to shock models, we suggest that a merger-induced shock, which is further supported by the higher-than-average [O I] 63 μm- and [C II] 158 μm-to-PAH ratios, plays a role in heating the gas in NGC 1222. We also show evidence for gas inflow by analyzing the kinematic properties of NGC 1222.