$\textit{Herschel}$ Photometric Observations of $\mathrm{L{\small{ITTLE}}}$ $\mathrm{T{\small{HINGS}}}$ Dwarf Galaxies

Abstract: We present here far-infrared photometry of galaxies in a sample that is relatively unexplored at these wavelengths: low-metallicity dwarf galaxies with moderate star formation rates. Four dwarf irregular galaxies from the $\mathrm{L{\small{ITTLE}}}$ $\mathrm{T{\small{HINGS}}}$ survey are considered, with deep $\textit{Herschel}$ PACS and SPIRE observations at 100 $\mu$m, 160 $\mu$m, 250 $\mu$m, 350 $\mu$m, and 500 $\mu$m. Results from modified-blackbody fits indicate that these galaxies have low dust masses and cooler dust temperatures than more actively star-forming dwarfs, occupying the lowest $L_\mathrm{TIR}$ and $M_\mathrm{dust}$ regimes seen among these samples. Dust-to-gas mass ratios of $\sim$10$^{-5}$ are lower, overall, than in more massive and active galaxies, but are roughly consistent with the broken power law relation between the dust-to-gas ratio and metallicity found for other low-metallicity systems. Chemical evolution modeling suggests that these dwarf galaxies are likely forming very little dust via stars or grain growth, and have very high dust destruction rates.