Resolving the Transition from Molecular to Atomic at 1/5 Solar Metallicity in the Small Magellanic Cloud

At a distance of 61 kpc, the Small Magellanic Cloud (SMC) affords an absolutely unique view of the low metallicity star-forming interstellar medium, providing the nearest laboratory to study processes relevant to star formation at high redshifts. We present new ALMA 7m-array maps of CO and ¹²CO (2-1) for one of the four observed regions in the Southwest Bar of the SMC. These maps are the first high-resolution (~6'' ~ 1.7 pc) images of CO in a molecular cloud at 1/5 Solar metallicity. We show the structure of photodissociation regions for the first time at 1/5 Solar metallicity by combining the new ALMA data with Herschel maps of [C ii] and [O i]. We present preliminary evidence that there is extended, faint ¹²CO (2-1) emission near where we expect the Hi-to-H₂ transition. We also compare our data to the low metallicity 3D simulations by Glover & Mac Low (2011) and Shetty et al. (2011).