Molecular Cloud Structure at Low Metallicity

Detecting and mapping molecular cloud tracers in gas-rich, low metallicity dwarf irregular galaxies is relevant for the study of star formation in the early universe when metallicities were low. Because of the lower in metallicity it is expected the (giant) molecular clouds to have thicker shells of predominantly H2 and tinier CO cores than GMCs in the Milky Way because there is a commensurate lower abundance of dust to absorb UV light. We identified 47 CO-cores in the Wolf-Lundmark-Melotte (WLM) galaxy from ALMA radio interferometer data using the automated cloud-finding algorithm CLOUDPROPS. We present a study of the CO clouds found in WLM and a review of three other nearby dwarf galaxies with lower abundances than WLM and discuss the upper limits found there. We plotted the CO-cores on FUV and FIR images of WLM to analyze the correlation between CO clouds, HI, and young star clumps in this galaxy. A comparison of the intensity-velocity spectrum of CO-cores and HI is presented. We discuss the relationship between the CO-cores, molecular H2, and young stars. L.T. acknowledges grant AST-1461200 from the National Science Foundation to Northern Arizona University to fund the 2019 REU program and as well as support from the 2019 CAMPARE Scholar program.