The Metallicity Dependence of the CO-to-H2 Conversion Factor from Observations of Local Group Galaxies

Six additional molecular clouds have been mapped in the nearby metal-poor dwarf irregular galaxy IC 10 using the Owens Valley Millimeter-Wave Interferometer. Since a good distance measurement is now available for IC 10, it is possible to measure accurately the CO-to-H2 conversion factor in this galaxy. The result for IC 10 is combined with published data for four other Local Group galaxies (M31, M33, NGC 6822, and the SMC) to trace the …