FIRST OBSERVATIONS OF INDIVIDUAL MOLECULAR CLOUDS IN THE IRREGULAR GALAXY NGC-6822

Three molecular clouds have been mapped in the nearby metal-poor dwarf irregular galaxy NGC 6822 using the Owens Valley Millimeter-Wave Inte rferometer. These molecular clouds are similar to molecular clouds rec ently studied in the Small Magellanic Cloud, and are somewhat less mas sive on average than molecular clouds in Local Group spiral galaxies. Based on upper limits to the virial masses of the clouds, the CO-to-H- 2 conversion factor in NGC 6822 is <2.2 +/- 1.3 times larger than the Galactic value [3 x 10(20) cm(-2) (K km s(-1))(-1)]. Conversion factor s obtained for Galactic molecular clouds, NGC 6822, and the SMC are co nsistent with the variation in the CO-to-H-2 conversion factor being l inearly proportional to the oxygen abundance of the galaxy. However, t he uncertainties are sufficiently large that equal conversion factors in NGC 6822 and the Galaxy cannot be ruled out. The gas depletion time obtained for the H II region Hubble V is comparable to those of giant H II regions in M33. Thus high-efficiency star formation is not limit ed to the giant H II regions seen spiral galaxies, but can also occur in a small group of relatively low-mass (a few times 10(4) M(circle do t)) molecular clouds.