Abstract

view Abstract Citations (37) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS First Observations of Individual Molecular Clouds in the Irregular Galaxy NGC 6822 Wilson, Christine D. Abstract Three molecular clouds have been mapped in the nearby metal-poor dwarf irregular galaxy NGC 6822 using the Owens Valley Millimeter-Wave Interferometer. These molecular clouds are similar to molecular clouds recently studied in the Small Magellanic Cloud, and are somewhat less massive 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 factors obtained for Galactic molecular clouds, NGC 6822, and the SMC are consistent with the variation in the CO-to-H_2_ conversion factor being linearly proportional to the oxygen abundance of the galaxy. However, the 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 limited 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_sun_) molecular clouds. Publication: The Astrophysical Journal Pub Date: October 1994 DOI: 10.1086/187560 arXiv: arXiv:astro-ph/9407070 Bibcode: 1994ApJ...434L..11W Keywords: Abundance; Irregular Galaxies; Local Group (Astronomy); Molecular Clouds; Astronomical Interferometry; Brightness Temperature; Galactic Mass; Oxygen; Star Formation; Astrophysics; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 6822; GALAXIES: IRREGULAR; GALAXIES: ISM; GALAXIES: LOCAL GROUP; ISM: MOLECULES; Astrophysics E-Print: 8 pages + 5 figures, uuencoded compressed postscript file, CDW-94-2 full text sources arXiv | ADS | data products SIMBAD (8) NED (1)

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