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Session 67 - ISM in Galaxies.
Display session, Wednesday, January 15
Metropolitan Ballroom,

[67.14] Atomic Carbon in Normal Galaxies: I. Individual Molecular Clouds in M33

C. D. Wilson (McMaster U.)

[CI] emission has been detected from four individual giant molecular clouds in the Local Group spiral galaxy M33. Observations with the 11" beam of the James Clerk Maxwell Telescope give peak temperatures of 0.2-0.3 K for the four clouds in the sample (MC 20, MC 32, NGC 604-2, and NGC 604-4). Comparing these data with published interferometric CO J=1-0 measurements yields an average [CI]/CO ratio of 0.12. The [CI]/CO line ratios for two clouds without optical HII regions are somewhat lower than for two clouds associated with HII regions. The average [CI] column density for these clouds will be compared with measurements of atomic carbon in Galactic molecular clouds, as well as with measurements of atomic carbon in nearby starburst galaxies. These observations of [CI] emission integrated over an entire molecular cloud will also be used to determine how important the presence of massive star formation is to the formation of atomic carbon in clouds.

Program listing for Wednesday