We have constructed a 1.2-m submillimeter-wave telescope at the summit of Mt. Fuji to observe molecular clouds in two CI lines, 3 P 1 - 3 P 0 (492 GHz) and 3 P 2 - 3 P 1 (809 GHz). The telescope has been operated successfully for four observing seasons since the installation on 1998. We have obtained large-scale CI 492 GHz distributions of many molecular clouds, including Orion MC, Taurus MC, DR15, ρ-Oph, DR21, NGC2264, M17, W3, W44, W51, Rosette MC, covering more than 40 square degrees of the sky. The distribution of CI 492 GHz emission is found to be different from those of the 13 CO or C 18 O emission in some clouds. We found C 0 -rich areas (C/CO ∼ 1) in several dark clouds without strong UV sources. Away from UV sources the spatial sequence appears to be C + /CO/C 0 . This seems to be inconsistent with the standard photodissociation region picture. These results are discussed in relation to formation processes of molecular clouds and dense cloud cores.
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