AAS 204th Meeting, June 2004
Session 61 Structures in the Interstellar Medium
Poster, Wednesday, June 2, 2004, 10:00am-7:00pm, Ballroom

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[61.05] Observation of the [CI] 3P1-3P0 line toward the IC1396 region

K. Tanaka (Dept. of Physics, Univ of Tokyo), T. Oka, S. Yamamoto (Dpet. of Physucs, Univ of Tokyo)

We present the result of a [CI]{{3P1}--{3P0}} observation toward the IC1396 region carried out with the Mount Fuji submillimeter-wave telescope in 2002.

The IC1396 region is an HII region containing a lot of bright-rimmed globules, which are considered as ideal samples of edge-on PDRs. The PDR models predict that {\rm C0} mainly distributes on the surface of the cloud, and [CI] emission should have a rim-brightening structure in the bright-rimmed globules. We conducted a mapping observation of [CI]{{3P1}--{3P0}} emission toward the IC1396 region in order to examine wheather the [CI] emission is rim-brightening. We also observed the {\rm C{18O}}\ J=1-0, SO J\rm N=32-21 and {\rm N2H+}\ J=1-0 emissions with the NRO 45 m telescope.

We mapped 0.5 \rm deg2 area containing 13 globules, and found that [CI] does not have a rim-brightening structure in any globule. The maximuma of N(\rm C0) appear at the positions where the N(\rm C0) is also peaked, or behind the CO peak with respect to the UV source. In order to explain the observed distribution, an additional component of {\rm C0} which does not originate from a PDR should be considered.

We found that the globules with IRAS point sources or \rm N2H+ cores (group I) systematically have lower {\rm C0}/CO ratio than the globules without those objects (group II). There is a tendency that the globules of the group I are nearly gravitationally bound, while the globules of the group II seem to be pressure bound. We also estimated N({\rm SO})/N({\rm CO}) ratio and found that the group I have a higher N({\rm SO})/N({{\rm CO}}) ratio than the group II. These results indicate that the globules of the group I would be in advanced phase of dynamical and chemical evolution, supporting the {\rm C0}/CO ratio reflects the evolutionary stage of the cloud.

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