title: Large-Scale Mapping Observations of the C i (3P1-3P0) and CO (J = 3-2) Lines toward the Orion A Molecular Cloud.
abstract: Large-scale mapping observations of the 3P1-3P0 fine-structure transition of atomic carbon (C i, 492 GHz) and the J=3-2 transition of CO (346 GHz) toward the Orion A molecular cloud have been carried out with the Mount Fuji submillimeter-wave telescope. The observations cover 9 deg2 and include the Orion Nebula M42 and the L1641 dark cloud complex. The C i emission extends over almost the entire region of the Orion A cloud and is surprisingly similar to that of 13CO (J=1-0). The CO (J=3-2) emission shows a more featureless and extended distribution than C i. The C i/CO (J=3-2) integrated intensity ratio shows a spatial gradient running from the north (0.10) to the south (1.2) of the Orion A cloud, which we interpret as a consequence of the temperature gradient. On the other hand, the C i/13CO (J=1-0) intensity ratio shows no systematic gradient. We have found a good correlation between the C i and 13CO (J=1-0) intensities over the Orion A cloud. This result is discussed on the basis of photodissociation region models.
authors.initials: M
authors.lastname: Ikeda
authors.initials: H
authors.lastname: Maezawa
authors.initials: T
authors.lastname: Ito
authors.initials: G
authors.lastname: Saito
authors.initials: Y
authors.lastname: Sekimoto
authors.initials: S
authors.lastname: Yamamoto
authors.initials: K
authors.lastname: Tatematsu
authors.initials: Y
authors.lastname: Arikawa
authors.initials: Y
authors.lastname: Aso
authors.initials: T
authors.lastname: Noguchi
authors.initials: SC
authors.lastname: Shi
authors.initials: K
authors.lastname: Miyazawa
authors.initials: S
authors.lastname: Saito
authors.initials: H
authors.lastname: Ozeki
authors.initials: H
authors.lastname: Fujiwara
authors.initials: M
authors.lastname: Ohishi
authors.initials: J
authors.lastname: Inatani