We present new, wide, and deep images in the 1.1 mm continuum and the CO ( 1–0) emission toward the northern part of the Orion A Giant Molecular Cloud (Orion-A GMC). The 1.1 mm data were taken with the AzTEC camera mounted on the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope in Chile, and the CO ( 1–0) data were with the 25 beam receiver (BEARS) on the Nobeyama Radio Observatory (NRO) 45 m telescope in the On-The-Fly (OTF) mode. The present AzTEC observations are the widest (17 23, corresponding to 12 pc 17 pc) and the highest-sensitivity (9 mJy beam) 1.1 mm dust-continuum imaging of the Orion-A GMC with an effective spatial resolution of 40. The CO ( 1–0) image was taken over the northern 12 12 (corresponding 9 pc 9 pc) area with a sensitivity of 0.93 K in , a velocity resolution of 1.0 km s, and an effective spatial resolution of 21. With these data, together with the MSX 8m, Spitzer 24m, and the 2MASS data, we have investigated the detailed structure and kinematics of molecular gas associated with the Orion-A GMC, and have found evidence for interactions between molecular clouds and the external forces that may trigger star formation. Two types of possible triggers were revealed: (1) Collisions of the diffuse gas on the cloud surface, particularly at the eastern side of the OMC-2/3 region, and (2) Irradiation of UV on the pre-existing filaments and dense molecular cloud cores. Our wide-field and high-sensitivity imaging has provided the first comprehensive view of the potential sites of triggered star formation in the Orion-A GMC.
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN