2000ApJ...539L.133P

We present maps of the ¹³CO J=5⟶4 (551 GHz) and [C I] ³P₁⟶³P₀ (492 GHz) emission in the Orion A molecular cloud, covering a 0°.5x2° area. A large velocity gradient (LVG) analysis of ¹³CO J=5⟶4 and J=1⟶0 suggests that the gas temperatures in the northern part of OMC-1 (north of Δδ=-20') are ∼45 K and are, on average, at least 20 K higher than those to the south. The average ¹³CO column density is log(N/cm^–2)=16.4±0.3 and is fairly constant throughout the cloud, even in the low-temperature region south of BN/KL. LVG modeling of the [C I] emission shows a typical C⁰ column density of 2x10¹⁷ cm^–2, which yields a C/CO abundance ratio in the cloud of ∼0.1 (rising to levels in excess of 0.5 at the cloud edges). Comparison of the Δ-variance (which measures spatial structure in a manner similar to a power spectrum) of the Submillimeter Wave Astronomy Satellite [C I], Five College Radio Astronomy Observatory ¹³CO J=1⟶0, and CS J=1⟶0 velocity-integrated maps suggests that the [C I] and ¹³CO emission arise from the same gas. In contrast, the CS emission likely originates in gas that is considerably more clumpy.