OMC 1 reduced H_2_CO(3-2) datacubes

The cold dust components measured in the far infrared (FIR) are consistent with those measured with NH_3_ (2,2)/(1,1) and the CH_3_CCH(6-5) line series. With dust at MIR wavelengths and para-H_2_CO(3-2) on one side and dust at FIR wavelengths, NH_3_ (2,2)/(1,1), and CH_3_CCH(6-5) on the other, dust and gas temperatures appear to be equivalent in the dense gas (n(H_2_)>~10^4^cm^-3^) of the OMC-1 region, but provide a bimodal distribution, one more directly related to star formation than the other.

The non-thermal velocity dispersions of para-H2CO are positively correlated with the gas kinetic temperatures in regions of strong non-thermal motion (Mach number >~2.5) of the OMC-1, implying that the higher temperature traced by para-H2CO is related to turbulence on a ~0.06pc scale. Combining the temperature measurements with para-H_2_CO and NH3 (2,2)/(1,1) line ratios, we find direct evidence for the dense gas along the northern part of the OMC-1 10km/s filament heated by radiation from the central Orion nebula.