1999ApJ...525..343W

We have used the Heinrich Hertz submillimeter telescope to measure the J=3-2 and J=2-1 lines of ¹²C¹⁶O and ¹²C¹⁸O, and the J=3-2 line of ¹³C¹⁶O toward 125 high-density cores in the prominent S-shaped feature in L1640. We have also measured the (J,K)=(1,1) and (2,2) inversion transitions of NH₃ from these sources. These results have been used to determine kinetic temperatures, H₂ densities, and column densities. Estimates of the stability of these cores are made. Comparisons are also made with other nearby star formation regions such as the Taurus clouds. Sources in the northern part of the region surveyed have larger line widths, kinetic temperatures, T_k, and higher ratios of the J=3-2 to J=2-1 lines of C¹⁸O. It is likely that these sources are heated externally. Except for cores in the southern part of this cloud, T_k exceeds 10 K, the value found for dark dust clouds. The average density for all cores is ∼3x10⁴ cm^–3. Orion KL is an extraordinary source, with much larger T_k, local density, and column density than any other source in our sample.