Model results for ℳ2a (D/G observed, left) and ℳ2b (D/G scaled with metallicity, right). The plots on top show, from top to bottom, the total heating and cooling rate, the contributions to the heating rate, the contributions to the cooling rate, and the cumulative intensities of cooling lines for the radiation-bounded sector as a function of the depth within the cloud (the H ii-H i transition lies at ≈213 pc). For clarity, the heating and cooling mechanisms in the H ii region are not shown. The predicted dust SED is shown in the bottom panels for both models. The 20 cm measurement is thought to be dominated by synchrotron emission (see text). The vertical lines indicate the range used to calculate the total infrared luminosity (3−1100 μm) and the green shaded area shows the modeled emission in this range. The blue shaded area shows the input radiation field. The model ℳ2b shows weak silicate emission bands at 10 μm and 20 μm that are not seen in the IRS spectrum.