Orion B in 18 molecular tracers maps

For conditions similar to the Orion B molecular cloud, we obtain predictions of NH_2_ within a typical factor of 1.2 from the Herschel-based estimates. An analysis of the contributions of the different lines to the predictions show that the most important lines are ^13^CO(1-0), ^12^CO(1-0), C^18^O(1-0), and HCO+(1-0). A detailed analysis distinguishing between diffuse, translucent, filamentary, and dense core conditions show that the importance of these four lines depends on the regime, and that it is recommended to add the N_2_H+(1-0) and CH_3_OH(2_0_-1_0_) lines for the prediction of NH_2_ in dense core conditions.

This article opens a promising avenue to directly infer important physical parameters from the molecular line emission in the millimeter domain. The next step will be to try to infer several parameters simultaneously (e.g., NH_2_ and far-UV illumination field) to further test the method.