T–r profile of IRAS 4A2. The gas temperatures are derived accounting for all transitions and for the millimeter dust obscuration (bottom). The colored data points mark the best-fit gas temperature derived for each species as a function of the average emitting radius r̄. The emitting radius error bar encompasses the observed range of sizes per species. The error bar on the temperature is the 1σ confidence range of the LTE rotational diagram analysis (CH₃CHO), of the LTE population diagram analysis (HCOOCH₃, CH₃CH₂OH, and CH₂OHCHO), and of the non-LTE LVG analysis for CH₃OH. The gray solid line in both panels is the best fit to the data points excluding CH₃CHO (see Sect. 3.2).