Upper: rotational diagram at L1448-B2 for the H₂ emission lines detected with Spitzer by Giannini et al. (2011). The values have been derived from the H₂ fluxes integrated over a 13′′ area for comparison with the PACS data. The black dots are the observed values, whereas the empty dot represents the H₂ S(1) line corrected for an ortho-to-para ratio equal to 1 (see Giannini et al. 2011). The green solid line represents the linear fit to the S(0)–S(3) H₂ lines, while the green dotted line is the fit obtained using the S(0)–S(2) H₂ lines. Finally, the blue line is the linear fit to the S(3)–S(7) lines. The resulting parameters (T,N) or range of parameters of the linear fits are reported in the diagram. Lower: H₂ rotational diagram at L1157-R. The symbols are the same as in the upper panel.