Left: normalized histogram of R_1,2 in black for all the unmasked pixels in the maps. The colored normalized histograms represent the R_1,2 distributions within one-beam area (24″) around the central coordinates (see Table 1) of K04166 (red), K04169 (yellow), and Miz-8b (blue). The vertical dashed lines refer to the value of the ratio at the peak-intensity position of T Tauri (green), Miz-2, and HGBS-1 (blue). The upper x-axis shows the corresponding β values in the Rayleigh-Jeans limit (see Sect. 5.1). Right: same as in the left panel with shades that now represent ranges of R_1,2 corresponding to graybodies with 1) a constant temperature T_d of 15 K but a varying β between 0.5 and 3 in purple; 2) a constant β of 2, but varying T_d between 10 K and 20 K in green.