Stokes I visibility amplitudes vs. u,v distance averaged in bins of 2kλ. Top panel: uniform temperature profile. Bottom panel: radial temperature profile. Red and black dots: IRAS 4A full data and envelope data, respectively, with their statistical error bars. Vertical dashed line: u,v distance threshold used to derive the compact components map (see Fig. 1). Starting at  ~90 kλ the emission seems to match with an unresolved source of  ~1 Jy. Red, green, and blue solid curves: visibility amplitudes derived after convolving the Galli & Shu (1993a,b), Allen et al. (2003a,b), and Shu et al. (2006) models, respectively, used to generate the maps of left-hand panels of Figs. 7 and 8.