Fits to the 0.4–500 μm spectral energy distributions of the north (top) and south (bottom) nuclei of IRAS16399−0937. The symbols with error bars represent photometry from HST, 2MASS, Spitzer, and Herschel (see Table 1); the black lines represent IRS SL (solid) and IRS LL (dashed) spectra. The overall fit, shown by the red band, is the sum of three components: the GRASIL elliptical galaxy models (orange band, Silva et al. 1998), the ISM dust + PAH models of DL07 (blue band), and the clumpy AGN torus model of Nenkova et al. (2008a, 2008b; green band). The fits to both nuclei were carried out simultaneously using the clumpyDREAM code (see text). The width of each band represents, at a given wavelength, the full range of flux density permitted by the converged fit. In this model, it is assumed that the IRAS16399N nucleus contains an AGN, whereas the IRAS16399S nucleus is a pure starburst. Therefore, the fit to the IRAS16399N nucleus (top panel) includes all three components, whereas the fit to the IRAS16399S nucleus (bottom panel) includes only the stellar and ISM components. The two nuclei are not resolved in the LL IRS spectrum, or in the Spitzer MIPS and Herschel SPIRE images. Therefore the LL spectrum (dashed line) and photometry data points for λ ⩾ 30 μm (inverted triangles) refer to large aperture (7'') measurements of IRAS16399−0937 system and were treated as upper limits in the fits.