Our fiducial model fit (with parameters listed in Table 2) to the H₂O PACS lines (panel a), H₂O SPIRE lines (panel b), and the SED (panel c). Dashed blue, green, and gray lines indicate results for the three nuclear components: the core, the disk, and the envelope, respectively. Panels a–b: combined (total) absorption or emission of the three components is shown in red, and the small numbers at the bottom indicate the approximate wavelength of the line. Panel c: circles at < 200 μm show both IRAS data and Herschel/PACS spectrophotometric data (see Appendix A), with uncertainties better than 15%, and circles with error bars at > 400 μm are ALMA data for the nuclear region modeled in this work; we also show the Spitzer/IRS and the Herschel/SPIRE spectra. The continuum of the combined three nuclear components related to H₂O is shown in light-blue, and a nonnuclear (extended) component (in magenta, with T_dust = 28 K) is required to reproduce the full SED at long wavelengths. The red line indicates the total (nuclear+extended) modeled SED.