Top: Observed SED of IRAS 18276−1431 corrected by interstellar extinction (squares), SED predicted by CLOUDY for our best‐fit model (thin solid black line), and blackbody spectra for ﹩T_{\mathrm{dust}\,}=150﹩ and 20 K (dashed lines). A combined model spectrum (best‐fit CLOUDY model + 150 K blackbody) is shown with the thick solid blue line. Bottom: Spatial variation of the grain equilibrium temperature for the different grain size bins used in the model (solid black lines). The gas density (blue line), obtained by adopting a constant dust‐to‐gas mass ratio throughout the envelope (﹩\delta =200﹩), and the gas kinetic temperature (pink dashed line), predicted by CLOUDY for the best‐fit envelope parameters derived from SED modeling, are also shown.