Observational constraints. Bottom panel: illustrative spectral energy distribution (SED), produced using a THEMIS grain mixture (Jones et al. 2017, gray curve). The blue curve represents a single modified blackbody that best fits the far-infrared and millimeter range of the SED. Black markers are overlaid on the gray curve to indicate the SED coverage enabled by the observations listed in Table 1, with the horizontal bars representing the bandwidths. Top panel: beam size of the observations used in our analysis, with the wavelength of the observations indicated on top of each marker (in micron, except for ALMA markers). Vertical bars represent the distance-induced variation in physical beam size across the ALMA-IMF sample.