2025A&A...695A.147V

Context. Multi-wavelength dust continuum observations of protoplanetary disks are essential for accurately measuring two key ingredients of planet formation theories: dust mass and grain size. Unfortunately, they are also extremely time-expensive.
Aims. Our aim is to investigate the most economic way of performing this analysis by identifying the optimal combination of multiband observations and angular resolution that provides accurate results.
Methods. We benchmarked the dust characterization analysis on multi-wavelength observations of a compact disk model with shallow rings, and an extended double-ringed disk model. We tested three different combinations of bands (in the 0.45 mm → 7.46 mm range) to see how optically thick and thin observations aid in the reconstruction of the dust properties for different morphologies and in three different dust mass regimes. We also tested different spatial resolutions (0.05″; 0.1″; 0.2″).
Results. Dust properties are robustly measured in a multi-band analysis if optically thin observations are included. For typical disks, this requires wavelengths longer than 3 mm. Instead, from fully optically thick observations alone the dust properties cannot be robustly constrained. A high resolution (<0.03″-0.05″) is fundamental in order to resolve the changes in dust content of substructures. However, lower-resolution results still provide an accurate measurement of the total dust mass and of the level of grain growth of rings. Additionally, we propose a new approach that successfully combines lower- and higher-resolution observations in the multi-wavelength analysis without losing spatial information. We also tested enhancing the resolution of each radial intensity profile individually with a flux reconstruction tool (Frank), but we note the presence of artifacts. Finally, we discuss the total dust mass that we derived from the SED analyses and compare it with the traditional method of deriving dust masses from millimeter fluxes. Accurate dust mass measurements from the SED analysis can be derived by including optically thin tracers. On the other hand, single-wavelength flux-based masses are always underestimated. For the 0.87 mm flux, the underestimation can be more than one order of magnitude.