Far-infrared and (sub)millimeter fluxes can be used to study dust in protoplanetary disks, the building blocks of planets. Here, we combine observations from the Herschel Space Observatory with ancillary data of 284 protoplanetary disks in the Taurus, Chamaeleon I, and Ophiuchus star-forming regions, covering from the optical to mm/cm wavelengths. We analyze their spectral indices as a function of wavelength and determine their (sub)millimeter slopes when possible. Most disks display observational evidence of grain growth, in agreement with previous studies. No correlation is found between other tracers of disk evolution and the millimeter spectral indices. A simple disk model is used to fit these sources, and we derive posterior distributions for the optical depth at 1.3mm and 10au, the disk temperature at this same radius, and the dust opacity spectral index {beta}. We find the fluxes at 70{mu}m to correlate strongly with disk temperatures at 10au, as derived from these simple models. We find tentative evidence for spectral indices in Chamaeleon I being steeper than those of disks in Taurus/Ophiuchus, although more millimeter observations are needed to confirm this trend and identify its possible origin. Additionally, we determine the median spectral energy distribution of each region and find them to be similar across the entire wavelength range studied, possibly due to the large scatter in disk properties and morphologies.

Cone search capability for table J/ApJ/849/63/table11 (Summary of Herschel OBSIDs of large maps)

Cone search capability for table J/ApJ/849/63/ysos (*Adopted stellar parameters, millimeter and IR spectral indices, and 10 micron silicate feature properties for the -- from erratum published in 2020, ApJ, 901, 88)

Cone search capability for table J/ApJ/849/63/table12 (Additional Herschel observations of sources outside large maps)