Far-infrared to millimeter data of protoplanetary disks: dust growth in the Taurus, Ophiuchus, and Chamaeleon I star-forming regions

TL;DR

This study combines far-infrared to millimeter observations of 284 protoplanetary disks across three star-forming regions to analyze dust growth, disk properties, and regional differences, providing insights into planet formation processes.

Contribution

It offers a comprehensive analysis of dust growth and disk characteristics using combined Herschel and ancillary data, revealing regional spectral index differences and correlations with disk temperature.

Findings

Most disks show evidence of grain growth.

No correlation between disk evolution tracers and millimeter spectral indices.

Tentative evidence of steeper spectral indices in Chamaeleon I.

Abstract

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 1.3 mm and 10 au, the disk temperature at this same radius, and the dust opacity spectral index. We find the fluxes at 70 microns to correlate strongly with disk temperatures at 10 au, 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.