| Abstract: Understanding the origin of substructures in protoplanetary disks is a key challenge in planet-formation studies, yet current results are strongly biased toward small samples of bright, large disks. I present a high-resolution study of ~100 of the brightest disks from the Ophiuchus Disk Survey Employing ALMA (ODISEA), observed in Band 8 continuum (410 GHz; 0.7 mm), aimed at characterizing disk substructures as a function of SED class and disk mass.
The sample extends down to faint disks containing as little as ~2 M⊕ of dust. Guided by the flux–size relationship, the brightest disks were observed at ~20 au resolution, while fainter disks were targeted at resolutions improved by a factor of three. In all cases, we applied the Frankenstein code to further enhance spatial resolution. Disk substructures were classified within a unified evolutionary framework linking observed morphologies to stages of giant planet formation. We introduce Stage 0 to describe featureless disks and provide systematic definitions for Stages 0–V.
Despite higher optical depths, Band 8 proves to be an efficient tracer of disk substructures, recovering the same gaps and cavities seen at longer wavelengths with significantly shorter integration times. Massive disks (≳10 M⊕ of dust, estimated from optically thinner Band 4 data) consistently show substructures compatible with the proposed evolutionary sequence, even at modest resolution. In contrast, lower-mass disks rarely exhibit clear gaps or cavities, even at higher angular resolution, likely due to the steep size–flux relationship.
These results support the conclusion that giant planet formation drives substructures in disks with ≳10 M⊕ of dust and demonstrate the strong potential of Band 8 observations. With ALMA capable of achieving ~1 au resolution in Band 8, this wavelength offers a promising path to explore substructures in low-mass disks, a regime that remains largely unexplored. |
