Oral Presentation

New Insights of Substructures in Taurus-Auriga Circumstellar Disks

Author(s): Masayuki Yamaguchi (ASIAA)

Presenter: Masayuki Yamaguchi (ASIAA)

In the past decade, ALMA observations of circumstellar disks revealed various substructures including gaps and rings. However, the formation of these gaps remains controversial, leading to the question of whether there are observable characteristics that can be used to link them to specific formation mechanisms. In this talk, we present promising new findings regarding the correlation between substructures and their formation mechanisms. We used ALMA Band 6 archival continuum data from 43 disks in the Taurus-Auriga region, comprising 39 Class II disks and four disks around Herbig Ae stars. To enhance the fidelity and spatial resolution of the images, we employed a novel 2D super-resolution imaging technique based on sparse modeling. As a result, we obtained unprecedented disk images with high spatial resolutions on the scale of a few au (0".01 - 0".1), which is two to three times better than conventional methods. All dust disks are successfully spatially resolved, with radii ranging widely from 8 to 238 au and a median radius of 45 au. These disks exhibit a similar average surface brightness temperature of ~8 K. The disks in 50 percent reveal gap structures, showing a bimodal distribution with peaks at radial locations of 10-20 au and 30-100 au. Those gaps typically form annular structures, with some at smaller radii having asymmetry in adjacent rings. We find that the widths of these gaps increase not only with their depth but also with their radial location, establishing robust scaling relations for the first time in those substructures. These observational relations are at least consistent with the model of planet-disk interactions, suggesting that planet formation begins much earlier than previously thought before the disk is fully formed. These relations should be also a reference to other gap-opening mechanisms, though no gap-size relations are being theoretically established yet, such as dust processes including ice lines and streaming instability.