ALMA Super-resolution Imaging of Protoplanetary Disks in the Taurus-Auriga Region: Analysis of Substructures and Statistical Characteristics

Masayuki Yamaguchi, Takayuki Muto, Takashi Tsukagoshi, Hideko Nomura, Naomi Hirano, Takeshi Nakazato, Shiro Ikeda, Ryohei Kawabe

We present high-resolution 1.3 mm continuum emission images of 43 protoplanetary disks in the Taurus-Auriga region, comprised of 39 Class II disks and four disks around Herbig Ae stars. A novel super-resolution imaging technique utilizing sparse modeling was applied, with the aim of enhancing the fidelity and spatial resolution of the ALMA 2D images (Yamaguchi et al. 2020, 2021). Utilizing the ALMA archival data of Band 6, we achieved unprecedented disk images with spatial resolutions ranging from 0.01 to 0.1 arcseconds (corresponding to 1-14 au at a distance of 140 pc), 2-3 times higher than those obtained from conventional CLEAN images. The resolved dust disks have radii that widely range from 8 to 238 au with a median of 51 au but exhibit a roughly similar average surface brightness temperature of 8 K. Our analysis revealed various substructures regardless of disk size, including 22 disks with annular gaps and rings, 13 disks with abrupt changes in the slopes of the radial intensity profile but not identified as gaps, and three disks with a ring alone. The locations of the gaps show bimodal distribution peaking at 10-20 au and 30-100 au. We find that the locations of gaps and rings show a linear relationship with a correlation coefficient of 0.9, while five systems do not lie on this correlation. The outlier’s gap widths are 2-3 times larger than typical sizes on the corresponding locations. Assuming that the gaps are carved by planets and that their sizes are proportional to planetary masses, our findings suggest that two types of these disks with different gap sizes indicate the presence of two distinct planet-forming mechanisms.