ALMA Super-resolution Imaging of T Tau: r=12 au Gap in the Compact Dust Disk around T Tau N

Based on Atacama Large Millimeter/submillimeter Array (ALMA) observations, compact protoplanetary disks with dust radii of r less than or similar to 20-40 au were found to be dominant in nearby low-mass star formation regions. However, their substructures have not been investigated because of the limited spatial resolution achieved so far. We apply a newly developed super-resolution imaging technique utilizing sparse modeling (SpM) to explore several au-scale structures in such compact disks. SpM imaging can directly solve for the incomplete sampling of visibilities in the spatial frequency and potentially improve the fidelity and effective spatial resolution of ALMA images. Here we present the results of the application to the T Tau system. We use the ALMA 1.3 mm continuum data and achieve an effective spatial resolution of similar to 30% (5 au) compared with the conventional CLEAN beam size at a resolution of 17 au. The reconstructed image reveals a new annular gap structure at r = 12 au in the T Tau N compact disk, with a dust radius of 24 au, and resolves the T Tau Sa and Sb binary into two sources. If the observed gap structure in the T Tau N disk is caused by an embedded planet, we estimate a Saturn-mass planet when the viscous parameter of the disk is 10(-3). Ultimately, ALMA observations with enough angular resolution and sensitivity should be able to verify the consistency of the super-resolution imaging and definitely confirm the existence of this disk substructure.

Automated summary

Compact protoplanetary disks with dust radii of less than 20-40 au have been found to be predominant in nearby low-mass star formation regions. A newly developed super-resolution imaging technique utilizing sparse modeling (SpM) is applied to explore au-scale structures in such compact disks, revealing new structures like annular gaps and resolving binary star systems. Further ALMA observations are needed to confirm the existence of these substructures in the disks.