Substructures in Compact Disks of the Taurus Star-forming Region

TL;DR

This study reanalyzes ALMA observations of compact protoplanetary disks in Taurus, revealing substructures in half of them, and estimates planet occurrence rates, suggesting young planets are common and similar to other surveys.

Contribution

It identifies substructures in compact disks previously overlooked and estimates planet masses and occurrence rates, expanding understanding of planet formation in small disks.

Findings

Substructures detected in 6 of 12 compact disks.

Planet occurrence rate peaks near Neptune masses.

Similar planet occurrence rates to other surveys.

Abstract

Observations of substructure in protoplanetary disks have largely been limited to the brightest and largest disks, excluding the abundant population of compact disks which are likely sites of planet formation. Here, we reanalyze ~0.1'', 1.33 mm ALMA continuum observations of 12 compact protoplanetary disks in the Taurus star-forming region. By fitting visibilities directly, we identify substructures in 6 of the 12 compact disks. We then compare the substructures identified in the full Taurus sample of 24 disks in single star systems and the ALMA DSHARP survey, differentiating between compact (R_eff,90% < 50 au) and extended (R_eff,90% > 50 au) disk sources. We find that substructures are detected at nearly all radii in both small and large disks. Tentatively, we find fewer wide gaps in intermediate-sized disks with R_eff,90% between 30 and 90 au. We perform a series of planet-disk interaction simulations to constrain the sensitivity of our visibility-fitting approach. Under an assumption of planet-disk interaction, we use the gap widths and common disk parameters to calculate potential planet masses within the Taurus sample. We find that the young planet occurrence rate peaks near Neptune masses, similar to the DSHARP sample. For 0.01 $M_J/M_\odot$ $\lesssim$ $M_p/M_*$ $\lesssim$ 0.1 $M_J/M_\odot$, the rate is 17.4$\pm$8.3%; for 0.1 $M_J/M_\odot$ $\lesssim$ $M_p/M_*$ $\lesssim$ 1 $M_J/M_\odot$, it is 27.8$\pm$8.3%. Both of them are consistent with microlensing surveys. For gas giants more massive than 5 $M_J$, the occurrence rate is 4.2$\pm$4.2%, consistent with direct imaging surveys.