Early Planet Formation in Embedded Disks (eDisk). I. Overview of the Program and First Results

TL;DR

This study uses ALMA to investigate early planet formation by examining substructures in disks around young protostars, finding fewer features than in more evolved disks, which informs understanding of disk evolution and planet formation timing.

Contribution

The paper presents initial results from the eDisk ALMA program, revealing the presence or absence of substructures in embedded disks and providing physical parameters of protostars.

Findings

Few substructures detected in embedded disks compared to Class II disks.

Keplerian disks and dynamical masses of protostars identified.

Differences suggest rapid development of substructures during disk evolution.

Abstract

We present an overview of the Large Program, ``Early Planet Formation in Embedded Disks (eDisk)'', conducted with the Atacama Large Millimeter/submillimeter Array (ALMA). The ubiquitous detections of substructures, particularly rings and gaps, in protoplanetary disks around T Tauri stars raise the possibility that at least some planet formation may have already started during the embedded stages of star formation. In order to address exactly how and when planet formation is initiated, the program focuses on searching for substructures in disks around 12 Class 0 and 7 Class I protostars in nearby ($< $200 pc) star-forming regions through 1.3 mm continuum observations at a resolution of $\sim7$ au (0.04"). The initial results show that the continuum emission, mostly arising from dust disks around the sample protostars, has relatively few distinctive substructures, such as rings and spirals, in marked contrast to Class II disks. The dramatic difference may suggest that substructures quickly develop in disks when the systems evolve from protostars to Class II sources or alternatively that high optical depth of the continuum emission could obscure internal structures. Kinematic information obtained through CO isotopologue lines and other lines reveals the presence of Keplerian disks around protostars, providing us with crucial physical parameters, in particular, the dynamical mass of the central protostars. We describe the background of the eDisk program, the sample selection and their ALMA observations, the data reduction, and also highlight representative first-look results.