Early Planet Formation in Embedded Disks (eDisk) III: A first high-resolution view of sub-mm continuum and molecular line emission toward the Class 0 protostar L1527 IRS

TL;DR

This study presents high-resolution ALMA observations of the Class 0 protostar L1527 IRS, revealing a smooth, asymmetric disk with complex molecular emission, temperature structure, and potential misalignment, providing insights into early planet formation conditions.

Contribution

First high-resolution ALMA imaging of dust and molecular lines in a Class 0 protostar, revealing detailed physical and chemical disk properties and system misalignment.

Findings

Disk is smooth and asymmetric without substructures.

Molecular lines trace different components, with possible disk wind.

Snowline located at ~350 au, indicating warm disk conditions.

Abstract

Studying the physical and chemical conditions of young embedded disks is crucial to constrain the initial conditions for planet formation. Here, we present Atacama Large Millimeter/submillimeter Array (ALMA) observations of dust continuum at $\sim$0.06" (8 au) resolution and molecular line emission at $\sim$0.17" (24 au) resolution toward the Class 0 protostar L1527 IRS from the Large Program eDisk (Early Planet Formation in Embedded Disks). The continuum emission is smooth without substructures, but asymmetric along both the major and minor axes of the disk as previously observed. The detected lines of $^{12}$CO, $^{13}$CO, C$^{18}$O, H$_2$CO, c-C$_3$H$_2$, SO, SiO, and DCN trace different components of the protostellar system, with a disk wind potentially visible in $^{12}$CO. The $^{13}$CO brightness temperature and the H$_2$CO line ratio confirm that the disk is too warm for CO freeze out, with the snowline located at $\sim$350 au in the envelope. Both molecules show potential evidence of a temperature increase around the disk-envelope interface. SO seems to originate predominantly in UV-irradiated regions such as the disk surface and the outflow cavity walls rather than at the disk-envelope interface as previously suggested. Finally, the continuum asymmetry along the minor axis is consistent with the inclination derived from the large-scale (100" or 14,000 au) outflow, but opposite to that based on the molecular jet and envelope emission, suggesting a misalignment in the system. Overall, these results highlight the importance of observing multiple molecular species in multiple transitions to characterize the physical and chemical environment of young disks.