First results from the CALYPSO IRAM-PdBI survey. I. Kinematics of the inner envelope of NGC1333-IRAS2A

TL;DR

This study uses high-resolution observations of methanol lines to investigate the inner envelope of the Class 0 protostar NGC1333-IRAS2A, finding evidence of infalling envelope dynamics rather than a Keplerian disk.

Contribution

First high-angular-resolution analysis of NGC1333-IRAS2A's inner envelope, providing insights into its kinematics and disk presence compared to other protostars.

Findings

No clear Keplerian disk detected, suggesting a smaller or absent disk.

Evidence of infalling and slowly rotating envelope dynamics.

Protostar mass estimated at 0.1-0.2 M$_\odot$.

Abstract

The structure and kinematics of Class 0 protostars on scales of a few hundred AU is poorly known. Recent observations have revealed the presence of Keplerian disks with a diameter of 150-180 AU in L1527-IRS and VLA1623A, but it is not clear if such disks are common in Class 0 protostars. Here we present high-angular-resolution observations of two methanol lines in NGC1333-IRAS2A. We argue that these lines probe the inner envelope, and we use them to study the kinematics of this region. Our observations suggest the presence of a marginal velocity gradient normal to the direction of the outflow. However, the position velocity diagrams along the gradient direction appear inconsistent with a Keplerian disk. Instead, we suggest that the emission originates from the infalling and perhaps slowly rotating envelope, around a central protostar of 0.1-0.2 M$_\odot$. If a disk is present, it is smaller than the disk of L1527-IRS, perhaps suggesting that NGC1333-IRAS2A is younger.