Kinematics of the Envelope and Two Bipolar Jets in the Class 0 Protostellar System L1157

TL;DR

This study provides detailed observations of the envelope and bipolar jets in the youngest protostellar system L1157, revealing multiple jets, envelope dynamics, and physical properties through high-resolution molecular line imaging.

Contribution

It offers the first comprehensive map of the entire bipolar outflow in L1157, constrains jet precession, and analyzes the envelope's structure and mass distribution with high spatial resolution.

Findings

Multiple jets are consistent with the outflow structure.

The envelope shows signs of rotation and infall.

The dust opacity spectral index varies with radius.

Abstract

A massive envelope and a strong bipolar outflow are the two main structures characterizing the youngest protostellar systems. In order to understand the physical properties of a bipolar outflow and the relationship with those of the envelope, we obtained a mosaic map covering the whole bipolar outflow of the youngest protostellar system L1157 with about $5"$ angular resolution in CO J=2-1 using the Combined Array for Research in Millimeter-wave Astronomy. By utilizing these observations of the whole bipolar outflow, we estimate its physical properties and show that they are consistent with multiple jets. We also constrain a preferred precession direction. In addition, we observed the central envelope structure with $2"$ resolution in the $\lambda=1.3$ and 3 mm continua and various molecular lines: C$^{17}$O, C$^{18}$O, $^{13}$CO, CS, CN, N$_2$H$^+$, CH$_3$OH, H$_2$O, SO, and SO$_2$. All the CO isotopes and CS, CN, and N$_2$H$^+$ have been detected and imaged. We marginally detected the features that can be interpreted as a rotating inner envelope in C$^{17}$O and C$^{18}$O and as an infalling outer envelope in N$_2$H$^+$. We also estimated the envelope and central protostellar masses and found that the dust opacity spectral index changes with radius.