Confirming the Explosive Dispersal Outflow in DR21 with ALMA

TL;DR

This study uses ALMA observations to confirm an explosive dispersal outflow in the DR21 star-forming region, revealing multiple outflow streamers with high velocities, estimating their physical properties, and supporting the presence of explosive outflows in massive star formation.

Contribution

First detailed ALMA imaging of the DR21 outflow confirming explosive dispersal with new outflow sources and kinematic analysis.

Findings

Eighteen outflow streamers identified with high velocity spread.

Estimated outflow mass between 120-210 solar masses.

Dynamical age of the outflow approximately 8600 years.

Abstract

We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum and CO(2-1) line emission observations toward the high-mass star formation region DR21. Five new continuum sources are found. We identify eighteen outflow streamers detected in CO emission radially arising from a common origin. The velocity spread of the outflow streamers range between $-$100 to $+$70 km s$^{-1}$. The radial velocities of each outflow roughly follow linear gradients (Hubble-Lemaitre-like expansion motions). Using the CO emission of the whole ensemble of streamers we estimate a total outflow mass of 120-210M$_{\odot}$. Additionally, we derived the dynamical age (8600 yr), momentum ($\sim10^{3}$ M$_{\odot}$ km s$^{-1}$), and kinetic energy ($\sim10^{48}$ erg) of the outflow. The morphology and kinematics presented by the CO outflow streamers confirm the presence of an explosive dispersal outflow at the heart of DR21. Five dispersal explosive outflows associated with massive star-forming regions have been confirmed in our Galaxy (Orion BN/KL, G5.89-0.39, S106-IR, IRAS16076-5134 and IRAS 12326-6245). However, their frequency of occurrence in the Galaxy and the originating nature are still uncertain.