Confirming the explosive dispersal outflow in DR21 with ALMA

Abstract

We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3\,mm continuum and line emission observations toward the high-mass star formation region DR21. Five new continuum sources are found. We identify 18 outflow streamers detected in CO emission that radially arises from a common origin. The velocity spread of the outflow streamers ranges between $-$100 to $+$70 The radial velocities of each outflow roughly follow linear gradients i tre–like expansion motions). Using the CO emission of the whole ensemble of streamers, we estimate a total outflow mass of 120--210 Additionally, we derived the dynamical age (8600\,yr), momentum (sim 103 and kinetic energy (sim 1048\,erg) of the outflow. The morphology and kinematics presented by the CO outflow streamers confirm 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 occurrence frequency in the Galaxy and their origin are still uncertain.