Confirming the explosive dispersal outflow in DR21 with ALMA

¹ Instituto Argentino de Radioastronomía (CCT- La Plata, CONICET, CICPBA, UNLP), C.C. No. 5, 1894 Villa Elisa, Buenos Aires, Argentina
² Instituto de Radioastronomía y Astrofísica. Universidad Nacional Autónoma de México, 58090 Morelia, Michoacán, Mexico
³ Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences University of Colorado, Boulder, CO 80389, USA

Received: 6 March 2024
Accepted: 18 June 2024

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 18 outflow streamers detected in CO emission that radially arises from a common origin. The velocity spread of the outflow streamers ranges between −100 and +70 km s⁻¹. The radial velocities of each outflow roughly follow linear gradients (Hubble–Lemaître–like expansion motions). Using the CO emission of the whole ensemble of streamers, we estimate a total outflow mass of 120−210 M_⊙. Additionally, we derived the dynamical age (8600 yr), momentum (~10³ M_⊙ km s⁻¹), and kinetic energy (~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, IRAS 16076-5134, and IRAS 12326-6245). However, their occurrence frequency in the Galaxy and their origin are still uncertain.