The ALMA-QUARKS survey: Evidence of an explosive molecular outflow in IRAS 15520─5234

Abstract

We present a study of the massive protocluster IRAS 15520–5234, which displays evidence of an explosive molecular outflow that unleashed a kinetic energy of at least 1048 erg. The protocluster contains 16 dense cores detected in the Atacama Large Millimeter/submillimeter Array (ALMA) band 6 continuum emission maps, having masses in the range from 0.2 to 11.0 M⊙. Our analysis of CO (2−1) emission reveals 28 well-collimated outflow fingers, the majority of which follow a Hubble–Lemaître velocity law. The outflow fingers show no preferred orientation in the plane of sky and emerge from a common center of origin. We estimate the total mass, momentum, and kinetic energy of the outflow fingers and find that the values are at least 1 order of magnitude higher than the typical bipolar outflows associated with massive protostars. The morphology and kinematics of the outflow fingers suggest that the outflow associated with IRAS 15520–5234 is explosive in nature. We calculate the dynamical age of the explosive event to be approximately 6550 yr. Additionally, we estimate the frequency of such explosive outflows in the Galaxy, which is one event every 83 yr. Finally, we speculate that the rearrangement of masses within the massive protocluster and the dynamical interaction among the massive cores may result in the formation of such an energetic event.