Assessing molecular outflows and turbulence in the protostellar cluster Serpens South

TL;DR

This study combines multi-telescope CO observations to analyze molecular outflows in the Serpens South protostellar cluster, revealing outflows' role in sustaining turbulence but not disrupting the cluster's gravitational stability.

Contribution

It provides a detailed, multi-scale analysis of outflows and their impact on turbulence and gravity in a young protostellar cluster, incorporating corrections for line opacity and excitation temperature.

Findings

Outflows drive enough energy to sustain turbulence.

Outflows do not significantly counteract gravitational potential.

Comparison suggests evolutionary stage influences outflow-cluster interactions.

Abstract

Molecular outflows driven by protostellar cluster members likely impact their surroundings and contribute to turbulence, affecting subsequent star formation. The very young Serpens South cluster consists of a particularly high density and fraction of protostars, yielding a relevant case study for protostellar outflows and their impact on the cluster environment. We combined CO $J=1-0$ observations of this region using the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the Institut de Radioastronomie Millim\'{e}trique (IRAM) 30 m single dish telescope. The combined map allows us to probe CO outflows within the central, most active region at size scales of 0.01 pc to 0.8 pc. We account for effects of line opacity and excitation temperature variations by incorporating $^{12}$CO and $^{13}$CO data for the $J=1-0$ and $J=3-2$ transitions (using Atacama Pathfinder Experiment and Caltech Submillimeter Observatory observations for the higher CO transitions), and we calculate mass, momentum, and energy of the molecular outflows in this region. The outflow mass loss rate, force, and luminosity, compared with diagnostics of turbulence and gravity, suggest that outflows drive a sufficient amount of energy to sustain turbulence, but not enough energy to substantially counter the gravitational potential energy and disrupt the clump. Further, we compare Serpens South with the slightly more evolved cluster NGC 1333, and we propose an empirical scenario for outflow-cluster interaction at different evolutionary stages.