The First Detection of a Protostellar CO Outflow in the Small Magellanic Cloud with ALMA

TL;DR

This study reports the first detection of a protostellar CO outflow in the low-metallicity Small Magellanic Cloud using ALMA, showing outflows are similar to those in the Milky Way despite environmental differences.

Contribution

It provides the first observational evidence of molecular outflows in a low-metallicity galaxy, suggesting outflow properties are consistent across different metallicities.

Findings

Detected a bipolar CO outflow in the SMC at 0.2 Z_sun

Outflow properties match Galactic counterparts

Supports universality of protostellar outflows across metallicities

Abstract

Protostellar outflows are one of the most outstanding features of star formation. Observational studies over the last several decades have successfully demonstrated that outflows are ubiquitously associated with low- and high-mass protostars in the solar-metallicity Galactic conditions. However, the environmental dependence of protostellar outflow properties is still poorly understood, particularly in the low-metallicity regime. Here we report the first detection of a molecular outflow in the Small Magellanic Cloud with 0.2 $Z_{\odot}$, using Atacama Large Millimeter/submillimeter Array observations at a spatial resolution of 0.1 pc toward the massive protostar Y246. The bipolar outflow is nicely illustrated by high-velocity wings of CO(3-2) emission at $\gtrsim$15 km s$^{-1}$. The evaluated properties of the outflow (momentum, mechanical force, etc.) are consistent with those of the Galactic counterparts. Our results suggest that the molecular outflows, i.e., the guidepost of the disk accretion at the small scale, might be universally associated with protostars across the metallicity range of $\sim$0.2-1 $Z_{\odot}$.