Alignment Between Protostellar Outflows and Filamentary Structure

TL;DR

This study uses SMA observations to analyze the orientation of protostellar outflows relative to filamentary structures in the Perseus molecular cloud, revealing a complex, non-uniform alignment pattern that suggests protostellar angular momentum axes are independent of large-scale filaments.

Contribution

First comprehensive analysis of outflow-filament alignment in Perseus, showing a mix of parallel and perpendicular orientations, challenging simple alignment models.

Findings

Outflows are not exclusively parallel or perpendicular to filaments.

The distribution of angles suggests a mix of random and aligned orientations.

Protostellar angular momentum axes are likely independent of filament orientation.

Abstract

We present new Submillimeter Array (SMA) observations of CO(2-1) outflows toward young, embedded protostars in the Perseus molecular cloud as part of the Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES) survey. For 57 Perseus protostars, we characterize the orientation of the outflow angles and compare them with the orientation of the local filaments as derived from $Herschel$ observations. We find that the relative angles between outflows and filaments are inconsistent with purely parallel or purely perpendicular distributions. Instead, the observed distribution of outflow-filament angles are more consistent with either randomly aligned angles or a mix of projected parallel and perpendicular angles. A mix of parallel and perpendicular angles requires perpendicular alignment to be more common by a factor of $\sim$3. Our results show that the observed distributions probably hold regardless of the protostar's multiplicity, age, or the host core's opacity. These observations indicate that the angular momentum axis of a protostar may be independent of the large-scale structure. We discuss the significance of independent protostellar rotation axes in the general picture of filament-based star formation.