Why are (almost) all the protostellar outflows aligned in Serpens Main?

TL;DR

This study uses JWST imaging to analyze protostellar outflows in Serpens Main, revealing a strong alignment with the filament's axis and suggesting formation from a primordial, isolated filament with inherited angular momentum.

Contribution

It provides the first detailed analysis of outflow orientations in Serpens Main, linking them to filament structure and inherited angular momentum, and offers a catalog of outflows and shock features.

Findings

Outflows are aligned within +/- 24 degrees of the filament axis.

The probability of such alignment occurring by chance is 10^-4.

Evidence of systematic change in outflow orientation across the region.

Abstract

We present deep 1.4-4.8 um JWST-NIRCam imaging of the Serpens Main star-forming region and identify 20 candidate protostellar outflows, most with bipolar structure and identified driving sources. The outflow position angles (PAs) are strongly correlated, and aligned within +/- 24 degrees of the major axis of the Serpens filament. These orientations are further aligned with the angular momentum vectors of the two disk shadows in this region. We estimate that the probability of this number of young stars being co-aligned if sampled from a uniform PA distribution is 10^-4. This in turn suggests that the aligned protostars, which seem to be at similar evolutionary stages based on their outflow dynamics, formed at similar times with a similar spin inherited from a local cloud filament. Further, there is tentative evidence for a systematic change in average position angle between the north-western and south-eastern cluster, as well as increased scatter in the PAs of the south-eastern protostars. SOFIA-HAWC+ archival dust polarization observations of Serpens Main at 154 and 214 um are perpendicular to the dominant jet orientation in NW region in particular. We measure and locate shock knots and edges for all of the outflows and provide an identifying catalog. We suggest that Serpens main is a cluster that formed from an isolated filament, and due to its youth retains its primordial outflow alignment.