An extremely high velocity molecular jet surrounded by an ionized cavity in the protostellar source Serpens SMM1

TL;DR

This study presents ALMA and VLA observations of a highly collimated, high-velocity molecular jet from the young protostar Serpens SMM1-a, revealing for the first time ionized cavity walls directly detected via free-free emission in a Class 0 source.

Contribution

First direct detection of ionized outflow cavity walls in a very young, embedded protostar, linking ionization to UV radiation or jet impact in early star formation.

Findings

Detection of an extremely high-velocity molecular jet (~80 km/s).

First direct observation of ionized cavity walls in a Class 0 protostar.

Ionization likely caused by UV photons or jet impact, indicating commonality in young protostars.

Abstract

We report ALMA observations of a one-sided, high-velocity ($\sim$80 km s$^{-1}$) CO($J = 2 \rightarrow 1$) jet powered by the intermediate-mass protostellar source Serpens SMM1-a. The highly collimated molecular jet is flanked at the base by a wide-angle cavity; the walls of the cavity can be seen in both 4 cm free-free emission detected by the VLA and 1.3 mm thermal dust emission detected by ALMA. This is the first time that ionization of an outflow cavity has been directly detected via free-free emission in a very young, embedded Class 0 protostellar source that is still powering a molecular jet. The cavity walls are ionized either by UV photons escaping from the accreting protostellar source, or by the precessing molecular jet impacting the walls. These observations suggest that ionized outflow cavities may be common in Class 0 protostellar sources, shedding further light on the radiation, outflow, and jet environments in the youngest, most embedded forming stars.