EPISODE III: The Nested Jet/Outflow Morphology of EC 53 Revealed by JWST and ALMA

TL;DR

This study combines JWST and ALMA observations to reveal the detailed structure and kinematics of the jet and outflow of the protostar EC 53, uncovering stratified hot and cold components consistent with MHD disk wind models.

Contribution

It provides the first detailed multi-scale view of EC 53's jet and outflow, demonstrating the synergy of JWST and ALMA in studying protostellar environments.

Findings

Detection of a high-velocity ionized jet with a 40 au launching radius.

Identification of hot atomic and molecular outflow components with stratified kinematics.

Observation of cavity walls traced by colder molecular gas consistent with MHD wind models.

Abstract

We present an extensive study of the structure and kinematics of the jet and outflow of EC 53, a Class I protostar with a quasi-periodic variability, using combined James Webb Space Telescope (JWST) and Atacama Large Millimeter/submillimeter Array (ALMA) observations. ALMA continuum observations resolve a compact disk with a radius of $\sim$0.14\arcsec\ (60\,au). Scattered light from the outflow cavity is prominent in the short-wavelength NIRCam and NIRSpec observations, revealing only the southeast nearside lobe. We detected 27 H$_2$ emission lines tracing a narrow, cone-shaped structure within the outflow cavity. A high-velocity ionized jet is detected in several forbidden atomic lines, characterized by a position angle of 142\degree, an opening angle of 1.4\degree, and an estimated geometric launching radius of at most $\sim$40\,au. Mid-infrared CO ro-vibrational emission lines, stronger in the P-branch, show a similar distribution to the H$_2$ emission and are likely to originate from hot gas within the outflow cavity. CO and C$_2$H emission lines detected by ALMA trace slower, colder outflow components and cavity walls. The spatial and kinematic stratification between the hot atomic and molecular components and the colder molecular gas is consistent with predictions from MHD disk wind models, although envelope material entrained by a wide-angle wind or jet may also contribute. Our analysis highlights the powerful synergy between JWST and ALMA in advancing the understanding of protostellar jets and outflows across multiple spatial and physical scales.