2026ApJ..1000...83L

We present an extensive study of the structure and kinematics of the jet and outflow of EC 53, a Class I protostar with a quasiperiodic 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 ∼0$\mathop{.}\limits^{\unicode{x02033}}$14 (60 au). Scattered light from the outflow cavity is prominent in the short-wavelength NIRCam and NIRSpec observations, revealing only the southeast nearside lobe. We detect 27 H₂ emission lines tracing a narrow cone-shaped structure within the outflow cavity. A high-velocity ionized jet is detected in several forbidden atomic lines, characterized by a position angle of 142^∘, an opening angle of 1$\mathop{.}\limits^{\unicode{x000b0}}$4, and an estimated geometric launching radius of at most ∼40 au. Mid-IR CO rovibrational emission lines, stronger in the P-branch, show a similar distribution to the H₂ emission and are likely to originate from hot gas within the outflow cavity. CO and C₂H 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.