JWST Peers into the Class I Protostar TMC1A: Atomic Jet and Spatially Resolved Dissociative Shock Region

Abstract

Outflows and winds launched from young stars play a crucial role in the evolution of protostars and the early stages of planet formation. However, the specific details of the mechanism behind these phenomena, including how they affect the protoplanetary disk structure, are still debated. We present {\it JWST} NIRSpec Integral Field Unit (IFU) observations of atomic and H$_2$ lines from 1 -- 5.1 $\mu$m toward the low-mass protostar TMC1A. For the first time, a collimated atomic jet is detected from TMC1A in the [Fe II] line at 1.644 $\mu$m along with corresponding extended H$_2$ 2.12 $\mu$m emission. Towards the protostar, we detected spectrally broad H I and He I emissions with velocities up to 300 km/s that can be explained by a combination of protostellar accretion and a wide-angle wind. The 2$\mu$m continuum dust emission, H I, He I, and O I all show emission from the illuminated outflow cavity wall and scattered line emission. These observations demonstrate the potential of {\it JWST} to characterize and reveal new information about the hot inner regions of nearby protostars. In this case, a previously undetected atomic wind and ionized jet in a well-known outflow.