James Webb Space Telescope Feed Post

PROJECT-J: JWST observations of HH46~IRS and its outflow. Overview and first results

Continuum subtracted image of the H2 0–0 S(2) 12.3 µm line with overlaid contours of the H2 1–0 S(1) 2.12 µm observed by NIRSpec (magenta) and [Fe ii] 5.3 µm emission from the jet (cyan). Labels indicate the A1-A6 H2 knots and arcs discussed in the text. The figure shows the similar morphology displayed by the rotational and ro-vibrational lines. It also suggests that the extended H2 emission in the red-shifted outflow corresponds to a large bow-shock driven by the atomic jet. In contrast, the arc-shaped structures A5-A6 on the blue-shifted side are not oriented along the jet axis. Abstract: We present the first results of the JWST program PROJECT-J (PROtostellar JEts Cradle Tested with JWST ), designed to study the Class I source HH46 IRS and its outflow through NIRSpec and MIRI spectroscopy (1.66 to 28 micron). The data provide line-images (~ 6.6" in length with NIRSpec, and up to 20" with MIRI) revealing unprecedented details within the jet, the molecular outflow and the cavity. We detect, for the first time, the red-shifted jet within ~ 90 au from the source. Dozens of shock-excited forbidden lines are observed, including highly ionized species such as [Ne III] 15.5 micron, suggesting that the gas is excited by high velocity (> 80 km/s) shocks in a relatively high density medium. Images of H2 lines at different excitations outline a complex molecular flow, where a bright cavity, molecular shells, and a jet-driven bow-shock interact with and are shaped by the ambient conditions. Additional NIRCam 2 micron images resolve the HH46 IRS ~ 110 au binary system and suggest that the large asymmetries observed between the jet and the H2 wide angle emission could be due to two separate outflows being driven by the two sources. The spectra of the unresolved binary show deep ice bands and plenty of gaseous lines in absorption, likely originating in a cold envelope or disk. In conclusion, JWST has unraveled for the first time the origin of the HH46 IRS complex outflow demonstrating its capability to investigate embedded regions around young stars, which remain elusive even at near-IR wavelengths.