James Webb Space Telescope Feed Post

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

Continuum-subtracted NIRSpec image of the integrated H2 2.12 µm emission of the blue-shifted inner region of the HH46IRS outflow. Overlaid contour levels goes from 0.025 to 0.3 MJy sr-1 µm in an asinh scale. Contours of the 2.12 µm continuum emission (levels from 10 to 100 MJy sr-1) are overlaid on the image in the left panel, while contours of the [Fe ii] 1.8 µm emission (levels from 0.025 to 0.3 MJy sr-1 µm), tracing the collimated jet, are overplotted on the right panel. The H2 knots A1-A2 and the arc-shaped feature A3 located at the apex of the jet are labelled. The blue star indicates the position of the HH46 IRS source. 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.