Context. Dense atomic jets from young stars copiously emit in [Fe ii] IR lines, which can, therefore, be used to trace the immediate environments of embedded protostars.
Aims: We want to investigate the morphology of the bright [Fe ii] 1.64 μm line in the jet of the source HH34 IRS and compare it with the most commonly used optical tracer [S ii].
Methods: We analyse a 1.64 μm narrow-band filter image obtained with the Large Binocular Telescope (LBT) LUCI instrument, which covers the HH34 jet and counterjet. A point spread function deconvolution algorithm was applied to enhance spatial resolution and make the IR image directly comparable to a [S ii] HST image of the same source.
Results: The [Fe ii] emission is detected from both the jet, the (weak) counter-jet, and from the HH34-S and HH34-N bow shocks. The deconvolved image allows us to resolve jet knots close to about 1''from the central source. The morphology of the [Fe ii] emission is remarkably similar to that of the [S ii] emission, and the relative positions of [Fe ii] and [S ii] peaks are shifted according to proper motion measurements, which were previously derived from HST images. An analysis of the [Fe ii]/[S ii] emission ratio shows that Fe gas abundance is much lower than the solar value with up to 90% of Fe depletion in the inner jet knots. This confirms previous findings on dusty jets, where shocks are not efficient enough to remove refractory species from grains.
Astronomy and Astrophysics
- Pub Date:
- June 2014
- stars: protostars;
- stars: mass-loss;
- stars: jets;
- ISM: jets and outflows;
- ISM: abundances;
- techniques: image processing;
- Astrophysics - Solar and Stellar Astrophysics
- 5 pages, 4 figures, note accepted by A&