http://arxiv.org/abs/2211.12599
We present a two-epoch Hubble Space Telescope (HST) near-infrared (NIR) study of NGC 2071 IR highlighting HOPS 361-C, a protostar producing an arced 0.2 parsec-scale jet. Proper motions for the brightest knots decrease from 350 to 100 km/s with increasing distance from the source. The [Fe II] and Pa$\beta$ emission line intensity ratio gives a velocity jump through each knot of 40-50 km/s. We show a new [O I] 63 $\rm \mu$m spectrum taken with the German REciever for Astronomy at Terahertz frequencies (GREAT) instrument aboard Stratospheric Observatory for Infrared Astronomy (SOFIA), which give a low jet inclination. Proper motions and jump velocities then estimate total flow speed throughout the jet.
We model knot positions and speeds with a precessing jet that decelerates within the host molecular cloud. The measurements are matched with a precession period of a few thousand years and half opening angle of 15$\rm\deg$. The [Fe II] 1.26 $\rm \mu$m to 1.64 $\rm \mu$m line intensity ratio gives the extinction to each knot ranging from 5-30 mag. Relative to $\sim$14 mag of extinction through the cloud from C$^{18}$O emission maps, the jet is well embedded at a fractional depth from 1/5 to 4/5, and can interact with the cloud. Our model suggests the jet is locally dissipated over 0.2 pc. This may be because knots sweep through a wide angle, giving the cloud time to fill in cavities opened by the jet. This contrasts with nearly unidirectional protostellar jets that puncture host clouds and can propagate significantly further than a quarter pc.
A. Rubinstein, N. Karnath, A. Quillen, et. al.
Thu, 24 Nov 22
2/71
Comments: 24 pages, 9 figures, submitted to ApJ
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