HOPS 361-C's Jet Decelerating and Precessing Through NGC 2071 IR by Adam E. Rubinstein et al. on Thursday 24 November

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.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.12599v1