Discovery of a Collimated Jet from the Low-luminosity Protostar IRAS 16253−2429 in a Quiescent Accretion Phase with the JWST
Mayank Narang, P. Manoj, Himanshu Tyagi, D. M. Watson, S. T. Megeath, Samuel Federman, Adam E. Rubinstein, Robert Gutermuth, A. Caratti o Garatti, H. Beuther, Tyler L. Bourke, E. F. van Dishoeck, Neal J. Evans, Guillem Anglada, Mayra Osorio, Thomas Stanke, James Muzerolle, Leslie W. Looney, Yao-Lun Yang, Pamela Klaassen, Nicole Karnath, Prabhani Atnagulov, Nashanty G. C. Brunken, William J. Fischer, Elise Furlan, Joel D. Green, Nolan Habel, Lee Hartmann, H. Linz, Pooneh Nazari, Riwaj Pokhrel, Rohan Rahatgaonkar, W. R. M. Rocha, Patrick Sheehan, K. Slavicinska, Amelia M. Stutz, John Tobin, Łukasz Tychoniec, S. J. Wolk
Abstract
Abstract Investigating Protostellar Accretion (IPA) is a JWST Cycle 1 GO program that uses NIRSpec integral field units and MIRI Medium Resolution Spectrograph to obtain 2.9–28 μ m spectral cubes of young, deeply embedded protostars with luminosities of 0.2–10,000 L ⊙ and central masses of 0.15–12 M ⊙ . In this Letter, we report the discovery of a highly collimated atomic jet from the Class 0 protostar IRAS 16253−2429, the lowest-luminosity source ( L bol = 0.2 L ⊙ ) in the IPA program. The collimated jet is detected in multiple [Fe ii ] lines and [Ne ii ], [Ni ii ], and H i lines but not in molecular emission. The atomic jet has a velocity of about 169 ± 15 km s −1 , after correcting for inclination. The width of the jet increases with distance from the central protostar from 23 to 60 au, corresponding to an opening angle of 2.°6 ± 0.°5. By comparing the measured flux ratios of various fine-structure lines to those predicted by simple shock models, we derive a shock speed of 54 km s −1 and a preshock density of 2.0 × 10 3 cm −3 at the base of the jet. From these quantities and using a suite of jet models and extinction laws, we compute a mass-loss rate between 0.4 and 1.1 ×10 −10 M ⊙ yr −1 . The low mass-loss rate is consistent with simultaneous measurements of low mass accretion rate (2.4 ± 0.8 × 10 −9 M ⊙ yr −1 ) for IRAS 16253−2429 from JWST observations, indicating that the protostar is in a quiescent accretion phase. Our results demonstrate that very low-mass protostars can drive highly collimated, atomic jets, even during the quiescent phase.