Discovery of a Collimated Jet from the Low-luminosity Protostar IRAS 16253‑2429 in a Quiescent Accretion Phase with the JWST
Manoj, P.; Narang, Mayank; Bourke, Tyler L.; Beuther, Henrik; Pokhrel, Riwaj; Caratti o Garatti, Alessio; Fischer, William J.; Hartmann, Lee; Habel, Nolan; Rubinstein, Adam E.; Evans, Neal J.; Tyagi, Himanshu; Nazari, Pooneh; Gutermuth, Robert; Federman, Samuel; Watson, Dan M.; Megeath, S. Thomas; Rocha, Will R. M.; Slavicinska, Katerina; Klaassen, Pamela; Linz, Hendrik; Looney, Leslie W.; Muzerolle, James; Stanke, Thomas; Tobin, John J.; Yang, Yao-Lun; Furlan, Elise; Green, Joel; Osorio, Mayra; Anglada, Guillem; Stutz, Amelia M.; Karnath, Nicole; Sheehan, Patrick; Atnagulov, Prabhani; Rahatgaonkar, Rohan; Wolk, Scott; Van Dishoeck, Ewine F.; Brunken, Nashanty; Tychoniec, Lukasz
Taiwan, India, United States, Italy, Germany, United Kingdom, Netherlands, Spain, Japan, Chile
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 μm 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 × 103 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.