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Title: The asymmetric bipolar [Fe II] jet and H 2 outflow of TMC1A resolved with the JWST NIRSpec Integral Field Unit
Context. Protostellar outflows exhibit large variations in their structure depending on the observed gas emission. To understand the origin of the observed variations, it is important to analyze the differences in the observed morphology and kinematics of the different tracers. TheJames WebbSpace Telescope (JWST) allows us to study the physical structure of the protostellar outflow through well-known near-infrared shock tracers in a manner unrivaled by other existing ground-based and space-based telescopes at these wavelengths. Aims. This study analyzes the atomic jet and molecular outflow in the Class I protostar, TMC1A, utilizing spatially resolved [Fe II] and H2lines to characterize the morphology and to identify previously undetected spatial features, and compare them to existing observations of TMC1A and its outflows observed at other wavelengths. Methods. We identified a large number of [Fe II] and H2lines within the G140H, G235H, and G395H gratings of the NIRSpec IFU observations. We analyzed their morphology and position-velocity (PV) diagrams. From the observed [Fe II] line ratios, the extinction toward the jet is estimated. Results. We detected the bipolar Fe jet by revealing, for the first time, the presence of a redshifted atomic jet. Similarly, the red-shifted component of the H2slower wide-angle outflow was observed. The [Fe II] and H2redhifted emission both exhibit significantly lower flux densities compared to their blueshifted counterparts. Additionally, we report the detection of a collimated high-velocity (~100 km s−1), blueshifted H2outflow, suggesting the presence of a molecular jet in addition to the well-known wider angle low-velocity structure. The [Fe II] and H2jets show multiple intensity peaks along the jet axis, which may be associated with ongoing or recent outburst events. In addition to the variation in their intensities, the H2wide-angle outflow exhibits a ring-like structure. The blueshifted H2outflow also shows a left-right brightness asymmetry likely due to interactions with the surrounding ambient medium and molecular outflows. Using the [Fe II] line ratios, the extinction along the atomic jet is estimated to be betweenAV= 10–30 on the blueshifted side, with a trend of decreasing extinction with distance from the protostar. A similarAVis found for the redshifted side, supporting the argument for an intrinsic red-blue outflow lobe asymmetry rather than environmental effects such as extinction. This intrinsic difference revealed by the unprecedented sensitivity of JWST, suggests that younger outflows already exhibit the red-blue side asymmetry more commonly observed toward jets associated with Class II disks.  more » « less
Award ID(s):
1910106
PAR ID:
10549422
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
Astronomy & Astrophysics
Date Published:
Journal Name:
Astronomy & Astrophysics
Volume:
688
ISSN:
0004-6361
Page Range / eLocation ID:
A26
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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