JOYS: Launch and destruction of dust in protostellar jets: The case of BHR71-IRS1 with JWST MIRI
Journal article, 2026
Context. Protostellar winds can theoretically lift solids from the planet-forming disks, but direct evidence for launched dust has been scarce so far. Numerous atomic lines that are unique to mid-infrared (IR) wavelengths reveal refractories eroded from dust grains and provide information on wind properties in the earliest stages of the star formation process. Aims. We characterize the gas-phase composition, shock properties, and dust content of the jet from the Class 0 protostar BHR71-IRS1, one of the best cases of a resolved central jet inside a wide-angle wind. Methods. We present JWST MIRI-MRS spectral imaging of the inner 2000 au of the BHR71-IRS1 blueshifted side of the outflow. Atomic line intensities were compared to shock models to constrain the physical conditions and elemental abundances of the outflowing gas. Dust continuum maps were constructed from point spread function-subtracted cubes, and the spectral energy distribution of the dust was analyzed. Results. The ionized central jet of BHR71-IRS1 is spatially resolved and imaged for the first time, revealing a unique inventory of refractory, volatile, and noble-gas fine-structure lines (Fe, Ni, Co, Cl, S, Ne, and Ar). The emission is concentrated along four bright knots that wiggle along the jet axis. Point spread function-subtracted continuum maps reveal extended mid-IR continuum emission cospatial with the jet bullets and within the H2-traced outflow cone. Spectral energy distributions along the jet were fit together with the extinction, revealing a warm (200-400 K) and a cold (70-90 K) dust component. The shock modeling constrained by the mid-IR lines indicates a decline in the shock velocity from 70 to 35 km s−1 and in the pre-shock density from >105 to 4 × 104 cm−3 with distance from the protostar. Gas-phase Fe and Ni are measurably depleted relative to solar abundances. This is consistent with a substantial fraction of refractories remaining locked in grains in spite of the shocks. Conclusions. These JWST observations provide direct evidence that dust is launched in a Class 0 jet and at least partly survives shock processing. The richness of refractory tracers in the BHR71-IRS1 jet provides a window into the inner-disk composition at the onset of planet formation.
stars: formation
dust, extinction
stars: protostars
infrared: ISM
ISM: jets and outflows
Author
Łukasz Tychoniec
Leiden University
L. Francis
Leiden University
M. G. Navarro
Osservatorio Astronomico di Roma
Jakobus M. Vorster
University of Helsinki
E. F. van Dishoeck
Max Planck Society
Leiden University
A. Caratti o. Garatti
Osservatorio Astronomico di Capodimonte
K. D. Assani
University of Virginia
Valentin J. M. Le Gouellec
Spanish National Research Council (CSIC)
Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
Benoît Tabone
Institut d'Astrophysique Spatiale
Pamela Klaassen
Royal Observatory
A. G.M. Janssen
Leiden University
Kay Justtanont
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
D. Harsono
National Tsing Hua University
P. Nazari
European Southern Observatory (ESO)
Simon D. Reyes-Reyes
Max Planck Society
K. Slavicinska
Leiden University
C. Gieser
Max Planck Society
T. L. Bourke
SKA Organisation
Yao-Lun Yang
RIKEN
B. Nisini
Osservatorio Astronomico di Roma
T. Giannini
Osservatorio Astronomico di Roma
H. Beuther
Max Planck Society
R. Devaraj
Dublin Institute for Advanced Studies
Tom Ray
Dublin Institute for Advanced Studies
N. G.C. Brunken
Leiden University
Y. Chen
Leiden University
M. L. Van Gelder
Leiden University
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 710 A370Subject Categories (SSIF 2025)
Atom and Molecular Physics and Optics
Astronomy, Astrophysics, and Cosmology
DOI
10.1051/0004-6361/202558711