JWST Observations of Young protoStars (JOYS)

Linked accretion and ejection in a Class I protobinary system

¹ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
e-mail: tychoniec@strw.leidenuniv.nl
² European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
³ Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
⁴ Laboratory for Astrophysics, Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
⁵ INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy
⁶ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
⁷ Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden
⁸ NASA Ames Research Center, Space Science and Astrobiology Division, M.S.245-6, Moffett Field, CA 94035, USA
⁹ School of Cosmic Physics, Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2, Ireland
¹⁰ Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405 Orsay, France
¹¹ Department of Experimental Physics, Maynooth University, Maynooth, Co Kildare, Ireland
¹² UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
¹³ Dept. of Astrophysics, University of Vienna, Türkenschanzstr. 17, 1180 Vienna, Austria
¹⁴ ETH Zürich, Institute for Particle Physics and Astrophysics, Wolfgang-Pauli-Str. 27, 8093 Zürich, Switzerland
¹⁵ Department of Astronomy, Oskar Klein Centre, Stockholm University, 106 91 Stockholm, Sweden

Received: 8 December 2023
Accepted: 6 February 2024

Abstract

Context. Accretion and ejection dictate the outcomes of star and planet formation processes. The mid-infrared (MIR) wavelength range offers key tracers of processes that have been difficult to detect and spatially resolve in protostars until now.

Aims. We aim to characterize the interplay between accretion and ejection in the low-mass Class I protobinary system TMC1, comprising two young stellar objects: TMC1-W and TMC1-E at a 85 au separation.

Methods. Using the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) observations in 5–28 μm range, we measured the intensities of emission lines of H₂, atoms, and ions, for instance, the [Fe II] and [Ne II], and HI recombination lines. We analyzed the spatial distribution of the different species using the MIRI Medium Resolution Spectrometer (MRS) capabilities to spatially resolve emission at 0″​​.2–0″​​.7 scales. we compared these results with the corresponding Atacama Large Millimeter/submillimeter Array (ALMA) maps tracing cold gas and dust.

Results. We detected H₂ outflow coming from TMC1-E, with no significant H₂ emission from TMC1-W. The H₂ emission from TMC1-E outflow appears narrow and extends to wider opening angles with decreasing E_up from S(8) to S(1) rotational transitions, indicating the disk wind as its origin. The outflow from TMC1-E protostar shows spatially extended emission lines of [Ne II], [Ne III], [Ar II], and [Ar III], with their line ratios consistent with UV radiation as a source of ionization. With ALMA, we detected an accretion streamer infalling from > 1000 au scales onto the TMC1-E component. The TMC1-W protostar powers a collimated jet, detected with [Fe II] and [Ni II], making it consistent with energetic flow. A much weaker ionized jet is observed from TMC1-E, and both jets appear strikingly parallel to each other, indicating that the disks are co-planar. TMC1-W is associated with strong emission from hydrogen recombination lines, tracing the accretion onto the young star.

Conclusions. MIRI-MRS observations provide an unprecedented view of protostellar accretion and ejection processes on 20 au scales. Observations of a binary Class I protostellar system show that the two processes are clearly intertwined, with accretion from the envelope onto the disk influencing a wide-angle wind ejected on disk scales. Finally, the accretion from the protostellar disk onto the protostar is associated with the source launching a collimated high-velocity jet within the innermost regions of the disk.