MINDS

Young binary systems with JWST/MIRI: Variable water-rich primaries and extended emission

¹ Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
² Earth and Planets Laboratory, Carnegie Institution for Science, 5241 Broad Branch Road, NW, Washington, DC 20015, USA
³ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
⁴ Max-Planck-Institut für Astronomie (MPIA), Königstuhl 17, 69117 Heidelberg, Germany
⁵ Kapteyn Astronomical Institute, Rijksuniversiteit Groningen, Postbus 800, 9700AV Groningen, The Netherlands
⁶ Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
⁷ STAR Institute, Université de Liège, Allée du Six Août 19c, 4000 Liège, Belgium
⁸ Department of Physics, Texas State University, 749 North Comanche Street, San Marcos, TX 78666, USA
⁹ School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
¹⁰ Dept. of Astrophysics, University of Vienna, Türkenschanzstr. 17, 1180 Vienna, Austria
¹¹ ETH Zürich, Institute for Particle Physics and Astrophysics, Wolfgang-Pauli-Str. 27, 8093 Zürich, Switzerland
¹² Université Paris-Saclay, Université Paris cité, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
¹³ Niels Bohr Institute, University of Copenhagen, NBB BA2, Jagtvej 155A, 2200 Copenhagen, Denmark

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Received: 1 April 2025
Accepted: 28 July 2025

Abstract

Context. Dynamical disk-companion interactions can have a significant impact on the evolution of circumstellar disks, as these can produce perturbations to the material distribution, density, and temperature, affecting their potential for planet formation.

Aims. As part of the JWST GTO program MINDS, we analyze the mid-infrared (MIR) emission of three Class II binary systems: VW Cha, WX Cha, and RW Aur. Our aim is to investigate the impact of stellar multiplicity on the chemistry and physics of their inner disk.

Methods. We analyzed the 1D spectrum from JWST/MIRI-MRS for primary and secondary disks separately, extracted via a combination of forward modeling with a theoretical PSF and aperture photometry. Following the continuum subtraction, we modeled the molecular lines with 0D slab models. We interpreted the results by comparing our JWST spectra to VLT/CRIRES+, Spitzer/IRS. The extended MIR emission was compared to ALMA data, with the inclusion of the binary DF Tau in our sample.

Results. Primary and secondary disks are dramatically different in their MIR emission, with primary disks exhibiting H₂O-rich spectra and secondary disks being mostly line-poor with respect to the sensitivity of our spectra. When comparing MIRI-MRS to Spitzer/IRS, we observed a broad variability in the line emission of VW Cha A and in the continuum of RW Aur A. The disks around VW Cha BC and RW Aur B show evidence of ionizing radiation and a further comparison with ALMA at high angular resolution dust continuum suggests that the spectrum of RW Aur B is well explained by its ~4 au cavity. All the systems show [Ne II] jet emission and three of them also show spatially resolved emission structures in H₂, likely originating from outflows and dynamical interactions.

Conclusions. Many of the observed features in the primary disks, such as enhanced water emission, could be linked to the increased accretion and radial drift produced by dynamical disk truncation. However, additional mechanisms are needed to explain the large differences between primary and secondary disks, potentially inner disk substructures. This work highlights the need for combining data from multiple facilities to fully understand the observations from JWST.