MINDS

Year: 2024

Type: article

Abstract: Context. The majority of young stars form in multiple systems, the properties of which can significantly impact the evolution of any circumstellar disks. Aims. We investigate the physical and chemical properties of the equal-mass, small-separation (~66 milliarcsecond, ~9 au) binary system DF Tau. Previous spatially resolved observations indicate that only DF Tau A has a circumstellar disk, while DF Tau B does not, as concluded by a lack of accretion signatures and a near-infrared excess. Methods. We present JWST-MIRI MRS observations of DF Tau. The MIRI spectrum shows emission from a forest of H2O lines and emission from CO, C2H2, HCN, CO2, and OH. Local thermodynamic equilibrium slab models were used to determine the properties of the gas. The binary system is not spatially or spectrally resolved in the MIRI observations; therefore, we analyzed high spatial and spectral resolution observations from ALMA, VLTI-GRAVITY, and IRTF-iSHELL to aid in the interpretation of the molecular emission observed with JWST. Results. The 1.3 mm ALMA observations show two equal-brightness sources of compact (R ≲ 3 au) continuum emission that are detected at high significance, with separations consistent with astrometry from VLTI-GRAVITY and movement consistent with the known orbital parameters of the system. We interpret this as a robust detection of the disk around DF Tau B, which we suggest may host a small (~1 au) cavity; such a cavity would reconcile all of the observations of this source. In contrast, the disk around DF Tau A is expected to be a full disk, and spatially and spectrally resolved dust and gas emission traced by ground-based infrared observations point to hot, close-in (≲0.2 au) material around this star. High-temperature emission (~500–1000 K) from H2O, HCN, and potentially C2H2 in the MIRI data likely originates in the disk around DF Tau A, while a cold H2O component (≲200 K) with an extended emitting area is consistent with an origin from both disks. Conclusions. Given the unique characteristics of this binary pair, complementary observations are critical for constraining the properties of these disks. Despite the very compact outer disk properties, the inner disk composition and the conditions of the DF Tau disks are remarkably similar to those of isolated systems, suggesting that neither the outer disk evolution nor the close binary nature are driving factors in setting the inner disk chemistry in this system. However, constraining the geometry of the disk around DF Tau B, via higher angular resolution ALMA observations for instance, would provide additional insight into the properties of the mid-infrared gas emission observed with MIRI. JWST observations of spatially resolved binaries, at a range of separations, will be important for understanding the impact of binarity on inner disk chemistry more generally.

Source: Springer Link (Chiba Institute of Technology)

DOI: 10.1051/0004-6361/202450768/pdf

Institutions: Max Planck Institute for Extraterrestrial Physics, Leiden University, Leiden Observatory, Max Planck Institute for Astronomy, University of Groningen, Centre National de la Recherche Scientifique, Institut de Planétologie et d'Astrophysique de Grenoble, Texas State University, University of Liège, KU Leuven, Université Paris-Saclay, Institut d'Astrophysique Spatiale, University of Vienna, ETH Zurich, Institute for Particle Physics and Astrophysics, Université Paris Cité, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Astrophysique, Instrumentation et Modélisation, Centro de Astrobiología, Dublin Institute For Advanced Studies, Astronomical Observatory of Capodimonte, Radboud University Nijmegen, Space Research Organisation Netherlands, Stockholm University, AlbaNova, University College Dublin, University of Arizona

Language: English

Topic: Astrophysics and Star Formation Studies

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: National Aeronautics and Space Administration, Université Grenoble Alpes, Space Telescope Science Institute, European Space Agency, National Research Foundation, Enterprise Ireland, Deutsche Forschungsgemeinschaft, Agence Nationale de la Recherche, Danmarks Grundforskningsfond, Swedish National Space Agency, Fonds De La Recherche Scientifique - FNRS, Belgian Federal Science Policy Office, Centre National d’Etudes Spatiales, Fonds Wetenschappelijk Onderzoek, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Max-Planck-Gesellschaft, European Southern Observatory, Centre National de la Recherche Scientifique, Universität zu Köln, Vlaamse regering, Max-Planck-Institut für Astronomie, Horizon 2020 Framework Programme, Observatoire de Paris, Université de Recherche Paris Sciences et Lettres, Science and Technology Facilities Council, Agencia Estatal de Investigación, H2020 European Research Council

OpenAlex ID: W6940952760