Letter to the Editor

FAUST

XIII. Dusty cavity and molecular shock driven by IRS7B in the Corona Australis cluster

¹ INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
e-mail: giovanni.sabatini@inaf.it
² Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
³ Materials Science and Engineering, College of Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan
⁴ European Southern Observatory, Karl-Schwarzschild Str. 2, 85748 Garching bei München, Germany
⁵ Excellence Cluster ORIGINS, Boltzmannstraße, 2D-85748 Garching, Germany
⁶ National Radio Astronomy Observatory, PO Box O Socorro, NM 87801, USA
⁷ RIKEN Cluster for Pioneering Research, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan
⁸ Dipartimento di Fisica e Astronomia “Augusto Righi”, Viale Berti Pichat 6/2, Bologna, Italy
⁹ Department of Astronomy, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
¹⁰ Department of Chemistry, Biology, and Biotechnology, The University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
¹¹ Leiden Observatory, Leiden University, PO Box 9513 2300 RA Leiden, The Netherlands
¹² Center for Astrochemical Studies, Max-Planck-Institut für extraterrestrische Physik (MPE), Gieenbachstr. 1, 85741 Garching, Germany
¹³ IRAP, Univ. de Toulouse, CNRS, CNES, UPS, Toulouse, France
¹⁴ Astrochemistry Laboratory, Code 691, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA
¹⁵ CY Cergy Paris Université, Sorbonne Université, Observatoire de Paris, PSL University, CNRS, LERMA, 95000 Cergy, France
¹⁶ School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
¹⁷ Department of Astronomy, Xiamen University, Xiamen, Fujian 361005, PR China
¹⁸ Komaba Institute for Science, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
¹⁹ Department of Basic Science, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
²⁰ Center for Frontier Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
²¹ Department of Chemistry, University of Virginia, McCormick Road, PO Box 400319 Charlottesville, VA 22904, USA
²² National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka-shi, Tokyo 181-8588, Japan
²³ Department of Physics and Astronomy, Rice University, 6100 Main Street, MS-108 Houston, TX 77005, USA
²⁴ Centro de Astrobiologíña (CSIC-INTA), Ctra. de Torrejón a Ajalvir, km 4, 28850, Torrejón de Ardoz, Spain
²⁵ NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
²⁶ Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 5C2, Canada
²⁷ Université de Bordeaux – CNRS Laboratoire d’Astrophysique de Bordeaux, 33600 Pessac, France
²⁸ Institut de Radioastronomie Millimétrique, 38406 Saint-Martin d’Hères, France
²⁹ Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, A.P. 3-72 (Xangari), 8701 Morelia, Mexico
³⁰ Instituto de Astronomía, Univ. Nacional Autonoma de Mexico, Ciudad Universitaria, A.P. 70-264, Cuidad de Mexico 04510, Mexico
³¹ Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No.1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan, R.O.C.
³² Division of Science, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
³³ Institute of Low Temperature Science, Hokkaido University, N19W8, Kita-ku, Sapporo, Hokkaido 060-0819, Japan
³⁴ Department of Physics, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
³⁵ Yukawa Institute for Theoretical Physics, Kyoto Univ. Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto-shi, Kyoto-fu 606-8502, Japan
³⁶ Departament de Quíñmica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
³⁷ Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
³⁸ Department of Astronomy, The University of Texas at Austin, 2515 Speedway, Austin, TX 78712, USA
³⁹ Steward Observatory, 933 N Cherry Ave., Tucson, AZ 85721, USA
⁴⁰ Star and Planet Formation Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
⁴¹ SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193, Japan

Received: 14 February 2024
Accepted: 23 March 2024

Abstract

Context. The origin of the chemical diversity observed around low-mass protostars probably resides in the earliest history of these systems.

Aims. We aim to investigate the impact of protostellar feedback on the chemistry and grain growth in the circumstellar medium of multiple stellar systems.

Methods. In the context of the ALMA Large Program FAUST, we present high-resolution (50 au) observations of CH₃OH, H₂CO, and SiO and continuum emission at 1.3 mm and 3 mm towards the Corona Australis star cluster.

Results. Methanol emission reveals an arc-like structure at ∼1800 au from the protostellar system IRS7B along the direction perpendicular to the major axis of the disc. The arc is located at the edge of two elongated continuum structures that define a cone emerging from IRS7B. The region inside the cone is probed by H₂CO, while the eastern wall of the arc shows bright emission in SiO, a typical shock tracer. Taking into account the association with a previously detected radio jet imaged with JVLA at 6 cm, the molecular arc reveals for the first time a bow shock driven by IRS7B and a two-sided dust cavity opened by the mass-loss process. For each cavity wall, we derive an average H₂ column density of ∼7 × 10²¹ cm⁻², a mass of ∼9 × 10⁻³ M_⊙, and a lower limit on the dust spectral index of 1.4.

Conclusions. These observations provide the first evidence of a shock and a conical dust cavity opened by the jet driven by IRS7B, with important implications for the chemical enrichment and grain growth in the envelope of Solar System analogues.