PDRs4All

II. JWST’s NIR and MIR imaging view of the Orion Nebula^★

¹ Institut d’Astrophysique Spatiale, Université Paris-Saclay, CNRS, Bâtiment121, 91405 Orsay Cedex, France
e-mail: pis@pdrs4all.org
² Department of Physics & Astronomy, The University of Western Ontario, London ON N6A 3K7, Canada
³ Institute for Earth and Space Exploration, The University of Western Ontario, London ON N6A 3K7, Canada
⁴ Carl Sagan Center, SETI Institute, 339 Bernardo Avenue, Suite 200, Mountain View, CA 94043, USA
⁵ Institut de Recherche en Astrophysique et Planétologie, Université Toulouse III – Paul Sabatier, CNRS, CNES, 9 Av. du colonel Roche, 31028 Toulouse Cedex 04, France
⁶ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁷ Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109, USA
⁸ Institut des Sciences Moléculaires d’Orsay, CNRS, Université Paris-Saclay, Bâtiment 520, 91405 Orsay Cedex, France
⁹ Instituto de Astrofísica e Ciências do Espaço, Tapada da Ajuda, Edifício Leste, 2° Piso, 1349-018 Lisboa, Portugal
¹⁰ ACRI-ST, Centre d’Études et de Recherche de Grasse (CERGA), 10 Av. Nicolas Copernic, 06130 Grasse, France
¹¹ INCLASS Common Laboratory, 10 Av. Nicolas Copernic, 06130 Grasse, France
¹² NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA
¹³ LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, 92190 Meudon, France
¹⁴ Instituto de Física Fundamental (CSIC), Calle Serrano 121-123, 28006, Madrid, Spain
¹⁵ UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
¹⁶ Observatorio Astronómico Nacional (OAN,IGN), Alfonso XII, 3, 28014 Madrid, Spain
¹⁷ Sterrenkundig Observatorium, Universiteit Gent, Gent, Belgium
¹⁸ Quantum Solid State Physics (QSP), Celestijnenlaan 200d – box 2414, 3001 Leuven, Belgium
¹⁹ Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), Université Grenoble Alpes, CNRS, 38000 Grenoble, France
²⁰ Institut de Radioastronomie Millimétrique (IRAM), 300 Rue de la Piscine, 38406 Saint-Martin d’Hères, France
²¹ I. Physikalisches Institut der Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
²² Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-0033, Japan
²³ Department of Physics, Faculty of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506, Japan
²⁴ Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
²⁵ Physikalischer Verein – Gesellschaft für Bildung und Wissenschaft, Robert-Mayer-Straße 2, 60325 Frankfurt am Main, Germany
²⁶ Institut für Angewandte Physik. Goethe-Universität Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany
²⁷ Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, S439 92 Onsala, Sweden
²⁸ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
²⁹ Astronomy Department, University of Maryland, College Park, MD 20742, USA
³⁰ AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France
³¹ Instituto de Física e Química, Universidade Federal de Itajubá, Av. BPS 1303, Pinheirinho, 37500-903, Itajubá, MG, Brazil
³² Bay Area Environmental Research Institute, Moffett Field, CA 94035, USA
³³ Australian Synchrotron, Australian Nuclear Science and Technology Organisation (ANSTO), Victoria, Australia
³⁴ INAF – Osservatorio Astrofisico di Catania, Via Santa Sofia 78, 95123 Catania, Italy
³⁵ Bay Area Environmental Research Institute, Moffett Field, CA 94035, USA
³⁶ Laboratoire de Physique de l’École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 75005 Paris, France
³⁷ Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA
³⁸ Department of Chemistry, University of Colorado, Boulder, CO 80309, USA
³⁹ Institute for Modeling Plasma, Atmospheres, and Cosmic Dust (IMPACT), University of Colorado, Boulder, CO 80303, USA
⁴⁰ Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS Delft, The Netherlands
⁴¹ Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
⁴² School of Physics, University of Hyderabad, Hyderabad, Telangana 500046, India
⁴³ Department of Physics, Wellesley College, 106 Central Street, Wellesley, MA 02481, USA
⁴⁴ Anton Pannekoek Institute for Astronomy (API), University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
⁴⁵ Delft University of Technology, Delft, The Netherlands
⁴⁶ Laboratoire de Physique des 2 Infinis Irène Joliot-Curie, Université Paris-Saclay, CNRS/IN2P3, Bâtiment 104, 91405 Orsay Cedex, France
⁴⁷ Department of Chemistry, GITAM school of Science, GITAM Deemed to be University, Bangalore, India
⁴⁸ Institut de Physique de Rennes, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
⁴⁹ Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada
⁵⁰ National Radio Astronomy Observatory (NRAO), 520 Edgemont Road, Charlottesville, VA 22903, USA
⁵¹ European Space Astronomy Centre (ESAC/ESA), Villanueva de la Cañada, 28692 Madrid, Spain
⁵² Observatoire de Paris, PSL University, Sorbonne Université, CNRS, LERMA, 75014 Paris, France
⁵³ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138, USA
⁵⁴ Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98bis bd Arago, 75014 Paris, France
⁵⁵ Institut Universitaire de France, Ministère de l’Enseignement Supérieur et de la Recherche, 1 rue Descartes, 75231 Paris Cedex 05, France
⁵⁶ Department of Physics and Astronomy, Rice University, Houston, TX 77005-1892, USA
⁵⁷ Yunnan Observatories, Chinese Academy of Sciences, 396 Yang-fangwang, Guandu District, Kunming 650216, PR China
⁵⁸ Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, CAS, Beijing 100101, PR China
⁵⁹ Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
⁶⁰ Departments of Chemistry and Astronomy, University of Virginia, Charlottesville, VA 22904, USA
⁶¹ InterCat and Dept. Physics and Astron., Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
⁶² Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 3, 07743 Jena, Germany
⁶³ Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, 05509-090 São Paulo, SP, Brazil
⁶⁴ Department of Physics and Astronomy, San José State University, San Jose, CA 95192, USA
⁶⁵ Institut de Ciencies de l’Espai (ICE, CSIC), Can Magrans, s/n, 08193 Bellaterra, Barcelona, Spain
⁶⁶ ICREA, Pg. Llu í is Company 23, 05010 Barcelona, Spain
⁶⁷ Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
⁶⁸ European Space Agency, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore MD 21218, USA
⁶⁹ Institute of Astronomy, Russian Academy of Sciences, 119017, Pyatnitskaya str., 48, Moscow, Russia
⁷⁰ Department of Earth, Ocean, & Atmospheric Sciences, University of British Columbia, V6T 1Z4, Canada
⁷¹ Telespazio UK for ESA, ESAC, 28692 Villanueva de la Cañada, Madrid, Spain
⁷² IPAC, California Institute of Technology, Pasadena, CA, USA
⁷³ LAB, Université de Bordeaux, CNRS, 33615 Pessac, France
⁷⁴ Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA
⁷⁵ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
⁷⁶ Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
⁷⁷ Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California – Berkeley, Berkeley, CA, USA
⁷⁸ Institut des Sciences Moléculaires, CNRS, Université de Bordeaux, 33405 Talence, France
⁷⁹ Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
⁸⁰ Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz 3, 28049 Madrid, Spain
⁸¹ Department of Physics, PO Box 64, 00014 University of Helsinki, Finland
⁸² Steward Observatory, University of Arizona, Tucson, AZ 85721-0065, USA
⁸³ AstronetX PBC, 55 Post Rd W FL 2, Westport, CT 06880, USA
⁸⁴ Department of Physics, College of Science, United Arab Emirates University (UAEU), Al-Ain, 15551, USA
⁸⁵ National Astronomical Observatory of Japan, National Institutes of Natural Science, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
⁸⁶ California Institute of Technology, IPAC, 770, S. Wilson Ave., Pasadena, CA 91125, USA
⁸⁷ Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005, India
⁸⁸ University of Central Florida, Orlando, FL 32765, USA
⁸⁹ Van’t Hoff Institute for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090 GD Amsterdam, The Netherlands
⁹⁰ Laboratoire de Chimie et Physique Quantiques LCPQ/IRSAMC, UMR5626, Université de Toulouse (UPS) and CNRS, 31062 Toulouse, France
⁹¹ Instituto de Matemática, Estatística e Física, Universidade Federal do Rio Grande, 96201-900, Rio Grande, RS, Brazil
⁹² Center for Astrophysics and Space Sciences, Department of Physics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
⁹³ School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
⁹⁴ Astronomy Department, Ohio State University, Columbus, OH 43210 USA
⁹⁵ Space Science Institute, 4765 Walnut St., R203, Boulder, CO 80301, USA
⁹⁶ Department of Physics, Stockholm University, 10691 Stockholm, Sweden
⁹⁷ Department of Physics, Texas State University, San Marcos, TX 78666, USA
⁹⁸ Ritter Astrophysical Research Center, University of Toledo, Toledo, OH 43606, USA
⁹⁹ Department of Physics, Stockholm University, 10691 Stockholm, Sweden
¹⁰⁰ School of Physics and Astronomy, Sun Yat-sen University, 2 Da Xue Road, Tangjia, Zhuhai 519000, Guangdong Province, PR China
¹⁰¹ Star and Planet Formation Laboratory, RIKEN Cluster for Pioneering Research, Hirosawa 2-1, Wako, Saitama 351-0198, Japan
¹⁰² Institute of Deep Space Sciences, Deep Space Exploration Laboratory, Hefei 230026, PR China

Received: 26 April 2023
Accepted: 24 July 2023

Abstract

Context. The James Webb Space Telescope (JWST) has captured the most detailed and sharpest infrared (IR) images ever taken of the inner region of the Orion Nebula, the nearest massive star formation region, and a prototypical highly irradiated dense photo-dissociation region (PDR).

Aims. We investigate the fundamental interaction of far-ultraviolet (FUV) photons with molecular clouds. The transitions across the ionization front (IF), dissociation front (DF), and the molecular cloud are studied at high-angular resolution. These transitions are relevant to understanding the effects of radiative feedback from massive stars and the dominant physical and chemical processes that lead to the IR emission that JWST will detect in many Galactic and extragalactic environments.

Methods. We utilized NIRCam and MIRI to obtain sub-arcsecond images over ~150″ and 42″ in key gas phase lines (e.g., Pa α, Br α, [FeII] 1.64 µm, H₂ 1−0 S(1) 2.12 µm, 0–0 S(9) 4.69 µm), aromatic and aliphatic infrared bands (aromatic infrared bands at 3.3–3.4 µm, 7.7, and 11.3 µm), dust emission, and scattered light. Their emission are powerful tracers of the IF and DF, FUV radiation field and density distribution. Using NIRSpec observations the fractional contributions of lines, AIBs, and continuum emission to our NIRCam images were estimated. A very good agreement is found for the distribution and intensity of lines and AIBs between the NIRCam and NIRSpec observations.

Results. Due to the proximity of the Orion Nebula and the unprecedented angular resolution of JWST, these data reveal that the molecular cloud borders are hyper structured at small angular scales of ~0.1–1″ (~0.0002–0.002 pc or ~40–400 au at 414 pc). A diverse set of features are observed such as ridges, waves, globules and photoevaporated protoplanetary disks. At the PDR atomic to molecular transition, several bright features are detected that are associated with the highly irradiated surroundings of the dense molecular condensations and embedded young star. Toward the Orion Bar PDR, a highly sculpted interface is detected with sharp edges and density increases near the IF and DF. This was predicted by previous modeling studies, but the fronts were unresolved in most tracers. The spatial distribution of the AIBs reveals that the PDR edge is steep and is followed by an extensive warm atomic layer up to the DF with multiple ridges. A complex, structured, and folded H⁰/H₂ DF surface was traced by the H₂ lines. This dataset was used to revisit the commonly adopted 2D PDR structure of the Orion Bar as our observations show that a 3D “terraced” geometry is required to explain the JWST observations. JWST provides us with a complete view of the PDR, all the way from the PDR edge to the substructured dense region, and this allowed us to determine, in detail, where the emission of the atomic and molecular lines, aromatic bands, and dust originate.

Conclusions. This study offers an unprecedented dataset to benchmark and transform PDR physico-chemical and dynamical models for the JWST era. A fundamental step forward in our understanding of the interaction of FUV photons with molecular clouds and the role of FUV irradiation along the star formation sequence is provided.