PDRs4All

Astronomy and Astrophysics, vol. 685, pp. A74

Abstract

Context . JWST has taken the sharpest and most sensitive infrared (IR) spectral imaging observations ever of the Orion Bar photodis-sociation region (PDR), which is part of the nearest massive star-forming region the Orion Nebula, and often considered to be the ‘prototypical’ strongly illuminated PDR. Aims . We investigate the impact of radiative feedback from massive stars on their natal cloud and focus on the transition from the H II region to the atomic PDR – crossing the ionisation front (IF) –, and the subsequent transition to the molecular PDR – crossing the dissociation front (DF). Given the prevalence of PDRs in the interstellar medium and their dominant contribution to IR radiation, understanding the response of the PDR gas to far-ultraviolet (FUV) photons and the associated physical and chemical processes is fundamental to our understanding of star and planet formation and for the interpretation of any unresolved PDR as seen by JWST. Methods . We used high-resolution near-IR integral field spectroscopic data from NIRSpec on JWST to observe the Orion Bar PDR as part of the PDRs4All JWST Early Release Science programme. We constructed a 3″ × 25″’ spatio-spectral mosaic covering 0.97– 5.27 μm at a spectral resolution R of ~2700 and an angular resolution of 0.075″–0.173″. To study the properties of key regions captured in this mosaic, we extracted five template spectra in apertures centred on the three H 2 dissociation fronts, the atomic PDR, and the H II region. This wealth of detailed spatial-spectral information was analysed in terms of variations in the physical conditions-incident UV field, density, and temperature – of the PDR gas. Results . The NIRSpec data reveal a forest of lines including, but not limited to, He I , H I , and C I recombination lines; ionic lines (e.g. Fe III and Fe II ); O I and N I fluorescence lines; aromatic infrared bands (AIBs, including aromatic CH, aliphatic CH, and their CD counterparts); pure rotational and ro-vibrational lines from H 2 ; and ro-vibrational lines from HD, CO, and CH + , with most of them having been detected for the first time towards a PDR. Their spatial distribution resolves the H and He ionisation structure in the Huygens region, gives insight into the geometry of the Bar, and confirms the large-scale stratification of PDRs. In addition, we observed numerous smaller-scale structures whose typical size decreases with distance from θ 1 Ori C and IR lines from C I , if solely arising from radiative recombination and cascade, reveal very high gas temperatures (a few 1000 K) consistent with the hot irradiated surface of small-scale dense clumps inside the PDR. The morphology of the Bar, in particular that of the H 2 lines, reveals multiple prominent filaments that exhibit different characteristics. This leaves the impression of a ‘terraced’ transition from the predominantly atomic surface region to the CO-rich molecular zone deeper in. We attribute the different characteristics of the H 2 filaments to their varying depth into the PDR and, in some cases, not reaching the C + /C/CO transition. These observations thus reveal what local conditions are required to drive the physical and chemical processes needed to explain the different characteristics of the DFs and the photochemical evolution of the AIB carriers. Conclusions . This study showcases the discovery space created by JWST to further our understanding of the impact radiation from young stars has on their natal molecular cloud and proto-planetary disk, which touches on star and planet formation as well as galaxy evolution.

Authors 98

1. E. Peeters

   Western University · Search for Extraterrestrial Intelligence

   Affiliation as printed

   Carl Sagan Center, SETI Institute, 339 Bernardo Avenue, Suite 200, Mountain View, CA 94043, USA

   Institute for Earth and Space Exploration, The University of Western Ontario, London ON N6A 3K7, Canada

2. E. Habart

   Institut d'Astrophysique Spatiale

   Affiliation as printed

   IAS - Institut d'astrophysique spatiale (Bâtiment 121 91405 ORSAY CEDEX - France)

3. Olivier Berné

   Institut de Recherche en Astrophysique et Planétologie

   Affiliation as printed

   IRAP - Institut de recherche en astrophysique et planétologie (9 avenue Colonel Roche 31028 Toulouse - France)

4. Ameek Sidhu

   Western University

   Affiliation as printed

   Department of Physics & Astronomy, The University of Western Ontario, London ON N6A 3K7, Canada;

   Institute for Earth and Space Exploration, The University of Western Ontario, London ON N6A 3K7, Canada

5. Ryan Chown

   Western University

   Affiliation as printed

   Department of Physics & Astronomy, The University of Western Ontario, London ON N6A 3K7, Canada;

   Institute for Earth and Space Exploration, The University of Western Ontario, London ON N6A 3K7, Canada

6. Dries Van De Putte

   Space Telescope Science Institute

   Affiliation as printed

   Space Telescope Science Institute, 3700 San Martin Drive, Balti-more, MD 21218, USA

7. Boris Trahin

   Institut d'Astrophysique Spatiale

   Affiliation as printed

   IAS - Institut d'astrophysique spatiale (Bâtiment 121 91405 ORSAY CEDEX - France)

8. Ilane Schroetter

   Institut de Recherche en Astrophysique et Planétologie

   Affiliation as printed

   IRAP - Institut de recherche en astrophysique et planétologie (9 avenue Colonel Roche 31028 Toulouse - France)

9. Amélie Canin

   Institut de Recherche en Astrophysique et Planétologie

   Affiliation as printed

   IRAP - Institut de recherche en astrophysique et planétologie (9 avenue Colonel Roche 31028 Toulouse - France)

10. Felipe Alarcón

    University of Michigan

    Affiliation as printed

    Department of Astronomy, University of Michigan, 1085 South Uni-versity Avenue, Ann Arbor, MI 48109, USA

11. Bethany R. Schefter

    Western University

    Affiliation as printed

    Department of Physics & Astronomy, The University of Western Ontario, London ON N6A 3K7, Canada;

    Institute for Earth and Space Exploration, The University of Western Ontario, London ON N6A 3K7, Canada

12. Baria Khan

    Western University

    Affiliation as printed

    Department of Physics & Astronomy, The University of Western Ontario, London ON N6A 3K7, Canada;

13. Sofia Pasquini

    Western University

    Affiliation as printed

    Department of Physics & Astronomy, The University of Western Ontario, London ON N6A 3K7, Canada;

14. Alexander G. G. M. Tielens Aachen Leiden Observatory

    Leiden University · Leiden Observatory · University of Maryland, College Park

    Affiliation as printed

    Astronomy Department, University of Maryland, College Park, MD 20742, USA

    Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands

15. Emmanuel Dartois

    Université Paris-Saclay · Institut des Sciences Moléculaires d'Orsay

    Affiliation as printed

    ISMO - Institut des Sciences Moléculaires d'Orsay (Université Paris-Saclay, 91405 Orsay cedex - France)

16. Javier R. Goicoechea

    Instituto de Física Fundamental

    Affiliation as printed

    Instituto de Física Fundamental (CSIC), Calle Serrano 121-123, 28006, Madrid, Spain

17. Alexandros Maragkoudakis

    Ames Research Center

    Affiliation as printed

    NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA

18. Takashi Onaka

    Meisei University · The University of Tokyo

    Affiliation as printed

    Department of Astronomy, Graduate School of Science, The Uni-versity of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-0033, Japan

    Department of Physics, Faculty of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506, Japan

19. Marc W. Pound

    University of Maryland, College Park

    Affiliation as printed

    Astronomy Department, University of Maryland, College Park, MD 20742, USA

20. S. Vicente

    Institute of Astrophysics and Space Sciences

    Affiliation as printed

    Instituto de Astrofísica e Ciências do Espaço, Tapada da Ajuda, Ed-ifício Leste, 2 • Piso, P-1349-018 Lisboa, Portugal

21. A. Abergel

    Institut d'Astrophysique Spatiale

    Affiliation as printed

    IAS - Institut d'astrophysique spatiale (Bâtiment 121 91405 ORSAY CEDEX - France)

22. Edwin A. Bergin

    University of Michigan

    Affiliation as printed

    Department of Astronomy, University of Michigan, 1085 South Uni-versity Avenue, Ann Arbor, MI 48109, USA

23. Jeronimo Bernard-Salas
    Affiliation as printed

    ACRI-ST, Centre d'Etudes et de Recherche de Grasse (CERGA), 10 Av. Nicolas Copernic, F-06130 Grasse, France

    INCLASS Common Laboratory., 10 Av. Nicolas Copernic, 06130 Grasse, France

24. Christiaan Boersma

    Ames Research Center

    Affiliation as printed

    NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA

25. Émeric Bron

    Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères

    Affiliation as printed

    LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (61, avenue de l'Observatoire - 75014 PARIS - France)

26. J. Cami

    Western University · Search for Extraterrestrial Intelligence

    Affiliation as printed

    Carl Sagan Center, SETI Institute, 339 Bernardo Avenue, Suite 200, Mountain View, CA 94043, USA

    Department of Physics & Astronomy, The University of Western Ontario, London ON N6A 3K7, Canada;

    Institute for Earth and Space Exploration, The University of Western Ontario, London ON N6A 3K7, Canada

27. Sara Cuadrado

    Instituto de Física Fundamental

    Affiliation as printed

    Instituto de Física Fundamental (CSIC), Calle Serrano 121-123, 28006, Madrid, Spain

28. D. Dicken

    Royal Observatory · UK Astronomy Technology Centre

    Affiliation as printed

    UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill EH9 3HJ, UK

29. M. Elyajouri

    Institut d'Astrophysique Spatiale

    Affiliation as printed

    IAS - Institut d'astrophysique spatiale (Bâtiment 121 91405 ORSAY CEDEX - France)

30. Asunción Fuente

    Spanish National Observatory

    Affiliation as printed

    Observatorio Astronómico Nacional (OAN,IGN), Alfonso XII, 3, E-28014 Madrid, Spain

31. Karl D. Gordon

    Space Telescope Science Institute · Ghent University

    Affiliation as printed

    Space Telescope Science Institute, 3700 San Martin Drive, Balti-more, MD 21218, USA

    Sterrenkundig Observatorium, Universiteit Gent, Gent, Belgium

32. Lina Issa

    Institut de Recherche en Astrophysique et Planétologie

    Affiliation as printed

    IRAP - Institut de recherche en astrophysique et planétologie (9 avenue Colonel Roche 31028 Toulouse - France)

33. C. Joblin

    Institut de Recherche en Astrophysique et Planétologie

    Affiliation as printed

    IRAP - Institut de recherche en astrophysique et planétologie (9 avenue Colonel Roche 31028 Toulouse - France)

34. Olga Kannavou

    Institut d'Astrophysique Spatiale

    Affiliation as printed

    IAS - Institut d'astrophysique spatiale (Bâtiment 121 91405 ORSAY CEDEX - France)

35. Ozan Lacinbala

    KU Leuven

    Affiliation as printed

    Quantum Solid State Physics (QSP), Celestijnenlaan 200d -box 2414, 3001 Leuven, Belgium

36. David Languignon

    Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères

    Affiliation as printed

    LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (61, avenue de l'Observatoire - 75014 PARIS - France)

37. Romane Le Gal

    Institut de Radioastronomie Millimétrique · Institut de Planétologie et d'Astrophysique de Grenoble

    Affiliation as printed

    IPAG - Institut de Planétologie et d'Astrophysique de Grenoble (414, Rue de la Piscine BP 53 38041 Grenoble Cedex 9 - France)

    IRAM - Institut de RadioAstronomie Millimétrique (300 rue de la Piscine, Domaine Universitaire 38406 Saint Martin d'Hères - France)

38. Raphaël Meshaka

    Institut d'Astrophysique Spatiale · Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères

    Affiliation as printed

    IAS - Institut d'astrophysique spatiale (Bâtiment 121 91405 ORSAY CEDEX - France)

    LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (61, avenue de l'Observatoire - 75014 PARIS - France)

39. Yoko Okada

    University of Cologne

    Affiliation as printed

    I. Physikalisches Institut der Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany

40. Massimo Robberto

    Space Telescope Science Institute · Johns Hopkins University

    Affiliation as printed

    Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, 21218, USA

    Space Telescope Science Institute, 3700 San Martin Drive, Balti-more, MD 21218, USA

41. Markus Röllig

    Goethe University Frankfurt

    Affiliation as printed

    Goethe-Universität, Physikalisches Institut, Frankfurt am Main, Germany

    Physikalischer Verein -Gesellschaft für Bildung und Wissenschaft, Robert-Mayer-Str. 2, 60325 Frankfurt, Germany

42. Thiébaut Schirmer

    Institut d'Astrophysique Spatiale

    Affiliation as printed

    IAS - Institut d'astrophysique spatiale (Bâtiment 121 91405 ORSAY CEDEX - France)

43. Benoît Tabone

    Institut d'Astrophysique Spatiale

    Affiliation as printed

    IAS - Institut d'astrophysique spatiale (Bâtiment 121 91405 ORSAY CEDEX - France)

44. Marion Zannese

    Institut d'Astrophysique Spatiale

    Affiliation as printed

    IAS - Institut d'astrophysique spatiale (Bâtiment 121 91405 ORSAY CEDEX - France)

45. Isabel Aleman
46. L. J. Allamandola

    Ames Research Center

    Affiliation as printed

    NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA

47. Rebecca Auchettl
48. G. A. Baratta
49. Salma Bejaoui

    Ames Research Center

    Affiliation as printed

    NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA

50. Partha Pratim Bera
51. J. H. Black
52. F. Boulanger

    École Normale Supérieure - PSL · Laboratoire de Physique de l'Ecole Normale Supérieure

    Affiliation as printed

    LPENS - Laboratoire de physique de l'ENS - ENS Paris (24, rue Lhomond 75005 Paris - France)

53. Jordy Bouwman
54. Bernhard R. Brandl
55. Philippe Bréchignac

    Université Paris-Saclay · Institut des Sciences Moléculaires d'Orsay

    Affiliation as printed

    ISMO - Institut des Sciences Moléculaires d'Orsay (Université Paris-Saclay, 91405 Orsay cedex - France)

56. Sandra Brünken
57. Mridusmita Buragohain
58. Andrew M. Burkhardt
59. Alessandra Candian
60. Stéphanie M. Cazaux
61. J. Cernicharo

    Instituto de Física Fundamental

    Affiliation as printed

    Instituto de Física Fundamental (CSIC), Calle Serrano 121-123, 28006, Madrid, Spain

62. M. Chabot

    Laboratoire de Physique des 2 Infinis Irène Joliot-Curie

    Affiliation as printed

    IJCLab - Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (Bât. 100 et 200, 15 rue Georges Clémenceau 91405 Orsay - France)

63. Shubhadip Chakraborty

    Institut de Physique de Rennes

    Affiliation as printed

    IPR - Institut de Physique de Rennes (Bâtiment 11A , B, C, E – 10B 263 av. Général Leclerc 35042 Rennes cedex FRANCE - France)

64. Jason Champion

    Institut de Recherche en Astrophysique et Planétologie

    Affiliation as printed

    IRAP - Institut de recherche en astrophysique et planétologie (9 avenue Colonel Roche 31028 Toulouse - France)

65. Sean W. J. Colgan
66. Ilsa R. Cooke
67. A. Coutens

    Institut de Recherche en Astrophysique et Planétologie

    Affiliation as printed

    IRAP - Institut de recherche en astrophysique et planétologie (9 avenue Colonel Roche 31028 Toulouse - France)

68. N. L. J. Cox
    Affiliation as printed

    ACRI-ST, Centre d'Etudes et de Recherche de Grasse (CERGA), 10 Av. Nicolas Copernic, F-06130 Grasse, France

    INCLASS Common Laboratory., 10 Av. Nicolas Copernic, 06130 Grasse, France

69. Karine Demyk

    Institut de Recherche en Astrophysique et Planétologie

    Affiliation as printed

    IRAP - Institut de recherche en astrophysique et planétologie (9 avenue Colonel Roche 31028 Toulouse - France)

70. Sacha Foschino

    Institut de Recherche en Astrophysique et Planétologie

    Affiliation as printed

    IRAP - Institut de recherche en astrophysique et planétologie (9 avenue Colonel Roche 31028 Toulouse - France)

71. Pedro García-Lario
72. Maryvonne Gérin

    Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères

    Affiliation as printed

    LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (61, avenue de l'Observatoire - 75014 PARIS - France)

73. C. A. Gottlieb
74. P. Guillard

    Institut Universitaire de France · Institut d'Astrophysique de Paris

    Affiliation as printed

    IAP - Institut d'Astrophysique de Paris (98bis, bd Arago - 75014 Paris France - France)

    IUF - Institut universitaire de France (Maison des Universités 103 Boulevard Saint-Michel 75005 Paris - France)

75. Antoine Gusdorf

    École Normale Supérieure - PSL · Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères · Laboratoire de Physique de l'Ecole Normale Supérieure

    Affiliation as printed

    LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (61, avenue de l'Observatoire - 75014 PARIS - France)

    LPENS - Laboratoire de physique de l'ENS - ENS Paris (24, rue Lhomond 75005 Paris - France)

76. Patrick M. Hartigan
77. Jinhua He

    Chinese Academy of Sciences · National Astronomical Observatories

    Affiliation as printed

    Chinese Academy of Sciences South America Center for Astron-omy, National Astronomical Observatories, CAS, Beijing 100101, China

78. Eric Herbst

    University of Virginia

    Affiliation as printed

    Departments of Chemistry and Astronomy, University of Virginia, Charlottesville, Virginia 22904, USA

79. Liv Hornekær

    Aarhus University

    Affiliation as printed

    InterCat and Dept. Physics and Astron., Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark

80. Cornelia Jäger

    Friedrich Schiller University Jena

    Affiliation as printed

    Laboratory Astrophysics Group of the Max Planck Institute for As-tronomy at the Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 3, 07743 Jena, Germany

81. E. Janot-Pacheco

    Universidade de São Paulo

    Affiliation as printed

    Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Univer-sidade de São Paulo, 05509-090 São Paulo, SP, Brazil

82. Michael J. Kaufman

    San Jose State University

    Affiliation as printed

    Department of Physics and Astronomy, San José State University, San Jose, CA 95192, USA

83. Sarah Kendrew

    Space Telescope Science Institute

    Affiliation as printed

    European Space Agency, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore MD 21218, USA

84. Maria S. Kirsanova

    Russian Academy of Sciences · Institute of Astronomy

    Affiliation as printed

    Institute of Astronomy, Russian Academy of Sciences, 119017, Py-atnitskaya str., 48 , Moscow, Russia

85. Pamela Klaassen

    Royal Observatory · UK Astronomy Technology Centre

    Affiliation as printed

    UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill EH9 3HJ, UK

86. Sun Kwok

    University of British Columbia

    Affiliation as printed

    Department of Earth, Ocean, & Atmospheric Sciences, University of British Columbia, Canada V6T 1Z4 67

    Telespazio UK for ESA, ESAC,

87. Alvaro Labiano
88. Thomas S. -Y. Lai
89. Timothy J. Lee
90. Bertrand Lefloch

    Institut de Planétologie et d'Astrophysique de Grenoble

    Affiliation as printed

    IPAG - Institut de Planétologie et d'Astrophysique de Grenoble (414, Rue de la Piscine BP 53 38041 Grenoble Cedex 9 - France)

91. Franck Le Petit

    Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères

    Affiliation as printed

    LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (61, avenue de l'Observatoire - 75014 PARIS - France)

92. Aigen Li
93. Hendrik Linz
94. Cameron J. Mackie
95. Suzanne C. Madden

    Commissariat à l'Énergie Atomique et aux Énergies Alternatives · CEA Paris-Saclay - Etablissement de Saclay · Astrophysique, Instrumentation et Modélisation · CEA Paris-Saclay

    Affiliation as printed

    AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation (AIM - UMR 7158 - UMR E 9005, ex 'Astrophysique Interactions Multi-échelles', Service d'astrophysique, CEA/Saclay, Orme des Merisiers F-91191 GIF SUR YVETTE CEDEX - France)

96. Joe̋lle Mascetti

    Université de Bordeaux

    Affiliation as printed

    UB - Université de Bordeaux (35, place Pey Berland - 33076 Bordeaux - France)

97. Brett A. McGuire
98. Pablo Merino