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Mazo-Sevillano PD, Aguado A, Goicoechea JR, Roncero O. Quantum study of the CH3+ photodissociation in full-dimensional neural network potential energy surfaces. J Chem Phys 2024; 160:184307. [PMID: 38738612 DOI: 10.1063/5.0206895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 04/22/2024] [Indexed: 05/14/2024] Open
Abstract
C H 3 + , a cornerstone intermediate in interstellar chemistry, has recently been detected for the first time by using the James Webb Space Telescope. The photodissociation of this ion is studied here. Accurate explicitly correlated multi-reference configuration interaction ab initio calculations are done, and full-dimensional potential energy surfaces are developed for the three lower electronic states, with a fundamental invariant neural network method. The photodissociation cross section is calculated using a full-dimensional quantum wave packet method in heliocentric Radau coordinates. The wave packet is represented in angular and radial grids, allowing us to reduce the number of points physically accessible, requiring to push up the spurious states appearing when evaluating the angular kinetic terms, through projection technique. The photodissociation spectra, when employed in astrochemical models to simulate the conditions of the Orion bar, result in a lesser destruction of CH3+ compared to that obtained when utilizing the recommended values in the kinetic database for astrochemistry.
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Affiliation(s)
- Pablo Del Mazo-Sevillano
- Unidad Asociada UAM-IFF-CSIC, Departamento de Química Física Aplicada, Facultad de Ciencias M-14, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Alfredo Aguado
- Unidad Asociada UAM-IFF-CSIC, Departamento de Química Física Aplicada, Facultad de Ciencias M-14, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Javier R Goicoechea
- Instituto de Física Fundamental (IFF-CSIC), C.S.I.C., Serrano 123, 28006 Madrid, Spain
| | - Octavio Roncero
- Instituto de Física Fundamental (IFF-CSIC), C.S.I.C., Serrano 123, 28006 Madrid, Spain
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Berné O, Habart E, Peeters E, Schroetter I, Canin A, Sidhu A, Chown R, Bron E, Haworth TJ, Klaassen P, Trahin B, Van De Putte D, Alarcón F, Zannese M, Abergel A, Bergin EA, Bernard-Salas J, Boersma C, Cami J, Cuadrado S, Dartois E, Dicken D, Elyajouri M, Fuente A, Goicoechea JR, Gordon KD, Issa L, Joblin C, Kannavou O, Khan B, Lacinbala O, Languignon D, Le Gal R, Maragkoudakis A, Meshaka R, Okada Y, Onaka T, Pasquini S, Pound MW, Robberto M, Röllig M, Schefter B, Schirmer T, Simmer T, Tabone B, Tielens AGGM, Vicente S, Wolfire MG, Aleman I, Allamandola L, Auchettl R, Baratta GA, Baruteau C, Bejaoui S, Bera PP, Black JH, Boulanger F, Bouwman J, Brandl B, Brechignac P, Brünken S, Buragohain M, Burkhardt A, Candian A, Cazaux S, Cernicharo J, Chabot M, Chakraborty S, Champion J, Colgan SWJ, Cooke IR, Coutens A, Cox NLJ, Demyk K, Meyer JD, Engrand C, Foschino S, García-Lario P, Gavilan L, Gerin M, Godard M, Gottlieb CA, Guillard P, Gusdorf A, Hartigan P, He J, Herbst E, Hornekaer L, Jäger C, Janot-Pacheco E, Kaufman M, Kemper F, Kendrew S, Kirsanova MS, Knight C, Kwok S, Labiano Á, Lai TSY, Lee TJ, Lefloch B, Le Petit F, Li A, Linz H, Mackie CJ, Madden SC, Mascetti J, McGuire BA, Merino P, Micelotta ER, Morse JA, Mulas G, Neelamkodan N, Ohsawa R, Paladini R, Palumbo ME, Pathak A, Pendleton YJ, Petrignani A, Pino T, Puga E, Rangwala N, Rapacioli M, Ricca A, Roman-Duval J, Roueff E, Rouillé G, Salama F, Sales DA, Sandstrom K, Sarre P, Sciamma-O'Brien E, Sellgren K, Shannon MJ, Simonnin A, Shenoy SS, Teyssier D, Thomas RD, Togi A, Verstraete L, Witt AN, Wootten A, Ysard N, Zettergren H, Zhang Y, Zhang ZE, Zhen J. A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk. Science 2024; 383:988-992. [PMID: 38422128 DOI: 10.1126/science.adh2861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 01/12/2024] [Indexed: 03/02/2024]
Abstract
Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modeling their kinematics and excitation allowed us to constrain the physical conditions within the gas. We quantified the mass-loss rate induced by the FUV irradiation and found that it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk.
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Affiliation(s)
- Olivier Berné
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
| | - Emilie Habart
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Els Peeters
- Department of Physics and 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
- Carl Sagan Center, Search for ExtraTerrestrial Intelligence Institute, Mountain View, CA 94043, USA
| | - Ilane Schroetter
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
| | - Amélie Canin
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
| | - Ameek Sidhu
- Department of Physics and 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
| | - Ryan Chown
- Department of Physics and 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
| | - Emeric Bron
- Laboratoire d'Etudes du Rayonnement et de la Matière, Observatoire de Paris, Université Paris Science et Lettres, CNRS, Sorbonne Universités, F-92190 Meudon, France
| | - Thomas J Haworth
- School of Physics and Astronomy, Queen Mary University of London, London E1 4NS, UK
| | - Pamela Klaassen
- UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill EH9 3HJ, UK
| | - Boris Trahin
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | | | - Felipe Alarcón
- Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA
| | - Marion Zannese
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Alain Abergel
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Edwin A Bergin
- Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jeronimo Bernard-Salas
- ACRI-ST, Centre d'Etudes et de Recherche de Grasse, F-06130 Grasse, France
- Innovative Common Laboratory for Space Spectroscopy, 06130 Grasse, France
| | | | - Jan Cami
- Department of Physics and 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
- Carl Sagan Center, Search for ExtraTerrestrial Intelligence Institute, Mountain View, CA 94043, USA
| | - Sara Cuadrado
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain
| | - Emmanuel Dartois
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Daniel Dicken
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Meriem Elyajouri
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Asunción Fuente
- Centro de Astrobiología, Consejo Superior de Investigaciones Científicas, and Instituto Nacional de Técnica Aeroespacial, 28850 Torrejón de Ardoz, Spain
| | - Javier R Goicoechea
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain
| | - Karl D Gordon
- Space Telescope Science Institute, Baltimore, MD 21218, USA
- Johns Hopkins University, Baltimore, MD 21218, USA
| | - Lina Issa
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
| | - Christine Joblin
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
| | - Olga Kannavou
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Baria Khan
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Ozan Lacinbala
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - David Languignon
- Laboratoire d'Etudes du Rayonnement et de la Matière, Observatoire de Paris, Université Paris Science et Lettres, CNRS, Sorbonne Universités, F-92190 Meudon, France
| | - Romane Le Gal
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
- Institut de Planétologie et d'Astrophysique de Grenoble, Université Grenoble Alpes, CNRS, F-38000 Grenoble, France
- Institut de Radioastronomie Millimétrique, F-38406 Saint-Martin d'Hères, France
| | | | - Raphael Meshaka
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Yoko Okada
- I. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany
| | - Takashi Onaka
- Department of Astronomy, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
- Department of Physics, Faculty of Science and Engineering, Meisei University, Hino, Tokyo 191-8506, Japan
| | - Sofia Pasquini
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Marc W Pound
- Astronomy Department, University of Maryland, College Park, MD 20742, USA
| | - Massimo Robberto
- Space Telescope Science Institute, Baltimore, MD 21218, USA
- Johns Hopkins University, Baltimore, MD 21218, USA
| | - Markus Röllig
- I. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany
| | - Bethany Schefter
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Thiébaut Schirmer
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
- Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala, Sweden
| | - Thomas Simmer
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Benoit Tabone
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Alexander G G M Tielens
- Astronomy Department, University of Maryland, College Park, MD 20742, USA
- Leiden Observatory, Leiden University, 2300 RA Leiden, Netherlands
| | - Sílvia Vicente
- Instituto de Astrofísica e Ciências do Espaço, P-1349-018 Lisboa, Portugal
| | - Mark G Wolfire
- Astronomy Department, University of Maryland, College Park, MD 20742, USA
| | - Isabel Aleman
- Instituto de Física e Química, Universidade Federal de Itajubá, Itajubá, Brazil
| | - Louis Allamandola
- Astronomy Department, University of Maryland, College Park, MD 20742, USA
- Bay Area Environmental Research Institute, Moffett Field, CA 94035, USA
| | - Rebecca Auchettl
- Australian Synchrotron, Australian Nuclear Science and Technology Organisation, Victoria, Australia
| | | | - Clément Baruteau
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
| | - Salma Bejaoui
- Astronomy Department, University of Maryland, College Park, MD 20742, USA
| | - Partha P Bera
- Astronomy Department, University of Maryland, College Park, MD 20742, USA
- Bay Area Environmental Research Institute, Moffett Field, CA 94035, USA
| | - John H Black
- Department of Space, Earth, and Environment, Chalmers University of Technology, Onsala Space Observatory, 43992 Onsala, Sweden
| | - Francois Boulanger
- Laboratoire de Physique de l'École Normale Supérieure, Université Paris Science et Lettres, CNRS, Sorbonne Université, Université de Paris, 75005, Paris, France
| | - Jordy Bouwman
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA
- Department of Chemistry, University of Colorado, Boulder, CO 80309, USA
- Institute for Modeling Plasma, Atmospheres, and Cosmic Dust, University of Colorado, Boulder, CO 80303, USA
| | - Bernhard Brandl
- I. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany
- Faculty of Aerospace Engineering, Delft University of Technology, 2629 HS Delft, Netherlands
| | | | - Sandra Brünken
- Institute for Molecules and Materials, Free-Electron Lasers for Infrared eXperiments Laboratory, Radboud University, 6525 ED Nijmegen, Netherlands
| | | | - Andrew Burkhardt
- Department of Physics, Wellesley College, Wellesley, MA 02481, USA
| | - Alessandra Candian
- I. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany
- Anton Pannekoek Institute for Astronomy, University of Amsterdam, 1098 XH Amsterdam, Netherlands
| | - Stéphanie Cazaux
- Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jose Cernicharo
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain
| | - Marin Chabot
- Laboratoire de Physique des deux infinis Irène Joliot-Curie, Université Paris-Saclay, CNRS, 91405 Orsay Cedex, France
| | - Shubhadip Chakraborty
- Institut de Physique de Rennes, CNRS, Université de Rennes 1, 35042 Rennes, France
- Department of Chemistry, Gandhi Institute of Technology and Management, Bangalore, India
| | - Jason Champion
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
| | - Sean W J Colgan
- Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala, Sweden
| | - Ilsa R Cooke
- Department of Chemistry, The University of British Columbia, Vancouver, BC, Canada
| | - Audrey Coutens
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
| | - Nick L J Cox
- ACRI-ST, Centre d'Etudes et de Recherche de Grasse, F-06130 Grasse, France
- Innovative Common Laboratory for Space Spectroscopy, 06130 Grasse, France
| | - Karine Demyk
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
| | | | - Cécile Engrand
- Laboratoire de Physique des deux infinis Irène Joliot-Curie, Université Paris-Saclay, CNRS, 91405 Orsay Cedex, France
| | - Sacha Foschino
- Institute for Earth and Space Exploration, The University of Western Ontario, London, ON N6A 3K7, Canada
| | | | - Lisseth Gavilan
- Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala, Sweden
| | - Maryvonne Gerin
- Laboratoire d'Etudes du Rayonnement et de la Matière, Observatoire de Paris, Paris Science et Lettres University, Sorbonne Université, 75014, Paris, France
| | - Marie Godard
- ACRI-ST, Centre d'Etudes et de Recherche de Grasse, F-06130 Grasse, France
| | - Carl A Gottlieb
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
| | - Pierre Guillard
- Institut d'Astrophysique de Paris, Sorbonne Université, CNRS, 75014 Paris, France
- Institut Universitaire de France, Ministère de l'Enseignement Supérieur et de la Recherche, 75231 Paris, France
| | - Antoine Gusdorf
- Laboratoire de Physique de l'École Normale Supérieure, Université Paris Science et Lettres, CNRS, Sorbonne Université, Université de Paris, 75005, Paris, France
- Laboratoire d'Etudes du Rayonnement et de la Matière, Observatoire de Paris, Paris Science et Lettres University, Sorbonne Université, 75014, Paris, France
| | - Patrick Hartigan
- Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
| | - Jinhua He
- Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216, China
- Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, Beijing 100101, China
- Departamento de Astronomía, Universidad de Chile, Santiago, Chile
| | - Eric Herbst
- Departments of Chemistry and Astronomy, University of Virginia, Charlottesville, VA 22904, USA
| | - Liv Hornekaer
- Center for Interstellar Catalysis, Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - Cornelia Jäger
- Institute of Solid State Physics, Max Planck Institute for Astronomy, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Eduardo Janot-Pacheco
- Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, 05509-090 São Paulo, Brazil
| | - Michael Kaufman
- Department of Physics and Astronomy, San José State University, San Jose, CA 95192, USA
| | - Francisca Kemper
- Institut de Ciencies de l'Espai, Centro Superior de Investigacion Cientifica, E-08193, Barcelona, Spain
- Institución Catalana de Investigación y Estudios Avanzados, E-08010 Barcelona, Spain
- Institut d'Estudis Espacials de Catalunya, E-08034 Barcelona, Spain
| | - Sarah Kendrew
- European Space Agency, Space Telescope Science Institute, Baltimore, MD 21218, USA
| | - Maria S Kirsanova
- Institute of Astronomy, Russian Academy of Sciences, 119017 Moscow, Russia
| | - Collin Knight
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Sun Kwok
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, BC V6T 1Z4, Canada
| | - Álvaro Labiano
- Telespazio UK, European Space Agency, E-28692 Villanueva de la Cañada, Madrid, Spain
| | - Thomas S-Y Lai
- Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA
| | - Timothy J Lee
- Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala, Sweden
| | - Bertrand Lefloch
- Leiden Observatory, Leiden University, 2300 RA Leiden, Netherlands
| | | | - Aigen Li
- Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA
| | - Hendrik Linz
- Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
| | - Cameron J Mackie
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Pitzer Center for Theoretical Chemistry, College of Chemistry, University of California, Berkeley, CA, USA
| | - Suzanne C Madden
- Astrophysics, Instrumentation and Modelling, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France
| | - Joëlle Mascetti
- Institut des Sciences Moléculaires, CNRS, Université de Bordeaux, 33405 Talence, France
| | - Brett A McGuire
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- National Radio Astronomy Observatory, Charlottesville, VA 22903, USA
| | - Pablo Merino
- Instituto de Ciencia de Materiales de Madrid, Centro Superior de Investigacion Cientifica, E28049, Madrid, Spain
| | | | - Jon A Morse
- Steward Observatory, University of Arizona, Tucson, AZ 85721, USA
| | - Giacomo Mulas
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
- Osservatorio Astronomico di Cagliari, Instituto Nazionale di Astrofisca, 09047 Selargius, Italy
| | - Naslim Neelamkodan
- Department of Physics, College of Science, United Arab Emirates University, Al-Ain 15551, United Arab Emirates
| | - Ryou Ohsawa
- National Astronomical Observatory of Japan, Tokyo 181-8588, Japan
| | - Roberta Paladini
- Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA
| | | | - Amit Pathak
- Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Yvonne J Pendleton
- Department of Physics, University of Central Florida, Orlando, FL 32816, USA
| | - Annemieke Petrignani
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, 1090 GD Amsterdam, Netherlands
| | - Thomas Pino
- Innovative Common Laboratory for Space Spectroscopy, 06130 Grasse, France
| | - Elena Puga
- European Space Agency, Villanueva de la Cañada, E-28692 Madrid, Spain
| | | | - Mathias Rapacioli
- Laboratoire de Chimie et Physique Quantiques, Université de Toulouse, CNRS, Toulouse, France
| | - Alessandra Ricca
- Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
- Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala, Sweden
| | - Julia Roman-Duval
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Evelyne Roueff
- Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA
| | - Gaël Rouillé
- Institute of Solid State Physics, Max Planck Institute for Astronomy, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Farid Salama
- NASA Ames Research Center, Moffett Field, CA 94035, USA
| | - Dinalva A Sales
- Instituto de Matemática, Estatística e Física, Universidade Federal do Rio Grande, 96201-900, Rio Grande, Brazil
| | - Karin Sandstrom
- Center for Astrophysics and Space Sciences, Department of Physics, University of California, San Diego, CA 92093, USA
| | - Peter Sarre
- School of Chemistry, The University of Nottingham, Nottingham NG7 2RD, UK
| | | | - Kris Sellgren
- Astronomy Department, Ohio State University, Columbus, OH 43210, USA
| | | | - Adrien Simonnin
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
| | | | - David Teyssier
- European Space Agency, Villanueva de la Cañada, E-28692 Madrid, Spain
| | - Richard D Thomas
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Aditya Togi
- Department of Physics, Texas State University, San Marcos, TX 78666, USA
| | - Laurent Verstraete
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Adolf N Witt
- Ritter Astrophysical Research Center, University of Toledo, Toledo, OH 43606, USA
| | - Alwyn Wootten
- National Radio Astronomy Observatory, Charlottesville, VA 22903, USA
| | - Nathalie Ysard
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales, 31028 Toulouse, France
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | | | - Yong Zhang
- School of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519000, China
| | - Ziwei E Zhang
- Star and Planet Formation Laboratory, Rikagaku Kenkyusho Cluster for Pioneering Research, Saitama 351-0198, Japan
| | - Junfeng Zhen
- Key Laboratory of Crust-Mantle Materials and Environment, Chinese Academy of Science, University of Science and Technology of China, Anhui 230026, China
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Goicoechea JR, Cuadrado S, Le Petit F. Multi-line Observations, Models, and Data Needed to Understand the Nature of UV-irradiated Interstellar Matter. EPJ WEB OF CONFERENCES 2022. [DOI: 10.1051/epjconf/202226500003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Far-ultraviolet photons from OB-type massive stars regulate the heating, ionization, and chemistry of much of the neutral interstellar gas in star-forming galaxies. The interaction of FUV radiation and interstellar matter takes place in environments broadly known as photodissociation regions (PDRs). PDR line diagnostics are the smoking gun of the radiative feedback from massive stars. Improving our understanding of stellar feedback in the ISM requires quantifying the energy budget, gas dynamics, and chemical composition of PDR environments. This goal demands astronomical instrumentation able to deliver multi-line spectroscopic images of the ISM (of the Milky Way and nearby galaxies). It also requires interdisciplinary collaborations to obtain the rate coefficients and cross sections of the many microphysical processes that occur in the ISM and that are included in models such as the Meudon PDR code.
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Veselinova A, Agúndez M, Goicoechea JR, Menéndez M, Zanchet A, Verdasco E, Jambrina PG, Aoiz FJ. Quantum study of reaction O( 3 P) + H 2 ( v, j) → OH + H: OH formation in strongly UV-irradiated gas. ASTRONOMY AND ASTROPHYSICS 2021; 648:A76. [PMID: 34257462 PMCID: PMC7611199 DOI: 10.1051/0004-6361/202140428] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The reaction between atomic oxygen and molecular hydrogen is an important one in astrochemistry as it regulates the abundance of the hydroxyl radical and serves to open the chemistry of oxygen in diverse astronomical environments. However, the existence of a high activation barrier in the reaction with ground state oxygen atoms limits its efficiency in cold gas. In this study we calculate the dependence of the reaction rate coefficient on the rotational and vibrational state of H2 and evaluate the impact on the abundance of OH in interstellar regions strongly irradiated by far-UV photons, where H2 can be efficiently pumped to excited vibrational states. We use a recently calculated potential energy surface and carry out time-independent quantum mechanical scattering calculations to compute rate coefficients for the reaction O(3 P) + H2 (v, j) → OH + H, with H2 in vibrational states v = 0-7 and rotational states j = 0-10. We find that the reaction becomes significantly faster with increasing vibrational quantum number of H2, although even for high vibrational states of H2 (v = 4-5) for which the reaction is barrierless, the rate coefficient does not strictly attain the collision limit and still maintains a positive dependence with temperature. We implemented the calculated state-specific rate coefficients in the Meudon PDR code to model the Orion Bar PDR and evaluate the impact on the abundance of the OH radical. We find the fractional abundance of OH is enhanced by up to one order of magnitude in regions of the cloud corresponding to A V = 1.3-2.3, compared to the use of a thermal rate coefficient for O + H2, although the impact on the column density of OH is modest, of about 60%. The calculated rate coefficients will be useful to model and interpret JWST observations of OH in strongly UV-illuminated environments.
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Affiliation(s)
- A. Veselinova
- Departamento de Química Física, University of Salamanca, Plaza Caidos S/N, E-37008, Salamanca, Spain
- Departamento de Química Física (Unidad Asociada al CSIC), Universidad Complutense de Madrid, Ciudad Universitaria, S/N, E-20840, Madrid, Spain
| | - M. Agúndez
- Instituto de Física Fundamental, CSIC, Calle Serrano 121-123, E-28006, Madrid, Spain
| | - J. R. Goicoechea
- Instituto de Física Fundamental, CSIC, Calle Serrano 121-123, E-28006, Madrid, Spain
| | - M. Menéndez
- Departamento de Química Física (Unidad Asociada al CSIC), Universidad Complutense de Madrid, Ciudad Universitaria, S/N, E-20840, Madrid, Spain
| | - A. Zanchet
- Instituto de Física Fundamental, CSIC, Calle Serrano 121-123, E-28006, Madrid, Spain
| | - E. Verdasco
- Departamento de Química Física (Unidad Asociada al CSIC), Universidad Complutense de Madrid, Ciudad Universitaria, S/N, E-20840, Madrid, Spain
| | - P. G. Jambrina
- Departamento de Química Física, University of Salamanca, Plaza Caidos S/N, E-37008, Salamanca, Spain
| | - F. J. Aoiz
- Departamento de Química Física (Unidad Asociada al CSIC), Universidad Complutense de Madrid, Ciudad Universitaria, S/N, E-20840, Madrid, Spain
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Pabst CHM, Goicoechea JR, Teyssier D, Berné O, Higgins RD, Chambers ET, Kabanovic S, Güsten R, Stutzki J, Tielens AGGM. Expanding bubbles in Orion A: [C II] observations of M42, M43, and NGC 1977. ASTRONOMY AND ASTROPHYSICS 2020; 639:A2. [PMID: 33173232 PMCID: PMC7116338 DOI: 10.1051/0004-6361/202037560] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
CONTEXT The Orion Molecular Cloud is the nearest massive-star forming region. Massive stars have profound effects on their environment due to their strong radiation fields and stellar winds. Stellar feedback is one of the most crucial cosmological parameters that determine the properties and evolution of the interstellar medium in galaxies. AIMS We aim to understand the role that feedback by stellar winds and radiation play in the evolution of the interstellar medium. Velocity-resolved observations of the [C II] 158μm fine-structure line allow us to study the kinematics of UV-illuminated gas. Here, we present a square-degree-sized map of [C II] emission from the Orion Nebula complex at a spatial resolution of 16″ and high spectral resolution of 0.2kms-1, covering the entire Orion Nebula (M42) plus M43 and the nebulae NGC 1973, 1975, and 1977 to the north. We compare the stellar characteristics of these three regions with the kinematics of the expanding bubbles surrounding them. METHODS We use [C II] 158μm line observations over an area of 1.2deg2 in the Orion Nebula complex obtained by the upGREAT instrument onboard SOFIA. RESULTS The bubble blown by the O7V star θ 1 Ori C in the Orion Nebula expands rapidly, at 13kms-1. Simple analytical models reproduce the characteristics of the hot interior gas and the neutral shell of this wind-blown bubble and give us an estimate of the expansion time of 0.2 Myr. M43 with the B0.5V star NU Ori also exhibits an expanding bubble structure, with an expansion velocity of 6kms-1. Comparison with analytical models for the pressure-driven expansion of H II regions gives an age estimate of 0.02 Myr. The bubble surrounding NGC 1973, 1975, and 1977 with the central B1V star 42 Orionis expands at 1.5kms-1, likely due to the over-pressurized ionized gas as in the case of M43. We derive an age of 0.4 Myr for this structure. CONCLUSIONS We conclude that the bubble of the Orion Nebula is driven by the mechanical energy input by the strong stellar wind from θ 1 Ori C, while the bubbles associated with M43 and NGC 1977 are caused by the thermal expansion of the gas ionized by their central later-type massive stars.
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Affiliation(s)
- C H M Pabst
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, Netherlands
| | - J R Goicoechea
- Instituto de Fisica Fundamental, CSIC, Calle Serrano 121-123, 28006 Madrid, Spain
| | - D Teyssier
- Telespazio Vega UK Ltd. for ESA/ESAC, Urbanizacion Villafranca del Castillo, 28691 Madrid, Spain
| | - O Berné
- IRAP, Université de Toulouse, CNRS, CNES, UPS, 9 Av. colonel Roche, 31028 Toulouse Cedex 4, France
| | - R D Higgins
- I. Physikalisches Institut der Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
| | - E T Chambers
- USRA/SOFIA, NASA Ames Research Center, Mail Stop 232-12, Building N232, P.O. Box 1, Moffett Field, CA 94035-0001, USA
| | - S Kabanovic
- I. Physikalisches Institut der Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
| | - R Güsten
- Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
| | - J Stutzki
- I. Physikalisches Institut der Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
| | - A G G M Tielens
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, Netherlands
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Rivière-Marichalar P, Fuente A, Goicoechea JR, Pety J, Le Gal R, Gratier P, Guzmán V, Roueff E, Loison JC, Wakelam V, Gerin M. Abundances of sulphur molecules in the Horsehead nebula First NS + detection in a photodissociation region. ASTRONOMY AND ASTROPHYSICS 2019; 628:A16. [PMID: 31511745 PMCID: PMC6739222 DOI: 10.1051/0004-6361/201935354] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
CONTEXT Sulphur is one of the most abundant elements in the Universe (S/H∼1.3×10 -5 ) and plays a crucial role in biological systems on Earth. The understanding of its chemistry is therefore of major importance. AIMS Our goal is to complete the inventory of S-bearing molecules and their abundances in the prototypical photodissociation region (PDR) the Horsehead nebula to gain insight into sulphur chemistry in UV irradiated regions. Based on the WHISPER (Wide-band High-resolution Iram-30m Surveys at two positions with Emir Receivers) millimeter (mm) line survey, our goal is to provide an improved and more accurate description of sulphur species and their abundances towards the core and PDR positions in the Horsehead. METHODS The Monte Carlo Markov Chain (MCMC) methodology and the molecular excitation and radiative transfer code RADEX were used to explore the parameter space and determine physical conditions and beam-averaged molecular abundances. RESULTS A total of 13 S-bearing species (CS, SO, SO2, OCS, H2CS - both ortho and para - HDCS, C2S, HCS+, SO+, H2S, S2H, NS and NS+) have been detected in the two targeted positions. This is the first detection of SO+ in the Horsehead and the first detection of NS+ in any PDR. We find a differentiated chemical behaviour between C-S and O-S bearing species within the nebula. The C-S bearing species C2S and o-H2CS present fractional abundances a factor of > two higher in the core than in the PDR. In contrast, the O-S bearing molecules SO, SO2, and OCS present similar abundances towards both positions. A few molecules, SO+, NS, and NS+, are more abundant towards the PDR than towards the core, and could be considered as PDR tracers. CONCLUSIONS This is the first complete study of S-bearing species towards a PDR. Our study shows that CS, SO, and H2S are the most abundant S-bearing molecules in the PDR with abundances of ∼ a few 10-9. We recall that SH, SH+, S, and S+ are not observable at the wavelengths covered by the WHISPER survey. At the spatial scale of our observations, the total abundance of S atoms locked in the detected species is < 10-8, only ∼0.1% of the cosmic sulphur abundance.
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Affiliation(s)
- P Rivière-Marichalar
- Instituto de Física Fundamental (CSIC), Calle Serrano 121, 28006 Madrid, Spain
- Observatorio Astronómico Nacional (OAN,IGN), Apdo 112, E-28803 Alcalá de Henares, Spain
| | - A Fuente
- Observatorio Astronómico Nacional (OAN,IGN), Apdo 112, E-28803 Alcalá de Henares, Spain
| | - J R Goicoechea
- Instituto de Física Fundamental (CSIC), Calle Serrano 121, 28006 Madrid, Spain
| | - J Pety
- Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38406 Saint Martin d'Hères, France
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Ecole Normale Supérieure, F-75005 Paris, France
| | - R Le Gal
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
| | - P Gratier
- Laboratoire d'Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
| | - V Guzmán
- Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicunña Mackenna, 4860, 7820436, Macul, Santiago, Chile
| | - E Roueff
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190 Meudon, France
| | - J C Loison
- Institut des Sciences Moléculaires de Bordeaux (ISM), CNRS, Univ. Bordeaux, 351 cours de la Libération, 33400, Talence, France
| | - V Wakelam
- Laboratoire d'Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
| | - M Gerin
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Ecole Normale Supérieure, F-75005 Paris, France
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7
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Cuadrado S, Salas P, Goicoechea JR, Cernicharo J, Tielens AGGM, Báez-Rubio A. Direct estimation of electron density in the Orion Bar PDR from mm-wave carbon recombination lines. ASTRONOMY AND ASTROPHYSICS 2019; 625:10.1051/0004-6361/201935556. [PMID: 31186576 PMCID: PMC6558286 DOI: 10.1051/0004-6361/201935556] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
CONTEXT A significant fraction of the molecular gas in star-forming regions is irradiated by stellar UV photons. In these environments, the electron density (n e) plays a critical role in the gas dynamics, chemistry, and collisional excitation of certain molecules. AIMS We determine n e in the prototypical strongly irradiated photodissociation region (PDR), the Orion Bar, from the detection of new millimeter-wave carbon recombination lines (mmCRLs) and existing far-IR [13Cii] hyperfine line observations. METHODS We detect 12 mmCRLs (including α, β, and γ transitions) observed with the IRAM 30m telescope, at ~ 25″ angular resolution, toward the H/H2 dissociation front (DF) of the Bar. We also present a mmCRL emission cut across the PDR. RESULTS These lines trace the C+/C/CO gas transition layer. As the much lower frequency carbon radio recombination lines, mmCRLs arise from neutral PDR gas and not from ionized gas in the adjacent Hii region. This is readily seen from their narrow line profiles (Δv = 2.6 ± 0.4 km s-1) and line peak velocities (ν LSR = +10.7 ± 0.2 km s-1). Optically thin [13Cii] hyperfine lines and molecular lines - emitted close to the DF by trace species such as reactive ions CO+ and HOC+ - show the same line profiles. We use non-LTE excitation models of [13Cii] and mmCRLs and derive n e = 60 - 100 cm-3 and T e = 500 - 600 K toward the DF. CONCLUSIONS The inferred electron densities are high, up to an order of magnitude higher than previously thought. They provide a lower limit to the gas thermal pressure at the PDR edge without using molecular tracers. We obtain P th ≥ (2 - 4)·108 cm-3 K assuming that the electron abundance is equal to or lower than the gas-phase elemental abundance of carbon. Such elevated thermal pressures leave little room for magnetic pressure support and agree with a scenario in which the PDR photoevaporates.
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Affiliation(s)
- S. Cuadrado
- Instituto de Física Fundamental (IFF-CSIC). Calle Serrano
121-123, E28006 Madrid, Spain
| | - P. Salas
- Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA
Leiden, The Netherlands
| | - J. R. Goicoechea
- Instituto de Física Fundamental (IFF-CSIC). Calle Serrano
121-123, E28006 Madrid, Spain
| | - J. Cernicharo
- Instituto de Física Fundamental (IFF-CSIC). Calle Serrano
121-123, E28006 Madrid, Spain
| | - A. G. G. M. Tielens
- Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA
Leiden, The Netherlands
| | - A. Báez-Rubio
- Centro de Astrobiología (CSIC-INTA), Ctra. de Torrejón
a Ajalvir, km 4, E28850 Torrejón de Ardoz, Madrid, Spain
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8
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Goicoechea JR, Santa-Maria MG, Bron E, Teyssier D, Marcelino N, Cernicharo J, Cuadrado S. Molecular tracers of radiative feedback in Orion (OMC-1) Widespread CH + ( J = 1-0), CO (10-9), HCN (6-5), and HCO + (6-5) emission. ASTRONOMY AND ASTROPHYSICS 2019; 622:A91. [PMID: 30820064 PMCID: PMC6390943 DOI: 10.1051/0004-6361/201834409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Young massive stars regulate the physical conditions, ionization, and fate of their natal molecular cloud and surroundings. It is important to find tracers that help quantifying the stellar feedback processes that take place at different spatial scales. We present ~85 arcmin2 (~1.3 pc2) velocity-resolved maps of several submillimeter molecular lines, taken with Herschel/HIFI, toward the closest high-mass star-forming region, the Orion molecular cloud 1 core (OMC-1). The observed rotational lines include probes of warm and dense molecular gas that are difficult, if not impossible, to detect from ground-based telescopes: CH+ (J = 1-0), CO (J = 10-9), HCO+ (J = 6-5) and HCN (J = 6-5), and CH (N, J =1, 3/2-1, 1/2). These lines trace an extended but thin layer (A V ≃3-6 mag or ~1016 cm) of molecular gas at high thermal pressure, P th = n H · T k ≈ 107 - 109 cm-3 K, associated with the far ultraviolet (FUV) irradiated surface of OMC-1. The intense FUV radiation field, emerging from massive stars in the Trapezium cluster, heats, compresses and photoevaporates the cloud edge. It also triggers the formation of specific reactive molecules such as CH+. We find that the CH+ (J = 1-0) emission spatially correlates with the flux of FUV photons impinging the cloud: G 0 from ~103 to ~105. This correlation is supported by constant-pressure photodissociation region (PDR) models in the parameter space P th/G 0 ≈ [5 · 103 - 8 · 104] cm-3 K where many observed PDRs seem to lie. The CH+ (J = 1-0) emission spatially correlates with the extended infrared emission from vibrationally excited H2 (v ≥ 1), and with that of [C ii] 158 μm and CO J = 10-9, all emerging from FUV-irradiated gas. These correlations link the presence of CH+ to the availability of C+ ions and of FUV-pumped H2 (v ≥ 1) molecules. We conclude that the parsec-scale CH+ emission and narrow-line (Δv ≃ 3 km s-1) mid-J CO emission arises from extended PDR gas and not from fast shocks. PDR line tracers are the smoking gun of the stellar feedback from young massive stars. The PDR cloud surface component in OMC-1, with a mass density of 120-240 M ⊙ pc-2, represents ~5% to ~10% of the total gas mass, however, it dominates the emitted line luminosity; the average CO J = 10-9 surface luminosity in the mapped region being ~35 times brighter than that of CO J = 2-1. These results provide insights into the source of submillimeter CH+ and mid-J CO emission from distant star-forming galaxies.
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Affiliation(s)
- Javier R Goicoechea
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain
| | - Miriam G Santa-Maria
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain
| | - Emeric Bron
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain
| | - David Teyssier
- Telespazio Vega UK Ltd for ESA/ESAC. Urbanización Villafranca del Castillo, Villanueva de la Cañada, E-28692 Madrid, Spain
| | - Nuria Marcelino
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain
| | - José Cernicharo
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain
| | - Sara Cuadrado
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain
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Goicoechea JR, Pety J, Chapillon E, Cernicharo J, Gerin M, Herrera C, Requena-Torres MA, Santa-Maria MG. High-speed molecular cloudlets around the Galactic center's supermassive black hole. ASTRONOMY AND ASTROPHYSICS 2018; 618:A35. [PMID: 30429617 PMCID: PMC6231548 DOI: 10.1051/0004-6361/201833558] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We present 1″-resolution ALMA observations of the circumnuclear disk (CND) and the interstellar environment around Sgr A*. The images unveil the presence of small spatial scale 12CO (J=3-2) molecular "cloudlets" (≲20,000 AU size) within the central parsec of the Milky Way, in other words, inside the cavity of the CND, and moving at high speeds, up to 300 km s-1 along the line-of-sight. The 12CO-emitting structures show intricate morphologies: extended and filamentary at high negative-velocities (vLSR ≲-150 km s-1), more localized and clumpy at extreme positive-velocities (vLSR ≳+200 km s-1). Based on the pencil-beam 12CO absorption spectrum toward Sgr A* synchrotron emission, we also present evidence for a diffuse molecular gas component producing absorption features at more extreme negative-velocities (vLSR <-200 km s-1). The CND shows a clumpy spatial distribution traced by the optically thin H13CN (J=4-3) emission. Its motion requires a bundle of non-uniformly rotating streams of slightly different inclinations. The inferred gas density peaks, molecular cores of a few 105 cm-3, are lower than the local Roche limit. This supports that CND cores are transient. We apply the two standard orbit models, spirals vs. ellipses, invoked to explain the kinematics of the ionized gas streamers around Sgr A*. The location and velocities of the 12CO cloudlets inside the cavity are inconsistent with the spiral model, and only two of them are consistent with the Keplerian ellipse model. Most cloudlets, however, show similar velocities that are incompatible with the motions of the ionized streamers or with gas bounded to the central gravity. We speculate that they are leftovers of more massive molecular clouds that fall into the cavity and are tidally disrupted, or that they originate from instabilities in the inner rim of the CND that lead to fragmentation and infall from there. In either case, we show that molecular cloudlets, all together with a mass of several 10 M ⊙, exist around Sgr A*. Most of them must be short-lived, ≲104 yr: photoevaporated by the intense stellar radiation field, G 0≃105.3 to 104.3, blown away by winds from massive stars in the central cluster, or disrupted by strong gravitational shears.
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Affiliation(s)
- Javier R Goicoechea
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, 28006, Madrid, Spain
| | - Jerome Pety
- Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, F-38406 Saint Martin d'Hères, France
- Sorbonne Université, Observatoire de Paris, Université PSL, École Normale Supérieure, CNRS, LERMA, F-75014, Paris, France
| | - Edwige Chapillon
- Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, F-38406 Saint Martin d'Hères, France
- OASU/LAB-UMR5804, CNRS, Université Bordeaux, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
| | - José Cernicharo
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, 28006, Madrid, Spain
| | - Maryvonne Gerin
- Sorbonne Université, Observatoire de Paris, Université PSL, École Normale Supérieure, CNRS, LERMA, F-75014, Paris, France
| | - Cinthya Herrera
- Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, F-38406 Saint Martin d'Hères, France
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Joblin C, Bron E, Pinto C, Pilleri P, Le Petit F, Gerin M, Le Bourlot J, Fuente A, Berne O, Goicoechea JR, Habart E, Köhler M, Teyssier D, Nagy Z, Montillaud J, Vastel C, Cernicharo J, Röllig M, Ossenkopf-Okada V, Bergin EA. Structure of photodissociation fronts in star-forming regions revealed by observations of high-J CO emission lines with Herschel. ASTRONOMY AND ASTROPHYSICS 2018; 615:A129. [PMID: 30185990 PMCID: PMC6120684 DOI: 10.1051/0004-6361/201832611] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
CONTEXT In bright photodissociation regions (PDRs) associated to massive star formation, the presence of dense "clumps" that are immersed in a less dense interclump medium is often proposed to explain the difficulty of models to account for the observed gas emission in high-excitation lines. AIMS We aim at presenting a comprehensive view of the modeling of the CO rotational ladder in PDRs, including the high-J lines that trace warm molecular gas at PDR interfaces. METHODS We observed the 12CO and 13CO ladders in two prototypical PDRs, the Orion Bar and NGC 7023 NW using the instruments onboard Herschel. We also considered line emission from key species in the gas cooling of PDRs (C+, O, H2) and other tracers of PDR edges such as OH and CH+. All the intensities are collected from Herschel observations, the literature and the Spitzer archive and are analyzed using the Meudon PDR code. RESULTS A grid of models was run to explore the parameter space of only two parameters: thermal gas pressure and a global scaling factor that corrects for approximations in the assumed geometry. We conclude that the emission in the high-J CO lines, which were observed up to J up =23 in the Orion Bar (J up =19 in NGC 7023), can only originate from small structures of typical thickness of a few 10-3 pc and at high thermal pressures (Pth ~ 108 K cm-3). CONCLUSIONS Compiling data from the literature, we found that the gas thermal pressure increases with the intensity of the UV radiation field given by G0, following a trend in line with recent simulations of the photoevaporation of illuminated edges of molecular clouds. This relation can help rationalising the analysis of high-J CO emission in massive star formation and provides an observational constraint for models that study stellar feedback on molecular clouds.
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Affiliation(s)
- C Joblin
- IRAP, Université de Toulouse, CNRS, UPS, CNES, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
| | - E Bron
- Instituto de Fisica Fundamental (CSIC), Calle Serrano 121-123, 28006, Madrid, Spain
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190, Meudon, France
| | - C Pinto
- Aix-Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
| | - P Pilleri
- IRAP, Université de Toulouse, CNRS, UPS, CNES, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
| | - F Le Petit
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190, Meudon, France
| | - M Gerin
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190, Meudon, France
| | - J Le Bourlot
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190, Meudon, France
- Université Paris-Diderot, Paris, France
| | - A Fuente
- Observatorio Astronómico Nacional, Apdo. 112, 28803 Alcalá de Henares, Madrid, Spain
| | - O Berne
- IRAP, Université de Toulouse, CNRS, UPS, CNES, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
| | - J R Goicoechea
- Instituto de Fisica Fundamental (CSIC), Calle Serrano 121-123, 28006, Madrid, Spain
| | - E Habart
- Institut d'Astrophysique Spatiale (IAS), Université Paris Sud & CNRS, 91405 Orsay, France
| | - M Köhler
- Institut d'Astrophysique Spatiale (IAS), Université Paris Sud & CNRS, 91405 Orsay, France
| | - D Teyssier
- European Space Astronomy Centre, ESA, PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
| | - Z Nagy
- I. Physikalisches Institut der Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
| | - J Montillaud
- Institut Utinam, CNRS UMR 6213, OSU THETA, Université de Franche-Comté, 41bis avenue de l'Observatoire, 25000 Besançon, France
| | - C Vastel
- IRAP, Université de Toulouse, CNRS, UPS, CNES, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
| | - J Cernicharo
- Instituto de Fisica Fundamental (CSIC), Calle Serrano 121-123, 28006, Madrid, Spain
| | - M Röllig
- I. Physikalisches Institut der Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
| | - V Ossenkopf-Okada
- I. Physikalisches Institut der Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
| | - E A Bergin
- Department of Astronomy, University of Michigan, 311 West Hall, 1085 S. University Avenue, Ann Arbor, MI 48109, USA
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11
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Champion J, Berné O, Vicente S, Kamp I, Le Petit F, Gusdorf A, Joblin C, Goicoechea JR. Herschel survey and modelling of externally-illuminated photoevaporating protoplanetary disks. ASTRONOMY AND ASTROPHYSICS 2017; 604:A69. [PMID: 29093599 PMCID: PMC5662148 DOI: 10.1051/0004-6361/201629404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
CONTEXT Protoplanetary disks undergo substantial mass-loss by photoevaporation, a mechanism which is crucial to their dynamical evolution. However, the processes regulating the gas energetics have not been well constrained by observations so far. AIMS We aim at studying the processes involved in disk photoevaporation when it is driven by far-UV photons (i.e. 6 < E < 13.6 eV). METHODS We present a unique Herschel survey and new ALMA observations of four externally-illuminated photoevaporating disks (a.k.a. proplyds). For the analysis of these data, we developed a 1D model of the photodissociation region (PDR) of a proplyd, based on the Meudon PDR code and we computed the far infrared line emission. RESULTS With this model, we successfully reproduce most of the observations and derive key physical parameters, i.e. densities at the disk surface of about 106 cm-3 and local gas temperatures of about 1000 K. Our modelling suggests that all studied disks are found in a transitional regime resulting from the interplay between several heating and cooling processes that we identify. These differ from those dominating in classical PDRs i.e. grain photo-electric effect and cooling by [OI] and [CII] FIR lines. This specific energetic regime is associated to an equilibrium dynamical point of the photoevaporation flow: the mass-loss rate is self-regulated to keep the envelope column density at a value that maintains the temperature at the disk surface around 1000 K. From the physical parameters derived from our best-fit models, we estimate mass-loss rates - of the order of 10-7 M⊙/yr - that are in agreement with earlier spectroscopic observation of ionised gas tracers. This holds only if we assume photoevaporation in the supercritical regime where the evaporation flow is launched from the disk surface at sound speed. CONCLUSIONS We have identified the energetic regime regulating FUV-photoevaporation in proplyds. This regime could be implemented into models of the dynamical evolution of protoplanetary disks.
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Affiliation(s)
- J Champion
- Université de Toulouse, UPS-OMP, IRAP, Toulouse, France
- CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
| | - O Berné
- Université de Toulouse, UPS-OMP, IRAP, Toulouse, France
- CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
| | - S Vicente
- Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV Groningen, The Netherlands
- Institute of Astrophysics and Space Sciences (IA), Tapada da Ajuda - Edificio Leste - 2° Piso, 1349-018 Lisboa, Portugal
| | - I Kamp
- Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV Groningen, The Netherlands
| | - F Le Petit
- LERMA, Observatoire de Paris, PSL Research University, CNRS, UMR8112, F-92190 Meudon, France
| | - A Gusdorf
- LERMA, Observatoire de Paris, École normale supérieure, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-75231, Paris, France
| | - C Joblin
- Université de Toulouse, UPS-OMP, IRAP, Toulouse, France
- CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
| | - J R Goicoechea
- Grupo de Astrofisica Molecular, Instituto de Ciencia de Materiales de Madrid (CSIC), E-28049, Madrid, Spain
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12
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Cuadrado S, Goicoechea JR, Cernicharo J, Fuente A, Pety J, Tercero B. Complex organic molecules in strongly UV-irradiated gas. ASTRONOMY AND ASTROPHYSICS 2017; 603:A124. [PMID: 29142326 PMCID: PMC5683355 DOI: 10.1051/0004-6361/201730459] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We investigate the presence of complex organic molecules (COMs) in strongly UV-irradiated interstellar molecular gas. We have carried out a complete millimetre (mm) line survey using the IRAM 30 m telescope towards the edge of the Orion Bar photodissociation region (PDR), close to the H2 dissociation front, a position irradiated by a very intense far-UV (FUV) radiation field. These observations have been complemented with 8.5″ resolution maps of the H2CO JKa,Kc = 51,5 → 41,4 and C18O J = 3 → 2 emission at 0.9 mm. Despite being a harsh environment, we detect more than 250 lines from COMs and related precursors: H2CO, CH3OH, HCO, H2CCO, CH3CHO, H2CS, HCOOH, CH3CN, CH2NH, HNCO, [Formula: see text] and HC3N (in decreasing order of abundance). For each species, the large number of detected lines allowed us to accurately constrain their rotational temperatures (Trot) and column densities (N). Owing to subthermal excitation and intricate spectroscopy of some COMs (symmetric- and asymmetric-top molecules such as CH3CN and H2CO, respectively), a correct determination of N and Trot requires building rotational population diagrams of their rotational ladders separately. The inferred column densities are in the 1011 - 1013cm-2 range. We also provide accurate upper limit abundances for chemically related molecules that might have been expected, but are not conclusively detected at the edge of the PDR (HDCO, CH3O, CH3NC, CH3CCH, CH3OCH3, HCOOCH3, CH3CH2OH, CH3CH2CN, and CH2CHCN). A non-thermodynamic equilibrium excitation analysis for molecules with known collisional rate coefficients suggests that some COMs arise from different PDR layers but we cannot resolve them spatially. In particular, H2CO and CH3CN survive in the extended gas directly exposed to the strong FUV flux (Tk = 150 - 250 K and Td ≳ 60 K), whereas CH3OH only arises from denser and cooler gas clumps in the more shielded PDR interior (Tk = 40 - 50 K). The non-detection of HDCO towards the PDR edge is consistent with the minor role of pure gas-phase deuteration at very high temperatures. We find a HCO/H2CO/CH3OH ≃ 1/5/3 abundance ratio. These ratios are different from those inferred in hot cores and shocks. Taking into account the elevated gas and dust temperatures at the edge of the Bar (mostly mantle-free grains), we suggest the following scenarios for the formation of COMs: (i) hot gas-phase reactions not included in current models; (ii) warm grain-surface chemistry; or (iii) the PDR dynamics is such that COMs or precursors formed in cold icy grains deeper inside the molecular cloud desorb and advect into the PDR.
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Affiliation(s)
- S Cuadrado
- Grupo de Astrofísica Molecular. Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Inés de la Cruz 3, 28049 Cantoblanco, Madrid, Spain
| | - J R Goicoechea
- Grupo de Astrofísica Molecular. Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Inés de la Cruz 3, 28049 Cantoblanco, Madrid, Spain
| | - J Cernicharo
- Grupo de Astrofísica Molecular. Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Inés de la Cruz 3, 28049 Cantoblanco, Madrid, Spain
| | - A Fuente
- Observatorio Astronómico Nacional, Apdo. 112, 28803 Alcalá de Henares, Madrid, Spain
| | - J Pety
- Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, F-38406 Saint Martin d'Hères, France
- LERMA, Observatoire de Paris, CNRS UMR 8112, École Normale Supérieure, PSL research university, 24 rue Lhomond, 75231, Paris Cedex 05, France
| | - B Tercero
- Grupo de Astrofísica Molecular. Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Inés de la Cruz 3, 28049 Cantoblanco, Madrid, Spain
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13
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Faure A, Halvick P, Stoecklin T, Honvault P, Epée Epée MD, Mezei JZ, Motapon O, Schneider IF, Tennyson J, Roncero O, Bulut N, Zanchet A. State-to-state chemistry and rotational excitation of CH + in photon-dominated regions. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 2017; 469:612-620. [PMID: 28690343 PMCID: PMC5500105 DOI: 10.1093/mnras/stx892] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present a detailed theoretical study of the rotational excitation of CH+ due to reactive and nonreactive collisions involving C+(2P), H2, CH+, H and free electrons. Specifically, the formation of CH+ proceeds through the reaction between C+(2P) and H2(νH2 = 1, 2), while the collisional (de)excitation and destruction of CH+ is due to collisions with hydrogen atoms and free electrons. State-to-state and initial-state-specific rate coefficients are computed in the kinetic temperature range 10-3000 K for the inelastic, exchange, abstraction and dissociative recombination processes using accurate potential energy surfaces and the best scattering methods. Good agreement, within a factor of 2, is found between the experimental and theoretical thermal rate coefficients, except for the reaction of CH+ with H atoms at kinetic temperatures below 50 K. The full set of collisional and chemical data are then implemented in a radiative transfer model. Our Non-LTE calculations confirm that the formation pumping due to vibrationally excited H2 has a substantial effect on the excitation of CH+ in photon-dominated regions. In addition, we are able to reproduce, within error bars, the far-infrared observations of CH+ toward the Orion Bar and the planetary nebula NGC 7027. Our results further suggest that the population of νH2 = 2 might be significant in the photon-dominated region of NGC 7027.
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Affiliation(s)
- A. Faure
- Univ. Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France
| | - P. Halvick
- Univ. Bordeaux, CNRS, ISM, F-33400 Talence, France
| | - T. Stoecklin
- Univ. Bordeaux, CNRS, ISM, F-33400 Talence, France
| | - P. Honvault
- Univ. Bourgogne Franche-Comté, Laboratoire ICB, F-21078 Dijon, France
| | - M. D. Epée Epée
- UFD Mathématiques, Informatique Appliqúee et Physique Fondamentale, University of Douala, P. O. Box 24157, Douala, Cameroon
| | - J. Zs. Mezei
- Univ. Normandie, CNRS, LOMC, F-76058 Le Havre, France
- LSPM, Univ. Paris 13, 99 avenue Jean-Baptiste Clément, F-93430 Villetaneuse, France
- Univ. Paris-Sud, CNRS, Laboratoire Aimé Cotton, F-91405 Orsay, France
- Institute of Nuclear Research of the Hungarian Academy of Sciences, P.O. Box 51, Debrecen H-4001, Hungary
| | - O. Motapon
- UFD Mathématiques, Informatique Appliqúee et Physique Fondamentale, University of Douala, P. O. Box 24157, Douala, Cameroon
- University of Maroua, Faculty of Science, P. O. Box 814 Maroua, Cameroon
| | - I. F. Schneider
- Univ. Normandie, CNRS, LOMC, F-76058 Le Havre, France
- Univ. Paris-Sud, CNRS, Laboratoire Aimé Cotton, F-91405 Orsay, France
| | - J. Tennyson
- Department of Physics and Astronomy, University College, London, Gower St., London WC1E 6BT, UK
| | - O. Roncero
- Instituto de Física Fundamental, CSIC, C/ Serrano, 123, E-28006 Madrid, Spain
| | - N. Bulut
- Firat University, Department of Physics, 23169 Elazig̃, Turkey
| | - A. Zanchet
- Instituto de Física Fundamental, CSIC, C/ Serrano, 123, E-28006 Madrid, Spain
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Goicoechea JR, Cuadrado S, Pety J, Bron E, Black JH, Cernicharo J, Chapillon E, Fuente A, Gerin M. Spatially resolved images of reactive ions in the Orion Bar ,★★. ASTRONOMY AND ASTROPHYSICS 2017; 601:L9. [PMID: 28690335 PMCID: PMC5500010 DOI: 10.1051/0004-6361/201730716] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report high angular resolution (4.9″×3.0″) images of reactive ions SH+, HOC+, and SO+ toward the Orion Bar photodissociation region (PDR). We used ALMA-ACA to map several rotational lines at 0.8 mm, complemented with multi-line observations obtained with the IRAM 30 m telescope. The SH+ and HOC+ emission is restricted to a narrow layer of 2″- to 10″-width (≈800 to 4000 AU depending on the assumed PDR geometry) that follows the vibrationally excited [Formula: see text] emission. Both ions efficiently form very close to the H/H2 transition zone, at a depth of Av≲1 mag into the neutral cloud, where abundant C+, S+, and [Formula: see text] coexist. SO+ peaks slightly deeper into the cloud. The observed ions have low rotational temperatures (Trot≈10-30 K≪Tk) and narrow line-widths (~2-3 km s-1), a factor of ≃2 narrower that those of the lighter reactive ion CH+. This is consistent with the higher reactivity and faster radiative pumping rates of CH+ compared to the heavier ions, which are driven relatively faster toward smaller velocity dispersion by elastic collisions and toward lower Trot by inelastic collisions. We estimate column densities and average physical conditions from an excitation model (n(H2)≈105-106 cm-3, n(e-)≈10 cm-3, and Tk≈200 K). Regardless of the excitation details, SH+ and HOC+ clearly trace the most exposed layers of the UV-irradiated molecular cloud surface, whereas SO+ arises from slightly more shielded layers.
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Affiliation(s)
| | - Sara Cuadrado
- Instituto de Ciencias de Materiales de Madrid (CSIC), 28049, Madrid, Spain
| | - Jérôme Pety
- Institut de Radioastronomie Millimétrique, 38406, Saint Martin d'Hères, France
- LERMA, Obs. de Paris, PSL Research University, CNRS, Sorbonne Universiteés, UPMC Univ. Paris 06, ENS, F-75005, France
| | - Emeric Bron
- Instituto de Ciencias de Materiales de Madrid (CSIC), 28049, Madrid, Spain
- LERMA, Obs. de Paris, PSL Research University, CNRS, Sorbonne Universiteés, UPMC Univ. Paris 06, ENS, F-75005, France
| | - John H Black
- Chalmers University of Technology, Onsala Space Observatory, 43992 Onsala, Sweden
| | - José Cernicharo
- Instituto de Ciencias de Materiales de Madrid (CSIC), 28049, Madrid, Spain
| | - Edwige Chapillon
- Institut de Radioastronomie Millimétrique, 38406, Saint Martin d'Hères, France
- OASU/LAB-UMR5804, CNRS, Universiteé Bordeaux, 33615 Pessac, France
| | - Asunción Fuente
- Observatorio Astronómico Nacional (IGN). Apartado 112, 28803 Alcalá de Henares, Spain
| | - Maryvonne Gerin
- LERMA, Obs. de Paris, PSL Research University, CNRS, Sorbonne Universiteés, UPMC Univ. Paris 06, ENS, F-75005, France
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15
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Parikka A, Habart E, Bernard-Salas J, Goicoechea JR, Abergel A, Pilleri P, Dartois E, Joblin C, Gerin M, Godard B. Spatial distribution of FIR rotationally excited CH + and OH emission lines in the Orion Bar PDR. ASTRONOMY AND ASTROPHYSICS 2017; 599:A20. [PMID: 28260804 PMCID: PMC5334792 DOI: 10.1051/0004-6361/201629445] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
CONTEXT The methylidyne cation (CH+) and hydroxyl (OH) are key molecules in the warm interstellar chemistry, but their formation and excitation mechanisms are not well understood. Their abundance and excitation are predicted to be enhanced by the presence of vibrationally excited H2 or hot gas (~500-1000 K) in photodissociation regions with high incident FUV radiation field. The excitation may also originate in dense gas (> 105 cm-3) followed by nonreactive collisions with H2, H, and electrons. Previous observations of the Orion Bar suggest that the rotationally excited CH+ and OH correlate with the excited CO, a tracer of dense and warm gas, and formation pumping contributes to CH+ excitation. AIMS Our goal is to examine the spatial distribution of the rotationally excited CH+ and OH emission lines in the Orion Bar in order to establish their physical origin and main formation and excitation mechanisms. METHODS We present spatially sampled maps of the CH+ J=3-2 transition at 119.8 µm and the OH Λ-doublet at 84 µm in the Orion Bar over an area of 110″×110″ with Herschel (PACS). We compare the spatial distribution of these molecules with those of their chemical precursors, C+, O and H2, and tracers of warm and dense gas (high-J CO). We assess the spatial variation of CH+ J=2-1 velocity-resolved line profile at 1669 GHz with Herschel HIFI spectrometer observations. RESULTS The OH and especially CH+ lines correlate well with the high-J CO emission and delineate the warm and dense molecular region at the edge of the Bar. While notably similar, the differences in the CH+ and OH morphologies indicate that CH+ formation and excitation are strongly related to the observed vibrationally excited H2. This, together with the observed broad CH+ line widths, indicates that formation pumping contributes to the excitation of this reactive molecular ion. Interestingly, the peak of the rotationally excited OH 84 µm emission coincides with a bright young object, proplyd 244-440, which shows that OH can be an excellent tracer of UV-irradiated dense gas. CONCLUSIONS The spatial distribution of CH+ and OH revealed in our maps is consistent with previous modeling studies. Both formation pumping and nonreactive collisions in a UV-irradiated dense gas are important CH+ J=3-2 excitation processes. The excitation of the OH Λ-doublet at 84 µm is mainly sensitive to the temperature and density.
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Affiliation(s)
- A Parikka
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, 91405 Orsay Cedex, France; I. Physikalisches Institut der Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
| | - E Habart
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - J Bernard-Salas
- Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - J R Goicoechea
- Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz, 3, 28049 Madrid, Spain
| | - A Abergel
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - P Pilleri
- Université de Toulouse, UPS-OMP, IRAP, 31400 Toulouse, France; CNRS, IRAP, 9 Av. Colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
| | - E Dartois
- Institut d'Astrophysique Spatiale, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - C Joblin
- Université de Toulouse, UPS-OMP, IRAP, 31400 Toulouse, France; CNRS, IRAP, 9 Av. Colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
| | - M Gerin
- LERMA, Observatoire de Paris, PSL Research University, Ecole Normale Supérieure, CNRS, 75014 Paris; Sorbonne Universités, UPMC Paris 06, CNRS, LERMA, 75005 Paris
| | - B Godard
- LERMA, Observatoire de Paris, PSL Research University, Ecole Normale Supérieure, CNRS, 75014 Paris; Sorbonne Universités, UPMC Paris 06, CNRS, LERMA, 75005 Paris
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16
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Cuadrado S, Goicoechea JR, Roncero O, Aguado A, Tercero B, Cernicharo J. Trans-cis molecular photoswitching in interstellar Space. ASTRONOMY AND ASTROPHYSICS 2016; 596:L1. [PMID: 28003686 PMCID: PMC5166968 DOI: 10.1051/0004-6361/201629913] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
As many organic molecules, formic acid (HCOOH) has two conformers (trans and cis). The energy barrier to internal conversion from trans to cis is much higher than the thermal energy available in molecular clouds. Thus, only the most stable conformer (trans) is expected to exist in detectable amounts. We report the first interstellar detection of cis-HCOOH. Its presence in ultraviolet (UV) irradiated gas exclusively (the Orion Bar photodissociation region), with a low trans-to-cis abundance ratio of 2.8 ± 1.0, supports a photoswitching mechanism: a given conformer absorbs a stellar photon that radiatively excites the molecule to electronic states above the interconversion barrier. Subsequent fluorescent decay leaves the molecule in a different conformer form. This mechanism, which we specifically study with ab initio quantum calculations, was not considered in Space before but likely induces structural changes of a variety of interstellar molecules submitted to UV radiation.
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Affiliation(s)
- S Cuadrado
- Grupo de Astrofísica Molecular. Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Sor Juana Ines de la Cruz 3, E-28049 Cantoblanco, Madrid, Spain
| | - J R Goicoechea
- Grupo de Astrofísica Molecular. Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Sor Juana Ines de la Cruz 3, E-28049 Cantoblanco, Madrid, Spain
| | - O Roncero
- Instituto de Física Fundamental (IFF-CSIC). Calle Serrano 123, E-28006 Madrid, Spain
| | - A Aguado
- Facultad de Ciencias, Unidad Asociada de Química-Física Aplicada CSIC-UAM, Universidad Autónoma de Madrid, E-28049, Madrid, Spain
| | - B Tercero
- Grupo de Astrofísica Molecular. Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Sor Juana Ines de la Cruz 3, E-28049 Cantoblanco, Madrid, Spain
| | - J Cernicharo
- Grupo de Astrofísica Molecular. Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Sor Juana Ines de la Cruz 3, E-28049 Cantoblanco, Madrid, Spain
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17
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Treviño-Morales SP, Fuente A, Sánchez-Monge Á, Pilleri P, Goicoechea JR, Ossenkopf-Okada V, Roueff E, Rizzo JR, Gerin M, Berné O, Cernicharo J, Gónzalez-García M, Kramer C, García-Burillo S, Pety J. The first CO + image: I. Probing the HI/H 2 layer around the ultracompact HII region Mon R2. ASTRONOMY AND ASTROPHYSICS 2016; 593:L12. [PMID: 27721515 PMCID: PMC5055094 DOI: 10.1051/0004-6361/201628899] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The CO+ reactive ion is thought to be a tracer of the boundary between a HII region and the hot molecular gas. In this study, we present the spatial distribution of the CO+ rotational emission toward the Mon R2 star-forming region. The CO+ emission presents a clumpy ring-like morphology, arising from a narrow dense layer around the HII region. We compare the CO+ distribution with other species present in photon-dominated regions (PDR), such as [CII] 158 µm, H2 S(3) rotational line at 9.3 µm, polycyclic aromatic hydrocarbons (PAHs) and HCO+. We find that the CO+ emission is spatially coincident with the PAHs and [CII] emission. This confirms that the CO+ emission arises from a narrow dense layer of the HI/H2 interface. We have determined the CO+ fractional abundance, relative to C+ toward three positions. The abundances range from 0.1 to 1.9 ×10-10 and are in good agreement with previous chemical model, which predicts that the production of CO+ in PDRs only occurs in dense regions with high UV fields. The CO+ linewidth is larger than those found in molecular gas tracers, and their central velocity are blue-shifted with respect to the molecular gas velocity. We interpret this as a hint that the CO+ is probing photo-evaporating clump surfaces.
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Affiliation(s)
- S P Treviño-Morales
- Instituto de Ciencia de Materiales de Madrid, Sor Juana Inés de la Cruz 3, E-28049 Cantoblanco, Madrid, (Spain); Observatorio Astronómico Nacional, Apdo. 112, E-28803 Alcalá de Henares Madrid, (Spain)
| | - A Fuente
- Observatorio Astronómico Nacional, Apdo. 112, E-28803 Alcalá de Henares Madrid, (Spain)
| | - Á Sánchez-Monge
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, (Germany)
| | - P Pilleri
- CNRS; IRAP; 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4, (France); LERMA, Observatoire de Paris, PSL Research University, CNRS, UMR8112, Place Janssen, 92190 Meudon Cedex, (France)
| | - J R Goicoechea
- Instituto de Ciencia de Materiales de Madrid, Sor Juana Inés de la Cruz 3, E-28049 Cantoblanco, Madrid, (Spain)
| | - V Ossenkopf-Okada
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, (Germany)
| | - E Roueff
- LERMA, Observatoire de Paris, PSL Research University, CNRS, UMR8112, Place Janssen, 92190 Meudon Cedex, (France)
| | - J R Rizzo
- Centro de Astrobiología, E-28850 Torrejón de Ardoz, (Spain)
| | - M Gerin
- LERMA, Observatoire de Paris, PSL Research University, CNRS, UMR8112, Place Janssen, 92190 Meudon Cedex, (France)
| | - O Berné
- CNRS; IRAP; 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4, (France); Université de Toulouse, UPS-OMP, IRAP, 31000 Toulouse, (France)
| | - J Cernicharo
- Instituto de Ciencia de Materiales de Madrid, Sor Juana Inés de la Cruz 3, E-28049 Cantoblanco, Madrid, (Spain)
| | - M Gónzalez-García
- Instituto de Astrofísica de Andalucía, CSIC, E-18008, Granada, (Spain)
| | - C Kramer
- Instituto de Radioastronomía Milimétrica, Ave. Divina Pastora, 7, Local 20 18012, Granada (Spain)
| | - S García-Burillo
- Observatorio Astronómico Nacional, Apdo. 112, E-28803 Alcalá de Henares Madrid, (Spain)
| | - J Pety
- Institut de Radioastronomie Millimétrique, 300 Rue de la Piscine, F-38406 Saint Martin d'Hères, (France)
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18
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Röllig M. Violent emissions of newborn stars. Nature 2016; 537:174-5. [DOI: 10.1038/537174a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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