PDRs4All - IV. An embarrassment of riches: Aromatic infrared bands in the Orion Bar

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dc.citation.articleNumberA75en_US
dc.citation.journalTitleAstronomy & Astrophysicsen_US
dc.citation.volumeNumber685en_US
dc.contributor.authorChown, Ryanen_US
dc.contributor.authorSidhu, Ameeken_US
dc.contributor.authorPeeters, Elsen_US
dc.contributor.authorTielens, Alexander G. G. M.en_US
dc.contributor.authorCami, Janen_US
dc.contributor.authorBerné, Olivieren_US
dc.contributor.authorHabart, Emilieen_US
dc.contributor.authorAlarcón, Felipeen_US
dc.contributor.authorCanin, Amélieen_US
dc.contributor.authorSchroetter, Ilaneen_US
dc.contributor.authorTrahin, Borisen_US
dc.contributor.authorPutte, Dries Van Deen_US
dc.contributor.authorAbergel, Alainen_US
dc.contributor.authorBergin, Edwin A.en_US
dc.contributor.authorBernard-Salas, Jeronimoen_US
dc.contributor.authorBoersma, Christiaanen_US
dc.contributor.authorBron, Emericen_US
dc.contributor.authorCuadrado, Saraen_US
dc.contributor.authorDartois, Emmanuelen_US
dc.contributor.authorDicken, Danielen_US
dc.contributor.authorEl-Yajouri, Meriemen_US
dc.contributor.authorFuente, Asunciónen_US
dc.contributor.authorGoicoechea, Javier R.en_US
dc.contributor.authorGordon, Karl D.en_US
dc.contributor.authorIssa, Linaen_US
dc.contributor.authorJoblin, Christineen_US
dc.contributor.authorKannavou, Olgaen_US
dc.contributor.authorKhan, Bariaen_US
dc.contributor.authorLacinbala, Ozanen_US
dc.contributor.authorLanguignon, Daviden_US
dc.contributor.authorGal, Romane Leen_US
dc.contributor.authorMaragkoudakis, Alexandrosen_US
dc.contributor.authorMeshaka, Raphaelen_US
dc.contributor.authorOkada, Yokoen_US
dc.contributor.authorOnaka, Takashien_US
dc.contributor.authorPasquini, Sofiaen_US
dc.contributor.authorPound, Marc W.en_US
dc.contributor.authorRobberto, Massimoen_US
dc.contributor.authorRöllig, Markusen_US
dc.contributor.authorSchefter, Bethanyen_US
dc.contributor.authorSchirmer, Thiébauten_US
dc.contributor.authorVicente, Sílviaen_US
dc.contributor.authorWolfire, Mark G.en_US
dc.contributor.authorZannese, Marionen_US
dc.contributor.authorAleman, Isabelen_US
dc.contributor.authorAllamandola, Louisen_US
dc.contributor.authorAuchettl, Rebeccaen_US
dc.contributor.authorBaratta, Giuseppe Antonioen_US
dc.contributor.authorBejaoui, Salmaen_US
dc.contributor.authorBera, Partha P.en_US
dc.contributor.authorBlack, John H.en_US
dc.contributor.authorBoulanger, Françoisen_US
dc.contributor.authorBouwman, Jordyen_US
dc.contributor.authorBrandl, Bernharden_US
dc.contributor.authorBrechignac, Philippeen_US
dc.contributor.authorBrünken, Sandraen_US
dc.contributor.authorBuragohain, Mridusmitaen_US
dc.contributor.authorBurkhardt, Andrewen_US
dc.contributor.authorCandian, Alessandraen_US
dc.contributor.authorCazaux, Stéphanieen_US
dc.contributor.authorCernicharo, Joseen_US
dc.contributor.authorChabot, Marinen_US
dc.contributor.authorChakraborty, Shubhadipen_US
dc.contributor.authorChampion, Jasonen_US
dc.contributor.authorColgan, Sean W. J.en_US
dc.contributor.authorCooke, Ilsa R.en_US
dc.contributor.authorCoutens, Audreyen_US
dc.contributor.authorCox, Nick L. J.en_US
dc.contributor.authorDemyk, Karineen_US
dc.contributor.authorMeyer, Jennifer Donovanen_US
dc.contributor.authorFoschino, Sachaen_US
dc.contributor.authorGarcía-Lario, Pedroen_US
dc.contributor.authorGavilan, Lissethen_US
dc.contributor.authorGerin, Maryvonneen_US
dc.contributor.authorGottlieb, Carl A.en_US
dc.contributor.authorGuillard, Pierreen_US
dc.contributor.authorGusdorf, Antoineen_US
dc.contributor.authorHartigan, Patricken_US
dc.contributor.authorHe, Jinhuaen_US
dc.contributor.authorHerbst, Ericen_US
dc.contributor.authorHornekaer, Liven_US
dc.contributor.authorJäger, Corneliaen_US
dc.contributor.authorJanot-Pacheco, Eduardoen_US
dc.contributor.authorKaufman, Michaelen_US
dc.contributor.authorKemper, Franciscaen_US
dc.contributor.authorKendrew, Sarahen_US
dc.contributor.authorKirsanova, Maria S.en_US
dc.contributor.authorKlaassen, Pamelaen_US
dc.contributor.authorKwok, Sunen_US
dc.contributor.authorLabiano, Álvaroen_US
dc.contributor.authorLai, Thomas S.-Y.en_US
dc.contributor.authorLee, Timothy J.en_US
dc.contributor.authorLefloch, Bertranden_US
dc.contributor.authorPetit, Franck Leen_US
dc.contributor.authorLi, Aigenen_US
dc.contributor.authorLinz, Hendriken_US
dc.contributor.authorMackie, Cameron J.en_US
dc.contributor.authorMadden, Suzanne C.en_US
dc.contributor.authorMascetti, Joëlleen_US
dc.contributor.authorMcGuire, Brett A.en_US
dc.contributor.authorMerino, Pabloen_US
dc.contributor.authorMicelotta, Elisabetta R.en_US
dc.contributor.authorMisselt, Karlen_US
dc.contributor.authorMorse, Jon A.en_US
dc.contributor.authorMulas, Giacomoen_US
dc.contributor.authorNeelamkodan, Naslimen_US
dc.contributor.authorOhsawa, Ryouen_US
dc.contributor.authorOmont, Alainen_US
dc.contributor.authorPaladini, Robertaen_US
dc.contributor.authorPalumbo, Maria Elisabettaen_US
dc.contributor.authorPathak, Amiten_US
dc.contributor.authorPendleton, Yvonne J.en_US
dc.contributor.authorPetrignani, Annemiekeen_US
dc.contributor.authorPino, Thomasen_US
dc.contributor.authorPuga, Elenaen_US
dc.contributor.authorRangwala, Naseemen_US
dc.contributor.authorRapacioli, Mathiasen_US
dc.contributor.authorRicca, Alessandraen_US
dc.contributor.authorRoman-Duval, Juliaen_US
dc.contributor.authorRoser, Josephen_US
dc.contributor.authorRoueff, Evelyneen_US
dc.contributor.authorRouillé, Gaëlen_US
dc.contributor.authorSalama, Fariden_US
dc.contributor.authorSales, Dinalva A.en_US
dc.contributor.authorSandstrom, Karinen_US
dc.contributor.authorSarre, Peteren_US
dc.contributor.authorSciamma-O’Brien, Ellaen_US
dc.contributor.authorSellgren, Krisen_US
dc.contributor.authorShenoy, Sachindev S.en_US
dc.contributor.authorTeyssier, Daviden_US
dc.contributor.authorThomas, Richard D.en_US
dc.contributor.authorTogi, Adityaen_US
dc.contributor.authorVerstraete, Laurenten_US
dc.contributor.authorWitt, Adolf N.en_US
dc.contributor.authorWootten, Alwynen_US
dc.contributor.authorZettergren, Henningen_US
dc.contributor.authorZhang, Yongen_US
dc.contributor.authorZhang, Ziwei E.en_US
dc.contributor.authorZhen, Junfengen_US
dc.date.accessioned2024-08-29T21:11:44Zen_US
dc.date.available2024-08-29T21:11:44Zen_US
dc.date.issued2024en_US
dc.description.abstractContext. Mid-infrared observations of photodissociation regions (PDRs) are dominated by strong emission features called aromatic infrared bands (AIBs). The most prominent AIBs are found at 3.3, 6.2, 7.7, 8.6, and 11.2 µm. The most sensitive, highest-resolution infrared spectral imaging data ever taken of the prototypical PDR, the Orion Bar, have been captured by JWST. These high-quality data allow for an unprecedentedly detailed view of AIBs.<i>Aims<i/>. We provide an inventory of the AIBs found in the Orion Bar, along with mid-IR template spectra from five distinct regions in the Bar: the molecular PDR (i.e. the three H2 dissociation fronts), the atomic PDR, and the H II region. Methods. We used JWST NIRSpec IFU and MIRI MRS observations of the Orion Bar from the JWST Early Release Science Program, PDRs4All (ID: 1288). We extracted five template spectra to represent the morphology and environment of the Orion Bar PDR. We investigated and characterised the AIBs in these template spectra. We describe the variations among them here. Results. The superb sensitivity and the spectral and spatial resolution of these JWST observations reveal many details of the AIB emission and enable an improved characterization of their detailed profile shapes and sub-components. The Orion Bar spectra are dominated by the well-known AIBs at 3.3, 6.2, 7.7, 8.6, 11.2, and 12.7 µm with well-defined profiles. In addition, the spectra display a wealth of weaker features and sub-components. The widths of many AIBs show clear and systematic variations, being narrowest in the atomic PDR template, but showing a clear broadening in the H II region template while the broadest bands are found in the three dissociation front templates. In addition, the relative strengths of AIB (sub-)components vary among the template spectra as well. All AIB profiles are characteristic of class A sources as designated by Peeters (2022, A&A, 390, 1089), except for the 11.2 µm AIB profile deep in the molecular zone, which belongs to class B11.2. Furthermore, the observations show that the sub-components that contribute to the 5.75, 7.7, and 11.2 µm AIBs become much weaker in the PDR surface layers. We attribute this to the presence of small, more labile carriers in the deeper PDR layers that are photolysed away in the harsh radiation field near the surface. The 3.3/11.2 AIB intensity ratio decreases by about 40% between the dissociation fronts and the H II region, indicating a shift in the polycyclic aromatic hydrocarbon (PAH) size distribution to larger PAHs in the PDR surface layers, also likely due to the effects of photochemistry. The observed broadening of the bands in the molecular PDR is consistent with an enhanced importance of smaller PAHs since smaller PAHs attain a higher internal excitation energy at a fixed photon energy. Conclusions. Spectral-imaging observations of the Orion Bar using JWST yield key insights into the photochemical evolution of PAHs, such as the evolution responsible for the shift of 11.2 µm AIB emission from class B11.2 in the molecular PDR to class A11.2 in the PDR surface layers. This photochemical evolution is driven by the increased importance of FUV processing in the PDR surface layers, resulting in a “weeding out” of the weakest links of the PAH family in these layers. For now, these JWST observations are consistent with a model in which the underlying PAH family is composed of a few species: the so-called ‘grandPAHs’.en_US
dc.identifier.citationChown, R., Sidhu, A., Peeters, E., Tielens, A. G. G. M., Cami, J., Berné, O., Habart, E., Alarcón, F., Canin, A., Schroetter, I., Trahin, B., Putte, D. V. D., Abergel, A., Bergin, E. A., Bernard-Salas, J., Boersma, C., Bron, E., Cuadrado, S., Dartois, E., … Zhen, J. (2024). PDRs4All - IV. An embarrassment of riches: Aromatic infrared bands in the Orion Bar. Astronomy & Astrophysics, 685, A75. https://doi.org/10.1051/0004-6361/202346662en_US
dc.identifier.digitalaa46662-23en_US
dc.identifier.doihttps://doi.org/10.1051/0004-6361/202346662en_US
dc.identifier.urihttps://hdl.handle.net/1911/117724en_US
dc.language.isoengen_US
dc.publisherEDP Sciencesen_US
dc.rightsExcept where otherwise noted, this work is licensed under a Creative Commons Attribution (CC BY) license.  Permission to reuse, publish, or reproduce the work beyond the terms of the license or beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/en_US
dc.titlePDRs4All - IV. An embarrassment of riches: Aromatic infrared bands in the Orion Baren_US
dc.typeJournal articleen_US
dc.type.dcmiTexten_US
dc.type.publicationpublisher versionen_US
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