JWST observations of the planetary nebula NGC 6302 – IV. PAH spectral characteristics, formation, and evolution
Year: 2026
Type: article
Abstract: ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) and carbonaceous dust have been observed in oxygen-rich planetary nebulae (PNe), yet their formation and evolution in these environments is an open question. We aim to study the formation and evolution of the PAHs in the O-rich PN NGC 6302 (the Butterfly Nebula), by characterizing the PAH emission throughout this object. We obtained James Webb Space Telescope Mid-Infrared Instrument (MIRI) Integral Field Unit (IFU) spectroscopic observations of NGC 6302 pointed at its central source. From these, we extract four template spectra that are representative of the variation in PAH emission throughout NGC 6302. We detect the major PAH features at 6.2, 7.7, 8.6, 11.2, and 12.7 μm, and several minor PAH features. The template spectra vary in terms of their PAH feature widths, peak wavelengths, and relative intensities. The 11.2 μm PAH feature is class B, typical for PNe. The 6–9 μm PAH features are class A, which is less common for PNe. We estimate the PAH charge to be 75 per cent cations on average, based on the 7.7/11.2 PAH feature ratio. The relative strengths of the 11–15 μm PAH features indicate a range of PAH edge structures. To ensure consistency in our observations and explain variable PAH feature widths, we propose a variation in the size of the PAHs throughout NGC 6302, and suggest variation in the shielding of these PAHs. The PAHs range from large and non-compact, to small and compact. We find that NGC 6302 formed PAHs in situ in the current PN phase, likely from small hydrocarbons formed by the photodissociation of CO.
Authors: Nicholas Clark, Els Peeters, Jan Cami, Mikako Matsuura, Alexander G G M Tielens, Patrick J Kavanagh, Michael J Barlow, Joel Kastner, Kathleen E Kraemer, Hektor Monteiro, Raghvendra Sahai, G C Sloan, N C Sterling, Jeremy R Walsh, L B F M Waters, Nicholas J Wright, Isabel Aleman, Bruce Balick, Jeronimo Bernard-Salas, Charmi Bhatt, Joris Blommaert, Harriet L Dinerstein, Naomi Hirano, Olivia Jones, Francisca Kemper, Eric Lagadec, Paula Morgana Baez, Maryam Torki, Peter A M van Hoof, Kevin Volk, Roger Wesson, Albert Zijlstra
Institutions: Western University, Cardiff University, University of Maryland, College Park, National University of Ireland, Maynooth, University College London, Rochester Institute of Technology, Boston College, Universidade Federal de Itajubá, California Institute of Technology, Jet Propulsion Laboratory, University of North Carolina at Chapel Hill, Space Telescope Science Institute, University of West Georgia, European Southern Observatory, Radboud University Nijmegen, Space Research Organisation Netherlands, Keele University, Laboratório Nacional de Astrofísica, University of Washington, Vrije Universiteit Brussel, The University of Texas at Austin, Institute of Astronomy and Astrophysics, Academia Sinica, Academia Sinica, Royal Observatory, UK Astronomy Technology Centre, Institució Catalana de Recerca i Estudis Avançats, Institute of Space Sciences, Institut d'Estudis Espacials de Catalunya, Centre National de la Recherche Scientifique, Université Côte d'Azur, Lagrange Laboratory, Observatoire de la Côte d’Azur, Royal Observatory of Belgium, University of Manchester, Macquarie University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
Funders: National Aeronautics and Space Administration, Entomological Society of America, California Institute of Technology, Communal Studies Association, Space Telescope Science Institute, European Cooperation in Science and Technology, Western University, Jet Propulsion Laboratory, Canadian Space Agency, Natural Sciences and Engineering Research Council of Canada, Science and Technology Facilities Council
OpenAlex ID: W7223157916