The <i>JWST</i>/MIRI view of the planetary nebula NGC 6302 – I. A UV-irradiated torus and a hot bubble triggering PAH formation

ABSTRACT NGC 6302 is a spectacular bipolar planetary nebula (PN) whose spectrum exhibits fast outflows and highly ionized emission lines, indicating the presence of a very hot central star (${\sim}$220 000 K). Its infrared spectrum reveals a mixed oxygen and carbon dust chemistry, displaying both silicate and polycyclic aromatic hydrocarbon (PAH) features. Using the James Webb Space Telescope Mid-Infrared Instrument and Medium Resolution Spectrometer, a mosaic map was obtained over the core of NGC 6302, covering the wavelength range of 5–28 $\mu$m and spanning an area of ${\sim}$18.5 arcsec $\times$ 15arcsec. The spatially resolved spectrum reveals ${\sim}$200 molecular and ionized lines from species requiring ionization potentials of up to 205 eV. The spatial distributions highlight a complex structure at the nebula’s centre. Highly ionized species such as [Mg vii] and [Si vii] show compact structures, while lower ionization species such as H$^+$ extend much farther outwards, forming filament-defined rims that delineate a bubble. Within the bubble, the H$^+$ and H$_2$ emission coincide, while the PAH emission appears farther out, indicating an ionization structure distinct from typical photodissociation regions, such as the Orion Bar. This may be the first identification of a PAH formation site in a PN. This PN appears to be shaped not by a steady, continuous outflow, but by a series of dynamic, impulsive bubble ejections, creating local conditions conducive to PAH formation. A dusty torus surrounds the core, primarily composed of large ($\mu$m-sized) silicate grains with crystalline components. The long-lived torus contains a substantial mass of material, which could support an equilibrium chemistry and a slow dust-formation process.

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Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-08-18
DOI
https://doi.org/10.1093/mnras/staf1194
Citations
4
Primary Topic
Stellar, planetary, and galactic studies
Type
article
Field-Weighted Citation Impact
4.62

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article

The JWST/MIRI view of the planetary nebula NGC 6302 – I. A UV-irradiated torus and a hot bubble triggering PAH formation

Nicholas Clark, F. Kemper, J. Bernard‐Salas, A. A. Zijlstra et al.
4 citations
Monthly Notices of the Royal Astronomical Society
Stellar, planetary, and galactic studies
4.62
article

The JWST/MIRI view of the planetary nebula NGC 6302 – I. A UV-irradiated torus and a hot bubble triggering PAH formation

Nicholas Clark, F. Kemper, J. Bernard‐Salas, A. A. Zijlstra, H. L. Dinerstein, Raghvendra Sahai, G. C. Sloan, M. J. Barlow, Bruce Balick, J. Cami, R. Wesson, Patrick Kavanagh, J. A. D. L. Blommaert, Maryam Torki, Naomi Hirano, E. Peeters, A. M. S. Richards, N. C. Sterling, Joel H. Kastner, K. E. Kraemer, N. J. Wright, Paula Moraga Baez, F. J. Molster, Kevin Volk, J. R. Walsh, Olivia Jones, J. M. Laming, P. A. M. van Hoof, Isabel Aleman, H. Monteiro, E. Lagadec, M. Matsuura, Alexander Csukai, F. F. Wilson, K. Justtanont, L. B. F. M. Waters, Charmi Bhatt
article en
4 citations

Abstract

ABSTRACT NGC 6302 is a spectacular bipolar planetary nebula (PN) whose spectrum exhibits fast outflows and highly ionized emission lines, indicating the presence of a very hot central star (${\sim}$220 000 K). Its infrared spectrum reveals a mixed oxygen and carbon dust chemistry, displaying both silicate and polycyclic aromatic hydrocarbon (PAH) features. Using the James Webb Space Telescope Mid-Infrared Instrument and Medium Resolution Spectrometer, a mosaic map was obtained over the core of NGC 6302, covering the wavelength range of 5–28 $\mu$m and spanning an area of ${\sim}$18.5 arcsec $\times$ 15arcsec. The spatially resolved spectrum reveals ${\sim}$200 molecular and ionized lines from species requiring ionization potentials of up to 205 eV. The spatial distributions highlight a complex structure at the nebula’s centre. Highly ionized species such as [Mg vii] and [Si vii] show compact structures, while lower ionization species such as H$^+$ extend much farther outwards, forming filament-defined rims that delineate a bubble. Within the bubble, the H$^+$ and H$_2$ emission coincide, while the PAH emission appears farther out, indicating an ionization structure distinct from typical photodissociation regions, such as the Orion Bar. This may be the first identification of a PAH formation site in a PN. This PN appears to be shaped not by a steady, continuous outflow, but by a series of dynamic, impulsive bubble ejections, creating local conditions conducive to PAH formation. A dusty torus surrounds the core, primarily composed of large ($\mu$m-sized) silicate grains with crystalline components. The long-lived torus contains a substantial mass of material, which could support an equilibrium chemistry and a slow dust-formation process.

Monthly Notices of the Royal Astronomical SocietyVol. 542(2)
Boston College (US), University of North Carolina at Chapel Hill (US), Institució Catalana de Recerca i Estudis Avançats (ES), Leiden University (NL), Western University (CA), United States Naval Research Laboratory (US), Space Telescope Science Institute (US), Institute of Astronomy and Astrophysics, Academia Sinica (TW), European Southern Observatory (DE), Jet Propulsion Laboratory (US), Vrije Universiteit Brussel (BE), Radboud University Nijmegen (NL), Rochester Institute of Technology (US), National University of Ireland, Maynooth (IE), University of Washington (US), Royal Observatory of Belgium (BE), University of Manchester (GB), Nicolaus Copernicus University (PL), Institut d'Estudis Espacials de Catalunya (ES), Royal Observatory (GB), Institute of Space Sciences (ES), Université Bourgogne Franche-Comté (FR), Observatoire de la Côte d’Azur (FR), Netherlands Consortium for Healthy Ageing (NL), Laboratório Nacional de Astrofísica (BR), University College London (GB), Space Research Organisation Netherlands (NL), UK Astronomy Technology Centre (GB), Keele University (GB), Seattle University (US), University of West Georgia (US), Chalmers University of Technology (SE), Cardiff University (GB), Universidade Federal de Itajubá (BR), The University of Texas at Austin (US), Search for Extraterrestrial Intelligence (US), Netherlands Institute for Radio Astronomy (NL), Macquarie University (AU)
National Science Foundation, National Aeronautics and Space Administration, Entomological Society of America, Communal Studies Association, Space Telescope Science Institute, UK Research and Innovation, Diabetes Patient Advocacy Coalition, European Space Agency, Science Foundation Ireland, Irish Research Council, Western University, Ministerio de Ciencia e Innovación, Canadian Space Agency, Natural Sciences and Engineering Research Council of Canada, Science and Technology Facilities Council, Agencia Estatal de Investigación, Office of Naval Research, H2020 European Research Council
Openalex Percentile: Top 5%
Stellar, planetary, and galactic studies
4.62
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