Detection of CH <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow/> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> in the O-rich Planetary Nebula NGC 6302
Abstract Planetary nebulae are sites where ejected stellar material evolves into complex molecules, but the precise physical conditions and chemical routes that govern these processes are unclear. The presence of abundant carbon-rich molecules in O-rich environments poses particular challenges. Here we report the first detection of methyl cation (CH <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow/> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> ) in any planetary nebula, observed in the O-rich nebula NGC 6302 using JWST MIRI/Medium Resolution Spectrometer observations. CH <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow/> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> is a key driver of organic chemistry in UV-irradiated environments. Spatially resolved observations reveal that CH <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow/> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> is colocated with 12 CO, H 2 , H ii , HCO + , and polycyclic aromatic hydrocarbons. LTE modeling of the CH <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow/> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> emission yields excitation temperatures of 500–800 K in the inner bubble and torus, rising to 1000–2000 K in the outer bubble of NGC 6302, with column densities ranging from ∼10 11 to 10 13 cm −2 . This detection suggests that hydrocarbon radical chemistry must be incorporated into planetary nebulae chemical models. Further near-IR observations are crucial to map different chemical networks operating in these environments.
Authors
- R. Sahai (ORCID: https://orcid.org/0000-0002-6858-5063)
- Nicholas Clark (ORCID: https://orcid.org/0000-0002-5306-0993)
- F. Kemper (ORCID: https://orcid.org/0000-0003-2743-8240)
- J. Bernard‐Salas (ORCID: https://orcid.org/0000-0002-8452-8675)
- A. A. Zijlstra (ORCID: https://orcid.org/0000-0002-3171-5469)
- H. L. Dinerstein (ORCID: https://orcid.org/0000-0002-4017-5572)
- G. C. Sloan (ORCID: https://orcid.org/0000-0003-4520-1044)
- M. J. Barlow (ORCID: https://orcid.org/0000-0002-3875-1171)
- Bruce Balick (ORCID: https://orcid.org/0000-0002-3139-3201)
- J. Cami (ORCID: https://orcid.org/0000-0002-2666-9234)
- R. Wesson (ORCID: https://orcid.org/0000-0002-4000-4394)
- Patrick Kavanagh (ORCID: https://orcid.org/0000-0001-6872-2358)
- J. A. D. L. Blommaert (ORCID: https://orcid.org/0000-0002-5797-2439)
- Rens Waters (ORCID: https://orcid.org/0000-0002-5462-9387)
- Maryam Torki
- Naomi Hirano (ORCID: https://orcid.org/0000-0001-9304-7884)
- E. Peeters (ORCID: https://orcid.org/0000-0002-2541-1602)
- A. M. S. Richards (ORCID: https://orcid.org/0000-0002-3880-2450)
- Frank Molster
- N. C. Sterling (ORCID: https://orcid.org/0000-0002-9604-1434)
- Joel H. Kastner (ORCID: https://orcid.org/0000-0002-3138-8250)
- K. E. Kraemer (ORCID: https://orcid.org/0000-0002-2626-7155)
- N. J. Wright (ORCID: https://orcid.org/0000-0002-8389-8711)
- Paula Moraga Baez (ORCID: https://orcid.org/0000-0002-1042-235X)
- Kevin Volk (ORCID: https://orcid.org/0000-0002-3824-8832)
- J. R. Walsh (ORCID: https://orcid.org/0000-0002-8008-910X)
- Olivia Jones (ORCID: https://orcid.org/0000-0003-4870-5547)
- J. M. Laming (ORCID: https://orcid.org/0000-0002-3362-7040)
- P. A. M. van Hoof (ORCID: https://orcid.org/0000-0001-7490-0739)
- Isabel Aleman (ORCID: https://orcid.org/0000-0002-7989-9041)
- H. Monteiro (ORCID: https://orcid.org/0000-0002-0596-9115)
- E. Lagadec (ORCID: https://orcid.org/0000-0002-1335-5623)
- M. Matsuura (ORCID: https://orcid.org/0000-0002-5529-5593)
- F. F. Wilson (ORCID: https://orcid.org/0000-0002-5552-0842)
- K. Justtanont (ORCID: https://orcid.org/0000-0003-1689-9201)
- Charmi Bhatt (ORCID: https://orcid.org/0009-0000-0191-6756)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2025-12-04
- DOI
- https://doi.org/10.3847/1538-4357/ae1020
- Citations
- 1
- Primary Topic
- Astrophysics and Star Formation Studies
- Type
- article
- Field-Weighted Citation Impact
- 1.15
Funders
- National Science Foundation
- National Aeronautics and Space Administration
- California Institute of Technology
- Space Telescope Science Institute
- UK Research and Innovation
- Ministerio de Ciencia, Innovación y Universidades
- Science Foundation Ireland
- Irish Research Council
- Jet Propulsion Laboratory
- Canadian Space Agency
- Natural Sciences and Engineering Research Council of Canada
- Science and Technology Facilities Council
- Agencia Estatal de Investigación
- Office of Naval Research