First detection of CH3+ shows avenues for carbon chemistry in an O-rich planetary nebula.

First detection of CH3+ shows avenues for carbon chemistry in an O-rich planetary nebula. Charmi Bhatt ([email protected]), J. Cami, E. Peeters, N. Clark, P. Moraga Baez, K. Volk, G. C. Sloan, J. H. Kastner, H. L. Dinerstein, M. Matsuura, B. Balick, K. E. Kraemer, K. Justtanont, O. Jones, R. Sahai, I. Aleman, M. J. Barlow, J. Bernard-Salas, J. Blommaert, N. Hirano, P. Kavanagh, F. Kemper, E. Lagadec, J. M. Laming, F. Molster, H. Monteiro, A. M. S. Richards, N. C. Sterling, M. Torki, P. A. M. van Hoof, J. R. Walsh, L. B. F. M. Waters, R. Wesson, F. Wilson, N. J. Wright, A. A. Zijlstra •NGC 6302 is an O-rich PN (C/O ≈ 0.5, [1]). •It is a strongly UV-irradiated environment with CSPN’s Teff ≈ 220,000K [1]. •Recent JWST Mid-IR [2] observations reveal characteristic CH3+ emission band. •The emission is spatially extended and resolved across distinct regions including the torus, inner and outer bubble. •It exhibits spatial variations in excitation temperature and column densities. •Hydrocarbon radicals drive organic molecule formation via exothermic ionneutral reactions [6] —these networks must be included in PN models. •CH3+ is co-located CO, H2, PAHs and HCO+ indicating the potential for rich organic chemistry. CO and HCO+ maps are made by Baez et al. (under review) and PAH map is made by Clark et al (in prep). •This detection provides evidence for active carbon chemistry in PN NGC 6302; the formation pathway in UV-rich environment is [4,5]: C+ + H2 → CH+ → CH2+ → CH3+ References: [1] Wright, N. J., Barlow, M. J., Ercolano, B., & Rauch, T. 2011, MNRAS, 418, 370 [2] Matsuura, M., Zijlstra, A. A., Molster, F. J., et al. 2005, MNRAS, 359, 383, [3] Changala, P. B., Chen, N. L., Le, H. L., et al. 2023, A&A, 680, A19 [4] Bern´e, O., Martin-Drumel, M.-A., Schroetter, I., et al. 2023,639, Nature, 621, 56 [5] Zannese, M., Tabone, B., Habart, E., et al. 2025, A&A, 696, A99 [6] Smith, D. 1992, Chemical Reviews, 92, 1473 Acknowledgements: C.B, J.C., E.P. and N.C. acknowledge support from the University of Western Ontario, the Canadian Space Agency (CSA)[22JWGO1-22], and the Natural Sciences and Engineering Research Council of Canada. The continuum-subtracted JWST/MIRI spectrum of NGC 6302 (black) compared to a CH3+ model [3] (red) at excitation temperature of 600 K. Taken from Matsuura et al 2025 Link to the Article The Butterfly Nebula Key Takeaways: