O. Berné, M.-A. Martin-Drumel, I. Schroetter, J. R. Goicoechea, U. Jacovella, B. Gans, E. Dartois, L. H. Coudert, E. Bergin, F. Alarcon, J. Cami, E. Roueff, J. H. Black, O. Asvany, E. Habart, E. Peeters, A. Canin, B. Trahin, C. Joblin, S. Schlemmer, S. Thorwirth, J. Cernicharo, M. Gerin, A. Tielens, M. Zannese, A. Abergel, J. Bernard-Salas, C. Boersma, E. Bron, R. Chown, S. Cuadrado, D. Dicken, M. Elyajouri, A. Fuente, K. D. Gordon, L. Issa, O. Kannavou, B. Khan, O. Lacinbala, D. Languignon, R. Le Gal, A. Maragkoudakis, R Meshaka, Y. Okada, T. Onaka, S. Pasquini, M. W. Pound, M. Robberto, M. Röllig, B. Schefter, T. Schirmer, A. Sidhu, B. Tabone, D. van de Putte, S. Vicente, and M. G. Wolfire
observed the
Formation of the Methyl Cation by Photochemistry in a Protoplanetary Disk
Nature 621, 56–59 (2023).
The cation was detected with the James Webb Space Telescope toward the protoplanetary disc d203-506 in the Orion Bar, which, in turn, is part of the Orion Nebula. The molecule was identified by its heavily mutually perturbed v₂ and v₄ bands near 1400 cm⁻¹ or ~7.2 µm. The inferred rotational temperature is nearly 1000 K. Accurate laboratory data are not yet available for these two bands. The estimated spectroscopic parameters reproduce the spectrum reasonably well. Better parameters should be availbale soon.

A much better modeling of the observed spectrum was achieved later by
P. B. Changala, N. L. Chen, H. L. Le, B. Gans, K. Steenbakkers, T. Salomon, L. Bonah, I. Schroetter, A. Canin, M.-A. Martin-Drumel, U. Jacovella, E. Dartois, S. Boyé-Péronne, C. Alcaraz, O. Asvany, S. Brünken, S. Thorwirth, S. Schlemmer, J. R. Goicoechea, G. Rouillé, A. Sidhu, R. Chown, D. Van De Putte, B. Trahin, F. Alarcón, O. Berné, E. Habart, and E. Peeters
Astronomical CH3+ Rovibrational Assignments — A Combined Theoretical and Experimental Study Validating Observational Findings in the d203-506 UV-irradiated Protoplanetary Disk
Astron. Astrophys. 680, Art. No. A19 (2023).
Initial spectroscopic parameters were derived from a high-level quantum chemical calculation. The parameters were adjusted through a line-by-line fit of the observational spectrum in spite of the limitations of the latter.

T. Henning, I. Kamp, M. Samland, A. M. Arabhavi, J. Kanwar, E. F. van Dishoeck, M. Güdel, P.-O. Lagage, C. Waelkens, A. Abergel, O. Absil, D. Barrado, A. Boccaletti, J. Bouwman, A. Caratti o Garatti, V. Geers, A. M. Glauser, F. Lahuis, M. Mueller, C. Nehmé, G. Olofsson, E. Pantin, T. P. Ray, S. Scheithauer, B. Vandenbussche, L. B. F. M. Waters, G. Wright, I. Argyriou, V. Christiaens, R. Franceschi, D. Gasman, S. L. Grant, R. Guadarrama, H. Jang, M. Morales-Calderón, N. Pawellek, G. Perotti, D. Rodgers-Lee, J. Schreiber, K. Schwarz, B. Tabone, M. Temmink, M. Vlasblom, L. Colina, T. R. Greve, and G. Östlin
presented an account on
MINDS: The JWST MIRI Mid-INfrared Disk Survey
Publ. Astron. Soc. Pac. 136, Art. No. 054302 (2024).
The methylium cation was detected in the disk of the T Tauri star TW Hya.

M. Zannese, B. Tabone, E. Habart, E. Dartois, J. R. Goicoechea, L. Coudert, B. Gans, M.-A. Martin-Drumel, U. Jacovella, A. Faure, B. Godard, A. G. G. M. Tielens, R. Le Gal, J. H. Black, S. Vicente, O. Berné, E. Peeters, D. Van De Putte, R. Chown, A. Sidhu, I. Schroetter, A. Canin, and O. Kannavou
found the cation to be more wide-spread in the Orion Bar in their work
PDRs4All — XI. Detection of infrared CH+ and CH3+ rovibrational emission in the Orion Bar and disk d203-506: Evidence of chemical pumping
Astron. Astrophys. 696, Art. No. A99 (2025).

C. Bhatt, 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, and A. A. Zijlstra
reported more recently on
Detection of CH3+ in the O-rich Planetary Nebula NGC 6302
Astrophys. J. 995, Art. No. 67 (2025).

Contributor(s): H. S. P. Müller; 09, 2023; 12, 2025