Panchromatic JWST Observations and Models of the Dim Type Iax Supernova 2024vjm at 200 days

[2608.15040] Panchromatic JWST Observations and Models of the Dim Type Iax Supernova 2024vjm at 200 days Skip to main content Search Submit Donate Log in Search arXiv Press Enter to search · Advanced search Astrophysics > Solar and Stellar Astrophysics arXiv:2608.15040 (astro-ph) [Submitted on 15 Aug 2026] Title: Panchromatic JWST Observations and Models of the Dim Type Iax Supernova 2024vjm at 200 days Authors: E Baron , J. M. DerKacy , C. Ashall , M. Shahbandeh , Peter H. Hauschildt , T. Barman , J. P. Aufdenberg , C. R. Burns , N. Morrell , M. D. Stritzinger , P. Hoeflich , K. Medler , E. Fereidouni , C. M. Pfeffer , T. Mera , W. B. Hoogendam , S. Shiber , P. J. Brown , Divya Mishra , Inma Dominguez , L. Galbany , Paolo Mazzali , E. Y. Hsiao , Huangfei Xiao , T. de Jaeger , S. Kumar View a PDF of the paper titled Panchromatic JWST Observations and Models of the Dim Type Iax Supernova 2024vjm at 200 days, by E Baron and 25 other authors View PDF HTML (experimental) Abstract: We report JWST spectra and photometry of the underluminous SN Iax 2024vjm obtained 202.8 restframe days post-explosion. The spectrum exhibits a rich set of forbidden lines from low-ionization, intermediate-mass, and iron-group elements, notably the [Ni II] 6.64 micron resonance line, which is a direct indicator of stable nickel. Strong CO and SiO emission is detected alongside a warm dust continuum; the spectral properties are consistent with pre-existing rather than newly formed dust. Synthetic spectra were computed with the generalized stellar atmospheres code PHOENIX/1D using simplified ejecta models. The models reproduce the overall spectral energy distribution and the molecular emission features reasonably well, but substantially underestimate the strength of the mid-infrared atomic forbidden lines, leaving the synthetic spectrum dominated by molecular emission. Experiments in which the molecular opacity is suppressed do not recover the forbidden lines; instead, the emission peak migrates to Co and Fe transitions near 2 microns. We attribute this discrepancy to poorly constrained collisional rates and possibly to an excess of iron-group material in the current ejecta models. A prominent feature at 12.8 microns is not well accounted for by the [Ne II] 12.81 micron line, indicating that the 12.8 micron feature may be largely due to [Fe III]. The presence of CO, SiO, and stable nickel together with the non-detection of neon places tight constraints on the total ejecta mass and the nucleosynthetic yields of SNe Iax progenitor systems. Comments: 19 pages, 10 figures, to appear in ApJ (Letters) Subjects: Solar and Stellar Astrophysics (astro-ph.SR) ; High Energy Astrophysical Phenomena (astro-ph.HE) Cite as: arXiv:2608.15040 [astro-ph.SR] (or arXiv:2608.15040v1 [astro-ph.SR] for this version) https://doi.org/10.48550/arXiv.2608.15040 Focus to learn more arXiv-issued DOI via DataCite Submission history From: Edward A. Baron [ view email ] [v1] Sat, 15 Aug 2026 04:57:54 UTC (2,332 KB) Full-text links: Access Paper: View a PDF of the paper titled Panchromatic JWST Observations and Models of the Dim Type Iax Supernova 2024vjm at 200 days, by E Baron and 25 other authors View PDF HTML (experimental) TeX Source view license Current browse context: astro-ph.SR < prev | next > new | recent | 2026-08 Change to browse by: astro-ph astro-ph.HE References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... 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