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Abstract We present panchromatic 0.4–21μm observations of the nearby (∼7.2 Mpc) Type II supernova (SN) 2024ggi, obtained during the plateau phase at ∼55 days past explosion. Our data set includes JWST spectra spanning 1.7–14μm, mid-infrared (MIR) imaging at 7.7 and 21μm, and near-simultaneous ground-based optical and near-infrared (NIR) spectra covering 0.32−1.8μm. The NIR and MIR spectral features of SN 2024ggi are dominated by Hiemission. We present line IDs and a toy PHOENIX/1D model that reproduces the observations well, especially the continuum redward of 0.9μm. We compare SN 2024ggi to SN 2022acko and SN 2023ixf, two other Type II SNe that were also observed by JWST, and highlight key similarities and differences in their spectral features. No evidence for a MIR excess or dust is found at these epochs, with the model matching the observed flux out to 21μm. We discuss the model’s shortcomings, focusing on the density profile, which suppresses line blanketing and produces features in the optical that are too narrow. Our results show the power of panchromatic studies in both exploring the nature of the SN ejecta and constraining detailed models of SNe.
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This content will become publicly available on November 4, 2026
JWST Observations of SN 2023ixf. II. The Panchromatic Evolution between 250 and 720 Days after the Explosion
Abstract We present the nebular phase spectroscopic and photometric observations of the nearby hydrogen-rich core-collapse supernova (CCSN) SN 2023ixf, obtained through our JWST programs. These observations, combined with ground-based optical and near-infrared spectra, cover +252.67–719.96 days, creating a comprehensive, panchromatic time-series data set spanning 0.32–30μm. In this second paper of the series, we focus on identifying key spectral emission features and tracking their evolution through the nebular phase. The JWST data reveal hydrogen emission from the Balmer to Humphreys series, as well as prominent forbidden lines from Ne, Ar, Fe, Co, and Ni. NIRSpec observations display strong emission from the first-overtone and fundamental bands of carbon monoxide, which weaken with time as the ejecta cools and dust emission dominates. The spectral energy distribution shows a clear infrared excess emerging by +252.67 days peaking around 10.0μm, with a secondary bump at 18.0μm developing by +719.96 days. We suggest that this evolution could arise from multiple warm dust components. In upcoming papers in this series, we will present detailed modeling of the molecular and dust properties. Overall, this work provides the community with a unique data set that can be used to advance our understanding of the mid-infrared properties of CCSNe, offering an unprecedented resource for studying their late-time line, molecular, and dust emission.
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- Award ID(s):
- 2306395
- PAR ID:
- 10688908
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Chicago Press
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 993
- Issue:
- 2
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 191
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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