K. Medler, C. Ashall, P. Hoêflich, E. Baron, James M. DerKacy, Melissa Shahbandeh, Tyco Mera Evans, C. M. Pfeffer, W. B. Hoogendam, D. O. Jones, Sagiv Shiber, E. Fereidouni, Ori D. Fox, J. Jencson, L. Galbany, Jason T. Hinkle, M. A. Tucker, B. J. Shappee, M. E. Huber, Katie Auchettl, C. R. Angus, D. Desai, A. Do, A. V. Payne, J. Shi, M. Kong, S. Romagnoli, A. Syncatto, C. R. Burns, Geoffrey C. Clayton, M. Dulude, Michael Engesser, A. V. Filippenko, Sebastián Gómez, E. Y. Hsiao, Thomas de Jaeger, J. Johansson, K. Krisciunas, Sahana Kumar, Jing Lü, M. Matsuura, P. A. Mazzali, D. Milisavljević, N. Morrell, Richard O’Steen, Seong Hyun Park, M. M. Phillips, Aravind P. Ravi, A. Rest, Jeonghee Rho, N. B. Suntzeff, Arkaprabha Sarangi, Nathan Smith, M. Stritzinger, Louis-Gregory Strolger, Tamás Szalai, Tea Temim, Samaporn Tinyanont, Schuyler D. Van Dyk, Lifan Wang, Qinan Wang, R. Wesson, Yi Yang, Szanna Zsíros
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 0.32–30 μ m. 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 10.0 μ m, with a secondary bump at 18.0 μ m 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.