SN 2024iss: A Multiwavelength Exposé of a Type IIb Supernova with an Early-time Ultraviolet Spectrum and Shock-breakout Constraints
Year: 2026
Type: article
Abstract: We present multiwavelength observations and analysis of SN 2024iss, a Type IIb supernova (SN IIb) located at ∼14 Mpc. The first Zwicky Transient Facility detection of SN 2024iss is ∼40 minutes after first light (one of the earliest detections of a SN IIb to date) and a Hubble Space Telescope (HST) UV spectrum was obtained at 7 days (the earliest HST UV SN IIb spectrum to date). We estimate an ejecta mass range of 1.1–3.3 M ⊙ and a 56 Ni mass of 0.11 ± 0.01 M ⊙ from bolometric light-curve modeling and He-star model comparisons. We fit shock-cooling emission models to estimate a progenitor radius of 100–320 R ⊙ and an envelope mass of 0.07–0.46 M ⊙ . We compare optical/UV spectra to binary progenitor models, which indicate a stripped H-rich envelope mass of 0.19–0.28 M ⊙ . We use early-time X-ray detections to calculate circumstellar material (CSM) densities that are consistent with a progenitor mass-loss rate of 5 × 10 −4 M ⊙ yr −1 ( v w = 100 km s −1 ), corresponding to 2–5 yr preexplosion. In the UV, we observe strong Mg ii emission extending to 15,000 km s −1 as well as weak P Cygni profiles of iron-group elements (e.g., Fe, Ti, Al, Ni) present in outer SN ejecta. The overall spectroscopic evolution of SN 2024iss is comparable to that of SNe IIb, but its increased brightness at peak is influenced by SN ejecta–CSM interaction. Nebular spectroscopy of SN 2024iss at ∼260–412 days reveals multipeaked forbidden-line profiles of O i and Mg i ] indicative of inner ejecta asymmetry and/or clumping. We demonstrate the utility of a rich, multiwavelength data set for constraining the progenitor systems and explosion dynamics of SNe IIb.
Source: The Astrophysical Journal
Authors: R. J. Yete, W. V. Jacobson-Galán, Ferdinand, L. Dessart, M. M. Kasliwal, K. W. Davis, A. L. Piro, V. A. Villar, I. Andreoni, K. Auchettl, K. C. Chambers, R. Chornock, M. W. Coughlin, D. A. Coulter, R. Dekany, R. J. Foley, O. D. Fox, L. Galbany, C. Gall, A. Gangopadhyay, J. A. Goldberg, G. Govindaraj, X. Guo, M. E. Huber, J. Castaneda Jaimes, J. Karcheski, R. Kaur, C. D. Kilpatrick, R. R. Laher, N. LeBaron, C.-C. Lin, R. Margutti, Y.-C. Pan, K. C. Patra, H. M. L. Perkins, P. J. Pessi, O. Pyshna, A. Rest, S. Romagnoli, S. Schulze, H. Sears, A. Sedgewick, M. R. Siebert, A. Singh, J. Sollerman, N. Sravan, S. Tinyanont, R. J. Wainscoat, Q. Wang, D. Warshofsky, Y. Yao, Y. Zenati
Institutions: University of North Carolina at Chapel Hill, California Institute of Technology, University of Illinois Urbana-Champaign, Centre National de la Recherche Scientifique, Sorbonne Université, Carnegie Institution for Science, Carnegie Observatories, Center for Astrophysics Harvard & Smithsonian, The University of Melbourne, University of Hawaiʻi at Mānoa, University of Hawaii System, University of Minnesota, Space Telescope Science Institute, Johns Hopkins University, Institute of Space Sciences, Institut d'Estudis Espacials de Catalunya, University of Copenhagen, Stockholm University, Michigan State University, Drexel University, Northwestern University, National Central University, Weizmann Institute of Science, Rutgers, The State University of New Jersey, National Astronomical Research Institute of Thailand, Massachusetts Institute of Technology, The Open University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W7140220176
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