Unveiling the progenitor of SN 2023ixf: Circumstellar dust and its implications for the red supergiant problem

¹ Università di Napoli Federico II, Dipartimento di Fisica “Ettore Pancini” Via Cinthia 9 I-80126 Naples, Italy
² INAF – Osservatorio Astronomico di Capodimonte Via Moiariello 16 I-80131 Naples, Italy
³ INAF – Osservatorio Astronomico di Roma Via di Frascati 33 I-00078 Monteporzio Catone, Italy
⁴ Università Tor Vergata, Dipartimento di Fisica Via della Ricerca Scientifica 1 I-00133 Rome, Italy
⁵ Institute of Space Sciences (ICE, CSIC), Campus UAB Carrer de Can Magrans s/n E-08193 Barcelona, Spain
⁶ Institut d’Estudis Espacials de Catalunya (IEEC) E-08860 Castelldefels (Barcelona), Spain
⁷ INAF–Osservatorio Astronomico di Brera Via Bianchi 46 I-23807 Merate (LC), Italy
⁸ Università La Sapienza, Dipartimento di Fisica Piazzale Aldo Moro 2 I-00185 Rome, Italy
⁹ INFN, Sezione di Roma, I-00133 Piazzale Aldo Moro 2 – 00185 Roma RM, Italy
¹⁰ Fundación Galileo Galilei – INAF, Rambla J.A.Fernández P. 7 38712 B.Baja (S.C.Tenerife), Spain
¹¹ Dipartimento di Fisica e Astronomia, Sezione Astrofisica, Università di Catania Via S. Sofia 78 I-95123 Catania, Italy

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Received: 3 November 2025
Accepted: 6 January 2026

Abstract

The nearby Type II supernova SN 2023ixf offers a critical test of the long-standing ‘red supergiant problem’ – the apparent absence of high-mass red-supergiant progenitors in pre-explosion imaging. We present new late-time observations of SN 2023ixf: SiFAP2 photometry (714–772 d) with a custom supernova calibration, Swift-UVOT detections (788–801 d), and the one of the latest spectroscopic observations beyond 100 days (DOLoRES at 772 d). Combining these with archival data, we obtain two discrepant progenitor-mass estimates: light-curve modelling yields 5.5–14 M_⊙, while nebular oxygen mass (∼2.3 M_⊙) and other spectroscopic diagnostics point to 17–19 M_⊙. We reconcile this tension with a Bayesian Monte-Carlo framework that includes anisotropic circumstellar dust. Our analysis demonstrates that even a modest, clumpy circumstellar medium can produce sufficient extinction to bias luminosity-based masses downwards by ∼9 M_⊙. Late-time photometry and spectroscopy further reveal clear signatures of shock interaction with circumstellar material (CSM) shells ejected centuries before explosion. SN 2023ixf thus provides direct evidence that circumstellar obscuration is a major contributor to the apparent lack of massive red-supergiant progenitors, underscoring the need for multi-method, multi-epoch observations for robust progenitor-mass determination.