The nearby He-rich superluminous supernova SN 2021bnw during photospheric phases

Fiore, A., Kozyreva, A., Yan, L., Benetti, S., Anderson, J.P. and Inserra, C. ORCID: https://orcid.org/0000-0002-3968-4409 2026. The nearby He-rich superluminous supernova SN 2021bnw during photospheric phases. Astronomy & Astrophysics 710 , A221. 10.1051/0004-6361/202659438

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Abstract

Aims. We present and interpret the data of the nearby hydrogen-deficient but helium-rich superluminous supernova SN 2021bnw, which reached a magnitude of –20.7 at maximum luminosity in g band. Methods. We discuss the light curves and spectra of SN 2021bnw based on its spectro-photometric follow-up, exploiting different observational facilities. We reproduced the near-IR spectrum of SN 2021bnw with TARDIS to inspect the chemical composition at late photospheric phases and identify helium features. We also used a STELLA model coupling hydrodynamics and radiation transport to constrain the physical parameters of the explosion assuming a 56 Ni+CSM scenario. Results. We suggest that SN 2021bnw was mainly powered by the interaction of the ejecta with a previously lost He-rich circumstellar material, coupled with a central power source. Conclusions. This work expands the data sample of He-rich superluminous supernovae (SLSNe Ib), and for a single-progenitor scenario, it can constrain the masses and physics of their progenitors.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Physics and Astronomy
Additional Information:	License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0, Start Date: 2026-06-22
Publisher:	EDP Sciences
ISSN:	0004-6361
Date of First Compliant Deposit:	6 July 2026
Date of Acceptance:	19 April 2026
Last Modified:	10 Jul 2026 15:45
URI:	https://orca.cardiff.ac.uk/id/eprint/187967

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