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

June 2026 • 2026A&A...710A.221F

Authors • Fiore, A. • Kozyreva, A. • Yan, L. • Benetti, S. • Anderson, J. P. • Baklanov, P. • Cai, Y.-Z. • Cappellaro, E. • Chen, T.-W. • Elias-Rosa, N. • Gal-Yam, A. • Graham, M. J. • Gromadzki, M. • Groom, S. L. • Gutiérrez, C. P. • Hiramatsu, D. • Howell, D. A. • Inserra, C. • Kasliwal, M. M. • Könyves-Tóth, R. • Lundqvist, P. • McCully, C. • Mironov, A. • Moran, S. • Müller-Bravo, T. E. • Newsome, M. • Nicholl, M. • Ochner, P. • Padilla Gonzalez, E. • Pessi, P. J. • Pignata, G. • Ragosta, F. • Reguitti, A. • Reynolds, T. M. • Riddle, R. L. • Rusholme, B. • Salmaso, I. • Schulze, S. • Sollerman, J. • Tomasella, L. • Warshofsky, D. • Yang, S. • Young, D. R.

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 ⁵⁶Ni+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.

Links

• POSTSCRIPT https://www.aanda.org/10.1051/0004-6361/202659438/postscript