SN 2021gno: a calcium-rich transient with double-peaked light curves

K Ertini, G Folatelli, L Martinez, M C Bersten, J P Anderson, C. Ashall, E Baron, S Bose, P J Brown, C Burns, J M DerKacy, L Ferrari, L Galbany, E Hsiao, S Kumar, J Lu, P Mazzali, N Morrell, M Orellana, P J PessiM M Phillips, A L Piro, A Polin, M Shahbandeh, B J Shappee, M Stritzinger, N B Suntzeff, M Tucker, N Elias-Rosa, H Kuncarayakti, C P Gutiérrez, A Kozyreva, T E Müller-Bravo, T -W Chen, J T Hinkle, A V Payne, P Székely, T Szalai, B Barna, R Könyves-Tóth, D Bánhidi, I B Bíró, I Csányi, L Kriskovits, A Pál, Zs Szabó, R Szakáts, K Vida, J Vinkó, M Gromadzki, L Harvey, M Nicholl, E Paraskeva, D. R. Young, B Englert

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We present extensive ultraviolet (UV) and optical photometric and optical spectroscopic follow-up of supernova (SN) 2021gno by the ‘Precision Observations of Infant Supernova Explosions’ (POISE) project, starting less than 2 d after the explosion. Given its intermediate luminosity, fast photometric evolution, and quick transition to the nebular phase with spectra dominated by [Ca II] lines, SN 2021gno belongs to the small family of Calcium-rich transients. Moreover, it shows double-peaked light curves, a phenomenon shared with only four other Calcium-rich events. The projected distance from the centre of the host galaxy is not as large as other objects in this family. The initial optical light-curve peaks coincide with a very quick decline of the UV flux, indicating a fast initial cooling phase. Through hydrodynamical modelling of the bolometric light curve and line velocity evolution, we found that the observations are compatible with the explosion of a highly stripped massive star with an ejecta mass of 0.8M and a 56Ni mass of 0.024 M. The initial cooling phase (first light-curve peak) is explained by the presence of an extended circumstellar material comprising ∼10-2M with an extension of 1100R⁠. We discuss if hydrogen features are present in both maximum-light and nebular spectra, and their implications in terms of the proposed progenitor scenarios for Calcium-rich transients.

Original languageEnglish
Pages (from-to)279-298
Number of pages20
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Early online date22 Sept 2023
Publication statusPublished - Nov 2023


  • Space and Planetary Science
  • Astronomy and Astrophysics


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