The transitional type Ibn/IIn SN 2022pda, with pre-explosion outbursts and a double-peaked light curve

Cai, Y. -Z., Pastorello, A., Chiba, R., Moriya, T. J., Reguitti, A. and Inserra, C. ORCID: https://orcid.org/0000-0002-3968-4409 2026. The transitional type Ibn/IIn SN 2022pda, with pre-explosion outbursts and a double-peaked light curve. The Astrophysical Journal Letters 1004 (2) , L37. 10.3847/2041-8213/ae734e

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Abstract

We report the results of a photometric and spectroscopic follow-up campaign of the unusual interacting supernova (SN) 2022pda. Precursor variability lasting ∼100 days is observed before the explosion. The SN light curve has a double-peak shape. It reached a first maximum of Mr = −19.6 ± 0.2 mag, followed by an initial 2 month decline and a second, broad peak lasting about 6 months. The early spectra show a blue continuum with dominant H and He emission lines. A high-resolution pre-maximum spectrum shows that the profile of the He i λ 5876 line consists of a moderately narrow (∼1900 km s−1) P Cygni absorption superposed on a broader (∼3300 km s−1) component. In the blue region, several spectral features are identified, including C iii/N iii/O ii blends. Two broad bumps at 4600–5200 Å and 6400–6800 Å regions reveal a complex profile, which are likely due to blends of H, He, and other emission lines. Late-time spectra are still dominated by prominent and broad H and He lines in emission. Shock-driven model fits to the bolometric light curve suggest that the SN is powered by interaction with a massive CSM with enhanced mass-loss rates ∼5 M⊙yr−1, expelled during two events that occurred ∼1 and ∼0.2 yr before the explosion. The overall SN evolution indicates that SN 2022pda is a transitional event between an H-rich SN IIn (SN 2009ip-like) and an He-rich SN Ibn. Our findings suggest that the progenitor was likely a luminous blue variable transitioning towards a Wolf–Rayet stage.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Physics and Astronomy
Additional Information:	Full author list can be seen here - https://doi.org/10.3847/2041-8213/ae734e License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0/, Type: cc-by
Publisher:	American Astronomical Society
ISSN:	2041-8205
Date of First Compliant Deposit:	2 July 2026
Date of Acceptance:	23 May 2026
Last Modified:	02 Jul 2026 08:58
URI:	https://orca.cardiff.ac.uk/id/eprint/187870

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