The Transitional Type Ibn/IIn SN 2022pda, with Pre-explosion Outbursts and a Double-peaked Light Curve

Cai, YZ ORCID: 0000-0002-7714-493X, Pastorello, A ORCID: 0000-0002-7259-4624, Chiba, R ORCID: 0009-0003-4594-3715, Moriya, TJ ORCID: 0000-0003-1169-1954, Reguitti, A ORCID: 0000-0003-4254-2724, Tartaglia, L ORCID: 0000-0003-3433-1492, Moran, S ORCID: 0000-0001-5221-0243, Campana, S ORCID: 0000-0001-6278-1576, Wang, ZY ORCID: 0000-0002-0025-0179, Zhao, JW ORCID: 0009-0009-8633-8582, Anderson, JP ORCID: 0000-0003-0227-3451, Benetti, S ORCID: 0000-0002-3256-0016, Brennan, SJ ORCID: 0000-0003-1325-6235, Cappellaro, E ORCID: 0000-0001-5008-8619, Chambers, KC ORCID: 0000-0001-6965-7789, Chen, TW ORCID: 0000-0002-1066-6098, Chen, ZH, de Boer, T, Dong, YZ ORCID: 0000-0002-7937-6371, Duarte, J ORCID: 0000-0002-1823-3860 et al (2026) The Transitional Type Ibn/IIn SN 2022pda, with Pre-explosion Outbursts and a Double-peaked Light Curve. The Astrophysical Journal Letters, 1004 (2). ISSN 2041-8205

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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
Uncontrolled Keywords:	5101 Astronomical Sciences; 51 Physical Sciences; 0201 Astronomical and Space Sciences; Astronomy & Astrophysics; 5101 Astronomical sciences; 5109 Space sciences
Subjects:	Q Science > QB Astronomy
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society
Date of acceptance:	23 May 2026
Date of first compliant Open Access:	22 September 2026
Date Deposited:	22 Sep 2026 09:13
Last Modified:	22 Sep 2026 09:13
DOI or ID number:	10.3847/2041-8213/ae734e
URI:	https://researchonline.ljmu.ac.uk/id/eprint/29497

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