Core-collapse supernovae 2022prr, 2023ucy, and 2024ljc in the luminous infrared galaxy NGC 6745

K. K. Matilainen; E. Kankare; T. Nagao; T. Reynolds; A. Efstathiou; S. Mattila; C. R. Angus; A. Reguitti; Y. -Z. Cai; M. Fraser; L. Galbany; M. González-Bañuelos; C. P. Gutiérrez; T. Kangas; T. L. Killestein; T. Kravtsov; P. Lundqvist; S. Moran; A. Pastorello; A. Popowicz; I. Salmaso; M. Stritzinger

arXiv · 2609.21742

Core-collapse supernovae 2022prr, 2023ucy, and 2024ljc in the luminous infrared galaxy NGC 6745

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Abstract

The core-collapse supernovae (CCSNe) 2022prr, 2023ucy, and 2024ljc exploded within the central regions of the nearby luminous infrared galaxy (LIRG) NGC6745. We present our follow-up data with the aim to characterise the spectrophotometric evolution of these CCSNe, determine their host-galaxy extinction, and to define their physical nature. The presented spectrophotometric data set covers the optical and near-infrared region for our three supernovae (SNe). The data are analysed and compared to other hydrogen-rich CCSNe, and a host-galaxy extinction value Av is derived based on broadband photometry for each of the targets. A spectral energy distribution (SED) for the host galaxy is constructed, and a combination of different galactic components are fitted to the SED to estimate the intrinsic CCSN rate and the age of the starburst of NGC6745. 2022prr is a SN2009ip-like event, whose light curve evolution consists of two consecutive luminous events A and B with peak magnitudes of Mr = -14.8 and -18.3 mag, respectively. The high degree of V and R-band polarisation (P=2.8%) near maximum light suggests interaction with highly aspherical circumstellar material. The spectral evolution of the SN is dominated by narrow Balmer emission lines, which have a complex evolution over time. 2022prr joins the growing sample of SN2009ip-like events that show early `flash ionisation' features of CIII, NIII, and HeII. 2023ucy is found to be a normal Type IIP SN. However, 2024ljc is a rapidly evolving Type IIb SN with a post-maximum r-band decline of roughly 3.2 mag by +41 d whereas normal IIb SNe decline typically by 1.5+/-0.3 mag during the same timescale. While the events exploded in a LIRG, the SNe are obscured by only moderate V-band host extinctions ranging from 0 to 1 mag. Based on the SED modelling we estimate an age of the host starburst to be 40Myr, and the intrinsic CCSN rate to be 0.4+/-0.1 SN/year.

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K. K. Matilainen, E. Kankare, T. Nagao, T. Reynolds, A. Efstathiou, S. Mattila, C. R. Angus, A. Reguitti, Y. -Z. Cai, M. Fraser, L. Galbany, M. González-Bañuelos, C. P. Gutiérrez, T. Kangas, T. L. Killestein, T. Kravtsov, P. Lundqvist, S. Moran, A. Pastorello, A. Popowicz, I. Salmaso, M. Stritzinger. 2026-09-18. Core-collapse supernovae 2022prr, 2023ucy, and 2024ljc in the luminous infrared galaxy NGC 6745. https://arxiv.org/abs/2609.21742

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