SN 2023zcu: A Type IIP SN with Early Flash Features

Abstract We present a detailed photometric and spectroscopic analysis of the Type IIP supernova (SN) SN 2023zcu, which exploded in the galaxy NGC 2139 (redshift z = 0.006). SN 2023zcu exhibits a well-sampled light curve covering the rise, plateau, and nebular phases. It has an optically thick phase of 100.6 ± 0.6 days with a magnitude drop of ∼1.7 mag in the V band during the transition between the plateau and nebular phases. Weak emission features in the early-time spectra indicate a low-level interaction between circumstellar material and the SN ejecta. The spectral evolution is well sampled and exhibits a prominent P Cygni profile of H α , a defining characteristic of Type IIP SNe. Signatures of metal-line formation (e.g., Fe ii , Ca ii near-infrared triplet) are also evident in the spectra as the SN evolves. Spectral modeling with the radiative transfer code TARDIS during the early photospheric phase (8.7–35.5 days since explosion) yields photospheric temperatures decreasing from ∼9000 to ∼6000 K and expansion velocities declining from ∼10,000 to ∼5400 km s −1 . A tailored expanding photosphere method fit based on the TARDIS models provides a distance estimate of 27.8 ± 2.0 Mpc. Nebular-phase spectra and bolometric light-curve modeling suggest a progenitor mass in the range 12–15 M ⊙ . This thorough analysis helps to constrain progenitor properties and explosion parameters, thereby strengthening our understanding of Type IIP SNe.