SN 2024acyl light curves

Our multiband light-curve modelling yields estimates of the ejecta mass of M_ej_=0.49^+0.11^_-0.09_M_{sun}_, with a kinetic energy of E_k_=0.06^+0.01^_-0.01_x10^51^erg, and a ^56^Ni mass of M_Ni_=0.018M_{sun}_. The inferred CSM properties are characterised by a mass of M_CSM_= 0.51 (+0.05/-0.04) M_sun, an inner radius of R_0_=17.8^+3.6^_-3.0_AU, and a density rho_CSM_=(8.3^+2.7^_-1.2_)x10^-12^g/cm^3^. The multi-epoch spectra are well reproduced by the CMFGEN/he4p0 model, corresponding to a He-ZAMS mass of 4M_{sun}_ (H-ZAMS mass 18.11M_{sun}_, pre-SN mass 3.16M_{sun}_).

These findings are consistent with a scenario of an SN powered by ejecta-CSM interaction, originating from a low-mass helium star that evolved within an interacting binary system where the CSM with some residual hydrogen may originate from the mass-transfer process. We also discuss an extreme scenario involving the possible merger of a helium white dwarf. In addition, a channel of core-collapse (CC) explosion of a late-type Wolf-Rayet (WR) star with hydrogen (WNH), or a transitional star between an Of and a WR type (e.g., an Ofpe/WN9 star) with fallback accretion, cannot be entirely ruled out.