Interacting binaries as a significant progenitor channel for Type II-P supernovae

Type II-P supernovae (SNe II-P) are the most common class of core-collapse SNe in the local Universe. While their progenitors have long been assumed to follow single-star evolution, recent theoretical studies suggest that 30–50% of all SNe II-P may instead originate from interacting binaries. These studies point to a potential paradigm shift in our understanding of this major SN class, but conclusive observational evidence still remains scarce. We propose that the possible binary origin for a SN II-P can be constrained through a combined analysis of direct progenitor detection, light-curve properties, and host environment. Applying this approach to 15 nearby SNe II-P, we identify 4 events (SN 2004A, SN 2012aw, SN 2018gj and SN 2020jfo) with likely binary origins: while the directly detected progenitors resemble those of other SNe II-P in terms of effective temperature and luminosity, they are located in old environments and/or have abnormal plateau lengths in the light curves. These characteristics are best explained if their progenitors have experienced significant binary interaction, which extends the lifetime far beyond what single-star models would predict and, under many circumstances, alters the final structure of the progenitor stars. Our results show that at least 27% of SNe II-P originate from the binary progenitor channel and robustly establish interacting binaries as a viable and significant pathway toward SNe II-P.