Measuring the Binary Fraction of Type II-P/II-L Supernova Progenitor Systems

Type II-P and II-L supernovae (SNe) are known to have red supergiant (RSG) progenitor stars with initial masses of M≈7-8 M⊙ (Smartt 2015). In recent years, it has been theorized that many of these RSGs evolve in binary systems with close interactions that affect their evolution (Zapartas et al. 2021). These RSGs may be interacting binaries actively undergoing mass transfer, allowing them to stray away from their stellar birthplaces and explode as violent SNe. Using data from the Hubble Space Telescope (HST), we present a statistical analysis of 43 Type II-P and II-L SNe within a distance of 40Mpc and discovery dates from 1999 to 2022. By collecting photometric data, we are able to identify the nearest O-type star to the SNe. Using the O-type star as an indicator of where the progenitor of the SN may have been born, we determine the distance between the O-type star and the SN through astrometry. Since the average separation between Type II SNe and RSGs, which are known to be effectively single stars in the Milky Way, LMC and SMC, any large differences between this separation and RSG stars observed in situ would favor the binary scenario. Using this, we can estimate whether binary interactions strongly affect the Type II SN progenitor star population relative to the population of RSGs.