The electron-capture origin of supernova 2018zd

In the transitional mass range (~8–10 solar masses) between white dwarf formation and iron core-collapse supernovae, stars are expected to produce an electron-capture supernova. Theoretically, these progenitors thought be super-asymptotic giant branch with a degenerate O + Ne Mg core, electron capture onto nuclei should initiate core collapse1–4. However, no supernovae have unequivocally been identified from origin, partly because of uncertainty in theoretical predictions. Here we present six indicators show that supernova 2018zd is only known strong evidence for or consistent all six: progenitor identification, circumstellar material, chemical composition5–7, explosion energy, light curve nucleosynthesis8–12. For 2018zd, infer based on faint candidate pre-explosion images chemically enriched material revealed by early ultraviolet colours flash spectroscopy. The light-curve morphology nebular emission lines can explained low energy neutron-rich nucleosynthesis produced This identification provides insights into complex stellar evolution, physics, cosmic remnant populations range. Electron-capture come narrow masses, thus they rare. authors find fulfils criteria.