Daichi Hiramatsu (UCSB) -- Progenitor Mass Spectrum of Core-Collapse Supernovae

While there is consensus that red supergiants (~9—18 Msun) undergo iron core collapse and explode as hydrogen-rich Type II supernovae, the fate at the low- and high-mass ends of the progenitor spectrum still remains uncertain. The complicated evolutionary path in the low-mass end (6—9 Msun; accounting for ~50% of massive stars >6 Msun) results in diverse outcomes, from C+O white dwarfs, to O+Ne white dwarfs, to electron-capture supernovae. The apparent lack of the high-mass end red supergiants (18–25 Msun) in observed progenitor samples also challenges our knowledge of the end products of massive-star evolution: supernovae+neutron stars/black holes or direct collapse to black holes. In this talk, I will highlight our recent candidate identifications of an electron-capture supernova and high-mass Type II supernovae, and discuss their implications to various astrophysical fields, such as stellar evolution, nuclear physics, and compact remnant populations.