Understand
Massive stars are linked with diverse astronomical processes and objects including star formation, supernovae and their remnants, cosmic rays, interstellar media, and galaxy evolution.
- Understanding their properties is of primary importance for modern astronomy, and finding simple rules that characterize them is especially useful.
- However, theoretical simulations have not yet realized such relations, instead finding that the late evolutionary phases are significantly affected by a complicated interplay between nuclear reactions, chemical mixing, and neutrino radiation, leading to non-monotonic initial mass dependencies of the iron core mass and the compactness parameter.
- We conduct a set of stellar evolution simulations, in which evolutions of He star models are followed until their central densities uniformly reach 10$^{10}$ g cm$^{-3}$, and analyze their final structures as well as their evolutionary properties including the lifetime, surface radius change, and presumable fates after core collapse.