UC Santa Barbara

New wide-field and high-cadence transient surveys have enabled us to watch supernovae (SNe) from the moment of explosion. Paired with rapid and continuous monitoring facilities, these observations have revealed unprecedented features that bridge our understanding of their progenitor systems to explosion mechanisms. The Global Supernova Project (GSP) is a world-wide collaboration that uses Las Cumbres Observatory and various other ground- and space-based telescopes to study SNe from their discovery through all phases of follow-up. Here, I present three major advancements in core-collapse and superluminous SN observations from GSP and numerical modeling with MESA and STELLA. (1) SN 2018zd is a hydrogen-rich (Type II) SN discovered within a few hours of explosion. Its early ultraviolet color and narrow emission lines, along with light-curve morphology and nebular emission lines, are all consistent with an electron-capture SN explosion of a super-asymptotic giant branch star — the lowest-mass Type II SN. (2) Short-plateau SNe are luminous Type II core-collapse SNe with short light-curve plateaus, indicating significant pre-explosion mass loss resulting in partially stripped hydrogen-rich envelopes and early circumstellar material (CSM) interaction. Our light-curve model grid puts them in a rare transitional class from stripped red supergiants on the high-mass end of Type II SN progenitors. (3) Superlinear superluminous SNe (SLSNe) are Type II SLSNe with superlinear light curves powered by CSM interaction. Sample comparison and modeling suggest that the superlinear SLSNe are possibly compatible to thermonuclear SNe interacting with massive CSM which might be produced during common envelope evolution.