Speaker
Description
Long-lived Type II supernovae (SNe) represent a rare subset of hydrogen-rich stellar explosions, whose origins remain relatively unconstrained. Their prolonged light curves suggest additional powering beyond the neutrino-driven core-collapse mechanism, which is typically used to describe Type II SNe. I will present an extensive photometric and spectroscopic dataset of two such events from the Zwicky Transient Facility. With rise times longer than 80 days, light curve durations exceeding 350 days, and peak absolute magnitudes below -19, these two SNe fall substantially outside the normal range of Type II events. At the same time, their spectra are consistent with typical Type II or II-P SNe, exhibiting normal P-cygni profiles rather than the narrow lines seen in interacting SNe. I will discuss the two objects in the context of other long-lived Type II SNe and explore what powering mechanisms could be responsible for their longevity.