Abstract

Type Ia supernovae (SNe Ia) have famously been used as standard candles, a use that led to the discovery that the expansion of the Universe was accelerating under the influence of a mysterious new phenomenon called “dark energy.” And yet, we still do not have a clear picture of the progenitors of SNe Ia, i.e., what types of star systems end up exploding as these supernovae. For obvious reasons, most observers study these supernovae when they are young and at their brightest. In my talk, I will present recent results from studies of SN Ia rates, from non-detections of SNe Ia in different types of observations, and from SN Ia observations taken thousands of days after explosion. I will specifically emphasize how Hubble Space Telescope observations of old SNe Ia >1000 days after explosion reveal new information on the progenitors and physics of the explosions and their aftermath.