17070

Hydrogen-rich (Type II) supernovae exhibit enormous photometric and spectroscopic diversity that is still poorly understood despite being the largest sub-class of supernovae in volume-limited surveys and having a large sample of directly detected progenitor stars. Much of this diversity is driven by mass loss comma which strips the progenitor star and pollutes its circumstellar environment with gas and dust. HST can make significant contributions to understanding both the properties of the progenitor system and nature of the circumstellar environment through targeted observations of a large comma statistical sample of Type II supernovae. We will use multi-band imaging to resolve the stellar population around a large number of Type II supernovae comma enabling isochrone fitting and thus an initial mass estimate comma and producing the largest and most constraining sample to date of progenitor star initial mass estimates. We will also look for late-time emission from nearby supernovae comma potentially revealing delayed circumstellar interaction and uncovering modes of mass loss from centuries before explosion. For the closest events comma our observations will enable us to search for surviving companion stars to Type II supernovae comma connecting the spectroscopic and photometric diversity we see to the configuration of their progenitor systems.