2019ApJ...879....3G

We present advances in modeling Type IIP supernovae (SNe IIP) using MESA for evolution to shock breakout coupled with STELLA for generating light and radial velocity curves. Explosion models and synthetic light curves can be used to translate observable properties of SNe (such as the luminosity at day 50 and the duration of the plateau, as well as the observable quantity ET, defined as the time-weighted integrated luminosity that would have been generated if there were no ⁵⁶Ni in the ejecta) into families of explosions that produce the same light curve and velocities on the plateau. These predicted families of explosions provide a useful guide toward modeling observed SNe and can constrain explosion properties when coupled with other observational or theoretical constraints. For an observed SN with a measured ⁵⁶Ni mass, breaking the degeneracies within these families of explosions (ejecta mass, explosion energy, and progenitor radius) requires independent knowledge of one parameter. We expect the most common case to be a progenitor radius measurement for a nearby SN. We show that ejecta velocities inferred from the Fe II λ5169 line measured during the majority of the plateau phase provide little additional information about explosion characteristics. Only during the initial shock cooling phase can photospheric velocity measurements potentially aid in unraveling light-curve degeneracies.