Understanding Type II-Plateau Supernovae And The Red Supergiants That Cause Them

Observations of the transient, explosive deaths of massive stars are well-poised to provide insight into stellar physics when combined with theoretical understanding. Using Modules for Experiments in Stellar Astrophysics (MESA) to model red supergiant (RSG) stars up to core collapse, followed by modeling with STELLA for the resulting Type IIP supernovae (SNe), we confirm and sharpen early analytic calculations for the Supernova plateau luminosity and duration. When the RSG radius is known from a pre-SN image, we show how the explosion energy and ejecta mass can be directly inferred. In the absence of such constraints, a family of explosions could produce the same photospheric emission. Motivated in part by the desire to understand the outermost 0.01M_sun of Red Supergiants (RSGs) responsible for early-time Supernova (SN) emission which might provide additional information, we have completed global 3D radiation-hydrodynamics (RHD) simulations of RSG envelopes with Athena++. These envelopes exhibit an extended density structure with large-scale convective plumes spanning large fractions of the stellar surface. Driving a strong shock through these simulations, we will show novel results on how the 3D convective structure dramatically impacts the duration and brightness of the UV shock breakout signal.