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I will present results from my Ph.D. dissertation. First, our new ground-based and archival Spitzer imaging observations provide the most precise determination to date of the reddening toward Cas A's expansion center, which constrain intrinsic brightness of its nascent supernova (which was either unobserved or unremarkable). Simple light-curve models and published gamma-ray observations give a 44Ti/56Ni yield that requires that the SN explosion was asymmetric, though the abundance ratio of their stable daughter nuclei (44Ca/56Fe) is broadly consistent with solar. Second, recent published Spitzer observations provide the first unambiguous detection of material interior to Cas A's reverse shock. We use a simple, coupled non-equilibrium ionization and hydrodynamics simulation to show this material is cold and overdense, photoionized by radiation from the shocked gas, and consists primarily of incomplete explosive oxygen-burning products, though a more quantitative analysis awaits the availability of more detailed spectroscopic information. If time permits, I will also show results from progress made on a new code that incorporates non-equilibrium ionization with multi-dimensional hydrodynamics, which we will use to model the spectra and morphology of supernova remnant shocks. |