The study of hydrodynamics (HD) is critical in several areas of astrophysics. One of those areas concerns certain brief phases of stellar evolution, lasting minutes or even seconds, in which very rapid structural changes can occur in the star, critically affecting their evolution. The most common of these events in the sudden core-collapse of a massive star, leading to the explosion of a "supernova" (SN). It has long been known that the remnant "shell" from supernova explosions aggregates into filamentary and "elephant trunk" structures that indicate HD instabilities as the SN blast wave expands into interstellar space. The most recent observations of the supernova "SN1987a" in the Large Magellanic Cloud show "finger" shaped structures rich in the element nickel that developed weeks or even days after the explosion. The Principal Investigator (PI) plans to use a new HD numerical calculation procedure, the Piecewise Parabolic Method (PPM) to perform numerical simulations of the detonation and explosion of Type II supernovae such as SN1987a. The new technique is generally far more efficient than old ones and will permit calculations to be done in two and even three dimensions, thereby permitting an understanding of the development of small structures in these remnants. Moreover, with a Co-Investigator and student, the PI will utilize a new theory of convection that is essential to understand the observed swirling of gas "blobs". Many of the heavy elements on the Earth are synthesized during the critical moments following this explosion. It now seems that heavy elements such as nickel are synthesized unevenly in the small "finger" structures. This project should provide some understanding of how and why this uneven formation of heavy elements occurs. The techniques and computer programs developed for this study are expected to find future application in several other astrophysical contexts, such as Type I supernovae (accreted matter on a hot white dwarf from a double star companion), pulsation in large amplitude variable stars, and convection in stable stars such as the Sun.
