Researchers from the U.S. Department of Energy's Lawrence Berkeley National Laboratory have developed the first full-star simulation of the conditions inside a white dwarf star in the hours before a Type Ia supernova. Type Ia supernovae are of particular interest to astrophysicists, who believe they can be used to measure the expansion of the universe.
For the past three years, the researchers have been developing MAESTRO, a program that simulates the flow of mass and heat throughout the star over time, using the power of supercomputers to model the entire star. The simulation is designed for processes that take place far slower than the speed of sound, allowing the simulation to create detailed results while using far less supercomputing time than traditional programs. MAESTRO's approach is different because the sound waves have been removed, allowing the program to run far more efficiently.
The simulation provided a valuable view into the end of a process that starts several billion years before the final supernova. Type Ia supernovae start as a white dwarf, the compact remnant of a low-mass star that never became hot enough to fuse its carbon and oxygen. However, if another star is close enough, a white dwarf can start taking on mass from the neighboring star until it reaches a critical limit. The simulations show that at the early stages, the motion of a fluid that carries heat within the star appears as random swirls, but as the heat in the center of the star increases, the flow clearly moves into the star's core on one side and out the other. Other simulations have seen this pattern, but the MAESTRO simulations are the first to capture the full star in three dimensions.
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