Astrophysics professor John Blondin recalls staring into the nighttime Wisconsin skies when he was growing up and marveling at the stars. “Even as a kid, I can remember being fascinated by the fact that our world here on Earth is such a small piece of the universe,” he says. Now, he exudes the same boyish enthusiasm as he marvels at some of the world’s most powerful computers, which are helping him solve a vexing problem of the universe: How does a supernova explode?
Supernovae have been observed for centuries, but it wasn’t until the 1960s that scientists linked them to dying stars. They theorized that the cooling iron core of a star running short on fuel collapses, and a shockwave of energy ripples back through the star and explodes. Observatory pictures later backed up that theory, showing dark areas in galaxies where once there were stars. But four decades later, no one has been able to simulate the explosion. Blondin says it’s primarily because of the complexity in recreating the death of a star, noting a single three-dimensional simulation can involve 40 quadrillion calculations.
The sheer volume of data involved is a primary reason the Department of Energy (DOE) funded the five-year, $10 million Terascale Supernova Initiative. The project, which includes NC State and seven other universities, pushes the limits of supercomputer processing and data transfer, leading to computer science advances. Supercomputers at DOE’s Oak Ridge National Laboratory can now crunch the numbers in the complex simulations in a weekend, compared to weeks of work on previous computer systems. “I was like a kid in a candy shop when I first got on the system at Oak Ridge,” Blondin says. But the reams of information overwhelm clusters of computers on campus, making data analysis a slower proposition.
The efforts of Blondin and his colleagues have already answered another question that has puzzled astrophysicists for yearswhy a neutron star spinsand the researchers believe replacing a spherical shockwave in their simulations with a rolling, off-kilter one finally has them on the path to solving the primary riddle as well. Because the DOE is also using their data to glean more information about high-energy explosions and the movement of radiation, Blondin hopes the government will continue funding the project now that its five-year term has ended so they can finish. “It would just be so cool,” he says, “to be able to figure out something no one’s been able to do for 45 years.”