At the heart of some of the smallest and densest stars in the universe lies nuclear matter that might exist in never-before-observed exotic phases. Neutron stars, which form when the cores of massive stars collapse in a luminous supernova explosion, are thought to contain matter at energies greater than what can be achieved in particle accelerator experiments, such as the ones at the Large Hadron Collider and the Relativistic Heavy Ion Collider.
Although scientists cannot recreate these extreme conditions on Earth, they can use neutron stars as ready-made laboratories to better understand exotic matter. Simulating neutron stars, many of which are only 12.5 miles in diameter but boast around 1.4 to two times the mass of our sun, can provide insight into the matter that might exist in their interiors and give clues as to how it behaves at such densities.
A team of nuclear astrophysicists led by Michael Zingale at Stony Brook University is using the Oak Ridge Leadership Computing Facility's (OLCF's) IBM AC922 Summit, the nation's fastest supercomputer, to model a neutron star phenomenon called an X-ray burst—a thermonuclear explosion that occurs on the surface of a neutron star when its gravitational field pulls a sufficiently large amount of matter off a nearby star. Now, the team has modeled a 2D X-ray burst flame moving across the surface of a neutron star to determine how the flame acts under different conditions. Simulating this astrophysical phenomenon provides scientists with data that can help them better measure the radii of neutron stars, a value that is crucial to studying the physics in the interior of neutron stars. The results were published in the Astrophysical Journal.
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