Princeton team uses Argonne supercomputers to simulate the collapse of a massive star
A team of scientists from Princeton University and the U.S. Department of Energy’s (DOE) Argonne National Laboratory leveraged the power of Argonne supercomputers to simulate the last seconds in the life of a massive star. Those last seconds end in a series of abrupt dynamic events that create a supernova — that is, a collapsed star caused by a huge explosion. Researchers simulated the collapse of more than 20 massive star models — ranging from nine to 60 times larger than our sun — and published their findings in the journals Nature and Monthly Notices of the Royal Astronomical Society.
World-class supercomputers like those at Argonne’s Leadership Computing Facility, a DOE Office of Science user facility, provide the power essential for conducting such complex 3D simulations, which help scientists understand the physics behind the collapse of a massive star. Improvements in these calculations have been driven, in part, by a state-of-the-art code called Fornax, developed at Princeton.
While the team’s research has given rise to numerous theories, further simulations are planned. This work was supported by the DOE Office of Science and the National Science Foundation.
Argonne APS helps identify how meteorite strikes affect planet Earth
Researchers from Princeton University, the Carnegie Institution for Science, Washington, D.C., and Washington State University, Pullman, used the capabilities of Argonne’s Advanced Photon Source (APS), a DOE Office of Science user facility, to learn more about how quartz transforms when struck by meteorites, and how such impacts affect the geological makeup of planets.
The team found a new crystal structure of quartz, one that lasts only about 100 nanoseconds after impact. The team analyzed the atomic-level changes that occurred in the quartz’s structure at the very moment of impact.
At the APS’ Dynamic Compression Sector, the team was able to capture the moment of impact on a quartz sample, taking snapshots of its structure at extremely short timescales. Researchers used a hydrogen gas gun to fire a projectile at the quartz, then used an X-ray beam to probe the changes the quartz underwent in the nanoseconds during and after impact.
Princeton scientists use APS to investigate chemical exposure in South Carolina wetlands
Naturally forming organic compounds containing halogens (fluorine, chlorine, bromine and iodine) are common in most environments. In wetlands and freshwater sediments, organic compounds containing chlorine are the most common. But when saltwater seeps into freshwater wetlands, higher levels of bromine are introduced, which can turn the chlorine compounds toxic. These new compounds, when they enter the atmosphere, add to the destruction of the ozone layer and contribute to a rising sea level.
Where four rivers — the Black, the Pee Dee, the Sampit and the Waccamaw — converge on the coast of eastern South Carolina, they form the Winyah Bay estuary. A team of scientists from Princeton University studied the level of bromine introduced into the freshwater wetlands of Winyah Bay in an effort to track long-term changes in the ecosystem as a result of bromide exposure.
Scientists used the extremely bright X-rays at the APS to analyze samples from leaf litter and soil in the bay. Their analysis revealed a strong relationship between the introduction of bromine and, on average, a 39% loss of organic chlorine from leaf litter and soil. Their discovery could offer insight into climate change.
The APS is a DOE Office of Science user facility.