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Gizmorama - Why do massive stars lose gas as they evolve?
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Gizmorama - November 28, 2016
Have you ever wondered why massive stars lose gas as they evolve? Well, today is your day because the Mira supercomputer might just have the answers.
Learn about this and more interesting stories from the scientific community in today's issue.
Until Next Time,
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*-- Why do massive stars lose gas as they evolve? Mira supercomputer may provide answers --*
SANTA BARBARA, Calif. - Scientists believe they're close to understanding why massive stars lose mass in the form of gas as they evolve. The only problem: a lack of computing power.
The processing power required to run models simulating the evolution of massive stars is immense. But scientists with the Kavli Institute for Theoretical Physics, at the University of California, Santa Barbara, have been gifted a solution.
Officials with the Innovative and Novel Computational Impact on Theory and Experiment, a Department of Energy program, have granted astrophysicists Matteo Cantiello and Yan-Fei Jiang 120 million CPU hours on the world's sixth-fastest computer. The researchers will get two years of access to the supercomputer Mira.
"Access to Mira means that we will be able to run calculations that otherwise would take about 150,000 years to run on our laptops," Cantiello said in a news release.
Unlike smaller one-dimensional stellar simulations, the model developed by Cantiello and Jiang will generate 3D simulations of the insides of massive stars, exploring the interactions of gas, radiation and magnetic fields. The researchers hope a better understanding of these interactions will yield insights into the nature of the episodic eruptions that bleed gas into space over the lifetime of a star.
The ways in which massive stars lose gas also have implications for the study of stellar structures created by supernovae, such as black holes and neutron stars. Scientists are hopeful revelations offered by their work with Mira will inform analysis of black hole systems like that one credited with producing the gravitational waves recorded by LIGO earlier this year.
"Understanding how these black hole binary systems formed in the first place requires a better understanding of the structure and mass loss of their stellar progenitors," said Jiang.
* Surprising carbon sink: Cement absorbs, stores greenhouse gas *
IRVINE, Calif. - Climate scientists have mostly treated cement as a net contributor to CO2 emissions. New research suggests the building material isn't all bad.
The cement production process is energy-intensive, rightly blamed for a sizable portion of carbon emissions, but an international team of scientists argues the material works as a carbon sink once poured.
"It sounds counterintuitive, but it's true," Steven Davis, an earth scientist at the University of California, Irvine, said in a news release. "The cement poured around the world since 1930 has taken up a substantial portion of the CO2 released when it was initially produced."
Over time, buildings and roads pull carbon from the atmosphere and store it away. Scientists from UCI, the University of East Anglia and elsewhere set out to calculate the carbon storage contribution offered by cement.
First, scientists need to calculate the amount of CO2 emitted by cement production.
Carbon is released into the atmosphere when limestone, calcium carbonate, is turned into lime, calcium oxide, cement's main ingredient. The process is doubly carbon-intensive because breaking down limestone is energy-intensive, requiring the burning of fossil fuels.
As part of their research, scientists estimated 76 billion tons of cement were generated globally between 1930 and 2013, releasing a total of 38.2 gigatons of CO2 into the atmosphere. During the same time, cement sucked up 4.5 gigatons of CO2, almost half the emissions contributed by limestone conversion.
"Cement has gotten a lot of attention for its sizable contribution to global climate change, but this research reinforces that the leading culprit continues to be fossil fuel burning," Davis said.
If engineers can find away to reduce the amount of carbon emitted during the cement production process, the material could ultimately become a net carbon sink.
"We suggest that if carbon capture and storage technology were applied to cement process emissions, the produced cements might represent a source of negative CO2 emissions," added Dabo Guan, a professor at UEA. "Policymakers might also investigate ways to increase the completeness and rate of carbonation of cement waste, for example as a part of an enhanced weathering scheme, to further reduce the climate impacts of cement emissions."
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