Image of the week - Stellar performance |
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Far beneath the Sun's surface, scientists suspect there are churning masses of plasma up to ten times larger then Earth. These masses, known as giant cells, play a critical role in solar variability, influencing magnetic storms that take aim at Earth to affect satellites as well as power and communications systems. A new model developed by a team of scientists led by Mark Miesch of the National Center for Atmospheric Research is able to simulate the convection patterns of these giant cells, providing an unprecedented view of how the solar interior works. "It opens a window on a number of important solar processes, including the delicate balance of forces that causes the Sun's equator to rotate faster than its poles," says Miesch. "This is our first indication of what the chaotic interior of a star looks like." To map the giant cells, Miesch and his team drew on data from helioseismology-a technique to measure sound waves that propagate deep within the interior of the Sun-and used Teragrid resources to solve the equations of stellar fluid dynamics. By analyzing variations in the light and velocity of the waves as they emerge on the Sun's surface, scientists can glean information about hidden subsurface structures. The model simulations capture processes in the outer 30 percent of the solar interior. They correspond to existing maps that are based on helioseismic data about subsurface processes. The simulations also capture the Sun's unusual rotational pattern, which occurs when the giant cells redistribute angular momentum, causing the solar equator to rotate every 28 days while higher latitudes take about 35 days. This image features on the cover of Teragrid's 2007 Science Highlights booklet, to be released at Supercomputing 2008 next month. |
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