Physics SlideShow

Helium rains inside Jovian planets

By determining the properties of hydrogen-helium mixtures at the millions of atmospheres of pressure present in the interior of Saturn and Jupiter, physicists at the University of Illinois at Urbana-Champaign and Lawrence Livermore National Laboratory have determined the temperature at a given pressure when helium becomes insoluble in dense metallic hydrogen. The results are directly relevant to models of the interior structure and evolution of Jovian planets.

Using first-principle molecular dynamics simulations, Miguel Morales, a DOE Stewardship Science graduate fellow from David Ceperley’s group at the University of Illinois worked with LLNL’s Eric Schwegler, Sebastien Hamel, Kyle Caspersen and Carlo Pierleoni from the University of L’Aquila in Italy to determine the equation of state of the hydrogen-helium system at extremely high temperatures (4,000-10,000 K), similar to conditions found in the interior of Saturn and Jupiter. 

The team used LLNL’s extensive high-performance computing facilities to conduct simulations over a wide range of densities, temperatures, and compositions. “Our simulation results are consistent with the idea that a large portion of the interior of Saturn has conditions such that hydrogen and helium phase separate,” Morales said. “This can account for the apparent discrepancy between the current evolutionary models for Saturn and observational data.”

The group's results appear in the January 26, 2009, online edition of The Proceedings of the National Academy of Sciences. Read the paper...

LLNL news release, January 26, 2009