Models of how Saturn and Jupiter formed may soon take on a different look. 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 Lawrence Livermore National Laboratory and the University of Illinois at Urbana-Champaign 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.
Hydrogen and helium are the two lightest and most common elements in the universe. Because of their ubiquitous nature, they are critical in cosmological nucleosynthesis and are essential elements of stars and giant planets. Hydrogen by itself in the observable universe provides clues to the origin and large-scale structures of galaxies.
However, scientists have struggled to determine what conditions are needed for the two elements to mix.
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 degrees Kelvin), similar to what would be found in the interior of Saturn and Jupiter.