Revision 1

Accepted · first revision · record

Title: Where and how much does helium rain out inside Jupiter and Saturn?
Plain: At high pressure, helium may stop mixing with hydrogen and sink as droplets, releasing heat. This could explain why Saturn is warmer than expected and why both atmospheres lack helium.
Precise: Determine the pressure-temperature extent of hydrogen-helium immiscibility in Jupiter and Saturn and the amount of helium depleted from the outer envelopes (the Galileo probe measured helium mass fraction about 0.234 versus a protosolar value near 0.27). An answer is an immiscibility curve and evolutionary model that fits both planets' atmospheric helium, luminosity and gravity.
Settled by: Ab initio and shock-compression determination of the H-He miscibility gap combined with evolution models fitting both planets.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: open
Status note: (empty)
Posed since: (empty)