P2-20 ガニメデの金属核形成と膨張地形形成 : カリスト・タイタンとの進化の分岐(ポスターセッション2,ポスター発表)

概要

論文の詳細を見る
Jupiter's largest moon Ganymede has an abundant evidence of extensional tectonics resulting from global expansion in relatively young age, and has a large metallic core which is implied by the existence of the intrinsic magnetic field and small value of the moment of inertia factor. To investigate these origins, here we show dehydration models of primordial hydrous silicate and metal-mixed core, which is heated by long-lived radiogenic isotopes and becomes dehydrated. The volume expansion accompanying the dehydration is possibly enough large for the extensional tectonics and its timing is consistent with the cratering age. Dehydration also results in the sharp viscosity increase, and the central temperature possibly exceeds the eutectic point of conductive materials, allowing the formation of a metallic core. Actual Ganymede's interior (and possibly also Titan) can form a conductive core while slightly smaller Callisto can escape from sufficient heating. This may explain the observed difference in the surface geology and internal structure among the giant icy moons.
日本惑星科学会の論文
2013-11-20