DPS 35th Meeting, 1-6 September 2003
Session 18. Extra Solar Planets II
Poster, Highlighted on, Wednesday, September 3, 2003, 3:00-5:30pm, Sierra Ballroom I-II

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[18.08] Volatile Cycles and Glaciation: Earth and Mars (Now and Near a Red Giant Sun), and Moons of Hot Jupiters

J.S. Kargel (U.S. Geol. Survey), M.B. Fegley (Washington University)

Glaciers are classically defined as perennial masses of ice showing geomorphic evidence of flow. This definition is expanded to include any flowing mass of solid volatiles condensed on planetary surfaces. Glacier-forming volatiles in this solar system may include water ice on Earth and Mars, carbon dioxide on Mars, sulfur on Io, and, in the future red giant phase of solar evolution, may encompass silicon monoxide or metallic magnesium and sodium glaciers on Earth and Mars. Comparable glaciers may occur on large rocky moons of hot Jupiters and comparably close-in ‘terrestrial’ type planets. We have modeled the temperature distribution across the surfaces of red-giant phase Earth and Mars, without considering radiative effects of the gases and clouds, to illustrate these points. We have assumed alternate conditions of asynchronous and synchronous rotation and calculated the temperatures during the run-up along the red giant evolutionary branch. Near red giant solar maximum, Earth’s subsolar temperature will exceed 2400 K for about a million years. A magma ocean will exist but will not be continuous across the globe; for a tidally locked Earth, solid continents will consist largely of atmospheric condensates of the more volatile metals and metal oxides, with shorelines and some buoyant 'bergs' composed of refractory Ca-Al-oxide residues, whereas some residues and condensates will sink to the core. Atmospheric partial pressures of Mg, MgO, SiO, SiO2, Fe, and FeO will total nearly 0.3 mbars. O and O2 partial pressures will sum to 1 mbar, and alkalis would initially be over 3 mbars. Condensation will occur by fractional chemical distillation. A chemical sequence of deposits will occur toward the pole and terminator. Some condensate deposits will flow glacier-like into the magma ocean, where they will redissolve, closing the cycle in a quasi-steady state familiar to glaciologists.

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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.