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K. Lodders (Planetary Chemistry Laboratory, Dept. of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University)
A comparison of elemental abundances in Jupiter with recently revised solar system abundances [1] shows that normalized to sulfur, abundances of Ar, Kr, and Xe are one times solar, oxygen (as water) is depleted by a factor of 4, carbon is enriched 1.7 times, and the fairly uncertain nitrogen abundance is 1-3 times solar [2]. The O abundance from the atmospheric water abundance is only a lower limit to the total planetary O because O is also bound to rock-forming elements (e.g., Mg, Si) sequestered deep in the planet. Sulfur is the most abundant refractory rock-forming element reliably determined in Jupiter's atmosphere by the Galileo probe and constrains the amount of rocky elements, which then gives the amount of O bound to rock. Adding O in water and rock gives the total Jovian O as 0.47 times solar system, still an overall O depletion.
A formation model for Jupiter to explain both the relative O depletion and the C enrichment suggests that abundant carbonaceous matter rather than abundant water ice was present near 5.2 AU at the time of Jupiter's formation [2]. Then carbonaceous matter, which has a high sticking probability, was the glue that enabled fast accumulation of solids to proto-Jupiter and led to run-away accretion of the planet. This scenario further implies that the water ice condensation front (the snowline) is replaced by a carbonaceous condensation/evaporation front (the "tar-line"), and that the snowline is located farther out in the solar nebula. Work supported by NASA NAG5-11958. [1] Lodders 2003, ApJ 591, 1220. [2] Lodders, 2004, ApJ 611, 587.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.