Berlin 2014 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 3: Erdnaher Weltraum / Planeten
EP 3.6: Vortrag
Dienstag, 18. März 2014, 12:00–12:15, DO24 1.103
Transient Water Vapor at Europa’s South Pole — •Lorenz Roth1,2, Joachim Saur2, Kurt Retherford1, Darrell Strobel3, Paul Feldman3, Melissa McGrath4, and Francis Nimmo5 — 1Southwest Research Institute — 2Universität zu Köln — 3Johns Hopkins University — 4Marshall Space Flight Center, NASA — 5University of California Santa Cruz
In November and December 2012 the Hubble Space Telescope (HST) imaged Europa’s ultraviolet emissions in the search for vapor plume activity. We report statistically significant coincident surpluses of hydrogen Lyman-α and oxygen OI130.4 nm emissions above the southern hemisphere in December 2012. These emissions are persistently found in the same area over ∼7 hours, suggesting atmospheric inhomogeneity; they are consistent with two 200 km high plumes of water vapor with line-of-sight column densities of about 1020 m−2. Non- detection in November and in previous HST images from 1999 suggests varying plume activity that might depend on changing surface stresses based on Europa’s orbital phases. The plume is present when Europa was near apocenter, and not detected close to its pericenter in agreement with tidal modeling predictions.