Transient Water Vapor at Europa's South Pole
Publication date: 12 December 2013
Authors: Roth, L., et al.
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-alpha 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. Nondetection 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.Link to publication