(by JIN Sheng)

Final internal configurations of the three models. It also shows
the ratio of each layer to the calculated Europa’s radius. The differences in
the models are the proportion of the cores. The largest core is close to the
half of Europa’s radius, while the smallest one is less than 30% of Europa’s radius.

　　 In January 2012, Prof. Ji Jianghui and his PhD student Jin Sheng of Purple Mountain Observatory present a new model of the interior of Europa in one paper published in Science China Physics, Mechanics and Astronomy. in which they consider that Europa is made up of three layers, a core, a mantle and a water shell, and the core is Fe-FeS alloy, different with previous models with only Fe or FeS core.

　 They propose three possible internal structure models for Europa using a method by which they set three layers of Europa and the composition of each layer in advance. All models are assumed to be differentiated into a metallic core, a (Mg, Fe)2SiO4 silicate mantle and an outer water shell. The only difference amongst these models are the composition of the core. The core of Model I is composed of Fe, while Model II composed of FeS. Model III has a core which consists of Fe-FeS alloy, similar to that of Earth’s outer core. In Model III, Europa has a 571 km radius, a 832 km (Mg,Fe)2SiO4 mantle and a 166 km water shell with the mass ratio of the core, mantle and water 12, 78 and 10 percent respectively.

　 This research issignificant to understand further the interior, formation and evolution of Europa, also helpful to explore the water and life in Europa. The published paper is linked by the webpage http://www.springerlink.com/content/m747k2h5h0282407/.