The Formation of Jupiter’s Satellites: Relation of Present Appearance with Past History

Abstract

After the recent observations made by Galileo of the Jupiter system, we are now ready to test the current theories on the formation of Jovian planets. One can ask how these new discoveries can be included in a general scheme on the formation of Jovian planets, and what is the memory that the present system has of the previous evolution. The giant planets, Jupiter and Saturn, are mostly gaseous and therefore accreted a large part of their mass from the surrounding nebula before its deplenishment of gas. The problem of formation and evolution of the so-called “regular satellites” of Jupiter is reviewed. The formation of regular satellite systems around giant planets is probably related to the formation of the central planet. Some characteristics of regular satellite systems are quite similar, and suggest a common origin in an accretion disk present around the central body. This disk can be originated through different mechanisms that we will describe, paying attention to the so called “accretion disk” model, in which the satellite-forming material is captured. The disk phase links the formation of the primary body with the formation of satellites.