New computer simulations suggest that shadows cast by the inner region of the circumplanetary disk (CPD) around infant Jupiter may have created cold spots in the outer region. These cold spots could have provided the conditions for materials to congeal into the moons Galileo discovered.
The study, published last month, models Jupiter's CPD in 2D, examining its cross-section and structure. Researchers Antoine Schneeberger and Olivier Mousis found that if the inner region of the disk expanded, it would cast a shadow on the outer portion, shielding it from heat. These shadows created cold spots on the disk.
The simulations suggest that about 100,000 years after the formation of the CPD, a frigid region 100 kelvins colder than its surroundings appeared and lasted for 80,000 years, reaching a distance 123.5 times Jupiter's radius. This region, centered approximately 629,000 kilometers from Jupiter, allowed gases such as ammonia, hydrogen sulfide, and carbon dioxide to condense, potentially forming the seeds for moons like Europa.
The researchers infer that if these cold traps influenced the formation of the Galilean moons, the inner moons (Io and Europa) should have a greater proportion of volatile gases than the outer moons (Ganymede and Callisto). The European Space Agency's JUICE and NASA's Europa Clipper missions will test this theory by analyzing Jupiter and its satellites.