How Our Solar System Got Its ‘Great Divide’

protoplanetary disk

Atacama Large Millimeter/submillimeter Array (ALMA) image of the protoplanetary disk around HL Tauri. Our early solar system’s protoplanetary disk may have had similar ring structures. Image credit: ALMA (ESO/NAOJ/NRAO)

Various types of meteorites sampled in our meteorite collection display a distinct dichotomy in their chemical and isotopic compositions, suggesting that there was a divide between the inner (terrestrial) and the outer (giant planets and beyond) regions of the early solar system. It has been proposed that early formation of Jupiter was responsible for this great divide. This was based on the idea that Jupiter is so massive that it acted as a gravitational barrier, preventing materials from the outer solar system from spiraling toward the Sun. However, a recent study published in Nature Astronomy used numerical simulations to suggest that while Jupiter is massive, it was probably never massive enough early in its formation to entirely block the flow of material moving sunward. An alternative explanation proposed for this dichotomy is that the early solar system was partitioned into at least two regions by a ring-like structure that formed a disk around the young Sun, creating a region of maximum pressure near Jupiter’s location. This pressure maximum blocked transport of material into the inner solar system and maintained the compositional partitioning between the two regions. This scenario suggests our young solar system’s protoplanetary disk developed at least one and probably multiple rings, which potentially triggered the formation of the giant planets. READ MORE