A research team from University of Zurich (UZH) and the National Centre of Competence in Research (NCCR) has utilised computer modelling systems to analyse and dissect Jupiter’s origin.
One of the most important questions that remains largely unanswered within the planetary formation field is the history of Jupiter’s origin. By employing sophisticated computer modelling, researchers from the University of Zurich (UZH) and the National Centre of Competence in Research (NCCR) PlanetS could be the key to shed light on Jupiter’s formation history. Their results were published in The Astrophysical Journal Letters.
Dissecting the enrichment of heavy elements
When the Galileo spacecraft released a probe that parachuted into Jupiter’s atmosphere in 1995, it revealed that heavy elements (elements heavier than helium) were enriched there. At the same time, recent structure models of Jupiter that are based on gravity field measurements by the Juno spacecraft suggest that Jupiter’s interior is not uniform but instead has a complex structure.
“Since we now know that the interior of Jupiter is not fully mixed, we would expect heavy elements to be in a giant gas planet’s deep interior as heavy elements are mostly accreted during the early stages of the planetary formation,” explained study co-author, Professor at the University of Zurich and member of the NCCR PlanetS, Ravit Helled.
“Only in later stages, when the growing planet is sufficiently massive, can it effectively attract large amounts of light element gases like hydrogen and helium. Finding a formation scenario of Jupiter which is consistent with the predicted interior structure as well as with the measured atmospheric enrichment is therefore challenging yet critical for our understanding of giant planets.”
Analysing Jupiter’s origin
“Our idea was that Jupiter had collected these heavy elements in the late stages of its formation by migrating. In doing so, it would have moved through regions filled with so-called planetesimals – small planetary building blocks that are composed of heavy element materials – and accumulated them in its atmosphere,” added study lead-author, Sho Shibata, who is also a member of the NCCR PlanetS, as well as a postdoctoral researcher at the University of Zurich.
Sho Shibata is a postdoctoral researcher at the University of Zurich and a member of the NCCR PlanetS.
However, migration alone is no guarantee for accreting the necessary material. “Because of complex dynamical interactions, the migrating planet does not necessarily accrete the planetesimals in its path. In many cases, the planet actually scatters them instead – not unlike a shepherding dog scattering sheep,” Shibata explained. The research team were therefore required to conduct numerous simulations in order to determine if any migration pathways resulted in sufficient material accretion.
“What we found was that a sufficient number of planetesimals could be captured if Jupiter formed in the outer regions of the solar system – about four times further away from the Sun than where it is located now – and then migrated to its current position,” Shibata explained. “In this scenario, it moved through a region where the conditions favoured material accretion – an accretion sweet spot, as we call it.”
Commencing a new era in planetary science
Combining the constraints introduced by the Galileo probe and Juno data, the team of researchers eventually concluded with a satisfactory explanation. “This shows how complex giant gas planets are and how difficult it is to realistically reproduce their characteristics,” Helled concluded. “It took us a long time in planetary science to get to a stage where we can finally explore these details with updated theoretical models and numerical simulations. This helps us close gaps in our understanding not only of Jupiter’s origin and our solar system, but also of the many observed giant planets orbiting far away stars.”
