DIX Planetary Science Seminar

Sihe Chen - Through years of observation, we have gained a comprehensive understanding of the characteristics and stability of the polar vortices of gaseous giant planets (Saturn and Jupiter). However, there has not been a unified theory to explain the cause of polar vortices. What conditions contribute to the formation of polar vortices in giant planets? Is the formation of polar vortices driven by similar forces as those forming mid-latitude zonal jets?

We will start by studying the polar vortex lattice of Jupiter, using a shallow water model based on the Athena++ SNAP architecture to investigate this series of questions. At the same time, we will compare some observational signals sent back by the Juno probe and contrast the related results with other polar models (quasi-geostrophic models, Siegelman et al., 2020 and three-dimensional model, Cai et al., 2021). We have calculated the parameter set required for the formation of a stable vortex lattice in Jupiter's polar region under ideal conditions and suggested the possible mechanisms for the observed pattern to form.

Matthew Belyakov - One of the few testable predictions of the dynamical instability predicted by the Nice Model is that Jupiter Trojans share a source population with the Kuiper belt. Concrete evidence of this prediction remains elusive, as Kuiper belt objects (KBOs) and Jupiter Trojans have radically different surface compositions. We present a possible solution to the long-standing mystery of the origin of the Jupiter Trojans by finding a dynamical sub-population in the Kuiper Belt that matches the colors of the Jupiter Trojans. We find that the low-perihelion (q<30 AU, a>30 AU) part of the Kuiper Belt has colors that bifurcate precisely into those of the Jupiter Trojans, unlike the Centaurs (a<30 AU) which strictly have Kuiper Belt-like colors. In order to settle the question of Jupiter Trojan origin, we test whether the Trojan-like colors of low-perihelion KBOs result from surface processing or come from a specific source within the Kuiper Belt. By simulating the evolution of a simulated Kuiper Belt for four billion years, we find that low-perihelion KBOs are not heated significantly more than the Centaurs. Instead, we find that they are uniquely sourced from the scattered disk (KBOs with e>0.6), suggesting that some proto-Trojans were dynamically implanted or scattered into the Kuiper belt as highly eccentric objects.