2009 Annual Science Report
University of Hawaii, Manoa Reporting | JUL 2008 – AUG 2009
Giant Planet Formation (Late Stage of the Formation of Jupiter)
Measurements of the abundance of elements in Jupiter’s atmosphere have indicated that high-density materials are several times more abundant in Jupiter’s envelope than in the Sun. To understand the reason for this anomaly, we have started a project on the interactions of planetesimals with Jupiter’s gaseous envelope at the last stage of the formation of this planet.
Results indicate that the deposition of sublimated materials from planetesimals due to gas drag can in crease the metalicity giant planets.
Both models of giant planet formation, namely the core-accretion and the disk instability scenarios, suggest that prior to the last stage of the formation of giant planets, the cores of these objects are surrounded by extended gaseous envelopes. Given that during giant planet formation, Solar System is populated by km-sized and larger bodies, many of these objects may scatter into such proto-atmospheres where their dynamics are affected by the drag force of the gas. To study the effect of the gas drag on the capture of planetesimlas, Haghighipour and Podolak have been simulating the interactions between planetesimals and the extended envelope of Jupiter by following the evolution of an isolated Jupiter mass clump of hydrogen and helium in solar composition. Their results indicate that planetesimals with radii of 1 and 10 km are efficiently captured even in the early stages of the evolution of the gaseous envelope when it is extended and dilute. Planetesimals with radii of 100 km, however, can pass through the gas during the early contraction stages. Haghighipour’s results show that the efficiency of the capture increases drastically even for 100 km planetesimals as the objects lose mass. The interaction between planetesimals and the envelope causes sublimation of material and its subsequent deposition in the gas. Haghighipour’s models have shown that this process can account for the higher-then-solar metalicity of the gaseous envelope of Jupiter.