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Project Progress

Mejia and Quinn in collaboration with Mayer (Zurich) have continued performing simulations of giant planet formation by fragmentation of a gaseous disk. They are extending previous work by considering models with radiative transfer. They are collaborating with other investigators to verify the accuracy of their calculations and to resolve discrepant results within the simulation community.

Mejia and Quinn are investigating the dynamics of gas and dust interaction in protoplanetary disks. There are two issues they are studying. The settling of dust into a thin layer in the midplane is a crucial aspect of building up the solids into large objects eventually leading to terrestrial planets. Dust may also move into the higher density regions of a fragmenting disk giving an alternative mechanism for forming giant planet cores.

Lufkin and Quinn performed simulations of giant planet migration and accretion in gaseous disks. These simulations confirm a puzzle that has been known from linear theory: that rapid migration should cause stars to swallow giant planets soon after they form, yet observational evidence shows that planet formation is robust.

Barnes and Quinn in collaboration with Lissauer (Ames) continue their simulations of planetesimal accretion in the terrestrial region. In a paper in preparation, they point out that runaway growth starts very soon after the first planetesimals form.

Barnes and Quinn continue to investigate the stability of extra-solar planetary systems as they are being discovered. They continue to find that most planetary systems, including our own, are on the edge of being unstable. This has implications for the efficiency of planet formation. Barnes and Raymond have also been investigating the formation of terrestrial planets within these known extra-solar systems.

Quinn and Kaib are starting to investigate the formation of cometary clouds under various galactic contexts. They are also investigating the resulting impact history of comets on terrestrial planets.