<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Semi-analytical Modeling of Planetesimal Formation.\r\nImplications for Planet Formation and the Solar Nebula"^^ . "Planetesimals are the hypothetical building blocks of planets, halfway between dust aggregation and the formation\r\nof planetary embryos. The typical diameter of newborn planetesimals was found to be around 100 km. The timedependent\r\nproduction of these planetesimals and their radial distribution in disks around young stars is still unclear.\r\nThis thesis proposes a semi-analytical model for the planetesimal formation rate that is regulated by the radial pebble\r\nflux. The model is implemented into a code that solves the evolution of gas as well as the growth and radial motion\r\nof grains. Within this model, planetesimals form as soon as micron-sized dust has grown to pebble-size (typically ~\r\nmm–cm) and a critical pebble flux is reached. The resulting spatial planetesimal profile is steeper compared to\r\nthe initial dust and gas distribution. E.g., for a temperature profile T∝r^-0.5, the planetesimal profile is expected to\r\nfollow Σ_p∝r^-2.25 in the inner disk regions. The maximum local planetesimal production is reached for a planetesimal\r\nformation efficiency that allows the planetesimal formation timescale and the pebbles drift timescale to be equal.\r\nA disk parameter study is performed which enables to set limits on possible parameters for the Solar Nebula by\r\ncomparing the produced planetesimal profiles with mass constraints for initial planetesimals. This thesis shows that\r\nthe Solar Nebula was not too large, enclosing most of the mass within 50 au. Outside of 50 au, particle traps needed\r\nseveral hundreds of orbits to form or never formed there. Compared to the mass constraints, the most appealing case\r\nthat is analyzed in this thesis has a disk mass of around 0.1 solar masses, a fragmentation speed of particles of 2 m/s,\r\nand moderate to weak turbulence (α = 3⋅10^-4). The model introduced in this thesis does not require fine tuning in\r\norder to meet mass constraints for the Solar Nebula which stresses the applicability of the proposed parameterization\r\nto models of planet formation. By sorting pebbles by their origins, this thesis shows that a significant amount of pebble\r\nmass passed major ice lines before forming planetesimals in the inner Solar Nebula or before they were accreted by\r\nplanetary embryos at the current positions of the asteroid belt and Earth. The relative contribution to planetesimals\r\nfrom regions of different particle origins changes for different times of planetesimal formation. This thesis concludes\r\nwith the importance of pebble transport and the planetesimal formation efficiency for shaping the spatial distribution\r\nof planetesimals. The presented planetesimal formation rate model can be used to bridge the gap between the phases\r\nof dust growth and the formation of planetary embryos."^^ . "2020" . . . . . . . "Christian Tobias"^^ . "Lenz"^^ . "Christian Tobias Lenz"^^ . . . . . . "Semi-analytical Modeling of Planetesimal Formation.\r\nImplications for Planet Formation and the Solar Nebula (PDF)"^^ . . . "Dissertation_ChristianLenz.pdf"^^ . . . "Semi-analytical Modeling of Planetesimal Formation.\r\nImplications for Planet Formation and the Solar Nebula (Other)"^^ . . . . . . "indexcodes.txt"^^ . . . "Semi-analytical Modeling of Planetesimal Formation.\r\nImplications for Planet Formation and the Solar Nebula (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Semi-analytical Modeling of Planetesimal Formation.\r\nImplications for Planet Formation and the Solar Nebula (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Semi-analytical Modeling of Planetesimal Formation.\r\nImplications for Planet Formation and the Solar Nebula (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Semi-analytical Modeling of Planetesimal Formation.\r\nImplications for Planet Formation and the Solar Nebula (Other)"^^ . . . . . . "small.jpg"^^ . . "HTML Summary of #28808 \n\nSemi-analytical Modeling of Planetesimal Formation. \nImplications for Planet Formation and the Solar Nebula\n\n" . "text/html" . . . "520 Astronomie"@de . "520 Astronomy and allied sciences"@en . . . "530 Physik"@de . "530 Physics"@en . .