Planetesimal growth through the accretion of small solids
department or school: Science, Faculty of
department or school: Physics and Astronomy, Department of
data provider: DSpace
degree campus: UBCV
creator: Hughes, Anna
issued: 2016-08-25T02:01:58
issued: 2016
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: The growth and migration of planetesimals in a young protoplanetary disk is fundamental to the planet formation process. However, in our modeling of early growth, there are a several processes that can inhibit smaller grains from growing to larger sizes, making growth beyond size scales of centimeters difficult. The observational data which are available ( e.g., relics from asteroids in our own solar system as well as gas lifetimes in other systems) suggest that early growth must be rapid. If a small number of 100-km-sized planetesimals do manage to form by some method such as streaming instability, then gas drag effects would enable such a body to efficiently accrete smaller solids from beyond its Hill sphere. This enhanced accretion cross-section, paired with dense gas and large populations of small solids enables a planet to grow at much faster rates. As the planetesimals accrete pebbles, they experience an additional angular momentum exchange, which could cause slow inward drift and a consequent back-reaction on growth rates. We present self-consistent hydrodynamic simulations with direct particle integration and gas-drag coupling to estimate the rate of planetesimal growth due to pebble accretion. We explore a range of particle sizes and disk conditions using a wind tunnel simulation. We also perform numerical analyses of planetesimal growth and drift rates for a range of distances from the star. The results of our models indicate that rapid growth of planeteismals under our assumed model must be at orbital distances inwards of 1 AU, and that at such distances centimeter-sized pebbles and larger are required for maximized accretion. We find that growth beyond 1 AU is possible under certain limited, optimized conditions.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/58965
note: Planetesimal Growth through theAccretion of Small SolidsbyAnna HughesB.Sc., Rensselaer Polytechnic Institute, 2013A THESIS SUBMITTED IN PARTIAL FULFILLMENT OFTHE REQUIREMENTS FOR THE DEGREE OFMASTER OF SCIENCEinThe Faculty of Graduate and Postdoctoral Studies(Physics)THE UNIVERSITY OF BRITISH COLUMBIA(Vancouver)August 2016c© Anna Hughes 2016AbstractThe growth and migration of planetesimals in a young protoplanetary disk is fundamental to theplanet formation process. However, in our modeling of early growth, there are a several processesthat can inhibit smaller grains from growing to larger sizes, making growth beyond size scales ofcentimeters difficult. The observational data which are available ( e.g., relics from asteroids inour own solar system as well as gas lifetimes in other systems) suggest that early growth mustbe rapid. If a small number of 100-km-sized planetesimals do manage to form by some methodsuch as streaming instability, then gas drag effects would enable such a body to efficiently accretesmaller solids from beyond its Hill sphere. This enhanced accretion cross-section, paired with densegas and large populations of small solids enables a planet to grow at much faster rates. As theplanetesimals accrete pebbles, they experience an additional angular momentum exchange, whichcould cause slow inward drift and a consequent back-reaction on growth rates.We present self-consistent hydrodynamic simulations with direct particle integration and gas-drag coupling to estimate the rate of planetesimal growth due to pebble accretion. We explorea range of particle sizes and disk conditions using a wind tunnel simulation. We also performnumerical analyses of planetesimal growth and drift rates for a range of distances from the star.The results of our models indicate that rapid growth of planeteismals under our assumed modelmust be at orbital distances inwards of 1 AU, and that at such distances centimeter-sized pebblesand larger are required for maximized accretion.…
has type: Thesis/Dissertation
date issued: 2016-09
is shown at: 10.14288/1.0308779
language: eng
degree discipline: Physics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/58965