Formation and Early Evolution of Planetary Systems
(2016)- Abstract
- Over the past 20 years we have discovered that exoplanets are common in the Galaxy, and are far more diverse than anyone expected. Half of all Sun-like stars are accompanied by at least one super-Earth (a planet with a size between Earth and Neptune), many planets have very high eccentricities indicative of a dynamical origin, and a small fraction of stars are accompanied by hot Jupiters, whose origin is poorly understood. In this thesis I investigate the formation and dynamical evolution of planetary systems. In half of this thesis I develop constraints for the formation of planetesimals by the runaway convergence of radial migration known as the streaming instability, and apply the result to a computer model of a photo-evaporating... (More)
- Over the past 20 years we have discovered that exoplanets are common in the Galaxy, and are far more diverse than anyone expected. Half of all Sun-like stars are accompanied by at least one super-Earth (a planet with a size between Earth and Neptune), many planets have very high eccentricities indicative of a dynamical origin, and a small fraction of stars are accompanied by hot Jupiters, whose origin is poorly understood. In this thesis I investigate the formation and dynamical evolution of planetary systems. In half of this thesis I develop constraints for the formation of planetesimals by the runaway convergence of radial migration known as the streaming instability, and apply the result to a computer model of a photo-evaporating protoplanetary disk. In the rest of this thesis I study the dynamical stability of planetary systems with multiple giant planets in order to learn about the past history of exoplanet systems.
All of my work relies heavily on computer modelling. I used hydrodynamic simulations of a shearing box inside a protoplanetary disk to determine the dust-to-gas ratio needed to trigger the streaming instability as a function of particle size. Similarly, the protoplanetary disk model is a one-dimensional hydrodynamic model that includes sink terms for photoevaporative outflows. The dynamical evolution of planetary systems occurs after planet formation is complete and the disk has fully dissipated. Dynamical simulations were performed with an N-body code designed for long-term modelling of planetary orbits.
My work has shown that the streaming instability is active for smaller particles than previously thought possible. I also found that in a protoplanetary disk, planetesimals begin to form early in the outer disk, where photoevaporation can more easily remove the gas component. As the disk evolves, planetesimal formation moves inward. From my dynamical simulations I am able to use present-day observations to estimate the probability that a habitable planet would have survived in a given planetary system, and I can estimate the masses of the planets that suffered ejections or collisions in that system. (Less) - Abstract (Swedish)
- Planeter är mycket vanliga i vår galax. De senaste 20 åren har man upptäckt att de flesta solliknande stjärnor har planeter kretsande omkring sig. Man vet också att det finns en stor variation av exoplaneter. Runt 50\% av alla solliknande stjärnor har superjordar (planeter med en massa eller radie mellan jordens och Neptunus) kretsande tätt intill sig vilket gör solsystemet otypiskt. Man har hittat bevis för att många planetsystem har genomgått perioder av dynamiskt kaos, under vilka gravitationella interaktioner mellan planeter har lett till radikala förändringar av deras banor och troligtvis utkastandet av en eller flera planeter. Det finns till och med bevis för att något sådant kan ha hänt i vårt eget solsystem. Målet med den här... (More)
- Planeter är mycket vanliga i vår galax. De senaste 20 åren har man upptäckt att de flesta solliknande stjärnor har planeter kretsande omkring sig. Man vet också att det finns en stor variation av exoplaneter. Runt 50\% av alla solliknande stjärnor har superjordar (planeter med en massa eller radie mellan jordens och Neptunus) kretsande tätt intill sig vilket gör solsystemet otypiskt. Man har hittat bevis för att många planetsystem har genomgått perioder av dynamiskt kaos, under vilka gravitationella interaktioner mellan planeter har lett till radikala förändringar av deras banor och troligtvis utkastandet av en eller flera planeter. Det finns till och med bevis för att något sådant kan ha hänt i vårt eget solsystem. Målet med den här avhandlingen är att utveckla vår förståelse av hur planeter bildas, och hur de utvecklas. Mitt arbete kan delas upp i två delar:
- Hälften av mitt arbete fokuserar på bildandet av planetesimaler. Planetesimaler är ett viktigt steg i bildandet av planeter. De är stora kroppar, mellan 1 och 100 km i diameter. Planetesimaler är byggstenarna för stenplaneter såsom jorden, men krävs också för bildandet av de stenkärnor som tros finnas i centrum av gasjättar såsom Jupiter och Saturnus. I min första undersökning använde jag datorsimuleringar för att bestämma villkoren för att planetesimaler skall kunna bildas (det beror huvudsakligen på densiteten av faska kroppar och gas samt på storleken av de fasta kropparna). I min senaste artikel kombinerade jag de resultaten med en datormodell av en planetbildande skiva. Vi upptäckte att bildandet av planetesimaler börjar i skivans yttersta delar. Med tiden börjar planetesimalerna att bildas närmare och närmare stjärnan.
- Resten av mitt arbete fokuserar på utvecklingen av planetsystem efter det att de har bildats. I ett planetsystem är de gravitationella interaktionerna mellan planeterna små men, över miljontals år, kan deras påverkan byggas upp och resultera i att planeter kolliderar eller kastas ut från systemet. När det här händer lämnas de planeter som överlever på mer excentriska (elliptiska) banor. Jag har utvecklat metoder för att använda den här excentriciteten för att, i sin tur, få information om planetsystemets historia. I ett publicerat arbete beräknar jag sannolikheten att en beboelig planet skulle både överleva och förbli beboelig. I ett pågående arbete beräknar jag massorna på planeter som kastas ut och hur ofta planeters banor ändras på grund av en andra stjärna i ett binärt stjärnsystem. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/5f548fd3-44a9-4cf4-b579-1d698cb48364
- author
- Carrera, Daniel LU
- supervisor
- opponent
-
- Dr. Raymond, Sean, Laboratoire d’Astrophysique de Bordeaux, France
- organization
- publishing date
- 2016-10
- type
- Thesis
- publication status
- published
- subject
- keywords
- planet formation, planets and satellites: dynamical evolution and stability -- planets and satellites: gaseous planets -- planets and satellites: terrestrial planets, planets and satellites: terrestrial planets
- pages
- 140 pages
- publisher
- Lund University, Faculty of Science, Department of Astronomy and Theoretical Physics
- defense location
- Lund Observatory, Lundmark lecture hall, Sölvegatan 27, Lund
- defense date
- 2016-11-24 09:00:00
- ISBN
- 978-91-7623-978-0
- 978-91-7623-979-7
- project
- Formation and Early Evolution of Planetary Systems
- From pebbles to planets: towards new horizons in the formation of planets
- language
- English
- LU publication?
- yes
- id
- 5f548fd3-44a9-4cf4-b579-1d698cb48364
- date added to LUP
- 2016-10-27 16:45:47
- date last changed
- 2018-11-21 21:26:55
@phdthesis{5f548fd3-44a9-4cf4-b579-1d698cb48364,
abstract = {{Over the past 20 years we have discovered that exoplanets are common in the Galaxy, and are far more diverse than anyone expected. Half of all Sun-like stars are accompanied by at least one super-Earth (a planet with a size between Earth and Neptune), many planets have very high eccentricities indicative of a dynamical origin, and a small fraction of stars are accompanied by hot Jupiters, whose origin is poorly understood. In this thesis I investigate the formation and dynamical evolution of planetary systems. In half of this thesis I develop constraints for the formation of planetesimals by the runaway convergence of radial migration known as the streaming instability, and apply the result to a computer model of a photo-evaporating protoplanetary disk. In the rest of this thesis I study the dynamical stability of planetary systems with multiple giant planets in order to learn about the past history of exoplanet systems.<br/>All of my work relies heavily on computer modelling. I used hydrodynamic simulations of a shearing box inside a protoplanetary disk to determine the dust-to-gas ratio needed to trigger the streaming instability as a function of particle size. Similarly, the protoplanetary disk model is a one-dimensional hydrodynamic model that includes sink terms for photoevaporative outflows. The dynamical evolution of planetary systems occurs after planet formation is complete and the disk has fully dissipated. Dynamical simulations were performed with an N-body code designed for long-term modelling of planetary orbits.<br/>My work has shown that the streaming instability is active for smaller particles than previously thought possible. I also found that in a protoplanetary disk, planetesimals begin to form early in the outer disk, where photoevaporation can more easily remove the gas component. As the disk evolves, planetesimal formation moves inward. From my dynamical simulations I am able to use present-day observations to estimate the probability that a habitable planet would have survived in a given planetary system, and I can estimate the masses of the planets that suffered ejections or collisions in that system.}},
author = {{Carrera, Daniel}},
isbn = {{978-91-7623-978-0}},
keywords = {{planet formation; planets and satellites: dynamical evolution and stability -- planets and satellites: gaseous planets -- planets and satellites: terrestrial planets; planets and satellites: terrestrial planets}},
language = {{eng}},
publisher = {{Lund University, Faculty of Science, Department of Astronomy and Theoretical Physics}},
school = {{Lund University}},
title = {{Formation and Early Evolution of Planetary Systems}},
year = {{2016}},
}