Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"protoplanetary discs"”.
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Magnetic Fields in Protoplanetary Discs
Protoplanetary discs are flattened discs of gas and dust surrounding young stars that are believed to be the sites of planet formation. They are believed to be threaded by large-scale magnetic fields, which significantly affect their dynamics through processes such as the magneto-rotational …
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Protoplanetary discs across the stellar mass range
… I discuss two studies concerned with modelling protoplanetary discs around stars from different ends of the stellar mass range. In Chapters 1 and 2, I give an introduction to the field of protoplanetary discs, both from an observational and a modelling point of view, and describe the radiative …
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Magnetohydrodynamics in the Inner Regions of Protoplanetary Discs
The inner regions of protoplanetary discs, which encompass the putative habitable zone, comprise a highly ionised, turbulent active region and a poorly ionised outer dead zone. The complex magnetohydrodynamic processes at this dead–active zone interface significantly impact the disc's evolution – …
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The migration of giant planets in massive protoplanetary discs
… migration patterns of giant planets in unstable discs using radiative hydrodynamic simulations. More specifically we examine the migration of planets within different mass discs and at different orbital radii. We find that planets initially migrate inwards quickly. They are able to open up a gap …
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The impact of environment on the evolution of protoplanetary discs
Protoplanetary discs represent the mass reservoir for planet formation, and the chemicophysical mechanisms occurring during their lifetime sculpt the fundamental properties of the planets born within them. Historically, protoplanetary discs have been initially considered as idealised isolated …
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The Importance of Photoevaporation in the Evolution of Protoplanetary Discs
Protoplanetary discs consist of gas and dust - the remnants of the star formation process - found around stars in the first few million years of their life. Photoevaporation, whereby high-energy radiation from the central star heats disc material causing it to flow away in a wind, is one process …
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A Global Hydrodynamic Investigation into the Transport of Material in Protoplanetary Discs
… of massive planets on gas and dust motion in protoplanetary discs, with a focus on material transport through planetary- induced gaps. Using 3D global hydrodynamic simulations with FARGO3D, we explore dust filtration and transport in discs with embedded planets with masses equal to or …
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ASSESSING THE ROLE OF EXTERNAL PHOTOEVAPORATION OF PROTOPLANETARY DISCS IN NEARBY STAR-FORMING REGIONS
Characterising the physical processes driving protoplanetary disc evolution and the connection to the star-forming environment is essential to understanding planet formation and diversity. Most stars (and their discs) in the Galaxy form in massive clusters where the intense UV radiation emitted by …
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The impact of star cluster environments on planet formation
… will not disrupt or disperse planet forming discs. Low-mass clusters containing massive stars may present a solution to this problem. The presence of massive stars within star-forming regions will affect planet forming discs to varying degrees, depending on the initial conditions of the …
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From Shadows to Hotspots: Imaging of Inner Protoplanetary Disc Structure
… characterise and image the innermost regions of protoplanetary discs, investigating disc geometry, accretion signatures, inner/outer disc misalignments, and temporal and azimuthal variability. Through these observations, I aim to target the dynamical processes that govern inner disc structure, …
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Planet formation and evolution in protoplanetary disc
… the formation of planets via core accretion in protoplanetary discs - disc-shaped structures made of dust and gas that form around newborn stars- and in their subsequent evolution as a consequence of disc-planet interaction from a numerical and theoretical perspective. In the core accretion …
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Dynamical instabilities in disc-planet interactions
Protoplanetary discs can be dynamically unstable due to structure induced by an embedded giant planet. In this thesis, I discuss the stability of such systems and explore the consequence of instability on planetary migration. I present semi-analytical models to understand the formation of the …
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High-resolution studies of exoplanetesimal belt formation and evolution
Stars are born with gas-rich protoplanetary discs that typically survive for a few Myr before dispersing, after which they are left with the planetary bodies that formed within the protoplanetary system: planets, and belts of planetesimals (km-sized rocky and icy bodies). Planetesimals within belts …
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The influence of stellar birth environment on protoplanetary disc dispersal
Protoplanetary discs (PPDs) are the progenitors of planets and represent the material available for their formation. Recent surveys indicate that exoplanetary architectures are diverse and the processes that govern the evolution of PPDs contribute significantly to the properties of these …
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Connecting models and observations of disc evolution and planet formation
… and composition from gas- and dust-rich discs orbiting young stars. Over the last decade, the Atacama Large Millimeter/submillimeter Array revolutionised our understanding of planet formation, opening up the possibility of determining the physical-chemical properties of protoplanetary …
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Protoplanetary disc evolution and dispersal
In this thesis I have studied how discs around young stars evolve and disperse. In particular, I build models which combine viscous evolution with photoevaporation, as previous work suggests that photoevaporation can reproduce the observed disc evolution and dispersal time-scales. The main question …
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Disc-planet interactions in inviscid discs
Planets are born in protoplanetary discs (PPDs), made of gas and dust, which surround newly formed stars. Gravitational coupling provides planets with means to interact with their birth environment, leading to the excitation of global spiral density waves, which drive evolution of the disc (such as …
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Planet formation, resonant drag instabilities, and vortices
… dust grains early in the life of almost every protoplanetary disc . I then describe the main stages of the leading ‘core acccretion’ scenario: Brownian coagulation, turbulent coagulation, the metre-scale barrier, planetesimal accretion, pebble accretion, cooling-limited gas accretion, and …
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The structure and stability of vortices in astrophysical discs
… planetesimals from dust within the lifetime of a protoplanetary disc and before such bodies spiral into the central star. Collecting matter in vortices is a promising mechanism for planetesimal growth, but little is known about their stability under these conditions. We therefore aim to produce a …
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Hydromagnetic Oscillations and Instabilities in Astrophysical Discs
… of oscillations and instabilities in accretion discs, developing theoretical and numerical models to explore the physical nature of variability encountered in a variety of astrophysical contexts. Through linear theory and semi-analytical calculations, I first consider the physical properties of …
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