Raving with the stars: structure, evolution and (in)stability of the inner regions of protoplanetary discs
The high occurrence rate of exoplanets on close-in orbits has raised fundamental ques- tions about their formation and has made the inner regions of protoplanetary discs a central subject of current planetary astrophysics. This thesis explores the structure and evolution of the inner disc regions ov...
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| Natura: | Book/Monograph Tesi |
| Lingua: | inglese |
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Heidelberg
28 Jul. 2026
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| DOI: | 10.11588/heidok.00039112 |
| Soggetti: | |
| Accesso online: | Resolving-System, kostenfrei: https://nbn-resolving.org/urn:nbn:de:bsz:16-heidok-391122 Resolving-System, kostenfrei: https://doi.org/10.11588/heidok.00039112 Verlag, kostenfrei, Volltext: http://www.ub.uni-heidelberg.de/archiv/39112 Langzeitarchivierung Nationalbibliothek, kostenfrei: https://d-nb.info/1414756801/34 
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| Note sull'autore: | put forward by Michael Cecil ; referees: Dr. Mario Flock [und eine weitere Gutachterin] |
| Riassunto: | The high occurrence rate of exoplanets on close-in orbits has raised fundamental ques- tions about their formation and has made the inner regions of protoplanetary discs a central subject of current planetary astrophysics. This thesis explores the structure and evolution of the inner disc regions over thousand- year timescales, with particular emphasis on the dynamics of the local turbulence tran- sition. Two- and three-dimensional radiation hydrodynamic simulations are employed to capture the complex interplay of physical processes within the inner few astronom- ical units, including increasingly realistic descriptions of radiative properties and tur- bulence conditions. The results show that the conventional picture of the inner disc is generally not a static configuration but undergoes periodic phases of instability, triggered by the emergence of strong turbulence in otherwise weakly turbulent regions. This phenomenon sub- stantially restructures the inner disc, destroying and re-establishing solid-trapping pressure peaks and generating observable stellar accretion outbursts. Starting from a simplified model, the triggering mechanism of instability cycles is characterised, and the resulting evolution, accretion signatures and consequences for planet-forming conditions are assessed. Subsequent refinements challenge typical sim- plifying assumptions about radiative and turbulent properties. They show, in particu- lar, that the gas component’s opacity strongly affects the inner disc’s thermal structure, while the instability behaviour and outburst morphologies depend sensitively on the magnetic field strength and the conditions for turbulence activation. This work implies that the study of planet formation and migration close to the host star must be embedded within an analysis of the inner disc’s long-term stability. The periodic structural reshaping revealed in this thesis provides a new framework for un- derstanding the emergence of close-in exoplanetary systems and may have implications for the origins of the terrestrial planets of our Solar System. |
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| Descrizione fisica: | Online Resource |
| DOI: | 10.11588/heidok.00039112 |