Thermal Evolution of Forming Planets: Isotope Enrichment, Differentiation & Volatile Retention
- Doctoral Thesis
Rights / licenseIn Copyright - Non-Commercial Use Permitted
Discoveries of extrasolar planets in the last decades raise the question of how common Earth-like worlds with clement surface environments are within the galaxy. Because astronomical observations are ultimately limited in providing a complete picture of the planetary census, a comprehensive understanding of planetary systems’ formation and evolution can deliver valuable insights into key physical and chemical properties that cannot be probed by remote sensing alone. In order to understand how terrestrial worlds are formed and distributed, I investigate in this thesis the early evolution of planetary systems and the interior dynamics and volatile retention of rocky protoplanets. To place the Solar system in the context of the extrasolar planet population, I model the enrichment of protoplanetary disks with short-lived radionuclides, namely Al-26 and Fe-60, in typical star-forming environments. I find their distribution to be dichotomous: many planetary systems with zero or negligible abundances, and fewer systems with levels comparable to the early Solar system. Further, I quantify the parametric controls on interior evolution and volatile loss of planetesimals that accrete to form terrestrial planets. I derive the primary thermochemical regimes for the build-up of internal magma oceans, core segregation, chemical differentiation, and volatile retention. Matching planetesimal interior evolution with meteoritic evidence, I constrain the accretion dynamics and reprocessing of planetary materials in the early Solar system, in order to gain a better understanding of planetary assembly. Finally, by extrapolating the derived mechanisms to the exoplanet population, I demonstrate the primary influence of short-lived radionuclides on the efficiency of volatile delivery to terrestrial planets: enriched systems with Solar-like or higher levels tend to form water-depleted planets, while not- or barely-enriched systems dominantly form ocean worlds. My findings provide a direct link between the star-forming birth environment of planetary systems and the compositional make-up and long-term evolution of rocky planets that form in them. The system-to-system deviations in the abundance of short-lived radionuclides across young star-forming regions qualitatively distinguish planetary systems’ formation and evolution, and control the distribution and prevalence of terrestrial planets with Earth-like bulk compositions Show more
External linksSearch via SFX
ContributorsExaminer: Gerya, Taras V.
Examiner: Meyer, Michael R.
Examiner: Golabek, Gregor J.
Examiner: Parker, Richard J.
Examiner: Tackley, Paul J.
Examiner: Ciesla, Fred. J.
Subjectplanet formation; star formation; exoplanets; solar system; volatile delivery; differentiation
Organisational unit02506 - Institut für Geophysik / Institute of Geophysics
03698 - Tackley, Paul / Tackley, Paul
MoreShow all metadata