Yale Astronomy Public PhD Defense - Emma Louden

The architecture of planetary systems - how planets are arranged around their stars - provides crucial clues about how these systems formed and evolved over time. While our own Solar System has planets orbiting in nearly circular paths aligned with the Sun’s equator, observations of planets around other stars reveal a surprising diversity of architectures. This thesis investigates what these varied planetary arrangements can tell us about how planetary systems are born and develop. By studying resonances (special orbital periods where planets regularly align), tilted orbits, and the long-term evolution of planetary systems, we gain insights into their origins. Key findings include evidence that hotter stars tend to have more misaligned planetary systems regardless of planet size, and that certain types of tilted planets can maintain their unusual orbits for billions of years. We also developed new methods to probe planetary composition by examining how orbits change over time. This research advances our understanding of the processes that shape planetary systems and helps explain why they display such remarkable diversity across our galaxy. The findings provide important constraints for theories of planet formation and evolution while raising intriguing questions for future exploration.