Implications for Planet Formation from Population Inference of Kepler-planet-candidates and Eclipsing Binaries

Open Access
Author:
Shabram, Megan Iris
Graduate Program:
Astronomy and Astrophysics
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
October 08, 2015
Committee Members:
  • Eric Ford, Dissertation Advisor
  • Steinn Sigurdsson, Committee Member
  • Ronald Lynn Gilliland, Committee Member
  • Kevin Luhman, Committee Member
  • Christopher Howard House, Committee Member
Keywords:
  • exoplanets
  • planet formation
Abstract:
The Kepler Space Science Mission has revolutionized our understanding of planetary system architectures, and the diversity of planet bulk densities. From Kepler, we now have a population of ∼4,700 planet candidates and ∼ 3000 eclipsing binaries with measured light curves, from which we can begin to characterize the distribution of stars and planets to tease out relationships between planet properties and host star properties in a robust statistical manner. The results of these investigations constrain proposed planet formation theories. This dissertation analyzes three particular sub-populations observed by Kepler that are well suited for hierarchical inference to characterize their population properties. First, we investigate the eccentricity distribution for a sample of short-period planet candidates from Kepler, where both the transit and occultation are observed for each system. This sub- sample lends a rare opportunity for tractable inference of its eccentricity distribution, exposing at least two populations within the eccentricity distribution and potential correlations of the eccentricity with host star metallicity and planet radius. Secondly, we investigate the mass-radius-eccentricity relation for a sample of near-resonant planet-pairs from Kepler. This study greatly improves upon previous research of constraining the mass-radius relation for small planets. Furthermore, we explore the period-eccentricity distribution of eclipsing binary stars from Kepler. We find that ∼ 72% of EBs below ∼ 11 days are very circularized, where as ∼ 87% of EBs above ∼ 11 days can take on a wide range in eccentricity values including some with significant eccentricities.