Date of Award

8-12-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics and Astronomy

First Advisor

Dr. Russel J. White

Second Advisor

Dr. David W. Latham

Third Advisor

Dr. Douglas R. Gies

Fourth Advisor

Dr. Sebastien Lepine

Fifth Advisor

Dr. Joshua Von Korff

Abstract

In this dissertation, we present three complementary studies of the processes that drive planetary migration. The first is a radial-velocity survey in search of giant planets in adolescent (<1 >Gyr) open clusters. While several different mechanisms may act to drive giant planets inward, only some mechanisms will excite high eccentricities while doing so. Measuring the eccentricities of young hot Jupiters in these clusters (at a time before the orbits have had a chance to circularize due to tidal friction with their host stars) will allow us to identify which mechanisms are most important. Through this survey, we detect the first 3 hot Jupiters in open clusters (and at least 4 long-period planets), and we measure the occurrence rate of hot Jupiters in clusters to be similar to that of the field (~1%). We determine via analyses of hot Jupiter eccentricities and outer companions in these systems that high eccentricity migration mechanisms (those requiring the presence of a third body) are important for migration. The second project, an adaptive optics imaging survey for stellar companions to known hot Jupiter hosts, aims to determine the role that stellar companions in particular play in giant planet migration. Through a preliminary analysis, we derive a lower limit on the binary frequency of 45% (greater than that of the typical field star), and we find that the presence of a companion is correlated with misalignment of the spin-orbit angle of the planetary system, as would be expected for stellar Kozai-Lidov migration: at least 74% of misaligned systems reside in binaries. We thus conclude that among high eccentricity migration mechanisms, those requiring a stellar companion play a significant role. Finally, we describe simulations of measurements of the planet population expected to be discovered by TESS, and use these to demonstrate that a strong constraint on the obliquity distribution of small planets can be derived using only TESS photometry, Gaia astrometry, and vsin(i) measurements of the host stars. This obliquity distribution will be a key piece of evidence to help detemine the likely formation and migration histories of small planets, and can contribute to the assessment of the potential for Earth-like planets to harbor life.

DOI

https://doi.org/10.57709/8851138

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