Dissertation

The Past, Present, and Future of Planetary Systems

Vanderburg, Andrew M

2017

Overview

Studying exoplanets which transit their host stars is a fruitful approach to developing a detailed understanding of their planetary systems. In this thesis, we develop data analysis methods and techniques to study transiting planets, and we use these methods to perform case studies to learn about the past histories, present-day characteristics, and future evolution of these planetary systems.In Chapters 2 and 3, we develop techniques to analyze data from the Kepler space telescope in its new K2 operating mode. After a mechanical failure ended the original Kepler mission, the spacecraft was repurposed to conduct a survey for transiting planets in the ecliptic plane. Data from K2 shows large systematic errors which were not present in the original Kepler mission, and which hinder searches for and studies of transiting exoplanets if they are not taken into account. In these two chapters, we develop techniques to correct these systematics and search the K2 light curves for exoplanets.In Chapters 4 and 5, we conduct a detailed investigation into a single planetary system for which it is possible to place unique constraints on its past formation and migration history. In Chapter 4, we present the discovery in K2 data of two additional transiting planets in the known hot Jupiter system, WASP-47. The existence of these planets shows that the system must have formed in a dynamically quiet enough manner to not disrupt their orbits. In Chapter 5, we continue studying the WASP-47 system using precise radial velocity observations with the HARPS-N spectrograph. We measure the masses of the two smaller planets, determining the composition of the inner planet to be inconsistent with an Earth-like rocky composition, making it likely this planet is the photo-evaporated remnant of a larger Neptune-like exoplanet. We also refine the orbit of a long-period gas giant planet discovered nearly simultaneous with our discovery of the two smaller transiting planets and find that it likely has an inclination very close to the inclination of the inner transiting planets, further suggesting a dynamically quiet formation history for the WASP-47 system.In Chapters 6, 7, and 8, we present the discovery in K2 data (and in one case, follow-up mass measurements) of new systems of planets transiting nearby bright stars. These planets are important because they are amenable to follow-up observations to learn about their masses, compositions, and atmospheres. It will be possible to learn more about the present-day characteristics of these exoplanets as we will continue to study them in detail.In Chapter 9, we present the discovery in K2 data and a study of remains of a minor planet that is transiting a white dwarf star. The star WD 1145+017 is a metal-polluted white dwarf star with infrared excess emission, characteristic of white dwarfs which were recently believed to have disrupted minor planets and accreted the remains onto their surfaces. We discovered that WD 1145+017 is being transited by the debris produced by the disruption of a minor planet, probably the size of Ceres, from the white dwarf progenitor's planetary system. Most of the stars in our galaxy will eventually become white dwarfs when they exhaust their nuclear fuel and evolved off the main sequence, so planetary systems around stellar remnants like WD 1145+017 represent the future fate of most of the exoplanets we know of today.

• Publisher: ProQuest Dissertations & Theses
• Subject: Astronomy
• ISBN: 9798678153135