Sean M. Mills
Graduate Student, Department of Astronomy and Astrophysics

Location: ERC 550

Scientific Advisor: Daniel Fabrycky

Exoplanet dynamics, evolution, formation, and migration. Photometry and TTV/TDV detection. Circumbinary exoplanets.
Publications: ADS | arXiv

Research Fields:
Check out my website for a description of what I do:

Ph.D. Thesis Defense
Defense date: July 7, 2017
Ph.D. Thesis: "Detecting and Interpreting the Dynamical Evolution of Transiting Multiplanet Systems"

Ph.D. Committee members: Jacob Bean, Fred Ciesla, Fausto Cattaneo

"Mills' thesis is a tour-de-force of planetary dynamics. Using data from NASA's Kepler mission, Mills explored sub-Neptunes in resonant orbits, Mars-mass planets in dynamically packed orbits, and gas giants torquing each other's orbits. To top it off, Mills has interpreted statistical trends in their orbits and their atmospheres that point to planetary evolution from their formation to today."
- Daniel Fabrycky, Ph.D. advisor

Thesis Abstract: The dynamical interactions of our Solar System have been studied in depth since Isaac Newton recognized that the planets may not be stable to each other's gravitational perturbations. Recently, the discovery of exoplanet systems, including approximately a thousand planet candidates in systems of more than two bodies, has opened an extremely vast and diverse laboratory for planetary dynamics. In this dissertation, I describe techniques for measuring the dynamical, post-Keplerian interactions of planetary systems. Such signals often require numerical N-body analysis and photodynamic techniques combined with Bayesian statistics to correctly determine the properties of the planetary systems causing them. By simultaneously fitting the entire lightcurve data set at once, I am able to extract low signal-to-noise effects such as the resonance dynamics of a very faint system (Kepler-223), the slow orbital precession of a giant planet system (Kepler-108), and transit timing variations among very small and low mass planets (Kepler-444). I use these analyses to gain physical insight into the system's history, such as Kepler-108's potentially chaotic, violent past. Kepler-223's present structure indicates a migration origin for at least some close-in, sub-Neptune planets, which I explore in terms of tidal dissipation, smooth and stochastic migration, and secular evolution. I also analyze circumbinary systems including the newly discovered KIC 10753734. Taken together, these results provide insight into planetary formation in a broad array of environments for planet from compact sub-Neptune systems to Jupiters and circumbinary planets.

Department Committees
Past Department Committees:
  • Admissions: 2016 - 2017