Terrestrial Planet Formation

Using computer models, I investigate the formation of terrestrial planets around the Sun and other Sun-like stars, around low mass M stars, around stars with different giant or stellar companions. My models can help determine where Earth-like planets can form and remain stable for billions of years. By tracking fragmentation during the late stages of planet formation, I can also quantify the abundance of water Earth-like planets can accrete in these various regimes, and determine the frequency of giant impacts onto these planets that could strip atmospheres and oceans and therefore be detrimental to habitability.
More than 70% of stars in our galaxy are M dwarfs, more than half of all main-sequence stars have a stellar companion, and the occurrence rate of Jupiter-analogs around Sun-like stars is thought to be low (<10%). Studying whether Earth-like planets can form and be habitable in these three regimes therefore has big implications for the abundance of habitable planets in our galaxy. My research aims to support target selection for NASA’s future space missions by predicting the best places to look for potentially habitable planets and signs of extraterrestrial life.

Exoplanet Discovery and Characterization

My research focuses on the detection, validation and characterization of exoplanets. I have worked on many facets of the Kepler and K2 Missions since 2006. One of the many highlights was my discovery and characterization of Kepler-186f, the first Earth-size planet found in the habitable zone of another star. I have also co-discovered and characterized hundreds of other exoplanets working with scientists from around the world. I combine algorithm development, modern statistics, and ground-based follow-up observations to find and confirm planets, and dynamical analyses to study their long-term evolution and stability.

Alpha Centauri

I study planet formation in the Alpha Centauri AB binary star system, the closest binary system to Earth. In 2002, I showed that terrestrial planets like Earth can form around either star as long as the inclination of the protoplanetary disk was less than about 30 degrees relative to the binary orbital plane. With improved models that take into account collisional fragmentation and improved computational resources (the NASA Ames supercomputer) I am running a large number of high resolution simulations. My models will determine not just where planets can form around either star, but will examine the impact flux of material onto the planets to determine if they can accrete water and retain atmospheres.