Direct detection and characterization of extrasolar planets

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We propose to study exoplanets and dusty debris disks around nearby stars using high angular resolution and high dynamic range imaging. We focus on the Gemini Planet Imager (GPI) instrument, which is an "extreme" adaptive optics coronagraph that will image self-luminous exoplanets orbiting stars in the solar neighborhood. The first stage of this task includes preparation for and execution of exoplanet surveys with GPI. Although the youngest stars (<100 Myr) are the best targets, GPI has good sensitivity to exoplanets with ages up to 2 Gyr. These "adolescent" host stars are more numerous than their youthful cousins and therefore they are important because they offer the statistical riches necessary to characterize planet populations. Although the majority of young stars within 100 pc have been located, a much smaller fraction of < 2 Gyr stars have been identified. We will pursue the identification of young stars and constrain their ages in a spectroscopic survey of about 1500 stars. We will measure Ca II H&K and Li I 6707 Å line strengths, as well as stellar v sin i and radial velocities. The second stage of this investigation involves actual observing with GPI to identify candidate exoplanets. We will conduct three core surveys that will: 1) establish the abundance of planetary systems; 2) test the core accretion model by conducting a census of regions where gas giants can only form via gravitational instability; 3) shed light on the origin of hot Jupiters by finding planets that migrated outwards; 4) show whether or not the architecture of our own planetary system is unique. The third stage involves confirmation and characterization of the candidates found using astrometry and spectroscopy. Once physical association has been confirmed the final phase involves measurement of atmospheric properties (effective temperature, gravity, and composition) and preliminary estimates of orbital elements. Each part of the proposed work is designed to attract the best students to pursue graduate research and engage them at the highest levels; it is planned that four PhD thesis will result from this program.