Physical Society Colloquium

Interview for Faculty Position

Transit Searches for Extrasolar Planets:
Properties, Pitfalls, Payoffs, and Promises

B. Scott Gaudi

Harvard-Smithsonian Center for Astrophysics

Planets orbiting other stars can be detected via the small drop in the stellar flux that occurs when a planet transits the face of its parent star. Searches for extrasolar planets using the transit method will likely prove invaluable in testing theories of the formation and evolution of planetary systems. I review the landscape of transit searches for extrasolar planets, highlighting some of their basic properties, primary obstacles, important results, and future prospects. The equations that describe the observables and detectability of planetary transits are deceptively simple. However, careful consideration of these equations can elucidate nearly all of the essential properties, requirements, and difficulties of transit searches. I demonstrate how such considerations, when combined with rudimentary knowledge of the properties of stars, can reveal important, mostly unappreciated aspects of two types of transit searches: deep searches in the Galactic field, and targeted searches toward simple stellar systems. I use these arguments to interpret the results of the field transit surveys by the OGLE collaboration, drawing important conclusions regarding the period distribution of close-in planets. I conclude by speculating on the future prospects for transit searches, in particular the search for Neptune-sized planets from the ground, and habitable terrestrial planets from space with the planned mission Kepler.