The Distribution of Transit Durations for Kepler Planet Candidates and Implications for their Orbital Eccentricities

Doppler planet searches have discovered that giant planets follow orbits with a wide range of orbital eccentricities, revolutionizing theories of planet formation. The discovery of hundreds of exoplanet candidates by NASA’s Kepler mission enables astronomers to characterize the eccentricity distribution of small exoplanets. Measuring the eccentricity of individual planets is only practical in favorable cases that are amenable to complementary techniques (e.g., radial velocities, transit timing variations, occultation photometry). Yet even in the absence of individual eccentricities, it is possible to study the distribution of eccentricities based on the distribution of transit durations (relative Astronomy Department, University of Florida, 211 Bryant Space Sciences Center, Gainesville, FL 32111, USA SETI Institute, Mountain View, CA 94043, USA NASA Ames Research Center, Moffett Field, CA, 94035, USA UCO/Lick Observatory, University of California, Santa Cruz, CA 95064, USA Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA San Jose State University, San Jose, CA 95192, USA Orbital Sciences Corp,oration/NASA Ames Research Center, Moffett Field, CA 94035, USA Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA 91109, USA Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, AL10 9AB, England University of California, Berkeley, Berkeley, CA 94720 Bay Area Environmental Research Institute/NASA Ames Research Center, Moffett Field, CA 94035, USA Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117, USA Department of Physics, Broida Hall, University of California, Santa Barbara, CA 93106, USA Mullard Space Science Laboratory, Department of Space and Climate Physics, University College London, Holmbury St. Mary, Dorking, Surrey, RH56NT, UK ar X iv :1 10 2. 05 47 v1 [ as tr oph .E P] 2 F eb 2 01 1