THE DISTRIBUTION OF TRANSIT DURATIONS FOR KEPLER PLANET CANDIDATES AND IMPLICATIONS FOR THEIR ORBITAL ECCENTRICITIES

Journal Article · Tue Nov 01 00:00:00 EDT 2011 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.1088/0067-0049/197/1/1· OSTI ID:21560321

Moorhead, Althea V; Ford, Eric B; Morehead, Robert C ^[1]; Rowe, Jason; Caldwell, Douglas A; Jenkins, Jon M; Jie, Li; Quintana, Elisa ^[2]; Borucki, William J; Bryson, Stephen T; Koch, David G; Lissauer, Jack J ^[3]; Batalha, Natalie M ^[4]; Fabrycky, Daniel C ^[5]; Gautier, Thomas N ^[6]; Holman, Matthew J; Quinn, Samuel N; Ragozzine, Darin ^[7]; Lucas, Philip ^[8]

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1. Astronomy Department, University of Florida, 211 Bryant Space Sciences Center, Gainesville, FL 32111 (United States)
2. SETI Institute, Mountain View, CA 94043 (United States)
3. NASA Ames Research Center, Moffett Field, CA 94035 (United States)
4. Department of Physics and Astronomy, San Jose State University, San Jose, CA 95192 (United States)
5. UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)
6. Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA 91109 (United States)
7. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
8. Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, AL10 9AB (United Kingdom)

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 to the maximum transit duration for a circular orbit). We analyze the transit duration distribution of Kepler planet candidates. We find that for host stars with T{sub eff} > 5100 K we cannot invert this to infer the eccentricity distribution at this time due to uncertainties and possible systematics in the host star densities. With this limitation in mind, we compare the observed transit duration distribution with models to rule out extreme distributions. If we assume a Rayleigh eccentricity distribution for Kepler planet candidates, then we find best fits with a mean eccentricity of 0.1-0.25 for host stars with T{sub eff} {<=} 5100 K. We compare the transit duration distribution for different subsets of Kepler planet candidates and discuss tentative trends with planetary radius and multiplicity. High-precision spectroscopic follow-up observations for a large sample of host stars will be required to confirm which trends are real and which are the results of systematic errors in stellar radii. Finally, we identify planet candidates that must be eccentric or have a significantly underestimated stellar radius.

• OSTI ID: 21560321
• Journal Information: Astrophysical Journal, Supplement Series, Vol. 197, Issue 1; Other Information: DOI: 10.1088/0067-0049/197/1/1; ISSN 0067-0049
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ORBITS
PLANETS
STARS