California-Kepler Survey. VIII. Eccentricities of Kepler Planets and Tentative Evidence of a High-metallicity Preference for Small Eccentric Planets
Abstract
Characterizing the dependence of the orbital architectures and formation environments on the eccentricity distribution of planets is vital for understanding planet formation. In this work, we perform statistical eccentricity studies of transiting exoplanets using transit durations measured via Kepler combined with precise and accurate stellar radii from the California-Kepler Survey and Gaia. Compared to previous works that characterized the eccentricity distribution from transit durations, our analysis benefits from both high-precision stellar radii (~3%) and a large sample of ~1000 planets. We observe that systems with only a single observed transiting planet have a higher mean eccentricity (e ~ 0.21) than systems with multiple transiting planets (e ~ 0.05), in agreement with previous studies. We confirm the preference for high- and low-eccentricity subpopulations among the single transiting systems. Finally, we show suggestive new evidence that high-e planets in the Kepler sample are preferentially found around high-metallicity ([Fe/H] > 0) stars. We conclude by discussing the implications on planetary formation theories.
Additional Information
© 2019 The American Astronomical Society. Received 2018 December 14; revised 2019 February 27; accepted 2019 March 7; published 2019 April 29. We thank the Kepler and Gaia teams for years of work making these precious data sets possible. We are grateful to the time assignment committees of the University of Hawaii, the University of California, the California Institute of Technology, and NASA for their generous allocations of Keck observing time that enabled this large project. This research has made use of NASA's Astrophysics Data System, the Exoplanet Orbit Database, and the Exoplanet Data Explorer at exoplanets.org. A.W.H. acknowledges NASA grant NNX12AJ23G. L.M.W. acknowledges support from the Beatrice Watson Parrent Fellowship. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has long had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.Attached Files
Published - Mills_2019_AJ_157_198.pdf
Submitted - 1905.04625.pdf
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Additional details
- Alternative title
- CKS VIII: Eccentricities of Kepler Planets and Tentative Evidence of a High Metallicity Preference for Small Eccentric Planets
- Eprint ID
- 95094
- Resolver ID
- CaltechAUTHORS:20190429-160306530
- NNX12AJ23G
- NASA
- Beatrice Watson Parrent Fellowship
- Created
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2019-04-29Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC), Astronomy Department