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

Abstract

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_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_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.

30 pages, 19 figures

References in corpus (18)

• Characteristics of planetary candidates observed by Kepler, II: Analysis of the first four months of data
• Dynamical Outcomes of Planet-Planet Scattering
• Kepler Input Catalog: Photometric Calibration and Stellar Classification
• The Occurrence and Mass Distribution of Close-in Super-Earths, Neptunes, and Jupiters
• Hot Jupiters from Secular Planet--Planet Interactions
• Formation of Hot Planets by a combination of planet scattering, tidal circularization, and Kozai mechanism
• KEPLER's First Rocky Planet: Kepler-10b
• Origins of Eccentric Extrasolar Planets: Testing the Planet-Planet Scattering Model
• Modeling Kepler transit light curves as false positives: Rejection of blend scenarios for Kepler-9, and validation of Kepler-9d, a super-Earth-size planet in a multiple system
• On the Low False Positive Probabilities of Kepler Planet Candidates
• Inferring the eccentricity distribution
• Hot Jupiters in binary star systems
• On the Eccentricity Distribution of Exoplanets from Radial Velocity Surveys
• The Distribution of Transit Durations for Kepler Planet Candidates and Implications for their Orbital Eccentricities
• Characterizing the Orbital Eccentricities of Transiting Extrasolar Planets with Photometric Observations
• Impact of Orbital Eccentricity on the Detection of Transiting Extrasolar Planets
• A ground-based measurement of the relativistic beaming effect in a detached double WD binary
• Quantifying the challenges of detecting unseen planetary companions with transit timing variations

Cited by in corpus (92)

• Planet Occurrence within 0.25 AU of Solar-type Stars from Kepler
• The false positive rate of Kepler and the occurrence of planets
• The Occurrence and Architecture of Exoplanetary Systems
• Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems
• Architecture of Kepler's Multi-transiting Systems: II. New investigations with twice as many candidates
• Breaking the Chains: Hot Super-Earth systems from migration and disruption of compact resonant chains
• Fundamental Properties of Kepler Planet-Candidate Host Stars using Asteroseismology
• A stellar-mass-dependent drop in planet occurrence rates
• Eccentricity from transit photometry: small planets in Kepler multi-planet systems have low eccentricities
• Trumpeting M Dwarfs with CONCH-SHELL: a Catalog of Nearby Cool Host-Stars for Habitable ExopLanets and Life
• On the Formation of Hot Jupiters in Stellar Binaries
• Testing In Situ Assembly with the Kepler Planet Candidate Sample
• Lack of Inflated Radii for Kepler Giant Planet Candidates Receiving Modest Stellar Irradiation
• Exoplanet Orbital Eccentricities Derived From LAMOST-Kepler Analysis
• Architecture of Planetary Systems Based on Kepler Data: Number of Planets and Coplanarity
• Planetary Candidates Observed by Kepler. VII. The First Fully Uniform Catalog Based on The Entire 48 Month Dataset (Q1-Q17 DR24)
• Exoplanet Statistics and Theoretical Implications
• Density and Eccentricity of Kepler Planets
• Planetary Candidates Observed by Kepler V: Planet Sample from Q1-Q12 (36 Months)
• The statistics of multi-planet systems
• A Statistical Reconstruction of the Planet Population Around Kepler Solar-Type Stars
• The Distribution of Transit Durations for Kepler Planet Candidates and Implications for their Orbital Eccentricities
• Hot super-Earths and giant planet cores from different migration histories
• The Photoeccentric Effect and Proto-Hot Jupiters I. Measuring photometric eccentricities of individual transiting planets
• The Kepler-19 System: A Transiting 2.2 R_Earth Planet and a Second Planet Detected via Transit Timing Variations
• Secure TTV Mass Measurements: Ten Kepler Exoplanets between 3 and 8 Earth Masses with Diverse Densities and Incident Fluxes
• AMD-stability and the classification of planetary systems
• The mass of the Mars-sized exoplanet Kepler-138 b from transit timing
• Architectures of Exoplanetary Systems. I: A Clustered Forward Model for Exoplanetary Systems around Kepler's FGK Stars
• Can planetary instability explain the Kepler dichotomy?
• M Dwarf Metallicities and Giant Planet Occurrence: Ironing Out Uncertainties and Systematics
• Comparing HARPS and Kepler surveys: The alignment of multiple-planet systems
• The Exoplanet Eccentricity Distribution from Kepler Planet Candidates
• Period ratios in multi-planetary systems discovered by Kepler are consistent with planet migration
• Transit Timing Observations from Kepler: I. Statistical Analysis of the First Four Months
• Advances in exoplanet science from Kepler
• Transit Timing Variation of Near-Resonance Planetary Pairs. II. Confirmation of 30 planets in 15 Multiple Planet Systems
• A reassessment of the in situ formation of close-in super-Earths
• Transit Timing Observations from Kepler: II. Confirmation of Two Multiplanet Systems via a Non-parametric Correlation Analysis
• Kepler-10c, a 2.2-Earth radius transiting planet in a multiple system
• A paucity of proto-hot Jupiters on super-eccentric orbits
• Climate of Earth-like planets with high obliquity and eccentric orbits: implications for habitability conditions
• Architectures of Exoplanetary Systems. III: Eccentricity and Mutual Inclination Distributions of AMD-stable Planetary Systems
• Correlations between compositions and orbits established by the giant impact era of planet formation
• Characterizing Distant Worlds with Asterodensity Profiling
• Rocky super-Earths or waterworlds: the interplay of planet migration, pebble accretion and disc evolution
• The Ĝ Search for Extraterrestrial Civilizations with Large Energy Supplies. IV. The Signatures and Information Content of Transiting Megastructures
• Transit Timing Variation of Near-Resonance Planetary Pairs: Confirmation of Twelve Multiple Planet Systems
• Candidate Planets in the Habitable Zones of Kepler Stars
• The statistical mechanics of planet orbits
• Kepler Exoplanet Candidate Host Stars are Preferentially Metal Rich
• Thermal Phases of Earth-Like Planets: Estimating Thermal Inertia from Eccentricity, Obliquity, and Diurnal Forcing
• CKS VIII: Eccentricities of Kepler Planets and Tentative Evidence of a High Metallicity Preference for Small Eccentric Planets
• A More Precise Mass for GJ 1214 b and the Frequency of Multi-Planet Systems Around Mid-M Dwarfs
• The Solar System as an Exoplanetary System
• Efficient Geometric Probabilities of Multi-Transiting Exoplanetary Systems from CORBITS
• The Eccentricity Distribution of Short-Period Planet Candidates Detected by Kepler in Occultation
• A Novel Method to Photometrically Constrain Orbital Eccentricities: Multibody Asterodensity Profiling (MAP)
• Warm Jupiters in TESS Full-Frame Images: A Catalog and Observed Eccentricity Distribution for Year 1
• An Understanding of the Shoulder of Giants: Jovian Planets around Late K Dwarf Stars and the Trend with Stellar Mass
• A resonant pair of warm giant planets revealed by TESS
• Architectures of Exoplanetary Systems. II: An Increase in Inner Planetary System Occurrence Toward Later Spectral Types for Kepler's FGK Dwarfs
• Formation of planetary systems by pebble accretion and migration: Hot super-Earth systems from breaking compact resonant chains
• Investigation of Kepler Objects of Interest Stellar Parameters from Observed Transit Durations
• Dynamical constraints on the origin of hot and warm Jupiters with close friends
• Understanding the origin of white dwarf atmospheric pollution by dynamical simulations based on detected three-planet systems
• How Low Can You Go? The Photoeccentric Effect for Planets of Various Sizes
• Zodiacal Exoplanets in Time (ZEIT) IX: a flat transmission spectrum and a highly eccentric orbit for the young Neptune K2-25b as revealed by Spitzer
• The Gold Standard: Accurate Stellar and Planetary Parameters for Eight Kepler M dwarf Systems Enabled by Parallaxes
• Completeness of Imaging Surveys for Eccentric Exoplanets
• On the Nature of Small Planets around the Coolest Kepler Stars
• The APOGEE Spectroscopic Survey of Kepler Planet Hosts: Feasibility, Efficiency, and First Results
• Dynamical evolution of two-planet systems and its connection with white dwarf atmospheric pollution
• Planet Occurrence Rate Correlated to Stellar Dynamical History: Evidence from Kepler and Gaia
• Planetary parameters, XUV environments and mass-loss rates for nearby gaseous planets with X-ray detected host-stars
• A Simplified Photodynamical Model for Planetary Mass Determination in Low-Eccentricity Multi-Transiting Systems
• Solar System Moons as Analogs for Compact Exoplanetary Systems
• Updated Catalog of Kepler Planet Candidates: Focus on Accuracy and Orbital Periods
• The origin and 9:7 MMR dynamics of the Kepler-29 system
• The TESS-Keck Survey. VI. Two Eccentric sub-Neptunes Orbiting HIP-97166
• A Flat Inner Disk Model as an Alternative to the Kepler Dichotomy in the Q1 to Q16 Planet Population
• Decoupling Phase Variations in Multi-Planet Systems
• Disentangling the parameter space: The role of planet multiplicity in triggering dynamical instabilities on planetary systems around white dwarfs
• Planetary Orbit Eccentricity Trends (POET). I. The Eccentricity-Metallicity Trend for Small Planets Revealed by the LAMOST-Gaia-Kepler Sample
• A Method to Identify the Boundary Between Rocky and Gaseous Exoplanets from Tidal Theory and Transit Durations
• Atmospheric Characterization via Broadband Color Filters on the PLAnetary Transits and Oscillations of stars (PLATO) Mission
• TOI-712: a system of adolescent mini-Neptunes extending to the habitable zone
• Period Ratio Sculpting Near Second-Order Mean-Motion Resonances
• The discovery and legacy of Kepler's multi-transiting planetary systems
• Combining Kepler and HARPS Occurrence Rates to Infer the Period-Mass-Radius Distribution of Super-Earths/Sub-Neptunes
• TOI-1634 b: an Ultra-Short Period Keystone Planet Sitting Inside the M Dwarf Radius Valley
• Electric Field Induced Agglomeration of Nearly Ferroelectric Superconducting YBa2Cu3O7-d Powders