Discovery of a Third Transiting Planet in the Kepler-47 Circumbinary System

Abstract

Of the nine confirmed transiting circumbinary planet systems, only Kepler-47 is known to contain more than one planet. Kepler-47 b (the "inner planet") has an orbital period of 49.5 days and a radius of about $3R_{\oplus }$. Kepler-47 c (the "outer planet") has an orbital period of 303.2 days and a radius of about $4.7R_{\oplus }$. Here we report the discovery of a third planet, Kepler-47 d (the "middle planet"), which has an orbital period of 187.4 days and a radius of about $7R_{\oplus }$. The presence of the middle planet allows us to place much better constraints on the masses of all three planets, where the $1\sigma$ ranges are less than $26M_{\oplus }$, between $7-43M_{\oplus }$, and between $2-5M_{\oplus }$ for the inner, middle, and outer planets, respectively. The middle and outer planets have low bulk densities, with ${\rho }_{\mathrm{middle}}<0.68$ g cm${}^{-3}$ and ${\rho }_{\mathrm{outer}}<0.26$ g cm${}^{-3}$ at the $1\sigma$ level. The two outer planets are "tightly packed," assuming the nominal masses, meaning no other planet could stably orbit between them. All of the orbits have low eccentricities and are nearly coplanar, disfavoring violent scattering scenarios and suggesting gentle migration in the protoplanetary disk.

68 pages, 30 figures

References in corpus (25)

• The Gaia mission
• The Dartmouth Stellar Evolution Database
• DHP Framework: Digital Health Passports Using Blockchain -- Use case on international tourism during the COVID-19 pandemic
• Habitable Zones Around Main-Sequence Stars: Dependence on Planetary Mass
• KEPLER's First Rocky Planet: Kepler-10b
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• The Transiting Circumbinary Planets Kepler-34 and Kepler-35
• The Mass of KOI-94d and a Relation for Planet Radius, Mass, and Incident Flux
• KOI-126: A Triply-Eclipsing Hierarchical Triple with Two Low-Mass Stars
• The Mass of Kepler-93b and The Composition of Terrestrial Planets
• A resonant chain of four transiting, sub-Neptune planets
• Alignment of the stellar spin with the orbits of a three-planet system
• The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet
• A Dynamical Analysis of the Kepler-80 System of Five Transiting Planets
• The mass of the Mars-sized exoplanet Kepler-138 b from transit timing
• On the formation and migration of giant planets in circumbinary discs
• Characterization of the K2-18 multi-planetary system with HARPS: A habitable zone super-Earth and discovery of a second, warm super-Earth on a non-coplanar orbit
• Characterizing K2 Planet Discoveries: A super-Earth transiting the bright K-dwarf HIP 116454
• Planet Hunters VII. Discovery of a New Low-Mass, Low-Density Planet (PH3 c) Orbiting Kepler-289 with Mass Measurements of Two Additional Planets (PH3 b and d)
• The discovery and mass measurement of a new ultra-short-period planet: EPIC~228732031b
• Time variation of Kepler transits induced by stellar rotating spots - a way to distinguish between prograde and retrograde motion I. Theory
• Predicting a third planet in the Kepler-47 circumbinary system
• K2-66b and K2-106b: Two extremely hot sub-Neptune-size planets with high densities
• Time variation of Kepler transits induced by stellar spots - a way to distinguish between prograde and retrograde motion. II. Application to KOIs
• The Pulsating sdB+M Eclipsing System NY Virginis and its Circumbinary Planets

Cited by in corpus (28)

• The Featureless Transmission Spectra of Two Super-Puff Planets
• TOI-1338: TESS' First Transiting Circumbinary Planet
• Gap, shadows, spirals, streamers: SPHERE observations of binary-disk interactions in GG Tau A
• Planets in Binaries: Formation and Dynamical Evolution
• Kepler-1661 b: A Neptune-sized Kepler Transiting Circumbinary Planet around a Grazing Eclipsing Binary
• Parking planets in circumbinary discs
• On dust evolution in planet-forming discs in binary systems. I -- Theoretical and numerical modelling: radial drift is faster in binary discs
• Instabilities in Multi-Planet Circumbinary Systems
• BEBOP III. Observations and an independent mass measurement of Kepler-16 (AB) b -- the first circumbinary planet detected with radial velocities
• Circumbinary discs with radiative cooling and embedded planets
• Eclipse timing the Milky Way's gravitational potential
• Dust Traffic Jams in Inclined Circumbinary Protoplanetary Discs I. Morphology and Formation Theory
• Dusty circumbinary discs: inner cavity structures and stopping locations of migrating planets
• Global N-body simulations of circumbinary planet formation around Kepler-16 and -34 analogues I: Exploring the pebble accretion scenario
• Running The Gauntlet -- Survival of Small Circumbinary Planets Migrating Through Destabilising Resonances
• Terrestrial planet formation in a circumbinary disc around a coplanar binary
• Sculpting the circumbinary planet size distribution through resonant interactions with companion planets
• Extremely precise age and metallicity of the open cluster NGC 2506 using detached eclipsing binaries
• Exomoons in Systems with a Strong Perturber: Applications to $\alpha$ Cen AB
• Periodic orbits in the 1:2:3 resonant chain and their impact on the orbital dynamics of the Kepler-51 planetary system
• Coplanar circumbinary planets can be unstable to large tilt oscillations in the presence of an inner polar planet
• Could there be an undetected inner planet near the stability limit in Kepler-1647?
• Effects of Flux Variation on the Surface Temperatures of Earth-like Circumbinary Planets
• Modeling Apsidal Motion in Eclipsing Binaries using ELC
• Tidal evolution of circumbinary systems with arbitrary eccentricities: applications for Kepler systems
• Mass Derivation of planets K2-21b and K2-21c from Transit Timing Variations
• Formation of Earth-sized planets within the Kepler-1647 System Habitable Zone
• BEBOP II: Sensitivity to sub-Saturn circumbinary planets using radial-velocities