Kepler-1661 b: A Neptune-sized Kepler Transiting Circumbinary Planet around a Grazing Eclipsing Binary

Abstract

We report the discovery of a Neptune-size (R_p = 3.87 +/- 0.06 R_Earth) transiting circumbinary planet, Kepler-1661 b, found in the Kepler photometry. The planet has a period of ~175 days and its orbit precesses with a period of only 35 years. The precession causes the alignment of the orbital planes to vary, and the planet is in a transiting configuration only ~7% of the time as seen from Earth. As with several other Kepler circumbinary planets, Kepler-1661 b orbits close to the stability radius, and is near the (hot) edge of habitable zone. The planet orbits a single-lined, grazing eclipsing binary, containing a 0.84 M_Sun and 0.26 M_Sun pair of stars in a mildly eccentric (e=0.11), 28.2-day orbit. The system is fairly young, with an estimated age of ~1-3 Gyrs, and exhibits significant starspot modulations. The grazing-eclipse configuration means the system is very sensitive to changes in the binary inclination, which manifests itself as a change in the eclipse depth. The starspots contaminate the eclipse photometry, but not in the usual way of inducing spurious eclipse timing variations. Rather, the starspots alter the normalization of the light curve, and hence the eclipse depths. This can lead to spurious eclipse depth variations, which are then incorrectly ascribed to binary orbital precession.

37 pages, 15 figures

References in corpus (10)

• The Gaia mission
• The Dartmouth Stellar Evolution Database
• Achieving better than 1 minute accuracy in the Heliocentric and Barycentric Julian Dates
• The Transiting Circumbinary Planets Kepler-34 and Kepler-35
• Measuring the rotation period distribution of field M-dwarfs with Kepler
• Eclipse Timing Variation Analyses of Eccentric Binaries with Close Tertiaries in the Kepler field
• Discovery of a Third Transiting Planet in the Kepler-47 Circumbinary System
• Uncovering Circumbinary Planetary Architectural Properties from Selection Biases
• Time variation of Kepler transits induced by stellar rotating spots - a way to distinguish between prograde and retrograde motion I. Theory
• Instabilities in Multi-Planet Circumbinary Systems

Cited by in corpus (13)

• TOI-1338: TESS' First Transiting Circumbinary Planet
• Evidence for a high mutual inclination between the cold Jupiter and transiting super Earth orbiting $\pi$ Men
• Parking planets in circumbinary discs
• BEBOP III. Observations and an independent mass measurement of Kepler-16 (AB) b -- the first circumbinary planet detected with radial velocities
• Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. I. Confirmation of an Eccentric, Cool Jupiter With an Interior Earth-sized Planet Orbiting Kepler-1514
• Running The Gauntlet -- Survival of Small Circumbinary Planets Migrating Through Destabilising Resonances
• Terrestrial planet formation in a circumbinary disc around a coplanar binary
• Exomoons in Systems with a Strong Perturber: Applications to $\alpha$ Cen AB
• Searching for Possible Exoplanet Transits from BRITE Data through a Machine Learning Technique
• Effects of Flux Variation on the Surface Temperatures of Earth-like Circumbinary Planets
• Multiple Transits during a Single Conjunction: Identifying Transiting Circumbinary Planetary Candidates from TESS
• The TESS-Keck Survey. XI. Mass Measurements for Four Transiting sub-Neptunes orbiting K dwarf TOI-1246
• BEBOP II: Sensitivity to sub-Saturn circumbinary planets using radial-velocities