Validation and Initial Characterization of the Long Period Planet Kepler-1654 b

Abstract

Fewer than 20 transiting Kepler planets have periods longer than one year. Our early search of the Kepler light curves revealed one such system, Kepler-1654 b (originally KIC~8410697b), which shows exactly two transit events and whose second transit occurred only 5 days before the failure of the second of two reaction wheels brought the primary Kepler mission to an end. A number of authors have also examined light curves from the Kepler mission searching for long period planets and identified this candidate. Starting in Sept. 2014 we began an observational program of imaging, reconnaissance spectroscopy and precision radial velocity measurements which confirm with a high degree of confidence that Kepler-1654 b is a {\it bona fide} transiting planet orbiting a mature G2V star (T${}_{eff}=5580$K, [Fe/H]=-0.08) with a semi-major axis of 2.03 AU, a period of 1047.84 days and a radius of 0.82$\pm$0.02 R${}_{Jup}$. Radial Velocity (RV) measurements using Keck's HIRES spectrometer obtained over 2.5 years set a limit to the planet's mass of $<0.5(3\sigma$) M${}_{Jup}$. The bulk density of the planet is similar to that of Saturn or possibly lower. We assess the suitability of temperate gas giants like Kepler-1654b for transit spectroscopy with the James Webb Space Telescope since their relatively cold equilibrium temperatures (T${}_{pl}\sim 200$K) make them interesting from the standpoint of exo-planet atmospheric physics. Unfortunately, these low temperatures also make the atmospheric scale heights small and thus transmission spectroscopy challenging. Finally, the long time between transits can make scheduling JWST observations difficult---as is the case with Kepler-1654b.

arXiv commentaccepted to Astronomical Journal

References in corpus (33)

• The NextGen Model Atmosphere grid for $3000\le \Teff \le 10000\K$
• batman: BAsic Transit Model cAlculatioN in Python
• Planetary Candidates Observed by Kepler, III: Analysis of the First 16 Months of Data
• Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b
• On the Unique Solution of Planet and Star Parameters from an Extrasolar Planet Transit Light Curve
• Kepler Input Catalog: Photometric Calibration and Stellar Classification
• EXOFAST: A fast exoplanetary fitting suite in IDL
• Overview of the Kepler Science Processing Pipeline
• Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets
• Revised Stellar Properties of Kepler Targets for the Quarter 1-16 Transit Detection Run
• False positive probabilties for all Kepler Objects of Interest: 1284 newly validated planets and 428 likely false positives
• The California Planet Survey I. Four New Giant Exoplanets
• Characterizing transiting exoplanet atmospheres with JWST
• A Systematic Retrieval Analysis of Secondary Eclipse Spectra I: A Comparison of Atmospheric Retrieval Techniques
• Understanding The Effects Of Stellar Multiplicity On The Derived Planet Radii From Transit Surveys: Implications for Kepler, K2, and TESS
• An ultrahot gas-giant exoplanet with a stratosphere
• An Efficient Automated Validation Procedure for Exoplanet Transit Candidates
• Probabilistic Mass-Radius Relationship for Sub-Neptune-Sized Planets
• Kepler-22b: A 2.4 Earth-radius Planet in the Habitable Zone of a Sun-like Star
• Observed Properties of Extrasolar Planets
• A Rocky Composition for an Earth-sized Exoplanet
• Discovery and Validation of Kepler-452b: A 1.6-Re Super Earth Exoplanet in the Habitable Zone of a G2 Star
• The NASA-UC Eta-Earth Program: I. A Super-Earth Orbiting HD 7924
• Kepler-1647b: the largest and longest-period Kepler transiting circumbinary planet
• The population of long-period transiting exoplanets
• Detection of Stars within $\sim$0.8 arcseconds of Kepler Objects of Interest
• Planet Hunters. VIII. Characterization of 41 Long-Period Exoplanet Candidates from Kepler Archival Data
• The contribution of secondary eclipses as astrophysical false positives to exoplanet transit surveys
• Planet Hunters. V. A Confirmed Jupiter-Size Planet in the Habitable Zone and 42 Planet Candidates from the Kepler Archive Data
• The Photoeccentric Effect and Proto-Hot Jupiters II. KOI-1474.01, a candidate eccentric planet perturbed by an unseen companion
• A Transiting Jupiter Analog
• Discovery of a Transiting Planet Near the Snow-Line
• A Search for Lost Planets in the Kepler Multi-planet Systems and the Discovery of the Long-period, Neptune-sized Exoplanet Kepler-150 f

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