No Timing Variations Observed in Third Transit of Snow-Line Exoplanet Kepler-421b

Abstract

We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler Spacecraft only observed two transits of Kepler-421b leaving the planet's transit ephemeris unconstrained. Our visible light, time-series observations from the 4.3-meter Discovery Channel Telescope were designed to capture pre-transit baseline and the partial transit of Kepler-421b barring significant TTVs. We use the light curves to assess the probabilities of various transit models using both the posterior odds ratio and the Bayesian Information Criterion (BIC) and find that a transit model with no TTVs is favored to 3.6-sigma confidence. These observations suggest that Kepler-421b is either alone in its system or is only experiencing minor dynamic interactions with an unseen companion. With the Kepler-421b ephemeris constrained, we calculate future transit times and discuss the opportunity to characterize the atmosphere of this cold, long-period exoplanet via transmission spectroscopy. Our investigation emphasizes the difficulties associated with observing long-period exoplanet transits and the consequences that arise from failing to refine transit ephemerides.

arXiv comment6 pages, 3 figures, 2 tables. Accepted to ApJ Letters on June 29, 2016

References in corpus (18)

• Analytic Lightcurves for Planetary Transit Searches
• The K2 Mission: Characterization and Early results
• The effects of snowlines on C/O in planetary atmospheres
• Towards a Deterministic Model of Planetary Formation I: a Desert in the Mass and Semi Major Axis Distributions of Extra Solar Planets
• The NASA Exoplanet Archive: Data and Tools for Exoplanet Research
• Kepler Input Catalog: Photometric Calibration and Stellar Classification
• The orbital motion, absolute mass, and high-altitude winds of exoplanet HD209458b
• The Transiting Exoplanet Survey Satellite: Simulations of planet detections and astrophysical false positives
• False positive probabilties for all Kepler Objects of Interest: 1284 newly validated planets and 428 likely false positives
• Detection of water absorption in the day side atmosphere of HD 189733 b using ground-based high-resolution spectroscopy at 3.2 microns
• Constraining Exoplanet Mass from Transmission Spectroscopy
• Planet Hunters: The First Two Planet Candidates Identified by the Public using the Kepler Public Archive Data
• Planet Hunters. VIII. Characterization of 41 Long-Period Exoplanet Candidates from Kepler Archival Data
• Transiting Planet Candidates Beyond the Snow Line Detected by Visual Inspection of 7557 Kepler Objects of Interest
• A Transiting Jupiter Analog
• Discovery of a Transiting Planet Near the Snow-Line
• Spitzer Observations of Exoplanets Discovered with The Kepler K2 Mission
• The Transit Transmission Spectrum of a Cold Gas Giant Planet

Cited by in corpus (19)

• The population of long-period transiting exoplanets
• Solar System Physics for Exoplanet Research
• Utilizing Small Telescopes Operated by Citizen Scientists for Transiting Exoplanet Follow-up
• The TESS-Keck Survey I: A Warm Sub-Saturn-mass Planet and a Caution about Stray Light in TESS Cameras
• A dearth of small particles in the transiting material around the white dwarf WD 1145+017
• The TESS-Keck Survey. VIII. Confirmation of a Transiting Giant Planet on an Eccentric 261 day Orbit with the Automated Planet Finder Telescope
• Transiting Planets near the Snow Line from Kepler. I. Catalog
• Spitzer Detection of the Transiting Jupiter-analog Exoplanet Kepler-167e
• Kepler-167e as a Probe of the Formation Histories of Cold Giants with Inner Super-Earths
• Diffuser-assisted Photometric Follow-up Observations of the Neptune-sized Planets K2-28b and K2-100b
• Shallow Ultraviolet Transits of WD 1145+017
• Predicted Yield of Transits of Known Radial Velocity Exoplanets from the TESS Primary and Extended Missions
• Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. I. Confirmation of an Eccentric, Cool Jupiter With an Interior Earth-sized Planet Orbiting Kepler-1514
• TESS Observations of Kepler systems with Transit Timing Variations
• Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Year, Highly Eccentric Orbit
• Kepler Transit Depths Contaminated by a Phantom Star
• Out-of-Transit Refracted Light in the Atmospheres of Transiting and Non-Transiting Exoplanets
• Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. VI: Confirmation of a Long-Period Giant Planet Discovered with a Single TESS Transit
• Following up TESS Single Transits With Archival Photometry and Radial Velocities