Multiple Explanations for the Single Transit of KIC 5951458 based on Radial Velocity Measurements Extracted with a Novel Matched-template Technique

Abstract

Planetary systems that show single-transit events are a critical pathway to increasing the yield of long-period exoplanets from transit surveys. From the primary Kepler mission, KIC 5951458b (Kepler-456b) was thought to be a single-transit giant planet with an orbital period of 1310 days. However, radial velocity (RV) observations of KIC 5951458 from the HIRES instrument on the Keck telescope suggest that the system is far more complicated. To extract precise RVs for this $V\approx 13$ star, we develop a novel matched-template technique that takes advantage of a broad library of template spectra acquired with HIRES. We validate this technique and measure its noise floor to be 4 - 8 m s${}^{-1}$ (in addition to internal RV error) for most stars that would be targeted for precision RVs. For KIC 5951458, we detect a long-term RV trend that suggests the existence of a stellar companion with an orbital period greater than a few thousand days. We also detect an additional signal in the RVs that is possibly caused by a planetary or brown dwarf companion with mass in the range of 0.6 - 82 $M_{\mathrm{J}}$ and orbital period below a few thousand days. Curiously, from just the data on hand, it is not possible to determine which object caused the single "transit" event. We demonstrate how a modest set of RVs allows us to update the properties of this unusual system and predict the optimal timing for future observations.

arXiv comment20 pages, 14 figures, accepted for publication in the Astronomical Journal

References in corpus (37)

• Gaia Data Release 2. Summary of the contents and survey properties
• The Transiting Exoplanet Survey Satellite
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The K2 Mission: Characterization and Early results
• The First Data Release (DR1) of the LAMOST general survey
• Radial Velocities for 889 Late-type Stars
• Chromospheric CaII Emission in Nearby F, G, K, and M stars
• Kepler Eclipsing Binary Stars. I. Catalog and Principal Characterization of 1879 Eclipsing Binaries in the First Data Release
• Chromospheric Activity and Jitter Measurements for 2630 Stars on the California Planet Search
• False positive probabilties for all Kepler Objects of Interest: 1284 newly validated planets and 428 likely false positives
• Planetary Candidates Observed by Kepler. VIII. A Fully Automated Catalog With Measured Completeness and Reliability Based on Data Release 25
• The California Planet Survey I. Four New Giant Exoplanets
• A library of high resolution synthetic stellar spectra from 300nm to 1.8 micron with solar and alpha-enhanced composition
• The California-Kepler Survey. I. High Resolution Spectroscopy of 1305 Stars Hosting Kepler Transiting Planets
• Parametrizing the exoplanet eccentricity distribution with the Beta distribution
• Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library
• Limits on Planetary Companions from Doppler Surveys of Nearby Stars
• 197 Candidates and 104 Validated Planets in K2's First Five Fields
• Gaia Data Release 2: Properties and validation of the radial velocities
• Gaia Data Release 2: The catalogue of radial velocity standard stars
• The Joker: A custom Monte Carlo sampler for binary-star and exoplanet radial velocity data
• SOPHIE velocimetry of Kepler transit candidates XII. KOI-1257 b: a highly eccentric three-month period transiting exoplanet
• Detection of Potential Transit Signals in 17 Quarters of Kepler Data: Results of the Final Kepler Mission Transiting Planet Search (DR25)
• A super-Earth-sized planet orbiting in or near the habitable zone around Sun-like star
• Planet Hunters. VIII. Characterization of 41 Long-Period Exoplanet Candidates from Kepler Archival Data
• Planet formation in Binaries
• KELT-8b: A highly inflated transiting hot Jupiter and a new technique for extracting high-precision radial velocities from noisy spectra
• Planet Hunters TESS I: TOI 813, a subgiant hosting a transiting Saturn-sized planet on an 84-day orbit
• An Estimate of the Yield of Single-Transit Planetary Events from the Transiting Exoplanet Survey Satellite
• NGTS-11 b / TOI-1847 b: A transiting warm Saturn recovered from a TESS single-transit event
• The TESS-Keck Survey I: A Warm Sub-Saturn-mass Planet and a Caution about Stray Light in TESS Cameras
• Eccentric Companions to Kepler-448b and Kepler-693b: Clues to the Formation of Warm Jupiters
• The Transit Transmission Spectrum of a Cold Gas Giant Planet
• Transiting Planets near the Snow Line from Kepler. I. Catalog
• Spitzer Detection of the Transiting Jupiter-analog Exoplanet Kepler-167e
• An ablating super-Earth in an eccentric binary from the Dispersed Matter Planet Project
• Kepler Transit Depths Contaminated by a Phantom Star

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• The TESS-Keck Survey. VIII. Confirmation of a Transiting Giant Planet on an Eccentric 261 day Orbit with the Automated Planet Finder Telescope
• The TESS Grand Unified Hot Jupiter Survey. II. Twenty New Giant Planets
• Kepler-167e as a Probe of the Formation Histories of Cold Giants with Inner Super-Earths
• The TESS Grand Unified Hot Jupiter Survey. I. Ten TESS Planets
• Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. I. Confirmation of an Eccentric, Cool Jupiter With an Interior Earth-sized Planet Orbiting Kepler-1514
• Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Year, Highly Eccentric Orbit
• On the follow-up efforts of long-period transiting planet candidates detected with Gaia astrometry
• The TESS-Keck Survey. XIX. A Warm Transiting Sub-Saturn Mass Planet and a non-Transiting Saturn Mass Planet Orbiting a Solar Analog
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