Planet Candidates from K2 Campaigns 5-8 and Follow-Up Optical Spectroscopy

Abstract

We present 151 planet candidates orbiting 141 stars from K2 campaigns 5-8 (C5-C8), identified through a systematic search of K2 photometry. In addition, we identify 16 targets as likely eclipsing binaries, based on their light curve morphology. We obtained follow-up optical spectra of 105/141 candidate host stars and 8/16 eclipsing binaries to improve stellar properties and to identify spectroscopic binaries. Importantly, spectroscopy enables measurements of host star radii with $\approx$10% precision, compared to $\approx$40% precision when only broadband photometry is available. The improved stellar radii enable improved planet radii. Our curated catalog of planet candidates provides a starting point for future efforts to confirm and characterize K2 discoveries.

arXiv commentAccepted for publication in the Astronomical Journal; 17 pages, 8 figures, 2 tables, download source for full tables

References in corpus (48)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• The Dartmouth Stellar Evolution Database
• The K2 Mission: Characterization and Early results
• batman: BAsic Transit Model cAlculatioN in Python
• The NASA Exoplanet Archive: Data and Tools for Exoplanet Research
• Kepler Input Catalog: Photometric Calibration and Stellar Classification
• Prevalence of Earth-size planets orbiting Sun-like stars
• Most 1.6 Earth-Radius Planets are not Rocky
• EXOFAST: A fast exoplanetary fitting suite in IDL
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• Stellar Diameters and Temperatures II. Main Sequence K & M Stars
• The Mass-Radius Relation for 65 Exoplanets Smaller than 4 Earth Radii
• Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets
• A disintegrating minor planet transiting a white dwarf
• A library of high resolution synthetic stellar spectra from 300nm to 1.8 micron with solar and alpha-enhanced composition
• Spectral Properties of Cool Stars: Extended Abundance Analysis of 1617 Planet Search Stars
• The California-Kepler Survey. I. High Resolution Spectroscopy of 1305 Stars Hosting Kepler Transiting Planets
• The Stellar Populations of Praesepe and Coma Berenices
• Almost All of Kepler's Multiple Planet Candidates are Planets
• Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library
• The K2 Ecliptic Plane Input Catalog (EPIC) and Stellar Classifications of 138,600 Targets in Campaigns 1-8
• Spitzer Secondary Eclipses of the Dense, Modestly-irradiated, Giant Exoplanet HAT-P-20b Using Pixel-Level Decorrelation
• Asteroseismology and Gaia: Testing Scaling Relations Using 2200 Kepler Stars with TGAS Parallaxes
• The Derivation, Properties and Value of Kepler's Combined Differential Photometric Precision
• Planetary Candidates Observed by Kepler VI: Planet Sample from Q1-Q16 (47 Months)
• EVEREST: Pixel Level Decorrelation of K2 Light curves
• LDTk: Limb Darkening Toolkit
• 197 Candidates and 104 Validated Planets in K2's First Five Fields
• A Neptune-sized transiting planet closely orbiting a 5-10-million-year-old star
• Stellar and Planetary Properties of K2 Campaign 1 Candidates and Validation of 17 Planets, Including a Planet Receiving Earth-like Insolation
• The California-Kepler Survey. II. Precise Physical Properties of 2025 Kepler Planets and Their Host Stars
• A Rocky Composition for an Earth-sized Exoplanet
• Zodiacal Exoplanets in Time (ZEIT) III: A short-period planet orbiting a pre-main-sequence star in the Upper Scorpius OB Association
• A nearby M star with three transiting super-Earths discovered by K2
• The mass of the Mars-sized exoplanet Kepler-138 b from transit timing
• Precise time-series photometry for the Kepler-2.0 mission
• New planetary and EB candidates from Campaigns 1-6 of the K2 mission
• Transiting exoplanet candidates from K2 Campaigns 5 and 6
• The GALEX Nearby Young-Star Survey
• Two Transiting Earth-size Planets Near Resonance Orbiting a Nearby Cool Star
• Detection of Stars within $\sim$0.8 arcseconds of Kepler Objects of Interest
• Characterizing K2 Candidate Planetary Systems Orbiting Low-Mass Stars I: Classifying Low-mass Host Stars Observed During Campaigns 1-7
• Two Small Temperate Planets Transiting Nearby M Dwarfs in K2 Campaigns 0 and 1
• Stellar & Planetary Parameters for K2's Late Type Dwarf Systems from C1 to C5

Cited by in corpus (39)

• Kepler Data Validation II -- Transit Model Fitting and Multiple-Planet Search
• The California-Kepler Survey. X. The Radius Gap as a Function of Stellar Mass, Metallicity, and Age
• Scaling K2. I. Revised Parameters for 222,088 K2 Stars and a K2 Planet Radius Valley at 1.9 $R_{\oplus }$
• A warm Jupiter-sized planet transiting the pre-main sequence star V1298 Tau
• 60 Validated Planets from K2 Campaigns 5-8
• Detection of Hundreds of New Planet Candidates and Eclipsing Binaries in K2 Campaigns 0-8
• Dynamics and Formation of the Near-Resonant K2-24 System: Insights from Transit-Timing Variations and Radial Velocities
• Zodiacal Exoplanets in Time. X. The Orbit and Atmosphere of the Young "Neptune Desert"-Dwelling Planet K2-100b
• Scaling K2. VI. Reduced Small Planet Occurrence in High Galactic Amplitude Stars
• Characterizing K2 Candidate Planetary Systems Orbiting Low-Mass Stars IV: Updated Properties for 86 Cool Dwarfs Observed During Campaigns 1-17
• Planetary Candidates from K2 Campaign 16
• K2-146: Discovery of Planet c, Precise Masses from Transit Timing, and Observed Precession
• Rapid Formation of Jupiter and Wide-Orbit Exoplanets in Disks with Pressure Bumps
• 37 New Validated Planets in Overlapping K2 Campaigns
• The K2-OjOS Project: New and revisited planets and candidates in K2 campaigns 5, 16, & 18
• Scaling K2. IV. A Uniform Planet Sample for Campaigns 1-8 and 10-18
• Scaling K2. II. Assembly of a Fully Automated C5 Planet Candidate Catalog Using EDI-Vetter
• HD 191939: Three Sub-Neptunes Transiting a Sun-like Star Only 54 pc Away
• A TESS Dress Rehearsal: Planetary Candidates and Variables from K2 Campaign 17
• K2-140b and K2-180b - Characterization of a hot Jupiter and a mini-Neptune from the K2 mission
• Transit least-squares survey -- II. Discovery and validation of 17 new sub- to super-Earth-sized planets in multi-planet systems from K2
• Spitzer transit follow-up of planet candidates from the K2 mission
• Evidence of a Sub-Saturn around EPIC~211945201
• Scaling K2 VII: Evidence for a high occurrence rate of hot sub-Neptunes at intermediate ages
• Transit least-squares survey - I. Discovery and validation of an Earth-sized planet in the four-planet system K2-32 near the 1:2:5:7 resonance
• K2-288Bb: A Small Temperate Planet in a Low-mass Binary System Discovered by Citizen Scientists
• K2-291 b: A rocky super-Earth in a 2.2 day orbit
• Scaling K2. III. Comparable Planet Occurrence in the FGK Samples of Campaign 5 and Kepler
• Catalog of New K2 Exoplanet Candidates from Citizen Scientists
• Four Small Planets Buried in K2 Systems: What Can We Learn for TESS?
• Another super-dense sub-Neptune in K2-182 b and refined mass measurements for K2-199 b and c
• K2-280b -- a low density warm sub-Saturn around a mildly evolved star
• The GALAH Survey: Improving our understanding of confirmed and candidate planetary systems with large stellar surveys
• A Spectroscopic Analysis of a Sample of K2 Planet-Host Stars: Stellar Parameters, Metallicities and Planetary Radii
• K2 Targets Observed with SPHERE/VLT: An M4-7 Dwarf Companion Resolved around EPIC 206011496
• More planetary candidates from K2 Campaign 5 by tran_k2
• Stellar Characterization and a Chromospheric Activity Analysis of a K2 Sample of Planet-Hosting Stars
• Search for Exoplanetary Transits in the Galactic Bulge
• Scaling K2. V. Statistical Validation of 60 New Exoplanets From K2 Campaigns 2-18