K2-137 b: an Earth-sized planet in a 4.3-hour orbit around an M-dwarf

Abstract

We report the discovery from K2 of a transiting terrestrial planet in an ultra-short-period orbit around an M3-dwarf. K2-137 b completes an orbit in only 4.3 hours, the second-shortest orbital period of any known planet, just 4 minutes longer than that of KOI 1843.03, which also orbits an M-dwarf. Using a combination of archival images, AO imaging, RV measurements, and light curve modelling, we show that no plausible eclipsing binary scenario can explain the K2 light curve, and thus confirm the planetary nature of the system. The planet, whose radius we determine to be 0.89 +/- 0.09 Earth radii, and which must have a iron mass fraction greater than 0.45, orbits a star of mass 0.463 +/- 0.052 Msol and radius 0.442 +/- 0.044 Rsol.

arXiv comment12 pages, 9 figures, accepted for publication in MNRAS

References in corpus (38)

• Astropy: A Community Python Package for Astronomy
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• Analytic Lightcurves for Planetary Transit Searches
• The VizieR database of Astronomical Catalogues
• Mass-Radius Relationships for Solid Exoplanets
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• Star counts in the Galaxy. Simulating from very deep to very shallow photometric surveys with the TRILEGAL code
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• Transiting exoplanets from the CoRoT space mission VIII. CoRoT-7b: the first Super-Earth with measured radius
• STELIB: a library of stellar spectra at R~2000
• Kepler Eclipsing Binary Stars. VII. The Catalog of Eclipsing Binaries Found in the Entire Kepler Data-Set
• Characterization of M,L and T dwarfs in the Sloan Digital Sky Survey
• Tidal Evolution of Close-in Extra-Solar Planets
• Binning is sinning: morphological light-curve distortions due to finite integration time
• Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library
• Low-Mass Dwarf Template Spectra from the Sloan Digital Sky Survey
• Stellar Limb-Darkening Coefficients for CoRot and Kepler
• On the tidal evolution of Hot Jupiters on inclined orbits
• A Study of the Shortest-Period Planets Found With Kepler
• An Earth-sized planet with an Earth-like density
• Comparative statistics and origin of triple and quadruple stars
• Kepler Eclipsing Binary Stars. III. Classification of Kepler Eclipsing Binary Light Curves with Locally Linear Embedding
• WASP-43b: The closest-orbiting hot Jupiter
• A Rocky Composition for an Earth-sized Exoplanet
• Transits and Occultations of an Earth-Sized Planet in an 8.5-Hour Orbit
• UCAC5: New Proper Motions using Gaia DR1
• The Roche limit for close-orbiting planets: Minimum density, composition constraints, and application to the 4.2-hour planet KOI 1843.03
• The star formation in the L1615/L1616 cometary cloud
• Absence of a metallicity effect for ultra-short-period planets
• Transiting exoplanets from the CoRoT space mission XXVIII. CoRoT-33b, an object in the brown dwarf desert with 2:3 commensurability with its host star
• Kepler423b: a half-Jupiter mass planet transiting a very old solar-like star
• A study of the performance of the transit detection tool DST in space-based surveys. Application of the CoRoT pipeline to Kepler data
• Ultra Short Period Planets in K2: SuPerPiG Results for Campaigns 0-5
• Characterizing the Cool KOIs. V. KOI-256: A Mutually Eclipsing Post-Common Envelope Binary
• An Independent Planet Search In The Kepler Dataset. I. A hundred new candidates and revised KOIs
• K2-99: a subgiant hosting a transiting warm Jupiter in an eccentric orbit and a long-period companion
• The K2-ESPRINT Project III: A Close-in Super-Earth around a Metal-rich Mid-M Dwarf
• Measuring the Number of M-Dwarfs per M-Dwarf Using Kepler Eclipsing Binaries

Cited by in corpus (34)

• Revisited Mass-Radius relations for exoplanets below 120 Earth masses
• REBOUNDx: A Library for Adding Conservative and Dissipative Forces to Otherwise Symplectic N-body Integrations
• Kepler-78 and the Ultra-Short-Period Planets
• Exoplanets around Low-mass Stars Unveiled by K2
• 44 Validated Planets from K2 Campaign 10
• Atmospheric Circulation on Black Widow Companions
• K2-141 b: A 5-M${}_{\oplus }$ super-Earth transiting a K7 V star every 6.7 hours
• Mass-Radius relationship for M dwarf exoplanets: Comparing nonparametric and parametric methods
• Super-Earth of 8 Mearth in a 2.2-day orbit around the K5V star K2-216
• NGTS-7Ab: An ultra-short period brown dwarf transiting a tidally-locked and active M dwarf
• K2-260 b: a hot Jupiter transiting an F star, and K2-261 b: a warm Saturn around a bright G star
• GJ 1252 b: A 1.2 $R_{\oplus }$ planet transiting an M3-dwarf at 20.4 pc
• Exomoons in the habitable zones of M dwarfs
• An ultra-short-period transiting super-Earth orbiting the M3 dwarf TOI-1685
• TKS X: Confirmation of TOI-1444b and a Comparative Analysis of the Ultra-short-period Planets with Hot Neptunes
• HD 89345: a bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2
• Validation of 13 Hot and Potentially Terrestrial TESS Planets
• Transmission Spectroscopy with the ACE-FTS Infrared Spectral Atlas of Earth: A Model Validation and Feasibility Study
• Atmospheric circulation of tidally locked gas giants with increasing rotation and implications for white-dwarf-brown-dwarf systems
• K2-140b and K2-180b - Characterization of a hot Jupiter and a mini-Neptune from the K2 mission
• HD 20329b: An ultra-short-period planet around a solar-type star found by TESS
• Migrating Planets into Ultra-Short-Period Orbits during Episodic Accretion Events
• The TEMPO Survey I: Predicting Yields of the Transiting Exosatellites, Moons, and Planets from a 30-day Survey of Orion with the Nancy Grace Roman Space Telescope
• Multiplicity of stars with planets in the solar neighbourhood
• Tidally-Distorted, Iron-Enhanced Exoplanets Closely Orbiting Their Stars
• Post-Newtonian effects on some characteristic timescales of transiting exoplanets
• The Gliese 86 Binary System: A Warm Jupiter Formed in a Disk Truncated at $\approx$2 AU
• A hot Mars-sized exoplanet transiting an M dwarf
• Atmospheric Characterization via Broadband Color Filters on the PLAnetary Transits and Oscillations of stars (PLATO) Mission
• Two neighbours of the ultra-short-period Earth-sized planet K2-157 b in the warm Neptunian savanna
• New Dynamical State and Habitability of the HD 45364 Planetary System
• A CHEOPS Search for Massive, Long-Period Companions to the Warm Jupiter K2-139 b
• Surface pressure impact on nitrogen-dominated USP super-Earth atmospheres
• Twinkle Twinkle Little Star, Roman Sees Where You Are: Predicting Exoplanet Transit Yields in the Rosette Nebula with the Nancy Grace Roman Space Telescope