Discovery of a Transiting Adolescent Sub-Neptune Exoplanet with K2

Abstract

The role of stellar age in the measured properties and occurrence rates of exoplanets is not well understood. This is in part due to a paucity of known young planets and the uncertainties in age-dating for most exoplanet host stars. Exoplanets with well-constrained ages, particularly those which are young, are useful as benchmarks for studies aiming to constrain the evolutionary timescales relevant for planets. Such timescales may concern orbital migration, gravitational contraction, or atmospheric photo-evaporation, among other mechanisms. Here we report the discovery of an adolescent transiting sub-Neptune from K2 photometry of the low-mass star K2-284. From multiple age indicators we estimate the age of the star to be 120 Myr, with a 68% confidence interval of 100-760 Myr. The size of K2-284 b ($R_P$ = 2.8 $\pm$ 0.1 $R_{\oplus }$) combined with its youth make it an intriguing case study for photo-evaporation models, which predict enhanced atmospheric mass loss during early evolutionary stages.

arXiv commentAccepted to AJ, 36 pages, 17 figures, 5 tables

References in corpus (116)

• emcee: The MCMC Hammer
• The Gaia mission
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Validation of the new Hipparcos reduction
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• The Galaxy Evolution Explorer: A Space Ultraviolet Survey Mission
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• Analytic Lightcurves for Planetary Transit Searches
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• The K2 Mission: Characterization and Early results
• The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• A Hipparcos census of the nearby OB associations
• Planet Occurrence within 0.25 AU of Solar-type Stars from Kepler
• A box-fitting algorithm in the search for periodic transits
• The Keck Planet Search: Detectability and the Minimum Mass and Orbital Period Distribution of Extrasolar Planets
• On the Unique Solution of Planet and Star Parameters from an Extrasolar Planet Transit Light Curve
• The NASA Exoplanet Archive: Data and Tools for Exoplanet Research
• Solar Chemical Abundances Determined with a CO5BOLD 3D Model Atmosphere
• Ages for illustrative field stars using gyrochronology: viability, limitations and errors
• Kepler planets: a tale of evaporation
• The Pan-STARRS1 Surveys
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• Improving PARSEC models for very low mass stars
• Star counts in the Galaxy. Simulating from very deep to very shallow photometric surveys with the TRILEGAL code
• Probabilistic Forecasting of the Masses and Radii of Other Worlds
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• Stellar Diameters and Temperatures II. Main Sequence K & M Stars
• RadVel: The Radial Velocity Modeling Toolkit
• BANYAN. XI. The BANYAN $\Sigma$ multivariate Bayesian algorithm to identify members of young associations within 150 pc
• The Role of Core Mass in Controlling Evaporation: the Kepler Radius Distribution and the Kepler-36 Density Dichotomy
• A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood
• Kepler Eclipsing Binary Stars. VII. The Catalog of Eclipsing Binaries Found in the Entire Kepler Data-Set
• X-ray astronomy of stellar coronae (Review)
• The Star-formation History and Accretion-Disk Fraction Among the K-Type Members of the Scorpius-Centaurus OB Association
• Imaging Extrasolar Giant Planets
• Empirical extinction coefficients for the GALEX, SDSS, 2MASS and WISE passbands
• The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets
• On the age of the $\beta$ Pictoris moving group
• Three regimes of extrasolar planets inferred from host star metallicities
• Pulkovo Compilation of Radial Velocities for 35495 Hipparcos Stars in a Common System
• The California-Kepler Survey. I. High Resolution Spectroscopy of 1305 Stars Hosting Kepler Transiting 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
• Understanding The Effects Of Stellar Multiplicity On The Derived Planet Radii From Transit Surveys: Implications for Kepler, K2, and TESS
• Asteroseismology and Gaia: Testing Scaling Relations Using 2200 Kepler Stars with TGAS Parallaxes
• Hot super-Earths stripped by their host stars
• The Extreme Ultraviolet and X-Ray Sun in Time: High-Energy Evolutionary Tracks of a Solar-Like Star
• The coronal X-ray - age relation and its implications for the evaporation of exoplanets
• PyTransit: Fast and Easy Exoplanet Transit Modelling in Python
• A Moving Cluster Distance to the Exoplanet 2M1207 B in the TW Hya Association
• Spectroscopy of Very Low Mass Stars and Brown Dwarfs in IC2391: Lithium depletion and Halpha emission
• Evolutionary Analysis of Gaseous Sub-Neptune-Mass Planets with MESA
• Planetary Candidates from the First Year of the K2 Mission
• Rotation in the Pleiades with K2: I. Data and First Results
• Calibrating Gyrochronology using Kepler Asteroseismic targets
• A Stellar Census of the Tucana-Horologium Moving Group
• XHIP: An Extended Hipparcos Compilation
• K2SC: Flexible systematics correction and detrending of K2 light curves using Gaussian Process regression
• A Neptune-sized transiting planet closely orbiting a 5-10-million-year-old star
• An Infrared/X-ray Survey for New Members of the Taurus Star-Forming Region
• GU Boo: A New 0.6 Msun Detached Eclipsing Binary
• A new catalogue of Stroemgren-Crawford uvbybeta photometry
• Zodiacal Exoplanets In Time (ZEIT) I: A Neptune-sized planet orbiting an M4.5 dwarf in the Hyades Star Cluster
• Lithium Depletion of Nearby Young Stellar Associations
• UCAC5: New Proper Motions using Gaia DR1
• How formation time-scales affect the period dependence of the transition between rocky super-Earths and gaseous sub-Neptunes and implications for ${\eta }_{\oplus }$
• Age Determinations of the Hyades, Praesepe, and Pleiades via MESA Models with Rotation
• The Age and Age Spread of the Praesepe and Hyades Clusters: a Consistent, ~800 Myr Picture from Rotating Stellar Models
• A hot Jupiter orbiting a 2-Myr-old solar-mass T Tauri star
• The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets
• Zodiacal Exoplanets in Time (ZEIT) IV: seven transiting planets in the Praesepe cluster
• Two 'b's in the Beehive: The Discovery of the First Hot Jupiters in an Open Cluster
• A recalibration of optical photometry: Tycho-2, Strömgren, and Johnson systems
• Searching for Young M Dwarfs with GALEX
• Keck Spectra of Brown Dwarf Candidates and a Precise Determination of the Lithium Depletion Boundary in the Alpha Persei Open Cluster
• The same frequency of planets inside and outside open clusters of stars
• WIYN Open Cluster Study. LXXV. Testing the Metallicity Dependence of Stellar Lithium Depletion Using Hyades-Aged Clusters. 1. Hyades & Praesepe
• Kepler-21b: A 1.6REarth Planet Transiting the Bright Oscillating F Subgiant Star HD 179070
• HD 285507b: An Eccentric Hot Jupiter in the Hyades Open Cluster
• Membership, lithium, and metallicity in the young open clusters IC 2602 and IC 2391: enlarging the sample
• Investigations of approximate expressions for the transit duration
• A Candidate Young Massive Planet in Orbit around the Classical T Tauri Star CI Tau
• K2 Rotation Periods for low-mass Hyads and the Implications for Gyrochronology
• Three planetary companions around M67 stars
• Abundances of four open clusters from solar stars
• Stellar Activity in the Broad-Band Ultraviolet
• Rotation of Late-Type Stars in Praesepe with K2
• A hot Jupiter around the very active weak-line T Tauri star TAP 26
• An Absence of Hot Jupiter Planets in 47 Tucanae: Results of a Wide-Field Transit Search
• The GALEX Nearby Young-Star Survey
• A New Method to Identify Nearby, Young, Low-mass Stars
• Zodiacal Exoplanets in Time (ZEIT) V: A Uniform Search for Transiting Planets in Young Clusters Observed by K2
• Exoplanets around Low-mass Stars Unveiled by K2
• Rotation in the Pleiades With K2: III. Speculations on Origins and Evolution
• Detection of Stars within $\sim$0.8 arcseconds of Kepler Objects of Interest
• K2 Discovers a Busy Bee: An Unusual Transiting Neptune Found in the Beehive Cluster
• Searching for Planets in the Hyades. I. The Keck Radial Velocity Survey
• Search for giant planets in M67 III: excess of hot Jupiters in dense open clusters
• New Pleiades Eclipsing Binaries and a Hyades Transiting System Identified by K2
• Radial velocities for the Hipparcos-Gaia Hundred-Thousand-Proper-Motion project
• Ensemble analysis of open cluster transit surveys: upper limits on the frequency of short-period planets consistent with the field
• Ultraviolet-Selected Field and Pre-Main-Sequence Stars Towards Taurus and Upper Scorpius
• The Frequency of Large Radius Hot and Very Hot Jupiters in omega Centauri
• A Low-Mass Exoplanet Candidate Detected By $K2$ Transiting the Praesepe M Dwarf JS 183
• Search for giant planets in M67 IV: survey results
• Zodiacal Exoplanets in Time (ZEIT) II. A "Super-Earth" Orbiting a Young K Dwarf in the Pleiades Neighborhood
• A PSF-based approach to Kepler/K2 data. II. Exoplanet candidates in Praesepe (M 44)
• Three Small Planets Transiting a Hyades Star
• Zodiacal Exoplanets in Time (ZEIT) VII: A Temperate Candidate Super-Earth in the Hyades Cluster
• K2-264: A transiting multi-planet system in the Praesepe open cluster
• Precise Radial Velocities of 2046 Nearby FGKM Stars and 131 Standards
• Reassessment of the Null Result of the HST Search for Planets in 47 Tucanae
• New BVIc Photometry of Low-mass Pleiades Stars: Exploring the Effects of Rotation on Broadband Colors
• Three small planets transiting the bright young field star K2-233

Cited by in corpus (20)

• Rotation of Low-Mass Stars in Taurus with K2
• TESS Hunt for Young and Maturing Exoplanets (THYME) VI: an 11 Myr giant planet transiting a very low-mass star in Lower Centaurus Crux
• ExoClock Project III: 450 new exoplanet ephemerides from ground and space observations
• TESS Hunt for Young and Maturing Exoplanets (THYME) V: A Sub-Neptune Transiting a Young Star in a Newly Discovered 250 Myr Association
• Two young planetary systems around field stars with ages between 20-320 Myr from TESS
• Cluster Difference Imaging Photometric Survey. II. TOI 837: A Young Validated Planet in IC 2602
• A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- II. Search for exoplanets in open clusters of the southern ecliptic hemisphere and their frequency
• The GAPS Programme with HARPS-N at TNG. XXXVII. A precise density measurement of the young ultra-short period planet TOI-1807 b
• Multi-band high resolution spectroscopy rules out the hot Jupiter BD+20 1790b - First data from the GIARPS Commissioning
• A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- III. Exploring the properties of young associations through their variables, dippers, and candidate exoplanets
• The TIME Table: Rotation and Ages of Cool Exoplanet Host Stars
• A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- IV. Candidate exoplanets around stars in open clusters: frequency and age-planetary radius distribution
• Stellar Rotation and Structure of the $\alpha$ Persei Complex: When Does Gyrochronology Start to Work?
• A Mini-Neptune from TESS and CHEOPS Around the 120 Myr Old AB Dor member HIP 94235
• K2-291 b: A rocky super-Earth in a 2.2 day orbit
• Two Terrestrial Planet Families With Different Origins
• TOI-1801 b: A temperate mini-Neptune around a young M0.5 dwarf
• Dynamical masses of two young transiting sub-Neptunes orbiting HD 63433
• Bayesian ages of local young stellar associations I. Through the expansion rate method
• A sub-Neptune transiting the young field star HD 18599 at 40 pc