K2-264: A transiting multi-planet system in the Praesepe open cluster

Abstract

Planet host stars with well-constrained ages provide a rare window to the time domain of planet formation and evolution. The NASA K2 mission has enabled the discovery of the vast majority of known planets transiting stars in clusters, providing a valuable sample of planets with known ages and radii. We present the discovery of two planets transiting K2-264, an M2 dwarf in the intermediate age (600-800 Myr) Praesepe open cluster (also known as the Beehive Cluster, M44, or NGC 2632), which was observed by K2 during Campaign 16. The planets have orbital periods of 5.8 and 19.7 days, and radii of $2.2\pm 0.2$ and $2.7\pm 0.2$ $R_{\oplus }$, respectively, and their equilibrium temperatures are $496\pm 10$ and $331\pm 7$ $K$, making this a system of two warm sub-Neptunes. When placed in the context of known planets orbiting field stars of similar mass to K2-264, these planets do not appear to have significantly inflated radii, as has previously been noted for some cluster planets. As the second known system of multiple planets transiting a star in a cluster, K2-264 should be valuable for testing theories of photoevaporation in systems of multiple planets. Follow-up observations with current near-infrared (NIR) spectrographs could yield planet mass measurements, which would provide information about the mean densities and compositions of small planets soon after photoevaporation is expected to have finished. Follow-up NIR transit observations using Spitzer or large ground-based telescopes could yield improved radius estimates, further enhancing the characterization of these interesting planets.

12 pages, 11 figures, 2 tables, published in MNRAS; see also secular dynamics at https://youtu.be/MSLodufHRes

References in corpus (75)

• emcee: The MCMC Hammer
• Gaia Data Release 2. Summary of the contents and survey properties
• The Gaia mission
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• Analytic Lightcurves for Planetary Transit Searches
• The Dartmouth Stellar Evolution Database
• The K2 Mission: Characterization and Early results
• The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
• The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
• Astrophysics Source Code Library
• batman: BAsic Transit Model cAlculatioN in Python
• A box-fitting algorithm in the search for periodic transits
• Importance Nested Sampling and the MultiNest Algorithm
• Models of Stars, Brown Dwarfs and Exoplanets
• Efficient, uninformative sampling of limb darkening coefficients for two-parameter laws
• 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
• DHP Framework: Digital Health Passports Using Blockchain -- Use case on international tourism during the COVID-19 pandemic
• On detecting terrestrial planets with timing of giant planet transits
• Kepler planets: a tale of evaporation
• Gaia Data Release 2: using Gaia parallaxes
• The Pan-STARRS1 Surveys
• Understanding the Mass-Radius Relation for Sub-Neptunes: Radius as a Proxy for Composition
• PARSEC evolutionary tracks of massive stars up to $350M_{\odot }$ at metallicities 0.0001$\le Z\le$0.04
• 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
• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• The California Kepler Survey VII. Precise Planet Radii Leveraging Gaia DR2 Reveal the Stellar Mass Dependence of the Planet Radius Gap
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• An asteroseismic view of the radius valley: stripped cores, not born rocky
• The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets
• The Stellar Populations of Praesepe and Coma Berenices
• Revised Radii of Kepler Stars and Planets Using Gaia Data Release 2
• Almost All of Kepler's Multiple Planet Candidates are Planets
• 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
• The Derivation, Properties and Value of Kepler's Combined Differential Photometric Precision
• Probabilistic Mass-Radius Relationship for Sub-Neptune-Sized Planets
• Planets around evolved intermediate-mass stars. I. Two substellar companions in the open clusters NGC 2423 and NGC 4349
• Calibrating Gyrochronology using Kepler Asteroseismic targets
• First order resonance overlap and the stability of close two planet systems
• The Habitable-Zone Planet Finder: A Stabilized Fiber-Fed NIR Spectrograph for the Hobby-Eberly Telescope
• A Neptune-sized transiting planet closely orbiting a 5-10-million-year-old star
• Zodiacal Exoplanets in Time (ZEIT) III: A short-period planet orbiting a pre-main-sequence star in the Upper Scorpius OB Association
• Zodiacal Exoplanets In Time (ZEIT) I: A Neptune-sized planet orbiting an M4.5 dwarf in the Hyades Star Cluster
• Determining the Mass of Kepler-78b With Nonparametric Gaussian Process Estimation
• The Age and Age Spread of the Praesepe and Hyades Clusters: a Consistent, ~800 Myr Picture from Rotating Stellar Models
• 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
• The GAPS programme with HARPS-N at TNG XI. Pr~0211 in M~44: the first multi-planet system in an open cluster
• HD 285507b: An Eccentric Hot Jupiter in the Hyades Open Cluster
• The effect of rotation on the abundances of the chemical elements of the A-type stars in the Praesepe cluster
• Zodiacal Exoplanets in Time (ZEIT) VI: a three-planet system in the Hyades cluster including an Earth-sized planet
• Exoplanets around Low-mass Stars Unveiled by K2
• Zodiacal Exoplanets in Time (ZEIT) VIII: A Two Planet System in Praesepe from K2 Campaign 16
• K2 Discovers a Busy Bee: An Unusual Transiting Neptune Found in the Beehive Cluster
• New PARSEC database of alpha-enhanced stellar evolutionary tracks and isochrones I. Calibration with 47 Tuc (NGC104) and the improvement on RGB bump
• K2-136: A Hyades Binary Star with a Neptune-sized Planet
• 44 Validated Planets from K2 Campaign 10
• The discovery and mass measurement of a new ultra-short-period planet: EPIC~228732031b
• New Pleiades Eclipsing Binaries and a Hyades Transiting System Identified by K2
• Hill stability in the AMD framework
• Optimizing the search for transiting planets in long time series
• Characterizing K2 Candidate Planetary Systems Orbiting Low-Mass Stars I: Classifying Low-mass Host Stars Observed During Campaigns 1-7
• The stellar mass function, binary content and radial structure of the open cluster Praesepe derived from PPMXL and SDSS data
• A Low-Mass Exoplanet Candidate Detected By $K2$ Transiting the Praesepe M Dwarf JS 183
• Zodiacal Exoplanets in Time (ZEIT) II. A "Super-Earth" Orbiting a Young K Dwarf in the Pleiades Neighborhood
• Orbital Dynamics of Multi-Planet Systems with Eccentricity Diversity
• The signatures of the parental cluster on field planetary systems
• Three Small Planets Transiting a Hyades Star
• Behavior of Apsidal Orientations in Planetary Systems
• The Chemical Composition of Praesepe (M44)
• The K2-ESPRINT Project III: A Close-in Super-Earth around a Metal-rich Mid-M Dwarf
• Characterization of the Praesepe Star Cluster by Photometry and Proper Motions with 2MASS, PPMXL, and Pan-STARRS

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• A warm Jupiter-sized planet transiting the pre-main sequence star V1298 Tau
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• Planets In Young Massive Clusters: On the survivability of planets in young massive clusters and its implication of planet orbital architectures in globular clusters
• TESS Hunt for Young and Maturing Exoplanets (THYME) V: A Sub-Neptune Transiting a Young Star in a Newly Discovered 250 Myr Association
• Cluster Difference Imaging Photometric Survey. II. TOI 837: A Young Validated Planet in IC 2602
• Two young planetary systems around field stars with ages between 20-320 Myr from TESS
• Characterizing Undetected Stellar Companions with Combined Datasets
• Rotation and Lithium Confirmation of a 500 Parsec Halo for the Open Cluster NGC 2516
• TOI-2076 and TOI-1807: Two young, comoving planetary systems within 50 pc identified by TESS that are ideal candidates for further follow-up
• Exomoons in the habitable zones of M dwarfs
• TOI-503: The first known brown dwarf-Am star binary from the TESS mission
• Survival Rates of Planets in Open Clusters: the Pleiades, Hyades, and Praesepe clusters
• Stellar population astrophysics (SPA) with the TNG. Revisiting the metallicity of Praesepe (M44)
• Discovery of a Transiting Adolescent Sub-Neptune Exoplanet with K2
• On the survival of resonant and non-resonant planetary systems in star clusters
• A Mini-Neptune from TESS and CHEOPS Around the 120 Myr Old AB Dor member HIP 94235
• Spitzer transit follow-up of planet candidates from the K2 mission
• TOI-1670 b and c: An Inner Sub-Neptune with an Outer Warm Jupiter Unlikely to have Originated from High-Eccentricity Migration
• Greening of the Brown Dwarf Desert. EPIC 212036875 b -- a 51 M${}_{\mathrm{J}}$ object in a 5 day orbit around an F7 V star
• TOI-712: a system of adolescent mini-Neptunes extending to the habitable zone
• Making hot Jupiters in stellar clusters: the importance of binary exchange
• The strongly irradiated planets in Praesepe
• Search for giant planets in M67 V: a warm Jupiter orbiting the turn-off star S1429
• TOI-1201 b: A mini-Neptune transiting a bright and moderately young M dwarf