Two massive rocky planets transiting a K-dwarf 6.5 parsecs away

Abstract

HD 219134 is a K-dwarf star at a distance of 6.5 parsecs around which several low-mass planets were recently discovered. The Spitzer space telescope detected a transit of the innermost of these planets, HD 219134 b, whose mass and radius (4.5 MEarth and 1.6 REarth respectively) are consistent with a rocky composition. Here, we report new highprecision time-series photometry of the star acquired with Spitzer revealing that the second innermost planet of the system, HD 219134 c, is also transiting. A global analysis of the Spitzer transit light curves and the most up-to-date HARPS-N velocity data set yields mass and radius estimations of 4.74+-0.19 MEarth and 1.602+-0.055 REarth for HD 219134 b, and of 4.36+-0.22 MEarth and 1.511+-0.047 REarth for HD 219134 c. These values suggest rocky compositions for both planets. Thanks to the proximity and the small size of their host star (0.778+-0.005 Rsun), these two transiting exoplanets - the nearest to the Earth to date - are well-suited for a detailed characterization (precision of a few percent on mass and radius, constraints on the atmospheric properties...) that could give important constraints on the nature and formation mechanism of the ubiquitous short-period planets of a few Earth masses.

arXiv comment16 pages

References in corpus (33)

• The chemical composition of the Sun
• The Infrared Array Camera (IRAC) for the Spitzer Space Telescope
• Analytic Lightcurves for Planetary Transit Searches
• Planet-disk interaction and orbital evolution
• Element Diffusion in the Solar Interior
• Stellar Diameters and Temperatures II. Main Sequence K & M Stars
• A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b
• The 3.6-8.0 Micron Broadband Emission Spectrum of HD 209458b: Evidence for an Atmospheric Temperature Inversion
• Mass-Radius Relation for Rocky Planets based on PREM
• Radial Velocity Jitter in Stars from the California and Carnegie Planet Search at Keck Observatory
• Migration then assembly: Formation of Neptune mass planets inside 1 AU
• Testing In Situ Assembly with the Kepler Planet Candidate Sample
• Oxygen Abundances in Nearby FGK Stars and the Galactic Chemical Evolution of the Local Disk and Halo
• The Atmospheric Signatures of Super-Earths: How to Distinguish Between Hydrogen-Rich and Hydrogen-Poor Atmospheres
• A Detailed Model Grid for Solid Planets from 0.1 through 100 Earth Masses
• Inside-Out Planet Formation
• Detection of an atmosphere around the super-Earth 55 Cancri e
• Lithium abundances in nearby FGK dwarf and subgiant stars: internal destruction, Galactic chemical evolution, and exoplanets
• The TRAPPIST survey of southern transiting planets. I. Thirty eclipses of the ultra-short period planet WASP-43 b
• Chromospheric activity as age indicator
• Transit and Eclipse Analyses of Exoplanet HD 149026b Using BLISS Mapping
• Systemic: A Testbed For Characterizing the Detection of Extrasolar Planets. I. The Systemic Console Package
• Constraining Exoplanet Mass from Transmission Spectroscopy
• The HARPS-N Rocky Planet Search I. HD219134b: A transiting rocky planet in a multi-planet system at 6.5 pc from the Sun
• The Liege Oscillation Code
• Search for an exosphere in sodium and calcium in the transmission spectrum of exoplanet 55 Cancri e
• A Six-Planet System Orbiting HD 219134
• Evolved stars and the origin of abundance trends in planet hosts
• Vulcan Planets: Inside-Out Formation of the Innermost Super-Earths
• A 12-Year Activity Cycle for HD 219134
• Two NIRCam channels are Better than One: How JWST Can Do More Science with NIRCam's Short-Wavelength Dispersed Hartmann Sensor
• On the Formation of Super-Earths with Implications for the Solar System
• An educated search for transiting habitable planets. Targetting M dwarfs with known transiting planets

Cited by in corpus (51)

• Large Interferometer For Exoplanets (LIFE): I. Improved exoplanet detection yield estimates for a large mid-infrared space-interferometer mission
• An Excess of Jupiter Analogs in Super-Earth Systems
• Evolution of the radius valley around low mass stars from $Kepler$ and $K2$
• A grid of upper atmosphere models for 1--40 MEARTH planets: application to CoRoT-7 b and HD219134 b,c
• The 10 parsec sample in the Gaia era
• Gaia DR3 astrometric orbit determination with Markov Chain Monte Carlo and Genetic Algorithms. Systems with stellar, substellar, and planetary mass companions
• Three Red Suns in the Sky: A Transiting, Terrestrial Planet in a Triple M Dwarf System at 6.9 Parsecs
• A new class of Super-Earths formed from high-temperature condensates: HD219134 b, 55 Cnc e, WASP-47 e
• Chemical Fingerprints of Formation in Rocky Super-Earths' Data
• Estimating magnetic filling factors from Zeeman-Doppler magnetograms
• Transit detection of the long-period volatile-rich super-Earth ${\nu }^2$ Lupi d with $CHEOPS$
• Beyond the Kepler/K2 bright limit: variability in the seven brightest members of the Pleiades
• ExoClock Project III: 450 new exoplanet ephemerides from ground and space observations
• A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds
• A detailed analysis of the Gl 486 planetary system
• The Volume-Complete Sample of M Dwarfs with Masses 0.1 <= M/M_sol <= 0.3 within 15 Parsecs
• Uncovering astrometric black hole binaries with massive main-sequence companions with Gaia
• Characterisation of the HD219134 multi-planet system II. Stellar-wind sputtered exospheres in rocky planets b & c
• Simulating the Exoplanet Yield of a Space-based MIR Interferometer Based on Kepler Statistics
• Caught in the Act: Core-powered Mass-loss Predictions for Observing Atmospheric Escape
• Characterisation of the HD 219134 multi-planet system I. Observations of stellar magnetism, wind, and high-energy flux
• The HD 260655 system: Two rocky worlds transiting a bright M dwarf at 10 pc
• Validation of 13 Hot and Potentially Terrestrial TESS Planets
• Transits of Known Planets Orbiting a Naked-Eye Star
• Proxima Centauri b is not a transiting exoplanet
• Simultaneous Optical Transmission Spectroscopy of a Terrestrial, Habitable-Zone Exoplanet with Two Ground-Based Multi-Object Spectrographs
• Inner Planetary System Gap Complexity is a Predictor of Outer Giant Planets
• TESS Reveals HD 118203 b to be a Transiting Planet
• Hidden Worlds: Dynamical Architecture Predictions of Undetected Planets in Multi-planet Systems and Applications to TESS Systems
• Secondary atmospheres on HD 219134 b and c
• TOI 540 b: A Planet Smaller than Earth Orbiting a Nearby Rapidly Rotating Low-mass Star
• MCMCI: A code to fully characterise an exoplanetary system
• Using JWST transits and occultations to determine $\sim 1\%$ stellar radii and temperatures of low-mass stars
• Catalogue of exoplanets accessible in reflected starlight to the Nancy Grace Roman Space Telescope. A population study and prospects for phase-curve measurements
• Detecting Biosignatures in the Atmospheres of Gas Dwarf Planets with the James Webb Space Telescope
• The Exosphere as a Boundary: Origin and Evolution of Airless Bodies in the Inner Solar System and Beyond Including Planets with Silicate Atmospheres
• Exoplanet atmosphere evolution: emulation with neural networks
• From the stellar properties of HD219134 to the internal compositions of its transiting exoplanets
• A compact multi-planet system around a bright nearby star from the Dispersed Matter Planet Project
• A Quantitative Comparison of Exoplanet Catalogs
• Characterization of the HD 108236 system with CHEOPS and TESS. Confirmation of a fifth transiting planet
• A review of planetary systems around HD 99492, HD 147379 and HD 190007 with HARPS-N
• An Integrative Analysis of the HD 219134 Planetary System and the Inner Solar System: Extending DYNAMITE with Enhanced Orbital Dynamical Stability Criteria
• Implications of an improved water equation of state for water-rich planets
• Transit Timing Variations in HIP 41378: CHEOPS and TESS confirm a non-transiting sixth planet in the system
• Null transit detections of 68 radial velocity exoplanets observed by TESS
• Discovery and Characterization of Kepler-36b
• HyDRo: Atmospheric Retrieval of Rocky Exoplanets in Thermal Emission
• SPORES-HWO. II. Companion Mass Limits and Updated Planet Properties for 120 Future Exoplanet Imaging Targets from 35 yr of Precise Doppler Monitoring
• A compositional link between rocky exoplanets and their host stars
• The Occurrence-weighted Median Planets Discovered by Transit Surveys Orbiting Solar-type Stars and Their Implications for Planet Formation and Evolution