K2-111: an old system with two planets in near-resonance

Abstract

This paper reports on the detailed characterisation of the K2-111 planetary system with K2, WASP, and ASAS-SN photometry as well as high-resolution spectroscopic data from HARPS-N and ESPRESSO. The host, K2-111, is confirmed to be a mildly evolved ($\log g=4.17$), iron-poor ([Fe/H]$=-0.46$), but alpha-enhanced ([$\alpha$/Fe]$=0.27$), chromospherically quiet, very old thick disc G2 star. A global fit, performed by using PyORBIT shows that the transiting planet, K2-111b, orbits with a period $P_b=5.3518\pm 0.0004$ d, and has a planet radius of $1.82_{-0.09}^{+0.11}$ R${}_{\oplus }$ and a mass of $5.29_{-0.77}^{+0.76}$ M${}_{\oplus }$, resulting in a bulk density slightly lower than that of the Earth. The stellar chemical composition and the planet properties are consistent with K2-111b being a terrestrial planet with an iron core mass fraction lower than the Earth. We announce the existence of a second signal in the radial velocity data that we attribute to a non-transiting planet, K2-111c, with an orbital period of $15.6785\pm 0.0064$ days, orbiting in near-3:1 mean-motion resonance with the transiting planet, and a minimum planet mass of $11.3\pm 1.1$ M${}_{\oplus }$. Both planet signals are independently detected in the HARPS-N and ESPRESSO data when fitted separately. There are potentially more planets in this resonant system, but more well-sampled data are required to confirm their presence and physical parameters.

arXiv commentAccepted for publication in MNRAS on 28 Sept 2020. Paper is 18 pages with an additional 12 pages of supplementary material. Data is available at https://vizier.u-strasbg.fr/viz-bin/VizieR?-source=J/MNRAS/499/5004

References in corpus (87)

• The chemical composition of the Sun
• Gaia Data Release 2. Summary of the contents and survey properties
• The Gaia mission
• The Transiting Exoplanet Survey Satellite
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The Dartmouth Stellar Evolution Database
• 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
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• REBOUND: An open-source multi-purpose N-body code for collisional dynamics
• batman: BAsic Transit Model cAlculatioN in Python
• Importance Nested Sampling and the MultiNest Algorithm
• Elemental Abundance Survey of The Galactic Thick Disk
• EXOFAST: A fast exoplanetary fitting suite in IDL
• Understanding the Mass-Radius Relation for Sub-Neptunes: Radius as a Proxy for Composition
• Probabilistic Forecasting of the Masses and Radii of Other Worlds
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program.Galactic stellar populations and planets
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• An asteroseismic view of the radius valley: stripped cores, not born rocky
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• Mass-Radius Relation for Rocky Planets based on PREM
• A Gaussian process framework for modelling stellar activity signals in radial velocity data
• Tidal Evolution of Close-in Extra-Solar Planets
• Unresolved stellar companions with Gaia DR2 astrometry
• Can we constrain interior structure of rocky exoplanets from mass and radius measurements?
• Three regimes of extrasolar planets inferred from host star metallicities
• Improved spectroscopic parameters for transiting planet hosts
• A Detailed Model Grid for Solid Planets from 0.1 through 100 Earth Masses
• TW Hydrae: evidence of stellar spots instead of a Hot Jupiter
• Long-term magnetic activity of a sample of M-dwarf stars from the HARPS program I. Comparison of activity indices
• Detecting Planets Around Very Low Mass Stars with the Radial Velocity Method
• A fast hybrid algorithm for exoplanetary transit searches
• Planetary Candidates from the First Year of the K2 Mission
• A generalized bayesian inference method for constraining the interiors of super Earths and sub-Neptunes
• Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program II: Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd and Eu
• Fluxes in Hαand Ca II H and K for a sample of Southern stars
• The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet
• Determining the Mass of Kepler-78b With Nonparametric Gaussian Process Estimation
• Three years of Sun-as-a-star radial-velocity observations on the approach to solar minimum
• The HARPS-N Rocky Planet Search I. HD219134b: A transiting rocky planet in a multi-planet system at 6.5 pc from the Sun
• BGLS: A Bayesian formalism for the generalised Lomb-Scargle periodogram
• Abundance to age ratios in the HARPS-GTO sample with Gaia DR2: Chemical clocks for a range of [Fe/H]
• The Mount Wilson Observatory S-index of the Sun
• An ultra-short period rocky super-Earth with a secondary eclipse and a Neptune-like companion around K2-141
• The GAPS programme with HARPS-N at TNG XI. Pr~0211 in M~44: the first multi-planet system in an open cluster
• Constraining planet structure from stellar chemistry: the cases of CoRoT-7, Kepler-10, and Kepler-93
• Elemental ratios in stars vs planets
• Exploring the alpha-enhancement of metal-poor planet-hosting stars. The Kepler and HARPS samples
• High-precision abundances of elements in solar-type stars. Evidence of two distinct sequences in abundance-age relations
• The HARPS search for southern extra-solar planets XXXV. The interesting case of HD41248: stellar activity, no planets?
• Revisiting Proxima with ESPRESSO
• New and updated stellar parameters for 90 transit hosts. The effect of the surface gravity
• The stability and fates of hierarchical two-planet systems
• Radial-Velocity Fitting Challenge. II. First results of the analysis of the data set
• Kepler-21b: A rocky planet around a V = 8.25 magnitude star
• Correcting the spectroscopic surface gravity using transits and asteroseismology. No significant effect on temperatures or metallicities with ARES+MOOG in LTE
• Stacked Bayesian general Lomb-Scargle periodogram: Identifying stellar activity signals
• Oxygen abundances in G- and F-type stars from HARPS
• Constraining planet structure and composition from stellar chemistry: trends in different stellar populations
• ARES+MOOG - a practical overview of an EW method to derive stellar parameters
• The Star-Planet Connection I: Using Stellar Composition to Observationally Constrain Planetary Mineralogy for the Ten Closest Stars
• On the correlation between metallicity and the presence of giant planets
• Characterisation of the radial velocity signal induced by rotation in late-type dwarfs
• CoRoT: harvest of the exoplanet program
• Confirmation of the radial velocity super-Earth K2-18c with HARPS and CARMENES
• Revised Masses and Densities of the Planets around Kepler-10
• Radial Velocities with CRIRES: Pushing precision down to 5-10 m/s
• The Kepler-19 system: a thick-envelope super-Earth with two Neptune-mass companions characterized using Radial Velocities and Transit Timing Variations
• Homogeneous spectroscopic parameters for bright planet host stars from the northern hemisphere
• EPIC 210894022b - A short period super-Earth transiting a metal poor, evolved old star
• Pinning down the mass of Kepler-10c: the importance of sampling and model comparison
• Exoplanet Imitators: A test of stellar activity behavior in radial velocity signals
• Decoding the radial velocity variations of HD41248 with ESPRESSO
• Temporal evolution and correlations of optical activity indicators measured in Sun-as-a-star observations
• The correlation between photometric variability and radial velocity jitter, based on TESS and HARPS observations
• The TROY project: Searching for co-orbital bodies to known planets. I. Project goals and first results from archival radial velocity
• Characterization of the K2-38 planetary system. Unraveling one of the densest planets known to date
• Atmospheric Stellar Parameters from Cross-Correlation Functions
• The TROY project: II. Multi-technique constraints on exotrojans in nine planetary systems
• Detection of co-orbital planets by combining transit and radial-velocity measurements
• The HARPS search for southern extra-solar planets. XXXIX. HD175607 b, the most metal-poor G dwarf with an orbiting sub-Neptune
• Using HARPS-N to characterise the long-period planets in the PH-2 and Kepler-103 systems
• Planetary mass-radius relations across the galaxy

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• Cold Jupiters and improved masses in 38 Kepler and K2 small planet systems from 3661 HARPS-N radial velocities. No excess of cold Jupiters in small planet systems
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• Exoplanet Characterization using Conditional Invertible Neural Networks
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• A HARPS-N mass for the elusive Kepler-37d: a case study in disentangling stellar activity and planetary signals
• Planetary system around LTT 1445A unveiled by ESPRESSO: Multiple planets in a triple M-dwarf system
• HD22496b: the first ESPRESSO standalone planet discovery
• Exoplanet atmosphere evolution: emulation with neural networks
• TOI-837b is a Young Saturn-sized Exoplanet with a Massive 70 $M_{\oplus }$ Core
• Planet Hunters TESS III: two transiting planets around the bright G dwarf HD 152843
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• Composition of super-Earths, super-Mercuries, and their host stars
• Independent validation of the temperate Super-Earth HD79211 b using HARPS-N
• Two neighbours of the ultra-short-period Earth-sized planet K2-157 b in the warm Neptunian savanna
• Tidally Heated Sub-Neptunes, Refined Planetary Compositions, and Confirmation of a Third Planet in the TOI-1266 System
• TOI-3568 b: a super-Neptune in the sub-Jovian desert
• TESS and HARPS-N unveil two planets transiting TOI-1453. A super-Earth and one of the lowest mass sub-Neptunes
• L 363-38 b: a planet newly discovered with ESPRESSO orbiting a nearby M dwarf star
• Confronting compositional confusion through the characterisation of the sub-Neptune orbiting HD 77946
• The Occurrence-weighted Median Planets Discovered by Transit Surveys Orbiting Solar-type Stars and Their Implications for Planet Formation and Evolution
• A compositional link between rocky exoplanets and their host stars
• Discovery of a multi-planetary system orbiting the aged Sun-like star HD 224018
• $\mathtt{KOBEsim}$: a Bayesian observing strategy algorithm for planet detection in radial velocity blind-search surveys
• On the stellar core physics of the 16 Cyg binary system: constraining the central hydrogen abundance using asteroseismology