GJ 357 b: A Super-Earth Orbiting an Extremely Inactive Host Star

Abstract

In this paper we present a deep X-ray observation of the nearby M dwarf GJ 357 and use it to put constraints on the atmospheric evolution of its planet, GJ 357 b. We also analyse the systematic errors in the stellar parameters of GJ 357 in order to see how they affect the perceived planetary properties. We estimate the age of GJ 357 b by comparing the observed X-ray luminosity of its host star, derived from a recent {\em XMM-Newton} observation {($\log L_{\mathrm{x}}[erg/s]=25.73$), with $L_{\mathrm{x}}-$ age relations for M dwarfs. We find that GJ 357 presents one of the lowest X-ray activity levels ever measured for an M dwarf, and we put a lower limit on its age of $5$\,Gyr.} Using this age limit, we perform a backwards reconstruction of the original primordial atmospheric reservoir. Furthermore, by considering the systematic errors in the stellar parameters, we find a range of possible planetary masses, radii, and densities. From the backwards reconstruction of GJ 357 b's irradiation history we find that the upper limit of its initial primordial atmospheric mass is $\sim 38{\mathrm{M}}_{\oplus }$. An initial atmospheric reservoir significantly larger than this may have survived through the X-ray and ultraviolet irradiation history, hence being inconsistent with current observations that suggest a telluric composition. In spite of the unlikelihood of a currently existing primordial envelope, volcanism and outgassing may have contributed to a secondary atmosphere. Under this assumption, we present three different synthetic infrared spectra for GJ 357 b that one might expect, consisting of $100\%\mathrm{C}{\mathrm{O}}_2$, $100\%\mathrm{S}{\mathrm{O}}_2$, and $75\%{\mathrm{N}}_2$, $24\%\mathrm{C}{\mathrm{O}}_2$ and $1\%{\mathrm{H}}_2\mathrm{O}$.

Accepted for publication in A&A

References in corpus (61)

• Gaia Data Release 2: The astrometric solution
• Kepler planets: a tale of evaporation
• The evaporation valley in the Kepler planets
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• Understanding the Mass-Radius Relation for Sub-Neptunes: Radius as a Proxy for Composition
• A Closely-Packed System of Low-Mass, Low-Density Planets Transiting Kepler-11
• ExoMol molecular line lists XXX: a complete high-accuracy line list for water
• Gaia Data Release 2: Catalogue validation
• The ExoMol database: molecular line lists for exoplanet and other hot atmospheres
• Core-powered mass loss and the radius distribution of small exoplanets
• Roche lobe effects on the atmospheric loss of "Hot Jupiters"
• Mass-Radius Relation for Rocky Planets based on PREM
• Estimation of the XUV radiation onto close planets and their evaporation
• How Thermal Evolution and Mass Loss Sculpt Populations of Super-Earths and Sub-Neptunes: Application to the Kepler-11 System and Beyond
• Characterizing transiting exoplanet atmospheres with JWST
• How to Constrain Your M dwarf II: the mass-luminosity-metallicity relation from 0.075 to 0.70$M_{\odot }$
• Planetary population synthesis coupled with atmospheric escape: a statistical view of evaporation
• The Mass and Size Distribution of Planetesimals Formed by the Streaming Instability. I. The Role of Self-Gravity
• The Mass-Dependence of Angular Momentum Evolution in Sun-Like Stars
• Super-Earth Atmospheres: Self-Consistent Gas Accretion and Retention
• Compositional imprints in density-distance-time: a rocky composition for close-in low-mass exoplanets from the location of the valley of evaporation
• Formation and Structure of Low Density Exo-Neptunes
• Chromospheric activity catalogue of 4454 cool stars. Questioning the active branch of stellar activity cycles
• A Detailed Model Grid for Solid Planets from 0.1 through 100 Earth Masses
• NEXXUS: A comprehensive ROSAT survey of coronal X-ray emission among nearby solar-like stars
• Spectro-Thermometry of M dwarfs and their candidate planets: too hot, too cool, or just right?
• In-situ Accretion of Hydrogen-Rich Atmospheres on Short-Period Super-Earths: Implications for the Kepler-11 Planets
• The CARMENES search for exoplanets around M dwarfs: Different roads to radii and masses of the target stars
• Geodynamics and Rate of Volcanism on Massive Earth-like Planets
• Mantle Dynamics in Super-Earths: Post-Perovskite Rheology and Self-Regulation of Viscosity
• Minimum Radii of Super-Earths: Constraints from Giant Impacts
• A grid of upper atmosphere models for 1--40 MEARTH planets: application to CoRoT-7 b and HD219134 b,c
• Planetary system around the nearby M dwarf GJ 357 including a transiting, hot, Earth-sized planet optimal for atmospheric characterization
• Overcoming the limitations of the energy-limited approximation for planet atmospheric escape
• A remnant planetary core in the hot-Neptune desert
• Mass-loss rates for transiting exoplanets
• Outgassing on stagnant-lid super-Earths
• Initial Planetesimal Sizes and the Size Distribution of Small Kuiper Belt Objects
• The CARMENES search for exoplanets around M dwarfs. Activity indicators at visible and near-infrared wavelengths
• Probing the Blow-Off Criteria of Hydrogen-Rich "Super-Earths"
• The CARMENES search for exoplanets around M dwarfs - Photospheric parameters of target stars from high-resolution spectroscopy
• Stellar parameters of early M dwarfs from ratios of spectral features at optical wavelengths
• Relation of X-ray activity and rotation in M dwarfs and predicted time-evolution of the X-ray luminosity
• Linking the Climate and Thermal Phase Curve of 55 Cancri e
• A Case for an Atmosphere on Super-Earth 55 Cancri e
• Living with a Red Dwarf: Rotation and X-ray and Ultraviolet Properties of the Halo Population Kapteyn's Star
• Exoplanet Spectroscopy and Photometry with the Twinkle Space Telescope
• Extreme hydrodynamic losses of Earth-like atmospheres in the habitable zones of very active stars
• On the Role of Dissolved Gases in the Atmosphere Retention of Low-Mass Low-Density Planets
• The Role of N2 as a Geo-Biosignature for the Detection and Characterization of Earth-like Habitats
• A 3D radiative transfer framework: VI. PHOENIX/3D example applications
• Atmospheric compositions and observability of nitrogen dominated ultra-short period super-Earths
• Testing Models of Stellar Structure and Evolution I. Comparison with Detached Eclipsing Binaries
• Effects of Magnetic Fields on the Location of the Evaporation Valley for Low-Mass Exoplanets
• Chemo-kinematic ages of eccentric-planet-hosting M dwarf stars
• GJ357: A low-mass planetary system uncovered by precision radial-velocities and dynamical simulations
• Photo-evaporation of close-in gas giants orbiting around G and M stars
• M Stars in the TW Hya Association: Stellar X-rays and Disk Dissipation
• The Bimodal Distribution in Exoplanet Radii: Considering Varying Core Compositions and ${\mathrm{H}}_2$ Envelope's Sizes
• Two Terrestrial Planet Families With Different Origins
• Hot Super-Earths with Hydrogen Atmospheres: A Model Explaining Their Paradoxical Existence

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