TOI-1695 b: A Water World Orbiting an Early M Dwarf in the Planet Radius Valley

Abstract

Characterizing the bulk compositions of transiting exoplanets within the M dwarf radius valley offers a unique means to establish whether the radius valley emerges from an atmospheric mass loss process or is imprinted by planet formation itself. We present the confirmation of such a planet orbiting an early M dwarf ($T_{\mathrm{mag}}=11.0294\pm 0.0074,M_s=0.513\pm 0.012M_{\odot },R_s=0.515\pm 0.015R_{\odot },T_{\mathrm{eff}}=3690\pm 50K$): TOI-1695 b ($P=3.13$ days, $R_p=1.90_{-0.14}^{+0.16}{R}_{\oplus }$). TOI-1695 b's radius and orbital period situate the planet between model predictions from thermally-driven mass loss versus gas depleted formation, offering an important test case for radius valley emergence models around early M dwarfs. We confirm the planetary nature of TOI-1695 b based on five sectors of TESS data and a suite of follow-up observations including 49 precise radial velocity measurements taken with the HARPS-N spectrograph. We measure a planetary mass of $6.36\pm 1.00M_{\oplus }$, which reveals that TOI-1695 b is inconsistent with a purely terrestrial composition of iron and magnesium silicate, and instead is likely a water-rich planet. Our finding that TOI-1695 b is not terrestrial is inconsistent with the planetary system being sculpted by thermally driven mass loss. We present a statistical analysis of seven well-characterized planets within the M dwarf radius valley demonstrating that a thermally-driven mass loss scenario is unlikely to explain this population.

arXiv comment22 pages, 11 figures. Accepted in AJ

References in corpus (88)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Astropy: A Community Python Package for Astronomy
• The Transiting Exoplanet Survey Satellite
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• 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 generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
• Las Cumbres Observatory Global Telescope Network
• The NextGen Model Atmosphere grid for $3000\le \Teff \le 10000\K$
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• Kepler Presearch Data Conditioning II - A Bayesian Approach to Systematic Error Correction
• Fast and scalable Gaussian process modeling with applications to astronomical time series
• The Revised TESS Input Catalog and Candidate Target List
• Efficient, uninformative sampling of limb darkening coefficients for two-parameter laws
• Evolution of the Solar Activity over Time and Effects on Planetary Atmospheres: I. High-energy Irradiances (1-1700 A)
• astroquery: An Astronomical Web-Querying Package in Python
• Kepler Presearch Data Conditioning I - Architecture and Algorithms for Error Correction in Kepler Light Curves
• 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
• AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light Curves
• AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light Curves (Expanded Edition)
• Growth Model Interpretation of Planet Size Distribution
• The Transiting Exoplanet Survey Satellite: Simulations of planet detections and astrophysical false positives
• The California Kepler Survey VII. Precise Planet Radii Leveraging Gaia DR2 Reveal the Stellar Mass Dependence of the Planet Radius Gap
• An asteroseismic view of the radius valley: stripped cores, not born rocky
• Core-powered mass loss and the radius distribution of small exoplanets
• Accurate, Empirical Radii and Masses of Planets and their Host Stars with Gaia Parallaxes
• Revised Catalog of GALEX Ultraviolet Sources. I. The All-sky Survey: GUVcat_AIS
• Sculpting the Valley in the Radius Distribution of Small Exoplanets as a by-product of Planet Formation: The Core-Powered Mass-Loss Mechanism
• The TESS Objects of Interest Catalog from the TESS Prime Mission
• The HARPS-TERRA project I. Description of the algorithms, performance and new measurements on a few remarkable stars observed by HARPS
• HAT-P-16b: A 4 Mj Planet Transiting A Bright Star On An Eccentric Orbit
• 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
• Kepler Data Validation I -- Architecture, Diagnostic Tests, and Data Products for Vetting Transiting Planet Candidates
• Parametrizing the exoplanet eccentricity distribution with the Beta distribution
• A new list of thorium and argon spectral lines in the visible
• Understanding The Effects Of Stellar Multiplicity On The Derived Planet Radii From Transit Surveys: Implications for Kepler, K2, and TESS
• Density, not radius, separates rocky and water-rich small planets orbiting M dwarf stars
• emcee v3: A Python ensemble sampling toolkit for affine-invariant MCMC
• Compositional imprints in density-distance-time: a rocky composition for close-in low-mass exoplanets from the location of the valley of evaporation
• Parallax Systematics and Photocenter Motions of Benchmark Eclipsing Binaries in Gaia EDR3
• The rotation and Galactic kinematics of mid M dwarfs in the Solar Neighborhood
• The Kepler Follow-Up Observation Program. I. A Catalog of Companions to Kepler Stars from High-Resolution Imaging
• The orbital eccentricity of small planet systems
• A Detailed Model Grid for Solid Planets from 0.1 through 100 Earth Masses
• Transit Least Squares: Optimized transit detection algorithm to search for periodic transits of small planets
• Real-time processing of the imaging data from the network of Las Cumbres Observatory Telescopes using BANZAI
• The MUSCLES Treasury Survey III: X-ray to Infrared Spectra of 11 M and K Stars Hosting Planets
• Evolutionary Analysis of Gaseous Sub-Neptune-Mass Planets with MESA
• Eclipsing Binary Stars as Benchmarks for Trigonometric Parallaxes in the Gaia Era
• Signatures of the Core-Powered Mass-Loss Mechanism in the Exoplanet Population: Dependence on Stellar Properties and Observational Predictions
• They are Small Worlds After All: Revised Properties of Kepler M Dwarf Stars and their Planets
• Magnetic activity in the HARPS M-dwarf sample. The rotation-activity relationship for very low-mass stars through R'HK
• The Gaia-Kepler Stellar Properties Catalog. II. Planet Radius Demographics as a Function of Stellar Mass and Age
• Empirical, Accurate Masses and Radii of Single Stars with TESS and Gaia
• 275 Candidates and 149 Validated Planets Orbiting Bright Stars in K2 Campaigns 0-10
• Evolution of the radius valley around low mass stars from $Kepler$ and $K2$
• Predictions of the atmospheric composition of GJ 1132b
• Minimum Radii of Super-Earths: Constraints from Giant Impacts
• The Kepler Dichotomy among the M Dwarfs: Half of Systems Contain Five or More Coplanar Planets
• How formation time-scales affect the period dependence of the transition between rocky super-Earths and gaseous sub-Neptunes and implications for ${\eta }_{\oplus }$
• A Spectroscopic Analysis of the California-Kepler Survey Sample: I. Stellar Parameters, Planetary Radii and a Slope in the Radius Gap
• Photoevaporation vs. core-powered mass-loss: model comparison with the 3D radius gap
• Predicting the Extreme Ultraviolet Radiation Environment of Exoplanets Around Low-Mass Stars: the TRAPPIST-1 System
• A new class of Super-Earths formed from high-temperature condensates: HD219134 b, 55 Cnc e, WASP-47 e
• The HARPS search for southern extra-solar planets XXXV. Planetary systems and stellar activity of the M dwarfs GJ 3293, GJ 3341, and GJ 3543
• Semi-empirical Modeling of the Photosphere, Chromosphere, Transition Region, and Corona of the M-dwarf Host Star GJ 832
• Primordial Radius Gap and Potentially Broad Core Mass Distributions of Super-Earths and Sub-Neptunes
• A sub-Neptune sized planet transiting the M2.5-dwarf G 9-40: Validation with the Habitable-zone Planet Finder
• Creating the Radius Gap without Mass Loss
• A More Precise Mass for GJ 1214 b and the Frequency of Multi-Planet Systems Around Mid-M Dwarfs
• HAZMAT VI: The Evolution of Extreme Ultraviolet Radiation Emitted from Early M Star
• TOI-1452 b: SPIRou and TESS reveal a super-Earth in a temperate orbit transiting an M4 dwarf
• Predicting the Extreme Ultraviolet Radiation Environment of Exoplanets Around Low-Mass Stars: GJ 832, GJ 176, GJ 436
• A planetary system with two transiting mini-Neptunes near the radius valley transition around the bright M dwarf TOI-776
• Precise mass and radius of a transiting super-Earth planet orbiting the M dwarf TOI-1235: a planet in the radius gap?
• TOI-1235 b: a keystone super-Earth for testing radius valley emergence models around early M dwarfs
• An ultra-short-period transiting super-Earth orbiting the M3 dwarf TOI-1685
• LHS 1610A: A Nearby Mid-M Dwarf with a Companion That is Likely A Brown Dwarf
• Precise mass determination for the keystone sub-Neptune planet transiting the mid-type M dwarf G 9-40
• A sub-Neptune planet around TOI-1695 discovered and characterized with SPIRou and TESS
• The California Legacy Survey I. A Catalog of 178 Planets from Precision Radial Velocity Monitoring of 719 Nearby Stars over Three Decades

Cited by in corpus (10)

• Super-Earths and Earth-like Exoplanets
• TOI-1801 b: A temperate mini-Neptune around a young M0.5 dwarf
• Building Wet Planets through High-Pressure Magma-Hydrogen Reactions
• Hundreds of TESS exoplanets might be larger than we thought
• TESS discovery of two super-Earths orbiting the M-dwarf stars TOI-6002 and TOI-5713 near the radius valley
• Characterisation of TOI-406 as showcase of the THIRSTEE program: A 2-planet system straddling the M-dwarf density gap
• TOI-733 b: a planet in the small-planet radius valley orbiting a Sun-like star
• Super-Earth masses and stellar abundances from NIRPS reveal tentative evidence for water-rich formation around M dwarfs
• No Robust Statistical Evidence for a Population of Water Worlds in a 2025 Sample of Planets Orbiting M Stars
• Confirmation of the hot super-Neptune TOI-672 b with NIRPS and HARPS and Insights into the Neptunian desert around M dwarfs