TOI-5108 b and TOI 5786 b: Two transiting sub-Saturns detected and characterized with TESS, MaHPS and SOPHIE

Abstract

We report the discovery and characterization of two sub-Saturns from the Transiting Exoplanet Survey Satellite (\textit{TESS}) using high-resolution spectroscopic observations from the MaHPS spectrograph at the Wendelstein Observatory and the SOPHIE spectrograph at the Haute-Provence Observatory. Combining photometry from TESS, KeplerCam, LCOGT, and MuSCAT2 with the radial velocity measurements from MaHPS and SOPHIE we measure precise radii and masses for both planets. TOI-5108 b is a sub-Saturn with a radius of $6.6\pm 0.1$ $R_{\oplus }$ and a mass of $32\pm 5$ $M_{\oplus }$. TOI-5786 b is similar to Saturn with a radius of $8.54\pm 0.13$ $R_{\oplus }$ and a mass of $73\pm 9$ $M_{\oplus }$. The host star for TOI-5108 b is a moderately bright (Vmag 9.75) G-type star. TOI-5786 is a slightly dimmer (Vmag 10.2) F-type star. Both planets are close to their host stars with periods of 6.75 days and 12.78 days respectively. This puts TOI-5108 b just inside the bounds of the Neptune desert while TOI-5786 b is right above the upper edge. We estimate hydrogen-helium envelope mass fractions of $38\%$ for TOI-5108 b and $74\%$ for TOI-5786 b. However, using a model for the interior structure that includes tidal effects the envelope fraction of TOI-5108 b could be much lower ($\sim 20\%$) depending on the obliquity. We estimate mass-loss rates between 1.0 * $10^9$ g/s and 9.8 * $10^9$ g/s for TOI-5108 b and between 3.6 * $10^8$ g/s and 3.5 * $10^9$ g/s for TOI-5786 b. Given their masses, this means that both planets are stable against photoevaporation. We also detect a transit signal for a second planet candidate in the TESS data of TOI-5786 with a period of 6.998 days and a radius of $3.83\pm 0.16$ $R_{\oplus }$. Using our RV data and photodynamical modeling, we are able to provide a 3-$\sigma$ upper limit of 26.5 $M_{\oplus }$ for the mass of the potential inner companion to TOI-5786 b.

arXiv comment25 pages, 13 figures. Accepted for publication in A&A

References in corpus (134)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• The Transiting Exoplanet Survey Satellite
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• The Galaxy Evolution Explorer: A Space Ultraviolet Survey Mission
• dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• A 3D Dust Map Based on Gaia, Pan-STARRS 1 and 2MASS
• Bayes in the sky: Bayesian inference and model selection in cosmology
• Las Cumbres Observatory Global Telescope Network
• The NextGen Model Atmosphere grid for $3000\le \Teff \le 10000\K$
• REBOUND: An open-source multi-purpose N-body code for collisional dynamics
• batman: BAsic Transit Model cAlculatioN in Python
• Kepler Presearch Data Conditioning II - A Bayesian Approach to Systematic Error Correction
• Fast and scalable Gaussian process modeling with applications to astronomical time series
• Efficient, uninformative sampling of limb darkening coefficients for two-parameter laws
• Kepler Presearch Data Conditioning I - Architecture and Algorithms for Error Correction in Kepler Light Curves
• Kepler planets: a tale of evaporation
• EXOFAST: A fast exoplanetary fitting suite in IDL
• IAS15: A fast, adaptive, high-order integrator for gravitational dynamics, accurate to machine precision over a billion orbits
• 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)
• A Framework for Prioritizing the TESS Planetary Candidates Most Amenable to Atmospheric Characterization
• A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b
• RadVel: The Radial Velocity Modeling Toolkit
• The California Kepler Survey VII. Precise Planet Radii Leveraging Gaia DR2 Reveal the Stellar Mass Dependence of the Planet Radius Gap
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• Planetary evaporation by UV & X-ray radiation: basic hydrodynamics
• The MUSCLES Treasury Survey I: Motivation and Overview
• How Thermal Evolution and Mass Loss Sculpt Populations of Super-Earths and Sub-Neptunes: Application to the Kepler-11 System and Beyond
• HAT-P-16b: A 4 Mj Planet Transiting A Bright Star On An Eccentric Orbit
• Helium in the eroding atmosphere of an exoplanet
• Evaporation of the planet HD189733b observed in HI Lyman-alpha
• The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets
• Dearth of short-period Neptunian exoplanets - a desert in period-mass and period-radius planes
• Juliet: a versatile modelling tool for transiting and non-transiting exoplanetary systems
• Three regimes of extrasolar planets inferred from host star metallicities
• PandExo: A Community Tool for Transiting Exoplanet Science with JWST & HST
• Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library
• SWEET-Cat: A catalogue of parameters for Stars With ExoplanETs I. New atmospheric parameters and masses for 48 stars with planets
• Understanding The Effects Of Stellar Multiplicity On The Derived Planet Radii From Transit Surveys: Implications for Kepler, K2, and TESS
• Atmospheric Escape and the Evolution of Close-in Exoplanets
• Synthetic Stellar Photometry - I. General considerations and new transformations for broad-band systems
• Asteroseismology and Gaia: Testing Scaling Relations Using 2200 Kepler Stars with TGAS Parallaxes
• Hot super-Earths stripped by their host stars
• A diagram for the evaporation status of extrasolar planets
• The Kepler Follow-Up Observation Program. I. A Catalog of Companions to Kepler Stars from High-Resolution Imaging
• The MUSCLES Treasury Survey II: Intrinsic Lyman Alpha and Extreme Ultraviolet Spectra of K and M Dwarfs with Exoplanets
• A Study of the Shortest-Period Planets Found With Kepler
• Kepler Data Validation II -- Transit Model Fitting and Multiple-Planet Search
• Photoevaporation and High-Eccentricity Migration Created the Sub-Jovian Desert
• SOAR TESS Survey. I: Sculpting of TESS planetary systems by stellar companions
• REBOUNDx: A Library for Adding Conservative and Dissipative Forces to Otherwise Symplectic N-body Integrations
• PyTransit: Fast and Easy Exoplanet Transit Modelling in Python
• A New Window into Escaping Exoplanet Atmospheres: 10830 Å Line of Helium
• The MUSCLES Treasury Survey III: X-ray to Infrared Spectra of 11 M and K Stars Hosting Planets
• A short-period censor of sub-Jupiter mass exoplanets with low density
• Occurrence Rates of Planets orbiting FGK Stars: Combining Kepler DR25, Gaia DR2 and Bayesian Inference
• Hubble PanCET: An extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470 b
• Ten years of speckle interferometry at SOAR
• Emerging Trends in a Period-Radius Distribution of Close-in Planets
• The low-level radial velocity variability in Barnard's star (=GJ 699). Secular acceleration, indications for convective redshift, and planet mass limits
• PALM-3000: Exoplanet Adaptive Optics for the 5-meter Hale Telescope
• A public HARPS radial velocity database corrected for systematic errors
• Vetting of 384 TESS Objects of Interest with TRICERATOPS and Statistical Validation of 12 Planet Candidates
• The CARMENES search for exoplanets around M dwarfs. First visual-channel radial-velocity measurements and orbital parameter updates of seven M-dwarf planetary systems
• Forward and Inverse Modeling of the Emission and Transmission Spectrum of GJ 436b: Investigating Metal Enrichment, Tidal Heating, and Clouds
• Orbital misalignment of the Neptune-mass exoplanet GJ 436b with the spin of its cool star
• Two 'b's in the Beehive: The Discovery of the First Hot Jupiters in an Open Cluster
• A candidate super-Earth planet orbiting near the snow line of Barnard's star
• The SOPHIE search for northern extrasolar planets III. A Jupiter-mass companion around HD 109246
• ARIADNE: Measuring accurate and precise stellar parameters through SED fitting
• Correcting HIRES radial velocities for small systematic errors
• Helium Absorption at 1083 nm from Extended Exoplanet Atmospheres: Dependence on Stellar Radiation
• SWEET-Cat 2.0: The Cat just got SWEETer; Higher quality spectra and precise parallaxes from GAIA eDR3
• On stellar limb darkening and exoplanetary transits
• Transiting exoplanet candidates from K2 Campaigns 5 and 6
• Superabundance of Exoplanet Sub-Neptunes Explained by Fugacity Crisis
• LAMOST telescope reveals that Neptunian cousins of hot Jupiters are mostly single offspring of stars that are rich in heavy elements
• Detection of Helium in the Atmosphere of the Exo-Neptune HAT-P-11b
• On the origin of the sub-Jovian desert in the orbital-period--planetary-mass plane
• Mass-Loss Evolution of Close-In Exoplanets: Evaporation of Hot Jupiters and the Effect on Population
• Multicolour photometry for exoplanet candidate validation
• Four Sub-Saturns with Dissimilar Densities: Windows into Planetary Cores and Envelopes
• Empirical limb-darkening coefficients & transit parameters of known exoplanets from TESS
• The Warm Neptune GJ 3470b has a Polar Orbit
• The SOPHIE search for northern extrasolar planets VIII. A warm Neptune orbiting HD164595
• A He I upper atmosphere around the warm Neptune GJ 3470b
• Evidence for He I 10830 Å~ absorption during the transit of a warm Neptune around the M-dwarf GJ 3470 with the Habitable-zone Planet Finder
• The Upper Edge of the Neptune Desert Is Stable Against Photoevaporation
• Metallicity-Dependent Signatures in the Kepler Planets
• p-winds: an open-source Python code to model planetary outflows and upper atmospheres
• Radial velocity confirmation of K2-100b: a young, highly irradiated, and low density transiting hot Neptune
• Planet Hunters TESS I: TOI 813, a subgiant hosting a transiting Saturn-sized planet on an 84-day orbit
• X-ray irradiation and evaporation of the four young planets around V1298 Tau
• Why do warm Neptunes present nonzero eccentricity?
• Survival of a planet in short-period Neptunian desert under effect of photo-evaporation
• Tidal Inflation Reconciles Low-Density Sub-Saturns with Core Accretion
• A New Model of Roche-lobe Overflow for Short-Period Gaseous Planets and Binary Stars
• No hydrogen exosphere detected around the super-Earth HD97658 b
• Overfitting Affects the Reliability of Radial Velocity Mass Estimates of the V1298 Tau Planets
• The JADE code: Coupling secular exoplanetary dynamics and photo-evaporation
• Quasi-periodic Gaussian Processes for stellar activity: from physical to kernel parameters
• The Hubble PanCET program: An extensive search for metallic ions in the exosphere of GJ 436 b
• Dynamics and Formation of the Near-Resonant K2-24 System: Insights from Transit-Timing Variations and Radial Velocities
• On the mass of gas giant planets: Is Saturn a failed gas giant?
• Two Transiting Low Density Sub-Saturns from K2
• Speckle Interferometry with CMOS Detector
• Exoplanet X-ray irradiation and evaporation rates with eROSITA
• TOI-1130: A photodynamical analysis of a hot Jupiter in resonance with an inner low-mass planet
• The MUSCLES Extension for Atmospheric and Transmission Spectroscopy: UV and X-ray Host-star Observations for JWST ERS & GTO Targets
• The HARPS search for southern extra-solar planets XLV. Two Neptune mass planets orbiting HD 13808: a study of stellar activity modelling's impact on planet detection
• A HARPS-N mass for the elusive Kepler-37d: a case study in disentangling stellar activity and planetary signals
• Revisiting K2-233 spectroscopic time-series with multidimensional Gaussian Processes
• K2-19b and c are in a 3:2 Commensurability but out of Resonance: A Challenge to Planet Assembly by Convergent Migration
• The TESS-Keck Survey. XV. Precise Properties of 108 TESS Planets and Their Host Stars
• Chaotic Excitation and Tidal Damping in the GJ 876 System
• The SOPHIE search for northern extrasolar planets-XIX. A system including a cold sub-Neptune potentially transiting a V = 6.5 star HD88986
• Going back to basics: accelerating exoplanet transit modelling using Taylor-series expansion of the orbital motion
• A warm super-Neptune around the G-dwarf star TOI-1710 revealed with TESS, SOPHIE and HARPS-N
• RoadRunner: a fast and flexible exoplanet transit model
• TOI-5344 b: A Saturn-like planet orbiting a super-Solar metallicity M0 dwarf
• TOI-1296b and TOI-1298b observed with TESS and SOPHIE: Two hot Saturn-mass exoplanets with different densities around metal-rich stars
• VaTEST I: Validation of Sub-Saturn Exoplanet TOI-181b in Narrow Orbit from its Host Star
• TOI-1736 and TOI-2141: two systems including sub-Neptunes around solar analogs revealed by TESS and SOPHIE
• K2-280b -- a low density warm sub-Saturn around a mildly evolved star
• TOI-1199 b and TOI-1273 b: Two new transiting hot Saturns detected and characterized with SOPHIE and TESS
• Confirmation of four hot Jupiters detected by TESS using follow-up spectroscopy from MaHPS at Wendelstein together with NEID and TRES

Cited by in corpus (2)

• The star HIP 41378 potentially misaligned with its cohort of long-period planets
• Evidence of a gap in the envelope mass fraction of sub-Saturns