The GAPS Programme at the TNG: LXX. TOI-5734b: A hot sub-Neptune orbiting a relatively young K dwarf with an Earth-like density

Abstract

Increasing interest in young exoplanets is leading to a growing effort to understand the formation and evolutionary processes responsible for their different architectures. One interesting target is TOI-5734, a relatively young K3-K4 dwarf star ($500_{-150}^{+300}$ Myr) showing a transiting candidate in photometric observations followed up with high-resolution spectroscopic data. Using Transiting Exoplanet Survey Satellite (TESS) photometry and High Accuracy Radial velocity Planet Searcher for the Northern hemisphere (HARPS-N) radial-velocity (RV) data, we aim to validate the presence of the companion TOI-5734b, measure its planetary mass, size, and its orbital parameters after having characterised its host star. We then aim to study its possible planetary composition and atmospheric evolution. By simultaneously modelling photometry and high-cadence RVs, we measured the radius, mass, and density of TOI-5734b precisely. In particular, we employed Gaussian processes (GPs) with a flexible kernel to discriminate between the stellar activity of the young host and planetary signals. We confirmed the planetary nature of TOI-5734b and measured its orbital period ($P_{\mathrm{b}}\sim 6.18$ d), radius ($R_{\mathrm{b}}=2.10_{-0.12}^{+0.12}$ $R_{\oplus }$), and mass ($M_{\mathrm{b}}=9.1_{-2.6}^{+2.6}$ $M_{\oplus }$). By measuring its density (${\rho }_{\mathrm{b}}=0.98_{-0.30}^{+0.36}$ ${\rho }_{\oplus }$), we infer that TOI-5734b is close to having a rocky composition and an almost completely depleted primary envelope. Our results point toward the possibility of considering the target for atmospheric studies with present and future ground- and space-based facilities.

arXiv comment19 pages, 20 figures. Accepted for publication on A&A. Language editor corrected version. Abstract abridged

References in corpus (100)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The Gaia mission
• Gaia Data Release 3: Summary of the content and survey properties
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
• Gaia Data Release 2: The astrometric solution
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• 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
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• Bayes in the sky: Bayesian inference and model selection in cosmology
• Las Cumbres Observatory Global Telescope Network
• Gaia Early Data Release 3: The astrometric solution
• batman: BAsic Transit Model cAlculatioN in Python
• Fast and scalable Gaussian process modeling with applications to astronomical time series
• Planetary Radii across Five Orders of Magnitude in Mass and Stellar Insolation: Application to Transits
• Towards a Deterministic Model of Planetary Formation I: a Desert in the Mass and Semi Major Axis Distributions of Extra Solar Planets
• Efficient, uninformative sampling of limb darkening coefficients for two-parameter laws
• EXOFAST: A fast exoplanetary fitting suite in IDL
• 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 Chandra Source Catalog
• 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
• BANYAN. XI. The BANYAN $\Sigma$ multivariate Bayesian algorithm to identify members of young associations within 150 pc
• Basic physical parameters of a selected sample of evolved stars
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• Late-type stars members of young stellar kinematic groups - I. Single stars
• Accurate, Empirical Radii and Masses of Planets and their Host Stars with Gaia Parallaxes
• On the use of empirical bolometric corrections for stars
• The SRG/eROSITA all-sky survey: First X-ray catalogues and data release of the western Galactic hemisphere
• Juliet: a versatile modelling tool for transiting and non-transiting exoplanetary systems
• Evidence for a systematic offset of -80 micro-arcseconds in the Gaia DR2 parallaxes
• Departures from LTE for neutral Li in late-type stars
• 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
• Parallax Systematics and Photocenter Motions of Benchmark Eclipsing Binaries in Gaia EDR3
• Planetary nebulae seen with TESS: Discovery of new binary central star candidates from Cycle 1
• The Kepler Follow-Up Observation Program. I. A Catalog of Companions to Kepler Stars from High-Resolution Imaging
• Transit Least Squares: Optimized transit detection algorithm to search for periodic transits of small planets
• Wotan: Comprehensive time-series de-trending in Python
• ARES v2 - new features and improved performance
• 3D maps of interstellar dust in the Local Arm: using $Gaia$, 2MASS and APOGEE-DR14
• Dust masses of young disks: constraining the initial solid reservoir for planet formation
• PALM-3000: Exoplanet Adaptive Optics for the 5-meter Hale Telescope
• When Do Stalled Stars Resume Spinning Down? Advancing Gyrochronology with Ruprecht 147
• TESS Hunt for Young and Maturing Exoplanets (THYME): A planet in the 45 Myr Tucana-Horologium association
• Vetting of 384 TESS Objects of Interest with TRICERATOPS and Statistical Validation of 12 Planet Candidates
• Images of Embedded Jovian Planet Formation At A Wide Separation Around AB Aurigae
• On the Relation Between Hot Jupiters & the Roche Limit
• The GAPS programme with HARPS-N at TNG. I: Observations of the Rossiter-McLaughlin effect and characterisation of the transiting system Qatar-1
• The California-Kepler Survey. X. The Radius Gap as a Function of Stellar Mass, Metallicity, and Age
• A new method to compute limb-darkening coefficients for stellar atmosphere models with spherical symmetry: the space missions TESS, Kepler, Corot, and MOST
• Overcoming the limitations of the energy-limited approximation for planet atmospheric escape
• 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
• Exploring the Habitable Zone for Kepler planetary candidates
• Evidence for a systematic offset of $-$0.25 mas in the Gaia DR1 parallaxes
• The VLT/NaCo Large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits: I- Sample definition and characterization
• The GALAH survey: effective temperature calibration from the InfraRed Flux Method in the Gaia system
• JWST/NIRISS reveals the water-rich "steam world" atmosphere of GJ 9827 d
• Planetary Formation Scenarios Revistied: Core-Accretion Versus Disk Instability
• Empirical limb-darkening coefficients & transit parameters of known exoplanets from TESS
• Photospheric activity, rotation, and radial velocity variations of the planet-hosting star CoRoT-7
• Consistent metallicity scale for cool dwarfs and giants. A benchmark test using the Hyades
• The Gaia-ESO Survey: Empirical estimates of stellar ages from lithium equivalent widths (EAGLES)
• Diving Beneath the Sea of Stellar Activity: Chromatic Radial Velocities of the Young AU Mic Planetary System
• A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- I. Search for exoplanets and variable stars in the field of 47 Tuc
• The Gaia-ESO Survey: a new approach to chemically characterising young open clusters
• The Structure of Exoplanets
• Kepler-411: a four-planet system with an active host star
• Comparison of the power-2 limb-darkening law from the Stagger-grid to Kepler light curves of transiting exoplanets
• The GAPS Programme at TNG XXI -- A GIARPS case-study of known young planetary candidates: confirmation of HD 285507 b and refutation of AD Leo b
• A possibly inflated planet around the bright, young star DS Tuc A
• Irradiation-driven escape of primordial planetary atmospheres II. Evaporation efficiency of sub-Neptunes through hot Jupiters
• A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- II. Search for exoplanets in open clusters of the southern ecliptic hemisphere and their frequency
• The mass-radius relation of exoplanets, revisited
• The GAPS Programme with HARPS-N at TNG. XXXV. Fundamental properties of transiting exoplanet host stars
• ArielRad: the Ariel Radiometric Model
• Irradiation-driven escape of primordial planetary atmospheres I. The ATES photoionization hydrodynamics code
• The young HD 73583 (TOI-560) planetary system: Two 10-M${}_{\oplus }$ mini-Neptunes transiting a 500-Myr-old, bright, and active K dwarf
• Constraints on the mass and atmospheric composition and evolution of the low-density young planet DS Tuc A b
• The GAPS Programme with HARPS-N at TNG. XXXVII. A precise density measurement of the young ultra-short period planet TOI-1807 b
• Speckle Interferometry with CMOS Detector
• The GAPS Programme at TNG XXVIII -- A pair of hot-Neptunes orbiting the young star TOI-942
• A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- III. Exploring the properties of young associations through their variables, dippers, and candidate exoplanets
• A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- IV. Candidate exoplanets around stars in open clusters: frequency and age-planetary radius distribution
• Photo-evaporation of close-in gas giants orbiting around G and M stars
• Connection between planetary He I $\lambda$10830 Å absorption and extreme-ultraviolet emission of planet-host stars
• The GAPS Programme at TNG -- XXV. Stellar atmospheric parameters and chemical composition through GIARPS optical and near-infrared spectra
• The GAPS Programme at TNG XLII. A characterisation study of the multi-planet system around the 400 Myr-old star HD 63433 (TOI-1726)
• TOI-179: a young system with a transiting compact Neptune-mass planet and a low-mass companion in outer orbit
• A dynamical mass for GJ 463 b: A massive super-Jupiter companion beyond the snow line of a nearby M dwarf
• The GAPS programme at TNG XLIV. Projected rotational velocities of 273 exoplanet-host stars observed with HARPS-N
• Dynamical masses of two young transiting sub-Neptunes orbiting HD 63433
• The GAPS programme at TNG LXIV: An inner eccentric sub-Neptune and an outer sub-Neptune-mass candidate around BD+00 444 (TOI-2443)
• In-depth characterization of the Kepler-10 three-planet system with HARPS-N radial velocities and Kepler transit timing variations
• The GAPS Programme at TNG. LXV. Precise density measurement of TOI-1430 b, a young planet with an evaporating atmosphere