TOI-2458 b: A mini-Neptune consistent with in situ hot Jupiter formation

Abstract

We report on the discovery and spectroscopic confirmation of TOI-2458 b, a transiting mini-Neptune around an F-type star leaving the main-sequence with a mass of $M_{\star }=1.05\pm 0.03$ M${}_{\odot }$, a radius of $R_{\star }=1.31\pm 0.03$ R${}_{\odot }$, an effective temperature of $T_{\mathrm{eff}}=6005\pm 50$ K, and a metallicity of $-0.10\pm 0.05$ dex. By combining TESS photometry with high-resolution spectra acquired with the HARPS spectrograph, we found that the transiting planet has an orbital period of $\sim$3.74 days, a mass of $M_p=13.31\pm 0.99$ M${}_{\oplus }$ and a radius of $R_p=2.83\pm 0.20$ R${}_{\oplus }$. The host star TOI-2458 shows a short activity cycle of $\sim$54 days revealed in the HARPS S-index and H$\alpha$ times series. We took the opportunity to investigate other F stars showing activity cycle periods comparable to that of TOI-2458 and found that they have shorter rotation periods than would be expected based on the gyrochronology predictions. In addition, we determined TOI-2458's stellar inclination angle to be $i_{\star }=10.6_{-10.6}^{+13.3}$ degrees. We discuss that both phenomena (fast stellar rotation and planet orbit inclination) could be explained by in situ formation of a hot Jupiter interior to TOI-2458 b. It is plausible that this hot Jupiter was recently engulfed by the star. Analysis of HARPS spectra has identified the presence of another planet with a period of $P=16.55\pm 0.06$ days and a minimum mass of $M_p\sin i=10.22\pm 1.90$ M${}_{\oplus }$. Using dynamical stability analysis, we constrained the mass of this planet to the range $M_c\simeq (10,25)$ M${}_{\oplus }$.

arXiv comment25 pages, 20 figures, accepted for publication in Astronomy & Astrophysics

References in corpus (106)

• emcee: The MCMC Hammer
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• 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
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• 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
• Shrinking binary and planetary orbits by Kozai cycles with tidal friction
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• 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
• REBOUND: An open-source multi-purpose N-body code for collisional dynamics
• Kepler Presearch Data Conditioning II - A Bayesian Approach to Systematic Error Correction
• Models of Stars, Brown Dwarfs and Exoplanets
• The Occurrence and Architecture of Exoplanetary Systems
• Prevalence of Earth-size planets orbiting Sun-like stars
• Kepler Presearch Data Conditioning I - Architecture and Algorithms for Error Correction in Kepler Light Curves
• The evaporation valley in the Kepler planets
• Planet-disk interaction and orbital evolution
• IAS15: A fast, adaptive, high-order integrator for gravitational dynamics, accurate to machine precision over a billion orbits
• The TESS Input Catalog and Candidate Target List
• 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)
• The Occurrence Rate of Small Planets around Small Stars
• Growth Model Interpretation of Planet Size Distribution
• Hot Jupiters from Secular Planet--Planet Interactions
• Extrasolar planet population synthesis I: Method, formation tracks and mass-distance distribution
• Determining stellar atmospheric parameters and chemical abundances of FGK stars with iSpec
• Core-powered mass loss and the radius distribution of small exoplanets
• Basic physical parameters of a selected sample of evolved stars
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• Secular Dynamics in Hierarchical Three-Body Systems
• Spectroscopy Made Easy: Evolution
• 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
• Friends of Hot Jupiters I: A Radial Velocity Search for Massive, Long-Period Companions to Close-In Gas Giant Planets
• The Frequency of Hot Jupiters Orbiting Nearby Solar-Type Stars
• Can we constrain interior structure of rocky exoplanets from mass and radius measurements?
• Atmospheres of protoplanetary cores: critical mass for nucleated instability
• Modern stellar spectroscopy caveats
• Kepler Data Validation I -- Architecture, Diagnostic Tests, and Data Products for Vetting Transiting Planet Candidates
• A stellar-mass-dependent drop in planet occurrence rates
• A new list of thorium and argon spectral lines in the visible
• Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library
• Debris disks around Sun-like stars
• Spitzer Secondary Eclipses of the Dense, Modestly-irradiated, Giant Exoplanet HAT-P-20b Using Pixel-Level Decorrelation
• WASP-47: A Hot Jupiter System with Two Additional Planets Discovered by K2
• In Situ Formation and Dynamical Evolution of Hot Jupiter Systems
• Planetary nebulae seen with TESS: Discovery of new binary central star candidates from Cycle 1
• Kepler Data Validation II -- Transit Model Fitting and Multiple-Planet Search
• PyTransit: Fast and Easy Exoplanet Transit Modelling in Python
• Migrating Planets
• Observational Evidence for Tidal Destruction of Exoplanets
• Rotation periods of late-type dwarf stars from time-series high-resolution spectroscopy of chromospheric indicators
• Ten years of speckle interferometry at SOAR
• Bayesian distances and extinctions for giants observed by Kepler and APOGEE
• Magnetic cycles of the planet-hosting star Tau Bootis: II. a second magnetic polarity reversal
• Statistics of Long Period Gas Giant Planets in Known Planetary Systems
• The Orbit of WASP-12b is Decaying
• Debris disc stirring by secular perturbations from giant planets
• When Do Stalled Stars Resume Spinning Down? Advancing Gyrochronology with Ruprecht 147
• Lithium Depletion of Nearby Young Stellar Associations
• Four newborn planets transiting the young solar analog V1298 Tau
• Surface rotation and photometric activity for Kepler targets I. M and K main-sequence stars
• On the Inference of a Star's Inclination Angle from its Rotation Velocity and Projected Rotation Velocity
• Atomic and Molecular Data for Optical Stellar Spectroscopy
• Rotation periods for cool stars in the 4 Gyr-old open cluster M67, the solar-stellar connection, and the applicability of gyrochronology to at least solar age
• ARIADNE: Measuring accurate and precise stellar parameters through SED fitting
• Pyaneti: a fast and powerful software suite for multi-planet radial velocity and transit fitting
• pyaneti II: A multidimensional Gaussian process approach to analysing spectroscopic time-series
• Spitzer 24 Micron Observations of Open Cluster IC 2391 and Debris Disk Evolution of FGK Stars
• The Evolving Magnetic Topology of $\tau$ Boötis
• TESS spots a hot Jupiter with an inner transiting Neptune
• Rotation Periods, Inclinations, and Obliquities of Cool Stars Hosting Directly Imaged Substellar Companions: Spin-Orbit Misalignments are Common
• The low level of debris disk activity at the time of the Late Heavy Bombardment: a Spitzer study of Praesepe
• Stellar Rotation in the Gaia Era: Revised Open Clusters Sequences
• Kepler-730: A hot Jupiter system with a close-in, transiting, Earth-sized planet
• Rotation Period Evolution in Low-Mass Binary Stars: The Impact of Tidal Torques and Magnetic Braking
• NGTS clusters survey. I. Rotation in the young benchmark open cluster Blanco 1
• SOAR TESS Survey. II: The impact of stellar companions on planetary populations
• A 4 Gyr M-dwarf Gyrochrone from CFHT/MegaPrime Monitoring of the Open Cluster M67
• Machine learning inference of the interior structure of low-mass exoplanets
• Evolution of star-planet systems under magnetic braking and tidal interaction
• TOI-2076 and TOI-1807: Two young, comoving planetary systems within 50 pc identified by TESS that are ideal candidates for further follow-up
• ExoMDN: Rapid characterization of exoplanet interior structures with Mixture Density Networks
• An estimate of the $k_2$ Love number of WASP-18Ab from its radial velocity measurements
• The Reversibility Error Method (REM): a new, dynamical fast indicator for planetary dynamics
• The Discovery of a Planetary Companion Interior to Hot Jupiter WASP-132 b
• Magnetic and tidal migration of close-in planets. Influence of secular evolution on their population
• Precise masses for the transiting planetary system HD 106315 with HARPS
• TOI-1130: A photodynamical analysis of a hot Jupiter in resonance with an inner low-mass planet
• Detectability of shape deformation in short-period exoplanets
• TOI-5005 b: A super-Neptune in the savanna near the ridge
• Discovery and characterization of the exoplanets WASP-148b and c. A transiting system with two interacting giant planets
• Discovery of a Companion at the L/T Transition with the Wide-field Infrared Survey Explorer
• TESS spots a mini-neptune interior to a hot saturn in the TOI-2000 system
• In situ formation of hot Jupiters with companion super-Earths
• Searching for IR excesses in Sun-like stars observed by WISE
• The influence of planetary engulfment on stellar rotation in metal-poor main-sequence stars
• Hot planets around cool stars -- two short-period mini-Neptunes transiting the late K-dwarf TOI-1260
• Search for planets around stars with wide brown dwarfs
• Close-in giant-planet formation via in-situ gas accretion and their natal disk properties

Cited by in corpus (1)

• Observational imprints of tidal internal gravity wave dissipation in star-planet systems