TOI-1231 b: A Temperate, Neptune-Sized Planet Transiting the Nearby M3 Dwarf NLTT 24399

Abstract

We report the discovery of a transiting, temperate, Neptune-sized exoplanet orbiting the nearby ($d$ = 27.5 pc), M3V star TOI-1231 (NLTT 24399, L 248-27, 2MASS J10265947-5228099). The planet was detected using photometric data from the Transiting Exoplanet Survey Satellite and followed up with observations from the Las Cumbres Observatory and the Antarctica Search for Transiting ExoPlanets program. Combining the photometric data sets, we find that the newly discovered planet has a radius of 3.65${}_{-0.15}^{+0.16}$ R${}_{\oplus }$, and an orbital period of 24.246 days. Radial velocity measurements obtained with the Planet Finder Spectrograph on the Magellan Clay telescope confirm the existence of the planet and lead to a mass measurement of 15.5$\pm$3.3 M${}_{\oplus }$. With an equilibrium temperature of just 330K TOI-1231 b is one of the coolest small planets accessible for atmospheric studies thus far, and its host star's bright NIR brightness (J=8.88, K${}_s$=8.07) make it an exciting target for HST and JWST. Future atmospheric observations would enable the first comparative planetology efforts in the 250-350 K temperature regime via comparisons with K2-18 b. Furthermore, TOI-1231's high systemic radial velocity (70.5 k\ms) may allow for the detection of low-velocity hydrogen atoms escaping the planet by Doppler shifting the H I Ly-alpha stellar emission away from the geocoronal and ISM absorption features.

arXiv comment20 pages, 9 figures. Accepted for publication in The Astronomical Journal

References in corpus (100)

• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2. Summary of the contents and survey properties
• MultiNest: an efficient and robust Bayesian inference tool for cosmology and particle physics
• dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
• Local Kinematics and the Local Standard of Rest
• X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue
• Las Cumbres Observatory Global Telescope Network
• Gaia Early Data Release 3: The astrometric solution
• Exploring the Milky Way stellar disk. A detailed elemental abundance study of 714 F and G dwarf stars in the Solar neighbourhood
• 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
• The Revised TESS Input Catalog and Candidate Target List
• Kepler Presearch Data Conditioning I - Architecture and Algorithms for Error Correction in Kepler Light Curves
• EXOFAST: A fast exoplanetary fitting suite in IDL
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light Curves (Expanded Edition)
• AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light Curves
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• A Framework for Prioritizing the TESS Planetary Candidates Most Amenable to Atmospheric Characterization
• petitRADTRANS: a Python radiative transfer package for exoplanet characterization and retrieval
• The Transiting Exoplanet Survey Satellite: Simulations of planet detections and astrophysical false positives
• A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b
• BANYAN. XI. The BANYAN $\Sigma$ multivariate Bayesian algorithm to identify members of young associations within 150 pc
• The Effect of the Outer Lindblad Resonance of the Galactic Bar on the Local Stellar Velocity Distribution
• Accurate, Empirical Radii and Masses of Planets and their Host Stars with Gaia Parallaxes
• The MUSCLES Treasury Survey I: Motivation and Overview
• The TESS Objects of Interest Catalog from the TESS Prime Mission
• Helium in the eroding atmosphere of an exoplanet
• The Structure of the Local Interstellar Medium V: Electron Densities
• How to Constrain Your M dwarf II: the mass-luminosity-metallicity relation from 0.075 to 0.70$M_{\odot }$
• Juliet: a versatile modelling tool for transiting and non-transiting exoplanetary systems
• PandExo: A Community Tool for Transiting Exoplanet Science with JWST & HST
• How to Distinguish between Cloudy Mini-Neptunes and Water/Volatile-Dominated Super-Earths
• Kepler Data Validation I -- Architecture, Diagnostic Tests, and Data Products for Vetting Transiting Planet Candidates
• A Revised Exoplanet Yield from the Transiting Exoplanet Survey Satellite (TESS)
• Water Vapor and Clouds on the Habitable-Zone Sub-Neptune Exoplanet K2-18b
• Trumpeting M Dwarfs with CONCH-SHELL: a Catalog of Nearby Cool Host-Stars for Habitable ExopLanets and Life
• Stellar Lyman-alpha Emission Lines in the Hubble Space Telescope Archive: Intrinsic Line Fluxes and Absorption from the Heliosphere and Astrospheres
• Water vapour in the atmosphere of the habitable-zone eight Earth-mass planet K2-18 b
• Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69b
• An All-Sky Catalog of Bright M Dwarfs
• Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18
• The MUSCLES Treasury Survey II: Intrinsic Lyman Alpha and Extreme Ultraviolet Spectra of K and M Dwarfs with Exoplanets
• Lyman-$\alpha$ Transit Spectroscopy and the Neutral Hydrogen Tail of the Hot Neptune GJ436b
• Chromospheric activity catalogue of 4454 cool stars. Questioning the active branch of stellar activity cycles
• Kepler Data Validation II -- Transit Model Fitting and Multiple-Planet Search
• SOAR TESS Survey. I: Sculpting of TESS planetary systems by stellar companions
• A statistical test for Nested Sampling algorithms
• A Sub-Neptune Exoplanet with a Low-Metallicity Methane-Depleted Atmosphere and Mie-Scattering Clouds
• 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
• Quantitatively Assessing the Role of Clouds in the Transmission Spectrum of GJ 1214b
• Eclipsing Binary Stars as Benchmarks for Trigonometric Parallaxes in the Gaia Era
• 3D maps of interstellar dust in the Local Arm: using $Gaia$, 2MASS and APOGEE-DR14
• TESS Discovery of a Transiting Super-Earth in the $\pi$ Mensae System
• Observing transiting planets with JWST -- Prime targets and their synthetic spectral observations
• The Intrinsic Extreme Ultraviolet Fluxes of F5 V to M5 V Stars
• A catalogue of rotation and activity in early-M stars
• M dwarfs: effective temperatures, radii and metallicities
• On the Metal-Richness of M Dwarfs with Planets
• Water Clouds in Y Dwarfs and Exoplanets
• Long Term Evolution of Close Planets Including the Effects of Secular Interactions
• Empirical, Accurate Masses and Radii of Single Stars with TESS and Gaia
• TESS Discovery of an ultra-short-period planet around the nearby M dwarf LHS 3844
• The AllWISE Motion Survey and The Quest for Cold Subdwarfs
• Two Classes of Hot Jupiters
• Energy-limited escape revised
• Trends in Atmospheric Properties of Neptune-Size Exoplanets
• Planetary system around the nearby M dwarf GJ 357 including a transiting, hot, Earth-sized planet optimal for atmospheric characterization
• H-alpha Activity of Old M Dwarfs: Stellar Cycles and Mean Activity Levels For 93 Low-Mass Stars in the Solar Neighborhood
• The MUSCLES Treasury Survey IV: Scaling Relations for Ultraviolet, Ca II K, and Energetic Particle Fluxes from M Dwarfs
• Forward modelling and retrievals with PLATON, a fast open source tool
• The Precision of Mass Measurements Required for Robust Atmospheric Characterization of Transiting Exoplanets
• A Physically-Motivated Photometric Calibration of M Dwarf Metallicity
• EXOFASTv2: A public, generalized, publication-quality exoplanet modeling code
• Helium Absorption at 1083 nm from Extended Exoplanet Atmospheres: Dependence on Stellar Radiation
• A Catalog of Cool Dwarf Targets for the Transiting Exoplanet Survey Satellite
• The signatures of the resonances of a large Galactic bar in local velocity space
• The Solar Neighborhood XXX: Fomalhaut C
• HD 202772A B: A Transiting Hot Jupiter Around A Bright, Mildly Evolved Star In A Visual Binary Discovered By Tess
• Fast estimation of orbital parameters in Milky-Way-like potentials
• TESS delivers its first Earth-sized planet and a warm sub-Neptune
• Multiple Star Formation to the Bottom of the IMF
• Updated Parameters and a New Transmission Spectrum of HD 97658b
• Global 3D hydrodynamic modeling of in-transit Lyα absorption of GJ436b
• A Proper Motion Survey Using the First Sky Pass of NEOWISE-Reactivation Data
• An Eccentric Massive Jupiter Orbiting a Sub-Giant on a 9.5 Day Period Discovered in the Transiting Exoplanet Survey Satellite Full Frame Images
• Predicting the Extreme Ultraviolet Radiation Environment of Exoplanets Around Low-Mass Stars: GJ 832, GJ 176, GJ 436
• Is pi Men c's atmosphere hydrogen-dominated? Insights from a non-detecton of Hy Ly-alpha absorption
• A catalogue of bright (K < 9) M dwarfs
• An Estimate of the Yield of Single-Transit Planetary Events from the Transiting Exoplanet Survey Satellite
• Speckle interferometry at SOAR in 2016 and 2017
• Galactic Tide and Local Stellar Perturbations on the Oort Cloud: Creation of Interstellar Comets
• Persistent starspot signals on M dwarfs: multi-wavelength Doppler observations with the Habitable-zone Planet Finder and Keck/HIRES
• Thermalizing a telescope in Antarctica: Analysis of ASTEP observations
• ExTrA: Exoplanets in Transit and their Atmospheres
• Lyman-alpha in the GJ 1132 System: Stellar Emission and Planetary Atmospheric Evolution
• Empirical Predictions for the Period Distribution of Planets to be Discovered by the Transiting Exoplanet Survey Satellite

Cited by in corpus (19)

• From super-Earths to sub-Neptunes: Observational constraints and connections to theoretical models
• TOI-1452 b: SPIRou and TESS reveal a super-Earth in a temperate orbit transiting an M4 dwarf
• Hubble Space Telescope transmission spectroscopy for the temperate sub-Neptune TOI-270d: a possible hydrogen-rich atmosphere containing water vapour
• Exoplanet weather and climate regimes with clouds and thermal ionospheres: A model grid study in support of large-scale observational campaigns
• A transiting, temperate mini-Neptune orbiting the M dwarf TOI-1759 unveiled by TESS
• Resonant sub-Neptunes are puffier
• GJ 3090 b: one of the most favourable mini-Neptune for atmospheric characterisation
• The LHS 1678 System: Two Earth-Sized Transiting Planets and an Astrometric Companion Orbiting an M Dwarf Near the Convective Boundary at 20 pc
• Hundreds of TESS exoplanets might be larger than we thought
• Observing exoplanets from Antarctica in two colours: Set-up and operation of ASTEP+
• Characterization of seven transiting systems including four warm Jupiters from SOPHIE and TESS
• The GAPS programme at TNG LXIV: An inner eccentric sub-Neptune and an outer sub-Neptune-mass candidate around BD+00 444 (TOI-2443)
• Not All Sub-Neptune Exoplanets Have Magma Oceans
• Can Carbon Fractionation Provide Evidence for Aerial Biospheres in the Atmospheres of Temperate Sub-Neptunes?
• No Robust Statistical Evidence for a Population of Water Worlds in a 2025 Sample of Planets Orbiting M Stars
• Earth-like planet predictor: A machine learning approach
• ExoEcho: Exoplanet Ephemerides Change Observations. III. A JWST Survey for Transit Timing Variations of 37 Exoplanets
• Impact of Clouds on the Atmosphere-Mantle Interface of Sub-Neptunes
• Photochemistry and Spectral Characterization of Temperate and Gas-Rich Exoplanets