NGTS-EB-7, an eccentric, long-period, low-mass eclipsing binary

Abstract

Despite being the most common types of stars in the Galaxy, the physical properties of late M dwarfs are often poorly constrained. A trend of radius inflation compared to evolutionary models has been observed for earlier type M dwarfs in eclipsing binaries, possibly caused by magnetic activity. It is currently unclear whether this trend also extends to later type M dwarfs below the convective boundary. This makes the discovery of lower-mass, fully convective, M dwarfs in eclipsing binaries valuable for testing evolutionary models especially in longer-period binaries where tidal interaction between the primary and secondary is negligible. With this context, we present the discovery of the NGTS-EB-7 AB system, an eclipsing binary containing a late M dwarf secondary and an evolved G-type primary star. The secondary star has a radius of $0.125\pm 0.006R_{\odot }$ , a mass of $0.096\pm 0.004M_{\odot }$ and follows a highly eccentric $(e=0.71436\pm 0.00085)$ orbit every $193.35875\pm 0.00034$ days. This makes NGTS-EB-7 AB the third longest-period eclipsing binary system with a secondary smaller than $200M_J$ with the mass and radius constrained to better than $5\%$. In addition, NGTS-EB-7 is situated near the centre of the proposed LOPS2 southern field of the upcoming PLATO mission, allowing for detection of the secondary eclipse and measurement of the companion`s temperature. With its long-period and well-constrained physical properties - NGTS-EB-7 B will make a valuable addition to the sample of M dwarfs in eclipsing binaries and help in determining accurate empirical mass/radius relations for later M dwarf stars.

Main body: 14 pages, 6 figures, 5 tables. Appendices: 7 pages, 5 figures, 5 tables

References in corpus (79)

• emcee: The MCMC Hammer
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Transiting Exoplanet Survey Satellite
• 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
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• The PLATO 2.0 Mission
• Exploring the Milky Way stellar disk. A detailed elemental abundance study of 714 F and G dwarf stars in the Solar neighbourhood
• REBOUND: An open-source multi-purpose N-body code for collisional dynamics
• 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
• Elemental Abundance Survey of The Galactic Thick Disk
• IAS15: A fast, adaptive, high-order integrator for gravitational dynamics, accurate to machine precision over a billion orbits
• SkyMapper and the Southern Sky Survey
• Determining stellar atmospheric parameters and chemical abundances of FGK stars with iSpec
• Tidal Evolution of Close-in Extra-Solar Planets
• Evolution of low-mass star and brown dwarf eclipsing binaries
• Modern stellar spectroscopy caveats
• Gaia FGK Benchmark Stars - Metallicity
• Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library
• On the Correlation between the Magnetic Activity Levels, the Metallicities and the Radii of Low-Mass Stars
• The Next Generation Transit Survey (NGTS)
• CERES: A Set of Automated Routines for Echelle Spectra
• LDTk: Limb Darkening Toolkit
• ARES v2 - new features and improved performance
• A Guide to Realistic Uncertainties on Fundamental Properties of Solar-Type Exoplanet Host Stars
• The radius discrepancy in low mass stars: single vs. binaries
• Population-Level Eccentricity Distributions of Imaged Exoplanets and Brown Dwarf Companions: Dynamical Evidence for Distinct Formation Channels
• ELLC - a fast, flexible light curve model for detached eclipsing binary stars and transiting exoplanets
• The EBLM Project I-Physical and orbital parameters, including spin-orbit angles, of two low-mass eclipsing binaries on opposite sides of the Brown Dwarf limit
• The scatter of the M dwarf mass-radius relationship
• ARIADNE: Measuring accurate and precise stellar parameters through SED fitting
• Chromospheric Activities and Kinematics for Solar Type Dwarfs and Subgiants: Analysis of the Activity Distribution and the AVR
• The Rossiter-McLaughlin effect in Exoplanet Research
• SPECULOOS -- Ultracool Dwarf Transit Survey: Target List and Strategy
• The EBLM Project IV. Spectroscopic orbits of over 100 eclipsing M dwarfs masquerading as transiting hot-Jupiters
• The HARPS search for southern extra-solar planets. XXXI. Magnetic activity cycles in solar-type stars: statistics and impact on precise radial velocities
• SPECIES I: Spectroscopic Parameters and atmosphEric ChemIstriEs of Stars
• Impact of a new H/He equation of state on the evolution of massive brown dwarfs. New determination of the hydrogen burning limit
• Analysis of Early Science observations with the CHaracterising ExOPlanets Satellite (CHEOPS) using pycheops
• The all-sky PLATO input catalogue
• HD 1397b: a transiting warm giant planet orbiting a V = 7.8 mag sub-giant star discovered by TESS
• Simultaneous TESS and NGTS Transit Observations of WASP-166b
• The EBLM Project V. Physical properties of ten fully convective, very-low-mass stars
• BAFFLES: Bayesian Ages for Field Lower-Mass Stars
• A transiting warm giant planet around the young active star TOI-201
• The EBLM project III. A Saturn-size low-mass star at the hydrogen-burning limit
• Chemical and Kinematic Properties of the Galactic Disk from the LAMOST and Gaia Sample Stars
• Planets Across Space and Time (PAST). I. Characterizing the Memberships of Galactic Components and Stellar Ages: Revisiting the Kinematic Methods and Applying to Planet Host Stars
• A method to estimate stellar ages from kinematical data
• The EBLM project. II. A very hot, low-mass M dwarf in an eccentric and long period eclipsing binary system from SuperWASP
• A Highly Eccentric Warm Jupiter Orbiting TIC 237913194
• TOI-2525 b and c: A pair of massive warm giant planets with a strong transit timing variations revealed by TESS
• Estimating the masses of extra-solar planets
• The EBLM Project VI. The mass and radius of five low-mass stars in F+M binaries discovered by the WASP survey
• The EBLM project -- VIII. First results for M-dwarf mass, radius and effective temperature measurements using CHEOPS light curves
• Long-term stellar activity variations and their effect on radial-velocity measurements
• Three long period transiting giant planets from TESS
• The EBLM project. VII. Spin-orbit alignment for the circumbinary planet host EBLM J0608-59 A/TOI-1338 A
• NGTS and WASP photometric recovery of a single-transit candidate from TESS
• The Observed Distribution of Spectroscopic Binaries from the Anglo-Australian Planet Search
• ATLAS and SYNTHE under Linux
• A low-mass eclipsing binary within the fully convective zone from the NGTS
• The EBLM project -- IX. Five fully convective M-dwarfs, precisely measured with CHEOPS and TESS light curves
• Fundamental Properties of Late-Type Stars in Eclipsing Binaries
• An eclipsing M-dwarf close to the hydrogen burning limit from NGTS
• The EBLM project X. Benchmark masses, radii and temperatures for two fully convective M-dwarfs using K2
• NGTS clusters survey -- III: A low-mass eclipsing binary in the Blanco 1 open cluster spanning the fully convective boundary
• The EBLM Project XII. An eccentric, long-period eclipsing binary with a companion near the hydrogen-burning limit
• Scintillation-limited photometry with the 20-cm NGTS telescopes at Paranal Observatory
• TIC-320687387 B: a long-period eclipsing M-dwarf close to the hydrogen burning limit
• NGTS J214358.5-380102 -- NGTS discovery of the most eccentric known eclipsing M-Dwarf binary system
• Viewing the PLATO LOPS2 Field Through the Lenses of TESS

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