NGTS-4b: A sub-Neptune Transiting in the Desert

Abstract

We report the discovery of NGTS-4b, a sub-Neptune-sized planet transiting a 13th magnitude K-dwarf in a 1.34d orbit. NGTS-4b has a mass M=$20.6\pm 3.0$M_E and radius R=$3.18\pm 0.26$R_E, which places it well within the so-called "Neptunian Desert". The mean density of the planet ($3.45\pm 0.95$g/cm^3) is consistent with a composition of 100% H${}_2$O or a rocky core with a volatile envelope. NGTS-4b is likely to suffer significant mass loss due to relatively strong EUV/X-ray irradiation. Its survival in the Neptunian desert may be due to an unusually high core mass, or it may have avoided the most intense X-ray irradiation by migrating after the initial activity of its host star had subsided. With a transit depth of $0.13\pm 0.02$%, NGTS-4b represents the shallowest transiting system ever discovered from the ground, and is the smallest planet discovered in a wide-field ground-based photometric survey.

arXiv commentSubmitted to MNRAS

References in corpus (58)

• Gaia Data Release 2. Summary of the contents and survey properties
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Transiting Exoplanet Survey Satellite
• Analytic Lightcurves for Planetary Transit Searches
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• Local Kinematics and the Local Standard of Rest
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• Astrophysics Source Code Library
• The WASP Project and the SuperWASP Cameras
• Las Cumbres Observatory Global Telescope Network
• A box-fitting algorithm in the search for periodic transits
• The NASA Exoplanet Archive: Data and Tools for Exoplanet Research
• Mass-Radius Relationships for Solid Exoplanets
• No planet for HD 166435
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• Understanding the Mass-Radius Relation for Sub-Neptunes: Radius as a Proxy for Composition
• Temperate Earth-sized planets transiting a nearby ultracool dwarf star
• Gaia Data Release 2: Catalogue validation
• Wide-field millimagnitude photometry with HAT: A Tool for Extra-solar Planet Detection
• Correcting systematic effects in a large set of photometric lightcurves
• A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b
• The California Kepler Survey VII. Precise Planet Radii Leveraging Gaia DR2 Reveal the Stellar Mass Dependence of the Planet Radius Gap
• Design Considerations for a Ground-based Transit Search for Habitable Planets Orbiting M dwarfs
• HAT-P-11b: A Super-Neptune Planet Transiting a Bright K Star in the Kepler Field
• The Kilodegree Extremely Little Telescope (KELT): A Small Robotic Telescope for Large-Area Synoptic Surveys
• How Dry is the Brown Dwarf Desert?: Quantifying the Relative Number of Planets, Brown Dwarfs and Stellar Companions around Nearby Sun-like Stars
• Gaia Data Release 1: Catalogue validation
• Dearth of short-period Neptunian exoplanets - a desert in period-mass and period-radius planes
• A Revised Exoplanet Yield from the Transiting Exoplanet Survey Satellite (TESS)
• The Next Generation Transit Survey (NGTS)
• A giant planet undergoing extreme ultraviolet irradiation by its hot massive-star host
• On Galactic density modeling in the presence of dust extinction
• A diagram for the evaporation status of extrasolar planets
• Photoevaporation and High-Eccentricity Migration Created the Sub-Jovian Desert
• The coronal X-ray - age relation and its implications for the evaporation of exoplanets
• LDTk: Limb Darkening Toolkit
• A fast hybrid algorithm for exoplanetary transit searches
• HATSouth: a global network of fully automated identical wide-field telescopes
• ARES v2 - new features and improved performance
• A short-period censor of sub-Jupiter mass exoplanets with low density
• The KELT-South Telescope
• WASP-42 b and WASP-49 b: two new transiting sub-Jupiters
• The long egress of GJ~436b's giant exosphere
• NGTS-1b: A hot Jupiter transiting an M-dwarf
• New low-mass eclipsing binary systems in Praesepe discovered by K2
• Neutral gas properties of Lyman continuum emitting galaxies: column densities and covering fractions from UV absorption lines
• Mass-Loss Evolution of Close-In Exoplanets: Evaporation of Hot Jupiters and the Effect on Population
• SPECIES I: Spectroscopic Parameters and atmosphEric ChemIstriEs of Stars
• The Next Generation Transit Survey (NGTS)
• WASP-64b and WASP-72b: two new transiting highly irradiated giant planets
• Evidence for the formation of the young counter-rotating stellar disk from gas acquired by IC 719
• DONUTS: A science frame autoguiding algorithm with sub-pixel precision, capable of guiding on defocused stars
• The XUV environments of exoplanets from Jupiter-size to super-Earth
• An Estimate of the Yield of Single-Transit Planetary Events from the Transiting Exoplanet Survey Satellite
• Centroid vetting of transiting planet candidates from the Next Generation Transit Survey
• The MEarth project: searching for transiting habitable super-Earths around nearby M-dwarfs
• SPECULOOS: a network of robotic telescopes to hunt for terrestrial planets around the nearest ultracool dwarfs
• The Next Generation Transit Survey - Prototyping Phase

Cited by in corpus (53)

• A remnant planetary core in the hot-Neptune desert
• Homogeneous Analysis of Hot Earths: Masses, Sizes, and Compositions
• An Ultra-Hot Neptune in the Neptune desert
• Radial velocity confirmation of K2-100b: a young, highly irradiated, and low density transiting hot Neptune
• NGTS clusters survey. I. Rotation in the young benchmark open cluster Blanco 1
• NGTS-7Ab: An ultra-short period brown dwarf transiting a tidally-locked and active M dwarf
• The CARMENES search for exoplanets around M dwarfs -- LP 714-47b (TOI 442.01): Populating the Neptune desert
• TKS X: Confirmation of TOI-1444b and a Comparative Analysis of the Ultra-short-period Planets with Hot Neptunes
• Zodiacal Exoplanets in Time. X. The Orbit and Atmosphere of the Young "Neptune Desert"-Dwelling Planet K2-100b
• TOI-674b: an oasis in the desert of exo-Neptunes transiting a nearby M dwarf
• Classifying Exoplanet Candidates with Convolutional Neural Networks: Application to the Next Generation Transit Survey
• Shallower radius valley around low-mass hosts: Evidence for icy planets, collisions or high-energy radiation scatter
• NGTS-10b: The shortest period hot Jupiter yet discovered
• TOI-132 b: A short-period planet in the Neptune desert transiting a $V=11.3$ G-type star
• NGTS-6b: An Ultra Short Period Hot-Jupiter Orbiting an Old K Dwarf
• Shallow transit follow-up from NGTS: simultaneous observations of HD106315 with 11 identical telescopes
• The PLATO field selection process. II. Characterization of LOPS2, the first long-pointing field
• A Mirage or an Oasis? Water Vapor in the Atmosphere of the Warm Neptune TOI-674 b
• TOI-4010: A System of Three Large Short-Period Planets With a Massive Long-Period Companion
• TOI-1696: a nearby M4 dwarf with a $3R_{\oplus }$ planet in the Neptunian desert
• The HD 93963 A transiting system: A 1.04d super-Earth and a 3.65 d sub-Neptune discovered by TESS and CHEOPS
• NGTS-14Ab: a Neptune-sized transiting planet in the desert
• The sub-Jovian desert of exoplanets: parameter dependent boundaries and implications on planet formation
• TOI-220 $b$: a warm sub-Neptune discovered by TESS
• WASP-169, WASP-171, WASP-175 and WASP-182: three hot Jupiters and one bloated sub-Saturn mass planet discovered by WASP-south
• HATS-37Ab and HATS-38b: Two Transiting Hot Neptunes in the Desert
• NGTS clusters survey -- III: A low-mass eclipsing binary in the Blanco 1 open cluster spanning the fully convective boundary
• Unraveling the evolution of hot Jupiter systems under the effect of tidal and magnetic interactions and mass loss
• A dense mini-Neptune orbiting the bright young star HD 18599
• NGTS-12b: A sub-Saturn mass transiting exoplanet in a 7.53 day orbit
• NGTS-8b and NGTS-9b: two non-inflated hot-Jupiters
• An old warm Jupiter orbiting the metal-poor G-dwarf TOI-5542
• A Holistic and Probabilistic Approach to the Ground-based Data of HAT-P-19 System
• NGTS J214358.5-380102 -- NGTS discovery of the most eccentric known eclipsing M-Dwarf binary system
• Unveiling the Planet Population at Birth
• Implications of an improved water equation of state for water-rich planets
• A hot mini-Neptune and a temperate, highly eccentric sub-Saturn around the bright K-dwarf TOI-2134
• TOI-908: a planet at the edge of the Neptune desert transiting a G-type star
• The discovery of three hot Jupiters, NGTS-23b, 24b and 25b, and updated parameters for HATS-54b from the Next Generation Transit Survey
• DMPP-4: Candidate sub-Neptune mass planets orbiting a naked-eye star
• Converting the sub-Jovian desert of exoplanets to a savanna with TESS, PLATO and Ariel
• The GALAH Survey: Improving our understanding of confirmed and candidate planetary systems with large stellar surveys
• NGTS-21b: An Inflated Super-Jupiter Orbiting a Metal-poor K dwarf
• SpecPhot: A Comparison of Spectroscopic and Photometric Exoplanet Follow-Up Methods
• TOI-3568 b: a super-Neptune in the sub-Jovian desert
• Planet Hunters NGTS: New Planet Candidates from a Citizen Science Search of the Next Generation Transit Survey Public Data
• Mass loss by atmospheric escape from extremely close-in planets
• SPECULOOS: five years hunting terrestrial planets around ultra-cool dwarfs
• The Occurrence-weighted Median Planets Discovered by Transit Surveys Orbiting Solar-type Stars and Their Implications for Planet Formation and Evolution
• No further evidence for a transiting inner companion to the hot Jupiter HATS-50b
• TFAW survey II: 6 Newly Validated Planets and 13 Planet Candidates from K2
• Revisiting the exoplanet radius valley with host stars from SWEET-Cat
• TOI-333b: A Neptune Desert planet around a F7V star