Migration then assembly: Formation of Neptune mass planets inside 1 AU

Abstract

We demonstrate that the observed distribution of `Hot Neptune'/`Super-Earth' systems is well reproduced by a model in which planet assembly occurs in situ, with no significant migration post-assembly. This is achieved only if the amount of mass in rocky material is $\sim 50$--$100M_{\oplus }$ interior to 1 AU. Such a reservoir of material implies that significant radial migration of solid material takes place, and that it occur before the stage of final planet assembly. The model not only reproduces the general distribution of mass versus period, but also the detailed statistics of multiple planet systems in the sample. We furthermore demonstrate that cores of this size are also likely to meet the criterion to gravitationally capture gas from the nebula, although accretion is rapidly limited by the opening of gaps in the gas disk. If the mass growth is limited by this tidal truncation, then the scenario sketched here naturally produces Neptune-mass objects with substantial components of both rock and gas, as is observed. The quantitative expectations of this scenario are that most planets in the `Hot Neptune/Super-Earth' class inhabit multiple-planet systems, with characteristic orbital spacings. The model also provides a natural division into gas-rich (Hot Neptune) and gas-poor (Super-Earth) classes at fixed period. The dividing mass ranges from $\sim 3M_{\oplus }$ at 10 day orbital periods to $\sim 10M_{\oplus }$ at 100 day orbital periods. For orbital periods $<10$ days, the division is less clear because a gas atmosphere may be significantly eroded by stellar radiation.

41 pages in preprint style, 15 figures, final version accepted to ApJ

References in corpus (25)

• Characteristics of planetary candidates observed by Kepler, II: Analysis of the first four months of data
• Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems
• Planet-disk interaction and orbital evolution
• Atmospheric Escape from Hot Jupiters
• A Closely-Packed System of Low-Mass, Low-Density Planets Transiting Kepler-11
• The Occurrence and Mass Distribution of Close-in Super-Earths, Neptunes, and Jupiters
• KEPLER's First Rocky Planet: Kepler-10b
• Migration and the formation of systems of hot super-Earths and Neptunes
• Models of the in situ formation of detected extrasolar giant planets
• The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets
• Radial velocity planets de-aliased. A new, short period for Super-Earth 55 Cnc e
• Halting Type I planet migration in non-isothermal disks
• A Super-Earth Transiting a Naked-Eye Star
• The Exoplanet Census: A General Method, Applied to Kepler
• The HARPS search for southern extra-solar planets. XIII. A planetary system with 3 Super-Earths (4.2, 6.9, & 9.2 Earth masses)
• Observable Consequences of Planet Formation Models in Systems with Close-in Terrestrial Planets
• HAT-P-26b: A Low-Density Neptune-Mass Planet Transiting a K Star
• The HARPS search for southern extra-solar planets. XXVII. Up to seven planets orbiting HD 10180: probing the architecture of low-mass planetary systems
• Mass-loss rates for transiting exoplanets
• Turbulent Torques on Protoplanets in a Dead Zone
• Formation and structure of the three Neptune-mass planets system around HD69830
• Orbital Orientations of Exoplanets: HAT-P-4b is Prograde and HAT-P-14b is Retrograde
• A Systematic Study of the Final Masses of Gas Giant Planets
• Hydrodynamic outcomes of planet scattering in transitional discs
• Combining Kepler and HARPS Occurrence Rates to Infer the Period-Mass-Radius Distribution of Super-Earths/Sub-Neptunes

Cited by in corpus (199)

• The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
• The Occurrence and Architecture of Exoplanetary Systems
• Kepler planets: a tale of evaporation
• Most 1.6 Earth-Radius Planets are not Rocky
• The Role of Core Mass in Controlling Evaporation: the Kepler Radius Distribution and the Kepler-36 Density Dichotomy
• The Minimum-Mass Extrasolar Nebula: In-Situ Formation of Close-In Super-Earths
• Planetary evaporation by UV & X-ray radiation: basic hydrodynamics
• How Thermal Evolution and Mass Loss Sculpt Populations of Super-Earths and Sub-Neptunes: Application to the Kepler-11 System and Beyond
• Breaking the Chains: Hot Super-Earth systems from migration and disruption of compact resonant chains
• A dynamically-packed planetary system around GJ667C with three super-Earths in its habitable zone
• Dearth of short-period Neptunian exoplanets - a desert in period-mass and period-radius planes
• Three regimes of extrasolar planets inferred from host star metallicities
• The California-Kepler Survey. I. High Resolution Spectroscopy of 1305 Stars Hosting Kepler Transiting Planets
• A stellar-mass-dependent drop in planet occurrence rates
• A Framework for Characterizing the Atmospheres of Low-Mass Low-Density Transiting Planets
• Compositional diversity in the atmospheres of hot Neptunes, with application to GJ 436b
• Make Super-Earths, Not Jupiters: Accreting Nebular Gas onto Solid Cores at 0.1 AU and Beyond
• In Situ Formation and Dynamical Evolution of Hot Jupiter Systems
• Testing In Situ Assembly with the Kepler Planet Candidate Sample
• A Plateau in the Planet Population Below Twice the Size of Earth
• Photoevaporation and High-Eccentricity Migration Created the Sub-Jovian Desert
• Inside-Out Planet Formation
• Atmospheres of low-mass planets: the "boil-off"
• An Increase in the Mass of Planetary Systems around Lower-Mass Stars
• Exoplanetary Atmospheres - Chemistry, Formation Conditions, and Habitability
• Hubble Space Telescope Near-IR Transmission Spectroscopy of the Super-Earth HD 97658b
• A Neptune-sized transiting planet closely orbiting a 5-10-million-year-old star
• The Super Earth-Cold Jupiter Relations
• Observed Properties of Extrasolar Planets
• Formation of TRAPPIST-1 and other compact systems
• The Radius Distribution of Planets Around Cool Stars
• The Formation of Super-Earths and Mini-Neptunes with Giant Impacts
• How formation time-scales affect the period dependence of the transition between rocky super-Earths and gaseous sub-Neptunes and implications for ${\eta }_{\oplus }$
• Four newborn planets transiting the young solar analog V1298 Tau
• No universal minimum-mass extrasolar nebula: Evidence against in-situ accretion of systems of hot super-Earths
• The nature and origins of sub-Neptune size planets
• Hot super-Earths and giant planet cores from different migration histories
• The Photoeccentric Effect and Proto-Hot Jupiters I. Measuring photometric eccentricities of individual transiting planets
• The New Generation Planetary Population Synthesis (NGPPS). II. Planetary population of solar-like stars and overview of statistical results
• Formation of close in Super-Earths \& Mini-Neptunes: Required Disk Masses \& Their Implications
• Magnetospheric Truncation, Tidal Inspiral, and the Creation of Short and Ultra-Short Period Planets
• Characterizing the Cool KOIs IV: Kepler-32 as a prototype for the formation of compact planetary systems throughout the Galaxy
• Herschel imaging of 61 Vir: implications for the prevalence of debris in low-mass planetary systems
• Catastrophic Evaporation of Rocky Planets
• The same frequency of planets inside and outside open clusters of stars
• Magnetic and Gravitational Disk-Star Interactions: An Interdependence of PMS Stellar Rotation Rates and Spin-Orbit Misalignments
• Kepler-20: A Sun-like Star with Three Sub-Neptune Exoplanets and Two Earth-size Candidates
• Eleven Multi-planet Systems from K2 Campaigns 1 & 2 and the Masses of Two Hot Super-Earths
• Detectable close-in planets around white dwarfs through late unpacking
• Gas giant planets as dynamical barriers to inward-migrating super-Earths
• A reassessment of the in situ formation of close-in super-Earths
• The Mass Budget of Planet Forming Discs: Isolating the Epoch of Planetesimal Formation
• Planetesimal Interactions Can Explain the Mysterious Period Ratios of Small Near-Resonant Planets
• Migration of two massive planets into (and out of) first order mean motion resonances
• A Metallicity Recipe for Rocky Planets
• Giant Impact: An Efficient Mechanism for the Devolatilization of Super-Earths
• Correlations between compositions and orbits established by the giant impact era of planet formation
• Orbital and physical properties of planets and their hosts: new insights on planet formation and evolution
• LAMOST telescope reveals that Neptunian cousins of hot Jupiters are mostly single offspring of stars that are rich in heavy elements
• Formation of close-in super-Earths in evolving protoplanetary disks due to disk winds
• Rocky super-Earths or waterworlds: the interplay of planet migration, pebble accretion and disc evolution
• Influence of sub- and super-solar metallicities on the compositions of solid planetary building blocks
• Two massive rocky planets transiting a K-dwarf 6.5 parsecs away
• A warm Jupiter-sized planet transiting the pre-main sequence star V1298 Tau
• Dynamical rearrangement of super-Earths during disk dispersal I. Outline of the magnetospheric rebound model
• Formation, Orbital and Internal Evolutions of Young Planetary Systems
• The Importance of Disk Structure in Stalling Type I Migration
• On the formation of compact planetary systems via concurrent core accretion and migration
• Orbital Architectures of Planet-Hosting Binaries: I. Forming Five Small Planets in the Truncated Disk of Kepler-444A
• Accretion and Evolution of ~2.5 Earth-mass Planets with Voluminous H/He Envelopes
• Warm Ice Giant GJ 3470b. I. A Flat Transmission Spectrum Indicates a Hazy, Low-methane, and/or Metal-rich Atmosphere
• A Six-Planet System Orbiting HD 219134
• The Kepler Dichotomy in Planetary Disks: Linking Kepler Observables to Simulations of Late-Stage Planet Formation
• Terrestrial Planet Formation in the Presence of Migrating Super-earths
• Formation, tidal evolution and habitability of the Kepler-186 system
• Three Super-Earths Orbiting HD 7924
• Constraints on Planet Occurrence around Nearby Mid-to-Late M Dwarfs from the MEarth Project
• Architectures of Planetary Systems and Implications for their Formation
• KELT-8b: A highly inflated transiting hot Jupiter and a new technique for extracting high-precision radial velocities from noisy spectra
• Creating the Radius Gap without Mass Loss
• New Formation Models for the Kepler-36 System
• Measurements of water surface snow lines in classical protoplanetary disks
• Disk Dispersal: Theoretical Understanding and Observational Constraints
• Solar System Physics for Exoplanet Research
• Tests of In-Situ Formation Scenarios for Compact Multiplanet Systems
• Chemical Diversity of Super-Earths As a Consequence of Formation
• The Photoeccentric Effect and Proto-Hot Jupiters II. KOI-1474.01, a candidate eccentric planet perturbed by an unseen companion
• The Exoplanet Population Observation Simulator. II -- Population Synthesis in the Era of Kepler
• Perturbation of Compact Planetary Systems by Distant Giant Planets
• To cool is to keep: Residual H/He atmospheres of super-Earths and sub-Neptunes
• Application of gas dynamical friction for planetesimals: I. Evolution of single planetesimals
• Exploring the realm of scaled Solar System analogs with HARPS
• The GAPS Programme with HARPS-N at TNG. XXXVII. A precise density measurement of the young ultra-short period planet TOI-1807 b
• Planetary migration and the origin of the 2:1 and 3:2 (near)-resonant population of close-in exoplanets
• A significant mutual inclination between the planets within the $\pi$ Mensae system
• Stability of the Kepler-11 System and its Origin
• A framework for the architecture of exoplanetary systems. I. Four classes of planetary system architecture
• Vulcan Planets: Inside-Out Formation of the Innermost Super-Earths
• The Magellan-TESS Survey I: Survey Description and Mid-Survey Results
• Orbital misalignment of the super-Earth $\pi$ Men c with the spin of its star
• Kuiper belt structure around nearby super-Earth host stars
• A dynamical study on the habitability of terrestrial exoplanets II: The super Earth HD 40307 g
• Insights into planet formation from debris disks: II. Giant impacts in extrasolar planetary systems
• Inside-Out Planet Formation. III. Planet-disk interaction at the dead zone inner boundary
• Discovery of a Transiting Planet Near the Snow-Line
• Understanding the assembly of Kepler's compact planetary systems
• Formation of compact systems of super-Earths via dynamical instabilities and giant impacts
• Variations on Debris Disks III. Collisional Cascades and Giant Impacts in the Terrestrial Zones of Solar-type Stars
• Formation of planetary systems by pebble accretion and migration: Hot super-Earth systems from breaking compact resonant chains
• Secular Effects of Tidal Damping in Compact Planetary Systems
• 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
• Observing the linked depletion of dust and CO gas at 0.1-10 au in disks of intermediate-mass stars
• Kojima-1Lb Is a Mildly Cold Neptune around the Brightest Microlensing Host Star
• ALMA observations of the multiplanet system 61 Vir: What lies outside super-Earth systems?
• Three Temperate Neptunes Orbiting Nearby Stars
• Effects of Magnetic Fields on the Location of the Evaporation Valley for Low-Mass Exoplanets
• The Origin of Systems of Tightly Packed Inner Planets with Misaligned, Ultra-Short-Period Companions
• Rocky Planet Formation: Quick and Neat
• Three Pathways for Observed Resonant Chains
• Inside-Out Planet Formation. V. Structure of the Inner Disk as Implied by the MRI
• Ohmic Dissipation in Mini-Neptunes
• Did Jupiter's core form in the innermost parts of the Sun's protoplanetary disk?
• Constraining the parameter space for the Solar Nebula
• Inside-Out Planet Formation. IV. Pebble Evolution and Planet Formation Timescales
• Trapping planets in an evolving protoplanetary disk: preferred time, locations and planet mass
• Multi-season optical modulation phased with the orbit of the super-Earth 55 Cnc e
• Edge-of-the-Multis: Evidence for a Transition in the Outer Architectures of Compact Multi-Planet Systems
• Circumbinary Planet Formation in the Kepler-16 System. II. A Toy Model for In-situ Planet Formation within a Debris Belt
• K2-110 b - a massive mini-Neptune exoplanet
• Formation of Close-in Super-Earths by Giant Impacts: Effects of Initial Eccentricities and Inclinations of Protoplanets
• Earths in Other Solar Systems N-body simulations: the Role of Orbital Damping in Reproducing the Kepler Planetary Systems
• Formation of Terrestrial Planets
• Identifying inflated super-Earths and photo-evaporated cores
• The dynamical evolution of transiting planetary systems including a realistic collision prescription
• Chains of Planets in Mean Motion Resonances Arising from Oligarchic Growth
• Dynamics and Origins of the Near-Resonant Kepler Planets
• Where are the Water Worlds?: Self-Consistent Models of Water-Rich Exoplanet Atmospheres
• Detection and characterization of an ultra-dense sub-Neptune planet orbiting the Sun-like star HD 119130
• Exoplanet Populations and their Dependence on Host Star Properties
• Building massive compact planetesimal disks from the accretion of pebbles
• Collisional Fragmentation is Not a Barrier to Close-in Planet Formation
• Close-in Super-Earths: The first and the last stages of planet formation in an MRI-accreting disc
• Water delivery to the TRAPPIST-1 planets
• The nearby, young, isolated, dusty star HD 166191
• Exploring plausible formation scenarios for the planet candidate orbiting Proxima Centauri
• Super-Earths and sub-Neptunes are Insensitive to Stellar Metallicity
• The circulation of dust in protoplanetary discs and the initial conditions of planet formation
• It takes two planets in resonance to tango around K2-146
• Stability Constrained Characterization of Multiplanet Systems
• Planetary Migration in Protoplanetary Disks
• Multiplanet systems in inviscid discs can avoid forming resonant chains
• Habitability from Tidally-Induced Tectonics
• Ejection of close-in super-Earths around low-mass stars in the giant impact stage
• Breaking mean-motion resonances during Type I planet migration
• No Metallicity Correlation Associated with the Kepler Dichotomy
• Disruption of co-orbital (1:1) planetary resonances during gas-driven orbital migration
• In Situ Models for Planet Assembly around Cool stars
• Terrestrial Planets Formation under Migration: the Systems near 4:2:1 Mean Motion Resonance
• Effects of Planetesimal Scattering: Explaining the Observed Offsets from Period Ratios 3:2 and 2:1
• Exoplanetary Geophysics -- An Emerging Discipline
• Exoplanet atmosphere evolution: emulation with neural networks
• In Situ and Ex Situ Formation Models of Kepler 11 Planets
• Super-Earths as Failed Cores in Orbital Migration Traps
• On the Formation of Super-Earths with Implications for the Solar System
• On the evolution of vortices in massive protoplanetary discs
• A Pluto-Charon Sonata: The Dynamical Architecture of the Circumbinary Satellite System
• Trawling for transits in a sea of noise: A Search for Exoplanets by Analysis of WASP Optical Lightcurves and Follow-up (SEAWOLF)
• Another super-dense sub-Neptune in K2-182 b and refined mass measurements for K2-199 b and c
• Dynamical rearrangement of super-Earths during disk dispersal II. Assessment of the magnetospheric rebound model for planet formation scenarios
• The Terrestrial Planet Formation around M Dwarfs: In-situ, Inward Migration or Reversed Migration
• On the origin of the eccentricity dichotomy displayed by compact super-Earths: dynamical heating by cold giants
• A limit on gas accretion onto close-in super-Earth cores from disk accretion
• Transit Duration Variations in Multi-Planet Systems
• Accurate modeling of grazing transits using umbrella sampling
• Characterizing K2 Candidate Planetary Systems Orbiting Low-Mass Stars III: A High Mass & Low Envelope Fraction for the Warm Neptune K2-55b
• Consequences of dynamically unstable moons in extrasolar systems
• Unveiling the Planet Population at Birth
• A Pluto-Charon Sonata III. Growth of Charon from a Circum-Pluto Ring of Debris
• A Spitzer Search for Transits of Radial Velocity Detected Super-Earths
• K2-79b and K2-222b: Mass measurements of two small exoplanets with periods beyond 10 days that overlap with periodic magnetic activity signals
• Can Rocky Exoplanets with Rings Pose as Sub-Neptunes?
• Searching for a cometary belt around Trappist-1 with ALMA
• Planet Occurrence: Doppler and Transit Surveys
• Obliquities of Exoplanet Host Stars from Precise Distances and Stellar Angular Diameters
• Planet formation: key mechanisms and global models
• An upper limit for the growth of inner planets?
• Formation of Super-Earths
• Separated twins or just siblings? A multi-planet system around an M dwarf including a cool sub-Neptune
• The GAPS Programme at TNG -- XXIII. HD 164922 d: a close-in super-Earth discovered with HARPS-N in a system with a long-period Saturn mass companion
• The Influence of Magnetic Field Geometry on the Formation of Close-in Exoplanets
• Photophoretic Levitation and Trapping of Dust in the Inner Regions of Protoplanetary Disks
• Predicting the Dominant Formation Mechanism of Multi-Planetary Systems
• The architecture of multi-planet systems as a tracer of their formation mechanisms
• Pebble Delivery for Inside-Out Planet Formation
• Halting Migration in Magnetospherically Sculpted Protoplanetary Disks
• Combining Kepler and HARPS Occurrence Rates to Infer the Period-Mass-Radius Distribution of Super-Earths/Sub-Neptunes
• Orbital migration and Resonance Offset of the Kepler-25 and K2-24 systems
• A Criterion for the Onset of Chaos in Compact, Eccentric Multiplanet Systems
• L 98-59: a Benchmark System of Small Planets for Future Atmospheric Characterization