The ionization fraction in alpha-models of protoplanetary disks

Abstract

We calculate the ionization fraction of protostellar alpha disks, taking into account vertical temperature structure, and the possible presence of trace metal atoms. Both thermal and X-ray ionization are considered. Previous investigations of layered disks used radial power-law models with isothermal vertical structure. But alpha models are used to model accretion, and the present work is a step towards a self-consistent treatment. The extent of the magnetically uncoupled (``dead'') zone depends sensitively on alpha, on the assumed accretion rate, and on the critical magnetic Reynolds number, below which MHD turbulence cannot be self-sustained. Its extent is extremely model-dependent. It is also shown that a tiny fraction of the cosmic abundance of metal atoms can dramatically affect the ionization balance. Gravitational instabilities are an unpromising source of transport, except in the early stages of disk formation.

25 pages including 8 figures, Latex in the MN style - Accepted by MNRAS

References in corpus (2)

• Disk Frequencies and Lifetimes in Young Clusters
• Episodic accretion in magnetically layered protoplanetary discs

Cited by in corpus (159)

• Theory of Star Formation
• Astrophysical magnetic fields and nonlinear dynamo theory
• Resolved Images of Large Cavities in Protoplanetary Transition Disks
• Dynamics of Protoplanetary Disks
• Enhanced Angular Momentum Transport in Accretion Disks
• Migration and the formation of systems of hot super-Earths and Neptunes
• The Physics of Star Formation
• The stellar mass spectrum from non-isothermal gravoturbulent fragmentation
• Local Magnetohydrodynamical Models of Layered Accretion Disks
• Thanatology in Protoplanetary Discs: the combined influence of Ohmic, Hall, and ambipolar diffusion on dead zones
• Global simulations of protoplanetary disks with net magnetic flux: I. Non-ideal MHD case
• Pseudo-viscous modeling of self-gravitating discs and the formation of low mass ratio binaries
• Exclusion of Cosmic Rays in Protoplanetary Disks: Stellar and Magnetic Effects
• Turbulent Mixing and the Dead Zone in Protostellar Disks
• The Sun in Time: Activity and Environment
• Dust settling in local simulations of turbulent protoplanetary disks
• Heat and Dust in Active Layers of Protostellar Disks
• Dust diffusion in protoplanetary discs by magnetorotational turbulence
• The Far-Ultraviolet Spectra of TW Hya. II. Models of H2 Fluorescence in a Disk
• Chemical evolution of turbulent protoplanetary disks and the Solar nebula
• Magnetorotational Instability Driven Accretion in Protoplanetary Disks
• On the Ionisation Fraction in Protoplanetary Disks I: Comparing Different Reaction Networks
• Protoplanetary Disk Winds by Magnetorotational Instability : Formation of an Inner Hole and a Crucial Assist for Planet Formation
• Magnetically driven accretion in protoplanetary discs
• Dead Zone Accretion Flows in Protostellar Disks
• Why Do T Tauri Disks Accrete?
• Planetesimal formation by the streaming instability in a photoevaporating disk
• Dust sedimentation and self-sustained Kelvin-Helmholtz turbulence in protoplanetary disk mid-planes. I. Radially symmetric simulations
• Hall-effect Controlled Gas Dynamics in Protoplanetary Disks: I. Wind Solutions at the Inner Disk
• Chemical Processes in Protoplanetary Disks II. On the importance of photochemistry and X-ray ionization
• Type I Planetary Migration with MHD Turbulence
• Low-Mass Proto-Planet Migration in T-Tauri Alpha-Disks
• Global MHD simulations of stratified and turbulent protoplanetary discs. I. Model properties
• Compton Thick AGN: the dark side of the X-ray background
• Magnetic self-organisation in Hall-dominated magnetorotational turbulence
• Inside-Out Evacuation of Transitional Protoplanetary Disks by the Magneto-Rotational Instability
• High-resolution simulations of planetesimal formation in turbulent protoplanetary discs
• Stopping inward planetary migration by a toroidal magnetic field
• Reduction of chemical networks. II. Analysis of the fractional ionisation in protoplanetary discs
• Hall diffusion and the magnetorotational instability in protoplanetary discs
• Continuum and CO/HCO+ Emission from the Disk Around the T Tauri Star LkCa 15
• On the Linear Stability of Weakly-Ionized, Magnetized Planar Shear Flows
• A Survey for Circumstellar Disks Around Young Substellar Objects
• On the migration-induced resonances in a system of two planets with masses in the Earth mass range
• Surface Layer Accretion in Transitional and Conventional Disks: From Polycyclic Aromatic Hydrocarbons to Planets
• Deuterium chemistry in protoplanetary disks II The inner 30 AU
• Bypass to Turbulence in Hydrodynamic Accretion: Lagrangian Analysis of Energy Growth
• Exclusion of Cosmic Rays in Protoplanetary Disks. II. Chemical Gradients and Observational Signatures
• Self-Sustained Ionization and Vanishing Dead Zones in Protoplanetary Disks
• Magnetorotational instability in protoplanetary discs
• Turbulent Torques on Protoplanets in a Dead Zone
• The Lifetime of Protoplanetary Disks in a Low-Metallicity Environment
• Mean-Field Magnetohydrodynamics of Accretion Disks
• Diffusive Migration of Low-Mass Proto-planets in Turbulent Disks
• New composite models of partially ionized protoplanetary disks
• Midplane sedimentation of large solid bodies in turbulent protoplanetary discs
• The Origin of Jovian Planets in Protostellar Disks: The Role of Dead Zones
• Saving Planetary Systems: Dead Zones & Planetary Migration
• Vortices in Thin, Compressible, Unmagnetized Disks
• Energetic Protons, Radionuclides and Magnetic Activity in Protostellar Disks
• Three Dimensional Compressible Hydrodynamic Simulations of Vortices in Disks
• Transport of magnetic flux and the vertical structure of accretion discs: II. Vertical profile of the diffusion coefficients
• On the migration of protoplanets embedded in circumbinary disks
• Bypass to Turbulence in Hydrodynamic Accretion Disks: An Eigenvalue Approach
• Turbulent transport and its effect on the dead zone in protoplanetary discs
• The Ionization Fraction of Barnard 68: Implications for Star and Planet Formation
• On the Ionisation Fraction in Protoplanetary Disks II: The Effect of Turbulent Mixing on Gas--phase Chemistry
• Magnetorotational instability in stratified, weakly ionised accretion discs
• Gap Formation by Planets in Turbulent Protostellar Disks
• Evolution of self-gravitating magnetized disks. II- Interaction between MHD turbulence and gravitational instabilities
• Mineral Processing by Short Circuits in Protoplanetary Disks
• Dead Zones around Young Stellar Objects: Dependence on Physical Parameters
• X-ray Super-Flares From Pre-Main Sequence Stars: Flare Energetics And Frequency
• From discs to planetesimals I: evolution of gas and dust discs
• Meridional circulation in turbulent protoplanetary disks
• Chondrule Formation and Protoplanetary Disk Heating by Current Sheets in Non-Ideal Magnetohydrodynamic Turbulence
• Stellar Mass Spectra from Non-Isothermal Gravoturbulent Fragmentation
• Dead Zones and Extrasolar Planetary Properties
• Short Circuits in Thermally Ionized Plasmas: A Mechanism for Intermittent Heating of Protoplanetary Disks
• Dead Zones and the Origin of Planetary Masses
• The effects of X-ray photoionization and heating on the structure of circumstellar discs
• On the evolution of the snow line in protoplanetary discs II: Analytic approximations
• On the dynamics of planetesimals embedded in turbulent protoplanetary discs with dead zones
• Formation of circumbinary planets in a dead zone
• The Growth & Migration of Jovian Planets in Evolving Protostellar Disks with Dead Zones
• Dead Zones around Young Stellar Objects: FU Orionis Outbursts and Transition Discs
• Planetesimal and Protoplanet Dynamics in a Turbulent Protoplanetary Disk: Ideal Unstratified Disks
• Global Simulations of the Vertical Shear Instability with Non-ideal Magnetohydrodynamical Effects
• Fossil magnetic field of accretion disks of young stars
• On self-sustaining processes in Rayleigh-stable rotating plane Couette flows and subcritical transition to turbulence in accretion disks
• On the ionisation fraction in protoplanetary disks III. The effect of X-ray flares on gas-phase chemistry
• Disc formation and fragmentation using radiative non-ideal magnetohydrodynamics
• Radial transport of refractory inclusions and their preservation in the dead zone
• Magnetic Coupling in the Disks Around Young Gas Giant Planets
• Turbulent Linewidths in Protoplanetary Disks: Predictions from Numerical Simulations
• The ionising effect of low energy cosmic rays from a class II object on its protoplanetary disk
• The Structure and Evolution of Circumbinary Disks in Cataclysmic Variable Systems
• Dead Zones as Thermal Barriers to Rapid Planetary Migration in Protoplanetary Disks
• The Local Instability of Steady Astrophysical Flows with non Circular Streamlines with Application to Differentially Rotating Disks with Free Eccentricity
• Radiation thermo-chemical models of protoplanetary disks. Grain and polycyclic aromatic hydrocarbon charging
• On the evolution of the CO snow line in protoplanetary disks
• Why are pulsar planets rare?
• Subcritical dynamos in shear flows
• Impact of convection and resistivity on angular momentum transport in dwarf novae
• Turbulence in circumstellar disks
• The evolution of Kerr discs and late-time tidal disruption event light curves
• Magnetically driven outflows from Jovian circum-planetaryaccretion disks
• Infrared 2-4 Micron Spectroscopy and Millimeter Interferometric HCN and HCO+ Observations of the Individual Merging Components of Arp299
• Magnetorotational instability in protoplanetary discs: The effect of dust grains
• Evolution of X-ray Activity in <25 Myr Old Pre-Main Sequence Stars
• Which planets trigger longer-lived vortices: low-mass or high-mass?
• Relic proto-stellar disks and the origin of luminous circumstellar interaction in core collapse supernovae
• A comparison of local simulations and reduced models of MRI-induced turbulence
• Magnetised Winds in Transition Discs I: 2.5D Global Simulations
• Global Structure of Magnetorotationally Turbulent Protoplanetary Discs
• The gravo-magneto disc instability with a viscous dead zone
• Impact of Cosmic-Ray Feedback on Accretion and Chemistry in Circumstellar Disks
• Linear coupling of modes in 2D radially stratified astrophysical discs
• External Photoevaporation of the Solar Nebula II: Effects on Disk Structure and Evolution with Non-Uniform Turbulent Viscosity due to the Magnetorotational Instability
• Electric heating and angular momentum transport in laminar models of protoplanetary disks
• Centrifugally driven winds from protostellar accretion discs. I - Formulation and initial results
• Two-dimensional models of layered protoplanetary discs - II. The effect of a residual viscosity in the dead zone
• The Hall instability of thin weakly-ionized stratified Keplerian disks
• Magneto-rotational instability in the protolunar disk
• Sub-arcsec mid-IR observations of NGC 1614: Nuclear star-formation or an intrinsically X-ray weak AGN?
• Dead Zones In Circumplanetary Discs as Formation Sites For Regular Satellites
• Magnetohydrodynamics of protoplanetary discs
• MHD accretion-ejection: jets launched by a non-isotropic accretion disk dynamo. I. Validation and application of selected dynamo tensorial components
• Grain charging in protoplanetary discs
• Cosmic-ray ionization rate in protoplanetary disks with sheared magnetic fields
• Hall equilibrium of thin Keplerian disks embedded in mixed poloidal and toroidal magnetic fields
• The Hall instability of weakly ionized, radially stratified, rotating disks
• Time-dependent, long-term hydrodynamic simulations of the inner protoplanetary disk II: The importance of stellar rotation
• On fan-shaped cold MHD winds from Keplerian accretion discs
• Chemical network reduction in protoplanetary disks
• MRI-driven angular momentum transport in protoplanetary disks
• Global multifluid simulations of the magnetorotational instability in radially stratified protoplanetary disks
• Dead zones in protostellar discs: the case of Jet Emitting Discs
• Eruptive Behavior of Magnetically Layered Protoplanetary Disks in Low Metallicity Environments
• Stellar cosmic rays as an important source of ionisation in protoplanetary disks: a disk mass dependent process
• A Theoretical Model of X-ray Jets from Young Stellar Objects
• The gas disk: Evolution and chemistry
• On the growth and orbital evolution of giant planets in layered protoplanetary disks
• Evolution of circumbinary protoplanetary disks with photoevaporative winds driven by External Far Ultraviolet Radiation
• Excitation of spiral density waves by convection in accretion discs
• Nebular dead zone effects on the D/H ratio in chondrites and comets
• Radially Magnetized Protoplanetary Disk: Vertical Profile
• The Role of Angular Momentum Transport in Establishing the Accretion Rate--Protostellar Mass Correlation
• Hybrid Mechanisms for Gas/Ice Giant Planet Formation
• A Self-Consistent Reduced Model for Dusty Magnetorotationally Unstable Discs
• The High-resolution Accretion Disks of Embedded protoStars (HADES) simulations. I. Impact of Protostellar Magnetic Fields on the Accretion Modes
• Turbulent protostellar discs
• Resolving stellar populations with integral field spectroscopy
• The Nature of Turbulence in the Outer Regions of Protoplanetary Disks
• Timescales diagnostics for saving viscous and MHD-driven dusty discs from external photoevaporation
• Note on the "Dead Zone" in Layered Accretion Models
• Hard X-ray flux from low-mass stars in the Cygnus OB2 Association
• Dynamical Evolution of Planetary Systems
• Axisymmetric Nonlinear Waves And Structures in Hall Plasmas