The dynamics of inner dead-zone boundaries in protoplanetary disks

Abstract

In protoplanetary disks, the inner radial boundary between the MRI turbulent (`active') and MRI quiescent (`dead') zones plays an important role in models of the disk evolution and in some planet formation scenarios. In reality, this boundary is not well-defined: thermal heating from the star in a passive disk yields a transition radius close to the star (<0.1 au), whereas if the disk is already MRI active, it can self-consistently maintain the requisite temperatures out to a transition radius of roughly 1 au. Moreover, the interface may not be static; it may be highly fluctuating or else unstable. In this paper, we study a reduced model of the dynamics of the active/dead zone interface that mimics several important aspects of a real disk system. We find that MRI-transition fronts propagate inward (a `dead front' suppressing the MRI) if they are initially at the larger transition radius, or propagate outward (an `active front' igniting the MRI) if starting from the smaller transition radius. In both cases, the front stalls at a well-defined intermediate radius, where it remains in a quasi-static equilibrium. We propose that it is this new, intermediate stalling radius that functions as the true boundary between the active and dead zones in protoplanetary disks. These dynamics are likely implicated in observations of variable accretion, such as FU Ori outbursts, as well as in those planet formation theories that require the accumulation of solid material at the dead/active interface.

16 pages, 10 figures; MNRAS accepted; v3 final corrections

References in corpus (5)

• Magnetic fields in protoplanetary disks
• Dead Zone Accretion Flows in Protostellar Disks
• Assembling the Building Blocks of Giant Planets around Intermediate Mass Stars
• New composite models of partially ionized protoplanetary disks
• Turbulent diffusion in protoplanetary discs: the effect of an imposed magnetic field

Cited by in corpus (20)

• Hall-effect Controlled Gas Dynamics in Protoplanetary Disks: I. Wind Solutions at the Inner Disk
• A self-consistent model for the evolution of the gas produced in the debris disc of $\beta$ Pictoris
• Rossby wave instability at dead zone boundaries in 3D resistive magnetohydrodynamical global models of protoplanetary disks
• On the survival of zombie vortices in protoplanetary discs
• Vortex cycles at the inner edges of dead zones in protoplanetary disks
• Inside-Out Planet Formation. III. Planet-disk interaction at the dead zone inner boundary
• Thermodynamics of the dead-zone inner edge in protoplanetary disks
• Inside-Out Planet Formation. V. Structure of the Inner Disk as Implied by the MRI
• Temperature Fluctuations driven by Magnetorotational Instability in Protoplanetary Disks
• 2D condensation model for the inner Solar Nebula: an enstatite-rich environment
• The Nonlinear Ohm's Law: Plasma Heating by Strong Electric Fields and its Effects on the Ionization Balance in Protoplanetary Disks
• Dust dynamics and vertical settling in gravitoturbulent protoplanetary discs
• A global two-layer radiative transfer model for axisymmetric, shadowed protoplanetary disks
• Axisymmetric simulations of the convective overstability in protoplanetary discs
• On the orbital evolution of a pair of giant planets in mean motion resonance
• MRI-driven angular momentum transport in protoplanetary disks
• Global magnetohydrodynamic simulations of the inner regions of protoplanetary discs. I. Zero-net flux regime
• The role of detailed gas and dust opacities in shaping the evolution of the inner disc edge subject to episodic accretion
• Global magnetohydrodynamic simulations of the inner regions of protoplanetary discs. II. Vertical-net-flux regime
• Thermal hysteresis and front propagation in dense planetary rings