Ionizing Protoplanetary Disks in Pebble Collisions

Abstract

We introduce collisions of solids as a new and efficient ionization mechanism for gas in protoplanetary disks, which especially operates in the dense midplane of protoplanetary disks. This idea is sparked by laboratory experiments where we found that charge, which is exchanged by grains in mutual collision (tribocharging), is not tied to their surfaces alone. As kind of collateral effect, charges also become entrained into the gas phase, i.e. collisions ionize the protoplanetary disk. Therefore, solids are not only sinks of charges in disks but also sources. A first estimate shows that ionization rates in the midplane at 1 AU in the range of $10^{-19}...10^{-15}{\mathrm{s}}^{-1}$ seem feasible depending on the assumption of rather calm or highly turbulent conditions with radial particle pile up.

Accepted for publication by Monthly Notices of the Royal Astronomical Society

References in corpus (24)

• Coagulation, fragmentation and radial motion of solid particles in protoplanetary disks
• Gas- and dust evolution in protoplanetary disks
• Closed-form expressions for particle relative velocities induced by turbulence
• Constraining the X-ray and Cosmic Ray Ionization Chemistry of the TW Hya Protoplanetary Disk: Evidence for a Sub-interstellar Cosmic Ray Rate
• Electrification of wind-blown sand on Mars and its implications for atmospheric chemistry
• Self-charging of identical grains in the absence of an external field
• Formation of intermediate-mass planets via magnetically-controlled disk fragmentation
• Evolution of the Water Snow Line in Magnetically Accreting Protoplanetary Disks
• Seeding the Formation of Mercurys: An Iron-sensitive Bouncing Barrier in Disk Magnetic Fields
• MRI-active inner regions of protoplanetary discs. I. A detailed model of disc structure
• Chemistry in Disks. II. -- Poor molecular content of the AB Aur disk
• A challenge for Martian lightning: Limits of collisional charging at low pressure
• Is There a Temperature Limit in Planet Formation at 1000 K?
• Composition and Size Dependent Sorting in Preplanetary Growth: Seeding the Formation of Mercury-like Planets
• Harvesting the decay energy of ${}^{26}$Al to drive lightning discharge in protoplanetary discs
• The Nonlinear Ohm's Law: Plasma Heating by Strong Electric Fields and its Effects on the Ionization Balance in Protoplanetary Disks
• Inhibited Coagulation of Micron-size Dust Due to the Electrostatic Barrier
• A Smoking Gun for Planetesimal Formation: Charge Driven Growth into a New Size Range
• Tracking Dust Grains During Transport and Growth in Protoplanetary Disks
• Observation of bottom-up formation for charged grain aggregates related to pre-planetary evolution beyond the bouncing barrier
• Planetesimal formation around the snow line: I. Monte Carlo simulations of silicate dust pile-up in a turbulent disk
• Dense Particle Clouds in Laboratory Experiments in Context of Drafting and Streaming Instability
• Experimental study of clusters in dense granular gas and implications for the particle stopping time in protoplanetary disks
• Laboratory Experiments on the Motion of Dense Dust Clouds