Chondrule Formation and Protoplanetary Disk Heating by Current Sheets in Non-Ideal Magnetohydrodynamic Turbulence

Abstract

We study magnetic field steepening due to ambipolar diffusion (Brandenburg & Zweibel 1994) in protoplanetary disk environments and draw the following conclusions. Current sheets are generated in magnetically active regions of the disk where the ionization fraction is high enough for the magnetorotational instability to operate. In late stages of solar nebula evolution, the surface density is expected to have lowered and dust grains to have gravitationally settled to the midplane. If the local dust-to-gas mass ratio near the midplane is increased above cosmic abundances by factors > 10^3, current sheets reach high enough temperatures to melt millimeter-sized dust grains, and hence may provide the mechanism to form meteoritic chondrules. In addition, these current sheets possibly explain the near-infrared excesses observed in spectral energy distributions (SEDs) of young stellar objects. Direct imaging of protoplanetary disks via a nulling interferometer or, in the future, a multi-band, adaptive optics coronagraph can test this hypothesis.

11 pages, 4 figures, submitted to ApJ

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Cited by in corpus (8)

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• Three-dimensional modeling of radiative disks in binaries
• Fast methods to track grain coagulation and ionization. II. Extension to thermal ionization
• Dust dynamics in current sheets within protoplanetary disks. I. Isothermal models including ambipolar diffusion and Ohmic resistivity
• Chondrule formation in the outer disk from the primary three-dimensional chemical composition of CM chondrules