SETI public: Self-Sustained Ionization and Vanishing Dead Zones in Protoplanetary Disks

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Paper: astro-ph/0506131
Date: Tue, 7 Jun 2005 03:49:45 GMT (57kb)

Title: Self-Sustained Ionization and Vanishing Dead Zones in Protoplanetary
Disks

Authors: Shu-ichiro Inutsuka, Takayoshi Sano
Comments: 10 pages, 2 figures
\\
We analyse the ionization state of the magnetohydrodynamically turbulent
protoplanetary disks and propose a new mechanism of sustaining ionization.
First, we show that in the quasi-steady state of turbulence driven by
magnetorotational instability in a typical protoplanetary disk with dust
grains
the amount of energy dissipation should be sufficient for providing the
ionization energy that is required for activating magnetorotational
instability. Second, we show that in the disk with dust grains the energetic
electrons in weakly ionized gas can provide collisional ionization,
depending
upon the actual saturation state of magnetorotational turbulence. Finally,
we
show that in the protoplanetary disks with the reduced effect of dust
grains,
the turbulent motion can homogenize the ionization degree, which can solely
activate magnetorotational instability. The results in this letter indicate
that the most of the regions in protoplanetary disks remain magnetically
active, thus, require a change in theoretical modeling of planet formation.

\\ ( http://arXiv.org/abs/astro-ph/0506131 , 57kb)

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