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| ID:
358545.0,
MPI für Astronomie / Publikationen_mpia |
| Turbulent mixing and the dead zone in protostellar disks |
| Authors: | Turner, N. J.; Sano, T.; Dziourkevitch, N. | | Date of Publication (YYYY-MM-DD): | 2007 | | Title of Journal: | The Astrophysical Journal | | Volume: | 659 | | Start Page: | 729 | | End Page: | 737 | | Audience: | Not Specified | | Abstract / Description: | We investigate the conditions for the presence of a magnetically inactive dead zone in protostellar disks using three-dimensional shearing-box MHD calculations, including vertical stratification, ohmic resistivity, and time-dependent ionization chemistry. Activity driven by the magneto-rotational instability fills the whole thickness of the disk at 5 AU, provided cosmic-ray ionization is present, small grains are absent, and the gas-phase metal abundance is sufficiently high. At 1 AU, the larger column density of 1700 g cm-2 means the midplane is shielded from ionizing particles and remains magneto-rotationally stable, even under the most favorable conditions considered. Nevertheless, the dead zone is effectively eliminated. Turbulence mixes free charges into the interior as they recombine, leading to a slight coupling of the midplane gas to the magnetic fields. Weak, large-scale radial fields diffuse to the midplane, where they are sheared out to produce stronger azimuthal fields. On average, the resulting midplane accretion stresses are just a few times less than in the surface layers. | | Free Keywords: | Stars: Circumstellar Matter; Instabilities; Magnetohydrodynamics: MHD; Solar System: Formation; Stars: Formation | | External Publication Status: | published | | Document Type: | Article |
| Communicated by: | N. N. | | Affiliations: | MPI für Astronomie | | Identifiers: | URL:http://adsabs.harvard.edu/abs/2007ApJ...659..729T
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