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On the Torque Exerted by a Magnetically Threaded Accretion Disk
Reference:1979ApJ...232..259G apj449L153
Reporter: Xu Kun
2015.3.17
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Outline
*The GL79a model
*Evaluation of the torque
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The Ghosh & Lamb (1979a,b) Model for Disk-Field Interaction
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Structure of the Transition Zone
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Equations of the Boundary LayerRadial-Structure Vertical-Structure
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Rewrite the Equations in Nondimensional Form
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Examples of Boundary-Layer Structure (1)0.3s
0 0.5
2.5
2b
p
C
C
0 1
1.5
1.5b
p
C
C
0 2
2
1.5b
p
C
C
0 4
4
1b
p
C
C
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Examples of Boundary-Layer Structure (2)0 1 2.5 2b pC C , ,
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Existence of Maximum Fastness
max 1
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Evaluation of the torque
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Discussion
• ranging from 0.875-0.950• The most plausible of the three is the third