太陽浮上磁場・活動領域形成 に関する 大規模 MHD 数値シミュレーション

Introduction of Miyagoshi et al

Miyagoshi et al Initial conditions Axial field strength Btube=15 4500 G radius ≒ Rtube=5

twist q=0~01 initial depth ztube=-10 Motivation observationally twist q is ~0002 (Pevtsov et al 1995)

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Introduction of Miyagoshi et al

Miyagoshi et al Result 1 Every tube emergedEven q=0 case

emerged

q large direct emergence without a tongue

q small two-step emergence with a tongue

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Introduction of Miyagoshi et al

Murray et al (2006) q=03 02 and 01 Case with q=01 cannot emerge

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Introduction of Miyagoshi et al

Miyagoshi et al vs Murray et al (2006)

Miyagoshi et al even q=0 emerged Which parameter is critical

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Miyagoshi et al Murray et al (2006)

Flux tube Gold-Hoyle type Gaussian type

Axial field strength Btube 15 ( 4500 G )≒ 29 (=3770 G)

Radius Rtube 5 25

Initial twist q 0 ~ 01 (6 runs) 01 02 and 03

Initial depth ztube -10 -10

Convection zone Unstable Neutrally stable

Trigger of the emergence Initial Vz perturbation Magnetic buoyancy

Result Every q emerged q=01 failed

Introduction of Miyagoshi et al

Miyagoshi et al Initial condition

plasma β = P Pmag lt 1

at the tube top Strong tubehellip

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Introduction of Miyagoshi et al

Miyagoshi et al Result 2 Coronal magnetic energy depends

on the initial twist q

q large direct emergence

　 Emag increases with q q small two-step emergence

　 Emag does not depend on q because the second-step emergence occurs only when the Acheson criterion is satisfied

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dVB

E corona

2

mag 8

Setup and Results

Conditions

q=0 cannot emerge consistent with Murray et al (2006)

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Our case Murray et al (2006)

Flux tube Gaussian type Gaussian type

Axial field strength Btube 15 (=3750 G) 29 (=3770 G)

Radius Rtube 25 25

Initial twist q 005 ~ 05 (10 runs) 01 02 and 03

Initial depth ztube -10 -10

Convection zone Neutrally stable Neutrally stable

Trigger of the emergence Magnetic buoyancy Magnetic buoyancy

Result qlt01 failed q=01 failed