Giant Convective Cell 観測と理論

太陽雑誌会（２００５．３．６）北井

概要• はじめに• 理論の紹介

　 GLOBAL-SCALE TURBULENT CONVECTION AND MAGNETIC DYNAMO 　 ACTION 　 IN THE SOLAR ENVELOPE

　 A. S. Brun, M. S. Miesch, J. Toomre (Ap J, 614:1073–1098, 2004)

• 観測の紹介 PHOTOMETRIC SEARCH FOR SOLAR GIANT CONVECTION CELLS W.-H. Chiang, L.D. Petro, P.V. Foukal (Solar Phy. 110, p129,1987)

THE DETECTION OF GIANT VELOCITY CELLS ON THE SUN J.G. Beck, T.L. Duvall, Jr, P.H.Sherrer, and J.H. Hoeksema( Soho6/GONG98 Workshop, 199

8) 62-DAYS AROUND THE SUN: A SEARCH FOR SUPERGRANULAR EVOLUTION AND GIAN

T CELLS L.H. Strous and G.W. Simon ( ASP conf. series 140, 161, 1988)

• SMART データによる観測計画案

Giant Convetive Cell

GLOBAL-SCALE TURBULENT CONVECTIONBrun’s 　 Numerical Simulation

• 3D spherical shell• Anelastic MHD Equation Neglection of Sound speed :infinite

• Thermodynamic Quantities

Sherical symmetiric component

+fluctuation • D : Viscous tensor

t

GLOBAL-SCALE TURBULENT CONVECTIONBrun’s 　 Numerical Simulation

• Boundary condition

• Shell 0.72-0.98 Solar Radius

GLOBAL-SCALE TURBULENT CONVECTIONBrun’s 　 Numerical Simulation

GLOBAL-SCALE TURBULENT CONVECTIONBrun’s 　 Numerical Simulation

GLOBAL-SCALE TURBULENT CONVECTIONBrun’s 　 Numerical Simulation

観測（１）　 Chiang et al

• Kitt Peak

• Search for large-scale temperature fluctuation

• Photometry atλ525.6nm by 512-diode Reticon through spectrometer

• Spatial scan perpendicular to the solar rotation axis

• 15days, 4 N-zone + 4 S-zone scan

観測（１）　 Chiang et al

観測（１）　 Chiang et al

• Temperature Fluctuation

RMS = 0.33K ( 0.023%)

Spatial scale 80-240Mm

⇒　 Detection of Giant Cell ?

　　　　　　（ Simulation predicts ΔT≒１K)

観測 (2)　 Beck et al

• SOHO/MDI Doppler data

Daily averaged frame / 1440 frames taken in 1-min cadence

• Low resolution data (12deg square)

May 1996-Sep 1997 : 505days time series

• Medium resolution data ( 32min square )

May 1996-Nov 1997 : 576days time series

観測 (2)　 Beck et al (Low Resolution)

27-days long-lived feature

Lifetime : 4months

V(horizontal) : 3.6m/s

L(horizontal) : 44deg

観測 (2)　 Beck et al (Medium Resolution)

Velocity amplitude : 3.2m/s

Cell : Horizontally elongated

( 56 deg x 7 deg )

⇒　　 Detection of Giant Cells

観測（３） Strous & Simon 　• 62-day time-series of full-dis

k SOHO/MDI Dopplergrams obtained at a one-minute cadence

• Subtraction of background Doppler signal (5-degree polynomial fitting)

• Spatial smoothing ( 85” and 171” )

• Movie Watch ⇒ 　　 No giant cells detect

ed

観測（３） Strous & Simon

• Feature Tracking ( SG cells as tracers )

観測（３） Strous & Simon

Result

Unexplained horizontal velocity field of 30m/sec

⇒　 Detection of Giant cell inconclusive

Hida-FMT での解析

Hida-FMT での解析

Hida-FMT での解析

Hida-FMT での解析

SMARTでの解析• Full-disk Hα wing image

• LCTM ( Even-Odd test, Reverse test )

• Tracer : Supergranulation

• Spatial resolution : 0.5” ( FMT 4”)

Merit : Tracers all over the disk

Deficit : Interrupttion by nights

END