Response of the Corona to Magnetic Activity in Underlying Plage Regions Ryutova, M., & Shine, R. 2004, ApJ, 606, 571 Plasma Seminar 2004 June 2 by Ayumi

Response of the Corona to Magnetic Activity in

Underlying Plage Regions

Ryutova, M., & Shine, R.

2004, ApJ, 606, 571

Plasma Seminar 2004 June 2 by Ayumi Asai

2004 June 2 Plasma Seminar by Ayumi Asai

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• 明後日 (6 月 4 日金曜日 ) 公聴会• 午後 2 時から• 「太陽フレアにおけるエネルギー解放

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Abstract

• The study on the response of the solar corona to magnetic activity in the underlying plage regions using MDI and TRACE data

• EUV emission above single-polarity plages has always an amorphous (braidlike) shape that topologically mimics the shape of the underlying plage

• Emission above mixed-polarity plages is highly discrete and consists of radiative transients


1. Introduction (1)

• Observation of solar atmosphere– photosphere, chromosphere, TR, corona

• Links between the effects observed at different heights is required for the understanding of physical processes in the solar atmosphere– coronal heating, etc.

How energy comes from below (photosphere)?

continuous hydromagnetic activity


1. Introduction (2)

• recent satellite observations direct connection between photospheric magnetic field and TR/coronal events

• fundamental differences between the corona above single-polarity plage and that above mixed-polarity plage

• distinct physical processes


2. Observations

• 1999 June 10 @DC• SOHO/MDI• TRACE/1600, 171,

195• several plages : uni-

polarity, mixed-polarity

SOHO/MDI

TRACE 171

uni

unimix

Fig 1


2. Time Slice Images

Fig 2


steady coronal loopsslow variation

2. Time Slice Image (1)

Fig 3



above unipolar plagebraidlike structureShine et al. 1999

Fig 3



above mixed-polarity plageradiative transients

above unipolar plagebraidlike structure Fig 4



mixed uni

The features in 195 (2X106K) images are quite similar to those in 171 (1X106K) images

Fig 4


2. Detailed Features of Braid (1)

• Braidlike structure is isotropic• Emergence of opposite

polarity disrupt braidlike structure

radiative transients• neighboring coherent

structure are not affected by the radiative transients

Fig 5


2. Detailed Features of Braid (2)

• Braid period depend on magnetic filling factor of plage

calculated from MDI magnetogram

rarefiedf~0.2

mediumf~0.3

densef>0.4

T~20min T~10min T~6min

Fig 5


2. Period of Braid

minimums

maximums

Fig 7


2. Mixed-Polarity Region

Fig 9

Fig 4

raidative transients


2. Chromospheric Structure

• unipolar : regular oscillation with periods 3-6 min• mix-polar : strong long-lasting brightenings

Fig 6

uni uni mix mix


2. Uni Polarity Region

Fig 9

Fig 6periodic oscillation


2. Summary of Unipolar Plage (1)

1. TRACE emission mimics the plage magnetic pattern

2. 171, 195 emissions exhibit coherent braidlike structure. The period depends on the magnetic filling factor; the denser the plage, the shorter the period

3. No direct connection between the coronal emission and individual magnetic elements


2. Summary of Unipolar Plage (2)

4. The only factor to disrupt the structures is the emergence of the opposite-polarity magnetic field

5. 1600 emission not only mimics the general shape of plage, but also traces the individual magnetic flux tubes

6. 1600 time-slice images show typical regular oscillation with a 3-6 minute period


2. Summary of Mixed Plage (1)

1. TRACE emission always exists above the mixed-polarity plages but is of a discrete nature

2. 171 and 195 emissions show random set of radiative transients at general boundaries of plage

3. There is a correlation between the numbers of radiative transients and the density of flux tubes


2. Summary of Mixed Plage (2)

4. Intrinsically prevent formation of stable structures and fill the corona by randomly distributed frequent radiative transients

5. 1600 emission is quite irregular and dynamic, but traces closely the magnetic pattern of plage

6. 1600 time-slice images show random flashes, which may be attributed as precursors for the radiative transients


3. Possible Mechanisms

• Discussion

• Physical processes that may extract the energy stored in the plages

• Provide the transport of the energy into the upper atmosphere– braidlike structure above uni-polar plages– radiative transients above mixed-polarity

plages


3.1. The Mixed-Polarity Plage

• Mixed polarity region site of various kinds of radiative transients

1. bright localized emission (blinker/microflare)

2. darker microflares, accompanied by jets

3. strong supersonic jet/other explosive event

correlated with magnetic cancellation• shock signatures soon after magnetic

cancellation, and before radiative transients

cascade of shock waves produced by magnetic cancellation/reconnection


3.1. Shock Generation

• Photospheric magnetic reconnection not effective for in situ heating

Highly unsteady state, triggering strongly nonlinear processes

• reconnection slingshot effect acoustic/MHD waves shocks

• shock collision radiative transients

ref. Tarbell et al. 1999, Ryutova et al. 2000,2001,2003


3.1. Shock Amplitude

Fig 10


3.2. The Unipolar Plage

• Post-reconnection mechanism is completely different

• Slingshot does not generate shock

Interaction of acoustic waves and unsteady wave packets with an ensemble of random magnetic flux tubes (resonant interaction)

• Resonant flux tubes absorb the energy of the sound wave and carry it to upper atmosphere by kink/sausage oscillation propagating along flux tubes


3.2. Radiation

radiative damping rate of resonant flux tubes is proportional to the tube radius (secondary waves)

patchy EUV emission


4. Summary (1)

• They have studied the energy production and its flow from solar surface to upper atmosphere using MDI and TRACE data

• The EUV emission above unipolar plage is much different from that above mixed polarity plage– uniplar : braidlike structure– mixed polarity : radiative transients

• Physical mechanisms are different for unipolar plages and mix-polarity plages


4. Summary (2)

• The primary energy source is associated with hydromagnetic activity among the photospheric magnetic flux tubes

• Radiative transients : cumulative effects occurring during interaction of shocks resulting from reconnection

• Braidlike structure : heated by the energy flux from collective phenomena in interaction of a random ensemble of flux tubes with acoustic waves and unsteady wave packets


高温コロナと低温コロナ

Yohkoh/SXT で観測Diffuse なループ構造

低温 (T ～ 1MK)高温 (T>2MK)

TRACE で観測細いループ構造

加熱に必要なネルギーフラックス~107erg cm-2s-1 ~106erg cm-2s-1

空間的に異なる位置に存在する


観測領域 (NOAA9231)

MDImag. flux in the photosphere

TRACE 171A1MK corona

Yohkoh/SXT>2MK corona


各領域の磁場の特徴

Moss 領域 ( 高温ループ )

低温ループ

磁場強度 (kG) 傾き角 (deg) filling factor continuum intensity


高温・低温ループの足下における磁場の特徴

Moss ( 高温ループ ) 低温ループ

黒点外浮上領域黒点外黒点上

磁場強度 1.2 kG 0.5-2.2kG 1.3 kG 1.3-2.8 kG

磁場の傾き < 30º 0º- 90º < 30º < 60º

Filling factor 0.05 - 0.3 0.3-0.9 0.2 - 0.6 0.5-1.0

plage (Transient) pore sunspot


光球磁場は磁気要素の集まり

• 最も顕著な違いは magnetic filling factor

　　 filling factor が小さい方が加熱に有利

光球における磁場は磁気要素の集合磁場強度（ 1-1.5kG) 、傾き ( 光球面に対して

垂直 ) 　 →　磁気要素の性質は同じ

G-band 高分解能観測

10arcsec

ASP の分解能

高温ループ低温ループ

微細磁束管

filling factor 　 ∝　磁気要素の数密度


磁気要素の運動• 磁気要素が集まると、光球における運動が抑制される傾向がある

quiet sun: 孤立した磁気要素～ 1 km/s (Nisenson et al. 2003)

磁気要素の束～ 400 m/s (van Ballegooijen et al. 1998)

pore 内 : 　　 200 m/s (umbral dot を使用、 Sobotka et al. 1999)

• 磁気要素の mean free path ( 一様、ランダムな運動 )

dl

d: 微細磁気要素の直径 ( 約 100km)


コロナ加熱のエネルギー

tnt BBfvF4

1

光球の運動によるコロナへのエネルギー供給

光球における磁気要素の運動で生じる Bt

L

lBB nt

ループの長さ

mean free pathd

d l

l

高温ループ

低温ループ

L=105km, f=0.1, vt=1km/s F=8×106erg/cm2/s高温成分を加熱できる

L=105km, f=0.5, vt=0.2km/s F=1×106erg/cm2/s低温成分を加熱できる


2. Period of Braid

Fig 8


3.2.

Documents

Response of the Corona to Magnetic Activity in Underlying Plage Regions Ryutova, M., & Shine, R. 2004, ApJ, 606, 571 Plasma Seminar 2004 June 2 by Ayumi