Plasma Seminar 2004 June 2 by Ayumi Asai Response of the Corona to Magnetic Activity in Underlying Plage Regions Ryutova, M., & Shine, R. 2004, ApJ, 606, 571 告知 • 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機構 の観測的研究」 ぜひご来場くださいますよう、ご案内申し上 げます 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 2. Observations uni • 1999 June 10 @DC • SOHO/MDI • TRACE/1600, 171, 195 • several plages : unipolarity, mixed-polarity mix Fig 1 2004 June 2 SOHO/MDI Plasma Seminar by Ayumi Asai uni TRACE 171 2. Time Slice Images Fig 2 2004 June 2 Plasma Seminar by Ayumi Asai 2. Time Slice Image (1) steady coronal loops slow variation 2004 June 2 Fig 3 Plasma Seminar by Ayumi Asai 2. Time Slice Image (2) above unipolar plage braidlike structure Shine et al. 1999 2004 June 2 Fig 3 Plasma Seminar by Ayumi Asai 2. Time Slice Image (3) above mixed-polarity plage radiative transients above unipolar plage braidlike structure 2004 June 2 Plasma Seminar by Ayumi Asai Fig 4 2. Time Slice Image (4) Fig 4 mixed uni The features in 195 (2X106K) images are quite similar to those in 171 (1X106K) images 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai Fig 5 2. Detailed Features of Braid (2) T~20min rarefied f~0.2 T~10min medium f~0.3 T~6min dense f>0.4 Fig 5 • Braid period depend on magnetic filling factor of plage calculated from MDI magnetogram 2004 June 2 Plasma Seminar by Ayumi Asai 2. Period of Braid minimums maximums 2004 June 2 Plasma Seminar by Ayumi Asai Fig 7 2. Mixed-Polarity Region raidative transients Fig 4 Fig 9 2004 June 2 Plasma Seminar by Ayumi Asai 2. Chromospheric Structure uni Fig 6 uni mix mix • unipolar : regular oscillation with periods 3-6 min • mix-polar : strong long-lasting brightenings 2004 June 2 Plasma Seminar by Ayumi Asai 2. Uni Polarity Region Fig 6 periodic oscillation Fig 9 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 3.1. Shock Amplitude Fig 10 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 3.2. Radiation radiative damping rate of resonant flux tubes is proportional to the tube radius (secondary waves) patchy EUV emission 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 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 2004 June 2 Plasma Seminar by Ayumi Asai 高温コロナと低温コロナ 空間的に異なる位置に存在する 高温 (T>2MK) Yohkoh/SXTで観測 Diffuseなループ構造 低温 (T～1MK) TRACEで観測 細いループ構造 ~107erg cm-2s-1 ~106erg cm-2s-1 加熱に必要なネルギーフラックス 2004 June 2 Plasma Seminar by Ayumi Asai 観測領域 (NOAA9231) TRACE 171A 1MK corona Yohkoh/SXT >2MK corona MDI mag. flux in the photosphere 2004 June 2 Plasma Seminar by Ayumi Asai 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) 2004 June 2 傾き角 (deg) filling factor Plasma Seminar by Ayumi Asai continuum intensity 高温・低温ループの足下における 磁場の特徴 低温ループ Moss (高温ループ) 磁場強度 磁場の傾き Filling factor 2004 June 2 黒点外 浮上領域 黒点外 黒点上 1.2 kG 0.5-2.2kG 1.3 kG 1.3-2.8 kG < 30º 0º- 90º < 30º < 60º 0.05 - 0.3 0.3-0.9 0.2 - 0.6 0.5-1.0 plage (Transient) pore sunspot Plasma Seminar by Ayumi Asai 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 10arcsec 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 ASPの分解能 て垂直) → 磁気要素の性質は同じ filling factor ∝ 磁気要素の数密度 微細磁束管 低温ループ 2004 June 2 高温ループ Plasma Seminar by Ayumi Asai G-band高分解能観測 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) pore内: 磁気要素の束 ～ 400 m/s (van Ballegooijen et al. 1998) 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) l d d: 微細磁気要素の直径 (約100km) 2004 June 2 Plasma Seminar by Ayumi Asai コロナ加熱のエネルギー 高温ループ 光球の運動によるコロナへのエネルギー供給 1 F fvt Bn Bt 4 光球における磁気要素の運動で生じるBt l Bt Bn L d mean free path ループの長さ L=105km, f=0.1, vt=1km/s F=8×106erg/cm2/s L=105km, f=0.5, vt=0.2km/s F=1×106erg/cm2/s 低温ループ 高温成分を加熱できる 低温成分を加熱できる 2004 June 2 l Plasma Seminar by Ayumi Asai d l 2. Period of Braid Fig 8 2004 June 2 Plasma Seminar by Ayumi Asai 3.2. 2004 June 2 Plasma Seminar by Ayumi Asai
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