A New Solar Flare Scenario - High-beta Plasma Disruption -

Presentation on theme: "A New Solar Flare Scenario - High-beta Plasma Disruption -"— Presentation transcript:

1 A New Solar Flare Scenario - High-beta Plasma Disruption -
Kiyoto Shibasaki (Nobeyama Radio Observatory) 2002 July 12 Nobeyama one-day Symposium

2 ACTON: I have difficulty thinking of things that I can’t draw pictures of, and Dr. Zirin’s comment reminds me of something that has puzzled me for a long time. If one looks at the H-alpha image of a larger solar flare, one sees an enormously complicated and convoluted object in the chromosphere, extending over a very large area. We now think that this brightening results from heat conducted from above. This says that in the corona the hot volumes must be interconnected in a most complex topology. The means by which this complex topology is established might be a key to understanding the whole flare process. I have become convinced that loops are physically interacting. But if I try to draw a picture of interacting loops, I find that the interaction can only take place on a surface. How can appreciable magnetic flux be annihilated there? The result in any case is that substantial volumes are filled with hot plasma. How does it get there? It seems to me that there are things happening to affect the transport of energy transverse to the field lines, and in a very complicated topology. I wonder if there is anybody here smart enough to explain how this happens? GROUP: (Hollow laughter.) from Solar Phys. 86 (1983)

3 Contents Current standard solar flare model
Difficulties with the current model Flare observations (movies) Proposal of a new solar flare model (high-beta plasma disruption) Application to the observed phenomena Further studies

4 Current Standard Solar Flare Model
Computer simulation by　Yokoyama

5 YOHKOH Observation (I)
Soft X-ray Telescope（SXT)

6 YOHKOH Observation (II)
SXT　＆HXT

7 Difficulties How to store all flare energy in a very thin current layer (we cannot observe due to its thinness) Plasma inflow observation (one candidate) How to realize the high energy state and how to keep it as quasi-equilibrium until release Number problem (thermal, non-thermal)

8 Observation by NoRH

9 Observation（TRACE/EUV）
１９９９ Oct. 22 (171Å, 1MK) 2001 Nov. 01 2001 Nov. 27 2001 Sep. 18 2002 Apr. 21 2002 May 27

10 Flare Configuration (Non-thermal)
Nishio and other: 14 events (impulsive events, M-class) Hanaoka: 13 events (remote source) Both came to the same conclusion, small + large loops (parallel magnetic field configuration, or three legged structure) Reconnection is suggested, but I interprete in different way

11 Flare Scenarios Low-beta scenario High-beta scenario
Magnetic free energy (= current) Dissipation by reconnection High-beta scenario Plasma free energy (confinement, curvature, flow) Dissipation by High-beta disruption (ballooning instability)

12 High-beta Disruption Scenario of Solar Flares (Shibasaki, ApJ 557, 2001)
Activities in small loops: Small curvature High density Flows along loops Activities above loops Injection from small loop to large loop Parallel magnetic field configuration (small, large loops)

13 Centrifugal force by thermal motion and bulk flow V.S. Gravity
gc ＝　ｖ２/R Bulk flow Thermal motion 　gc/go ~ 6 T6/R9 gc/go ~ 4 V72/R9 　go R9

14 Centrifugal Force v.s. Magnetic Tension
Fc Bulk Flow Thermal motion Fc / Ft = 2βk Fc / Ft = βT Ft

15 Definitions βk = (1/2)ρV2 / (B2/8π） = 2.1 ×N9V72 / BG2
βT = P / (B2/8π） = 6.9 ×N9T6 / BG2 βg = ρgoR / (B2/8π） =1.1 ×N9R9 / BG2 κc　=　1 / R κP = ∂ln(P)/∂ｎ 　　　　=　1 / lP κB =∂ln(B2/8π）/∂ｎ = 1 / lB

16 Equilibrium and Instability conditions
Equilibrium at the outer surface βTκP +κB = 2κc(1+βg/2‐βk) Instability condition βT＞2（lp/R）・ 　　　　　（ 1+βg/2‐βk ） Growth time τ(s) ~100 √(lp9R9/T6)

17 Magnetosphere Centrifugal force due to earth rotation is important.
Electric field due to space charge, alternative upward and downward

18 High-beta Disruption in Tokamaks
High density, high temperature in a weaker magnetic field is necessary for economic fusion. Non-linearly developed phase.

19 Prominence Eruption and Ballooning
Ballooning Instability （turbulence, particle accel., ejection,,,） １７GHｚ Prominence Eruption Spot Flare ribbons Event on 1999 Oct. 20

20 Summary and Conclusions
Common Features in Flares and Balloons: Turbulence, plasma ejection, high-energy particle acceleration (upward and downward), loop top plasma blobs, over-the-loop activity, impulsive nature, quasi-periodicity in particle acceleration

21 Further Studies Beta loading mechanism Energetics
High cadence imaging spectroscopy of loops at various temperature Numerical simulations of non-linearly developed ballooning instability under solar coronal condition (3-D)

22 LDEフレアにおけるエネルギーとプラズマの供給
柴崎清登 （NRO)

23 LDEフレアにおけるエネルギーとプラズマ供給
継続時間、温度、RAY構造、Inflow(YOHKOH, SoHO/LASCO) 磁気再結合シナリオ Inflow によるエネルギーとプラズマの供給 継続時間と温度 高ベータ崩壊シナリオとの関係

24 LDEフレア プロミネンス崩壊 / CME, Two ribbon flare 継続時間：数時間～1日 温度：８百万度、一定
RAY構造：YOHKOH／SXT Inflow RAY構造に沿った下降流 (YOHKOH/SXT) 上空コロナでの下降流 (SoHO/LASCO)

25 Inflowによるエネルギーとプラズマの供給
位置エネルギー ⇒運動エネルギー ⇒熱エネルギー 　　　　mpgoRo h　　　　　　　　　　　　　h T=　―――　 ―― T6=7.7 × ―― 3kB h h+1 プロミネンスの質量 ： 位置エネルギー 2×1015ｇ ～ 4×1030erg

26 高ベータ崩壊シナリオとの関係 プロミネンス上昇 上空のアーケード磁場に衝突 バルーニング（櫛状のfingers）
Fingersの上昇　：　RAY構造 上昇しきれなかったプラズマの下降 LASCO: inflow & SXT: inflow 位置エネルギーの解放とプラズマの供給 　　長時間（LDE),一定温度（８MK)のプラズマ供給