the physics of solar flares
DESCRIPTION
The Physics of Solar Flares. Examining Solar Flares and Radio Bursts By Caylin Mendelowitz and Claire Rosen. OUTLINE. Flares Bursts Solar Activity Energy Storage Energy Release Energy Requirements Flare Prediction Summary. Gregory, p. 202. Solar Interior. Solar interior. - PowerPoint PPT PresentationTRANSCRIPT
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The Physics of Solar Flares
Examining Solar Flares and Radio Bursts
By
Caylin Mendelowitz and Claire Rosen
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OUTLINE
• Flares• Bursts• Solar Activity• Energy Storage• Energy Release• Energy Requirements• Flare Prediction• Summary
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Solar Interior
• Solar interior
Gregory, p. 202
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Solar Flares
• What are they?
• Radiation– optical (H)– radio
• Phases– activation– impulsive– late
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Radio Bursts• Different Types
– type I : thermal– type II & IV: plasma oscillations (shock) & synchrotron – type III & V: plasma oscillations (electrons) &
synchrotron
• Association with flare phases– type III & V coincide with impulsive phase– type II & IV follow impulsive phase – type I in late phase (storm phase)
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Solar Activity
• 22 year cycle
• Signs of solar activity– flares, CME’s, filaments, sunspots
• Solar magnetic field– frozen field lines – differential rotation --> twisted magnetic
field lines– convection --> kinks– buoyancy -->loops (connect sunspots)
Gregory, p.221
BBv
BJF
)(
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Energy Storage• Open field lines
• B|| (above) – B|| (below) = 0K, where 0 is the permeability of free space and K is surface current density
Figure 4
Figure 3
Gregory, p.220
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Carroll, p. 424
Field Loop with Current Sheet
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Energy Release• Accelerated particles
– excite plasma oscillations --> type III bursts
– synchrotron radiation-- type IV and V bursts
– heat plasma --> H double ribbons
• X-ray or H loop prominence
• loop expands as CME -shock excites plasma oscillations --> type II bursts
Tandberg-Hanssen and Emslie, cover
http://sohowww.nascom.nasa.gov/
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Energy Requirements• Typical field strength of active region B = 300 G. Flare
energy is 1032 ergs• Magnetic energy density is = B2/8 = 3580 ergs/cm3 • W = P dV = PV. Solving for V we get V =
W/P and– so the minimum volume needed to contain the energy
is V = 2.79 * 1028 cm3
• Approximate to cube, so L = 3*109 cm
• Length of H ribbon is 1010 cm -- Physical dimensions compare
• Reconnection time R = ½ (R m)1/4A
1/2 D1/2 = 3sec
• Time scale compares
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Flare Prediction
• Coronal Mass Ejections (CME’s)
• Sigmoid regions
• Zeeman effect
• Magnetograph
Dooling, p. 2
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Summary
• Flares (general) - cause?– Origins --> magnetic energy storage– Mechanism --> reconnection
• Correlation between radio and optical emission– thermal emission --> H ribbon (optical)– plasma oscillations and synchrotron --> radio
waves
• Prediction