Phillip Chamberlin
University of Colorado
Laboratory for Atmospheric
and Space Physics (LASP)
Phil.Chamberlin@lasp.colorado.edu
(303)492-9318
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Outline
- Solar Atmosphere
- Flux Tubes
- Two Ribbon Flare
- Cartoons
- Movies
- Irradiance Measurements of Flares
- VUV
- White Light
- TSI
June 12, 2007
Chamberlin - Solar Flares - REU 2007
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XUV, EUV, and FUV Solar Spectrum
Transition Region
From Lean (1997)
June 12, 2007
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Solar Images - Oct. 28, 2003
Chromosphere
H-Alpha
Corona
Photosphere
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Transition
Region
(Images courtesy of Big Bear Solar
Observatory and SOHO EIT)
June 12, 2007
Chamberlin - Solar Flares - REU 2007
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Flux Tubes
(Schrijver and Zwaan, 2000)
June 12, 2007
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Flux Tubes
Initial rotating
convection zone
with weak
vertical B-field
lines
B-field lines
concentrated in
strands between
convection cells to
form Flux Tubes
Absence of B-field
within convection
cells due to B-field
line reconnection
(Schrijver and Zwaan, 2000)
June 12, 2007
Chamberlin - Solar Flares - REU 2007
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Emerging Flux
Solar Atmosphere
Active
Regions
Convection
Zone
Balance between
hydrostatic pressure
and magnetic
pressure causes the
flux tubes to be less
dense due to their
stronger magnetic
pressure
buoyant flux tubes
(Schrijver and Zwaan, 2000)
June 12, 2007
Chamberlin - Solar Flares - REU 2007
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Emerging Flux (Title, 2004)
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June 12, 2007
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Phases of Solar Flares
Radio (100-500 MHz)
(Adapted from Schrijver and
Zwaan, 2000)
Microwave Radio
(~3000 MHz)
H-alpha (656.2 nm)
Broadband EUV (1 - 103 nm)
Soft X-rays (< 10 keV)
X-rays (10-30 keV)
Main Phase
Impulsive Phase
Precursor
Hard X-rays (> 30 keV)
Note: Soft X-rays: 0.1-10 nm,
Hard X-rays: 0.001-0.1 nm
June 12, 2007
Chamberlin - Solar Flares - REU 2007
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Two-Ribbon Flare
Triggered by
Emerging
Flux?
“Stretching” of
field lines
Eruption when
some critical
limit is reached
Continued thermal
heating and
formation of postflare loops
(Priest, 1981)
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Two-Ribbon Reconnection
Reconnection after
instability accelerates
material down loop.
Observed Hard X-ray
(and EUV?)
enhancements at loop
top.
No enhanced
emissions
during the
impulsive
phase in the
corona due to
its low density.
June 12, 2007
[Ashwanden,
2004]
Thick-target model
produces Bremsstrahlung
radiation in the transition
region and chromosphere
due to their much higher
densities - Impulsive
Phase!
Energy deposited
during the impulsive
phase heats the plasma
up and rises
(chromospheric
evaporation) to fill
flux tube - Gradual
Phase!
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Two-Ribbon Flare
Post-Flare Loops
June 12, 2007
Impulsive Phases
for Each Loop
Chamberlin - Solar Flares - REU 2007
(Somov, 1992)
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X28 Flare, Nov 4, 2003
June 12, 2007
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Hinode SOT Observes Flare
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June 12, 2007
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SOHO (UV) and SORCE XPS
(XUV) Observations
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June 12, 2007
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Phases of Solar Flares
Radio (100-500 MHz)
(Adapted from Schrijver and
Zwaan, 2000)
Microwave Radio
(~3000 MHz)
H-alpha (656.2 nm)
Broadband EUV (1 - 103 nm)
Soft X-rays (< 10 keV)
X-rays (10-30 keV)
Main Phase
Impulsive Phase
Precursor
Hard X-rays (> 30 keV)
Note: Soft X-rays: 0.1-10 nm,
Hard X-rays: 0.001-0.1 nm
June 12, 2007
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Flare/Pre-Flare Irradiance Ratio
Transition
region
emissions
increased by up
to a factor of 10
during the
impulsive phase
Flare Variations were as large or larger than the
solar cycle variations for the Oct 28, 2003 flare
June 12, 2007
Chamberlin - Solar Flares - REU 2007
EUV irradiance
increased by a
factor of 2
during the
gradual phase
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X-Ray Classification
Due to the large,
order-ofmagnitude
increases in the
soft X-rays
makes for an
ideal and
sensitive
classifications of
the magnitude of
flares
June 12, 2007
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White Light Flare
• “Carrington Flare” September 1, 1859
– Carrington (M.N.R.A.S, 20, 13, 1860)
• One of the largest flares believed to have
occurred
since
then
• Two-Ribbon
flare
June 12, 2007
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White Light vs UV (170 nm) Flare
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White Light
TRACE
From Hudson et al., AGU/SPD 2005:
170 nm
http://sprg.ssl.berkeley.edu:80/~hhudson/presentations/spd_wl.050527/
June 12, 2007
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X17 flare observed in TSI
First detection of flare in TSI record
(G. Kopp, 2003)
Figures from G. Kopp, arranged by T. Woods
June 12, 2007
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Conclusions
• Multiple images and spectral measurements
are key to understanding energetic of flares
• New measurements (Hinode, EVE, AIA,
etc.) will lead to a much greater
understanding of these processes
• Biggest mystery still is the ‘trigger’
• Another topic to that is not fully understood
is the relationship of CMEs and Flares
June 12, 2007
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Extra Slides
June 12, 2007
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Simple Loop Flare
Existing Flux Loop that Brightens
TRANSITION
REGION
CORONA
CHROMOSPHERE
PHOTOSPHERE
-Most Common Type
-Only Enhanced Internal Motions
(Priest, 1981)
-Are these an actual separate type of flare?
June 12, 2007
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Flares drive waves in the
photosphere
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June 12, 2007
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Hinode SOT Movie #2
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June 12, 2007
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VUV Irradiance Increases Dominate Flare Variations
• VUV irradiance (0.1-200 nm)
accounts for only 0.007% of quite
Sun Total Solar Irradiance (TSI)
• VUV irradiance accounts for 3070% of the increase in the TSI
during a flare [Woods et al., 2006]
June 12, 2007
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Flares Cause Sudden Atmospheric Changes
Latitude (Deg)
GRACE daytime density (490 km)
• Increased neutral particle
density in low latitude regions on
the dayside.
• Sudden Ionospheric
Disturbances (SIDs) lead to
Single Frequency Deviations
(SFDs).
2003 Day of Year (E. Sutton, 2005)
Sudden increase in the dayside
density at low latitude regions
due to the X17 solar flare on
October 28, 2003
June 12, 2007
• Cause radio communication
blackouts
• Cause increased error in GPS
accuracy
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