Joint session WG4/5 Points for discussion: - Soft-hard-soft spectral behaviour – again -...
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Transcript of Joint session WG4/5 Points for discussion: - Soft-hard-soft spectral behaviour – again -...
Joint session WG4/5
Points for discussion:
- Soft-hard-soft spectral behaviour – again
- Non-thermal pre-impulsive coronal sources
- Very dense coronal loops (~ 1011 cm-3) and other dense structures
- Coronal sources that decrease in altitude (sometimes as footpoints approach), then increase
- tiny inferred size of flare footpoints high beam flux and implications
30-50 keV intensity
30-50 keV / 20-30 keV intensity ratio
50-70 keV / 30-50 keV intensity ratio
Correlation between impulsive phase intensity and spectral hardness - ubiquitous
Spectral soft – hard - soft
GOES 1-8 ADERIVATIVE
Non-thermal preflare coronal sources
RHESSI Preflare Maps 3-12 keV (color): 12-25 keV (contours)
01:07:00-01:08:30
01:08:00-01:10:30
01:11:00-01:12:30
Coronal source
RHESSI SPECTRA 5-50 keV Thermal+broken powerlaw Preflare period: 01:02:00-01:11:00
Broken powerlaw extends down to 5 keV Thermal component
never dominates EM and T are poorly
determined Chisquare ~ 1 if EM=0
White = photons, Green = thermal model,Red = broken powerlaw, Purple = background
(NB similar source in July 23rd 2002 event)
Dense coronal sources
Substantial high energy emission in corona: thermal and radio observations allow estimate of density – 1011cm-3
20-30 keV 30-50 keV 50-100 keV
20 July 2002, pixon image reconstruction
Descending loop top sources
Time evolution: blue white
Footpoints: 70-100 keVLoop top: 20-25 keV
H footpoint separation
HXR source ‘height’
Descending loop top sources – with decreasing footpoint separation
Flare footpoints – white light observations
WL coincides with HXR source locations – sizes at resolution of TRACE (few px = few 1000 km area ~ 1017 cm2)
M2.2 flare
Predicted ‘evaporation’ velocity as function of beam flux
Using A= 1018 cm2 Using A= 1017 cm2