1. RHESSI Spectral Analysis of the 1N/M1.9 flare of 20 October 2003
Hui Li1, A. Berlicki2 and B. Schmieder2
1 Purple Mountain Observatory, CAS, China
2 Observatoire de Paris, Section de Meudon, France
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The 4th RHESSI Workshop, Paris (25-28 July 2004)

2. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Contents
Introduction
Observations
Spectral Analysis
Results and Discussions
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The 4th RHESSI Workshop, Paris (25-28 July 2004)

3. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Introduction (1)
Energy transfer in solar flares
Thermal or non-thermal?
Neupert effect
e.g. McDonald et al. 1999
RHESSI
High resolution and wide energy band (Lin et al. 2002)
Comparison of theoretical models with observations (e.g. Liu et al. 2004)
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The 4th RHESSI Workshop, Paris (25-28 July 2004)

4. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Introduction (2)
Energy compositions of solar flares
Enth/Eth=(13-21)% thick target (McDonald et al. 1999)
Enth/Eth=( )% thin target (Berlicki et al. 2004)
HXR source motion
~ 10km/s (e.g. Gallagher et al. 2002, Liu et al. 2004)
Super-hot component in solar flares
30-47 MK (e.g. Lin et al. 1985; Pike et al. 1996; Lin et al. 2003; Ji et al. 2004)
? ? ?
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The 4th RHESSI Workshop, Paris (25-28 July 2004)

5. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Observations (1)
Summary of observational information for the 1N/M1.9 flare in AR10484 of 20 October 2003
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The 4th RHESSI Workshop, Paris (25-28 July 2004)

6. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Observations (2)
GOES 10
X-ray flux
Long duration impulsive phase
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7. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Observations (3)
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8. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Observations (4)
EIT/304Å Movie
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9. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Observations (5)
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10. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Observations (6)
RHESSI/12 – 25 keV, 10s
RHESSI/25 – 50 keV, 30s
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11. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Observations (7)
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12. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Observations (8)
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The 4th RHESSI Workshop, Paris (25-28 July 2004)

13. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Observations (9)
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The 4th RHESSI Workshop, Paris (25-28 July 2004)

14. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Observations (10)
EIT/304Å at 07:19:34 UT +
RHESSI/ :11-07:12 UT
Ha at 07:23:00 UT +
RHESSI/ :11-07:12 UT
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15. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Spectral Analysis (1)
Super-hot component?
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16. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Spectral Analysis (2)
RHESSI 12 –25 keV
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17. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Spectral Analysis (3)
Collimators & detectors:
1F, 3F-6F, 8F-9F
Model:
F_vth_bpow (thermal + broken power law)
Energy range:
15 – 50 keV
Time interval:
60 seconds
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18. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Spectral Analysis (4)
MODEL:
Thermal +
broken
power law
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The 4th RHESSI Workshop, Paris (25-28 July 2004)

19. Spectral Analysis (5) Thermal and non-thermal energy in the flare:
(cf. Hudson and Canfield, 1978, McDonald et al, 1999)
for thin-target model:
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20. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Spectral Analysis (6)
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The 4th RHESSI Workshop, Paris (25-28 July 2004)

21. Spectral Analysis (7) Thermal and non-thermal energy in the flare:
(cf. Hudson and Canfield, 1978, McDonald et al, 1999)
for thick-target model:
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22. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Spectral Analysis (8)
Ratio of non-thermal energy to thermal energy derived for different low energy cutoffs and models.
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23. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Discussions (1)
The flare shows
long duration impulsive phase
multiple magnetic reconnections
continuous energy release
confined flare
no CME associated
Superhot component
Temax  67 MK
Does it really exist ?
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The 4th RHESSI Workshop, Paris (25-28 July 2004)

24. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Discussions (2)
Energy composition:
Enontherm/Etherm< 0.38 (thick, Ecutoff =20keV)
Enontherm/Etherm< 0.13 (thin, Ecutoff =20keV)
The X-ray spectra are “soft”
Spectral index > 6
Energy transfer
thermal conduction
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25. The 4th RHESSI Workshop, Paris (25-28 July 2004)
Discussions (3)
The ratio of Enontherm/Etherm is
Sensitive to Ecutoff , 
Independent of V (thin-target)
Proportional to V-0.5 (thick-target)
What is the reasonable value for Ecutoff
20 keV ? 15 keV ?
or even 10 keV ?
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The 4th RHESSI Workshop, Paris (25-28 July 2004)