Composite Solar Flare Spectrum. Thermal Bremsstrahlung. T = 2 x 10 7 K. T = 4 x 10 7 K. Nonthermal Bremsstrahlung. π 0 Decay. Positron and Nuclear Gamma-Ray lines. ~ 10 32 ergs in ~ 10 3 seconds = ~10 29 ergs/s => ~10 36 electrons/s! => empty entire flare loop!!
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Composite Solar Flare Spectrum
T = 2 x 107 K
T = 4 x 107 K
Positron and Nuclear
~ 1032 ergs in ~ 103 seconds = ~1029 ergs/s
=> ~1036 electrons/s!
=> empty entire flare loop!!
=> ~1017 amps!!
What about thermal emission from confined
~108 K plasma?
e+ - e-
RHESSI solar count spectrum from 11:06:20 – 11:10:04 on Oct. 28, 2003
(Smith et al. Poster 2.01)
Stochastic Acceleration throughout the loop - Miller/Petrosian
To explore the basic physics of
particle acceleration and explosive energy release in solar flares
* Energy & Time (~μsec) of EVERY Photon Interaction
* Aspect Information –
Six solar limbs to ~arcsec, 16 times per spin (4s),
& roll angle to ~arcmin
=> ~ ARCSEC IMAGING WITH ARCMIN STRUCTURE
* Field of View ~ 1 ° > full Sun, ~0.2 ° pointing
* DATA Stored in 4 Gigabyte memory (> largest flare)
& dumped at 4 Mbps to Berkeley (& Wallops)
=> FULLY AUTONOMOUS OPERATION
(Lin et al. 2003)
WITH IMAGING DOWN TO THE 1% LEVEL AND ZERO NOISE
Contours of an 8'' FWHM Gaussian source with its associated albedo patch. (factor of 2 contours)
RHESSI-NESSI-II -- 24-27 March 2004
The green contours show the levels of integrated albedo flux. The 2nd green (~35''x100'') contour contains 75% of the albedo flux, assumed here to be 50% of the primary source flux.
E J Schmahl (2004)
Smith et al., 2003
Particle Acceleration by the Sun
Solar Flares - Large, small, microflares, nanoflares (?)
Coronal radio phenomena – Metric type I, II, III, IV, V
Low energy (sometimes down to ~0.1 keV) impulsive electron events, associated with 3He-rich ion events
Continuous (?) electron acceleration (~1-100keV superhalo)
Fast Coronal Mass Ejections (CMEs) with shock waves
Observed frequency distribution of flares is flat (slope below 2),
i.e. there is not enough energy in flares to heat the solar corona
(e.g. Crosby et al. 1993, Shimizu et al. 1997)
at lower energies?
Instrumental energy cutoff & sensitivity are important!
(from Krucker, 2003)
See Christe et al. talk 87.03
Panel 1,2: GOES (Class A3 above B8 bkgd) VERY small!
Panel 3: RHESSI Spectrogram
Panel 4: RHESSI non-thermal (12-15 keV)
Panel 5: thermal (3-12 keV) channel
Panel 6: Radio Spectrogram from WIND/WAVES
RHESSI Light Curve
RHESSI Images (10-25 keV)