IHY Workshop
A PERSONAL VIEW OF SOLAR DRIVERS
for
Solar Wind
Coronal Mass Ejections
Solar Energetic Particles
Solar Flares
Solar Energetic Particle (SEP) events observed in the Interplanetary Medium (IPM):
* Large (L)SEP events (~tens per year at solar maximum)
- dominated by >10 MeV protons normal coronal composition and charge states
- associated with fast Coronal Mass Ejections (CMEs) large flares (sometimes missing) gradual soft X-ray bursts
* Electron -3He-rich SEP events (~10
3s per year at solar maximum)
- dominated by ~ 1-100 keV electrons and ~ MeV/nuc 3He
enhanced Fe, Mg, Si, S; high charge states
- associated with small flares/coronal microflares Type III radio bursts impulsive soft X-ray bursts
The Sun is the most powerful particle accelerator in the solar system
Ions up to ~ 10s of GeV
Electrons up to ~100s of MeV
At the Sun:
* Solar Flares – the most powerful explosions in the solar system
Release up to ~ 1032
- 10 33
ergs in ~ 10 – 103 seconds
Flare-accelerated ~10-100 keV electrons contain ~10-50% ofenergy released
>~1 MeV ions may contain comparable energy
=> Acceleration is intimately related to flare energy release
* Energy released by flares -> microflares -> nano-flares may be
significant for heating of the solar corona
π0 Decay
Nonthermal Bremsstrahlung
Thermal Bremsstrahlung
Composite Solar Flare Spectrum
Positron and NuclearGamma-Ray lines
T = 2 x 107 K
T = 4 x 107 K
Results Comparison: 23 July 2003, 00:30:00 - 00:30:20
• White: Johns & Lin (1992)
• Red: Piana et al. 0th order regularization
Contours of an 8”'' FWHM Gaussian source with its associated albedo patch. (factor of 2 contours)
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.
WITH IMAGING DOWN TO THE 1% LEVEL AND ZERO NOISER
HESSI-
NESSI-
II --
24-2
7 M
arc
h 2
004
E J Schmahl (2004)
6%
3%
1.5%
Pileup Corrections:Use only those photons for which the live-time > 80%
No albedo
With albedo
Active Region 9901
Coronal Source
10-12 keV 12-14 keV 14-16 keV
Temperature Distribution (I)(04/15 23:11:00 UT)
(From Ohyama & Shibata 1998)
Cartoon of Flare Model
(From Lin 2003)
Flux Rope Model
Inner Heliosphere is unexplored
• Phenomena of critical importance to LWS (solar wind and CME origin and evolution, SEP acceleration) occur in the Inner Heliosphere
• No in situ measurements inside 0.3 AU and only Helios (two decades ago) between 0.3 and ~1 AU
• New diagnostics and technology available for inner heliosphere missions
• Multi-point measurements with a range of radial distances and longitudes (latitudes) desired
Missions being developed:
STEREO - 2006Solar B - 2006
Solar Dynamics Observatory - 2008
Missions being studied:
Solar Orbiter (ESA) - ~0.2 AU
Solar Probe - ~3 solar radii Inner Heliospheric Sentinels - ?