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 - ?