# Presentation: 267457

## Outstanding Issues

- Gordon Holman&The SPD Summer SchoolFaculty and Students

## Origin of Flares

- What active region evolution precedes flares and coronal mass ejections?
- What is the relationship between flares and filament eruptions?
- What is the relationship between flares and coronal mass ejections?

## Flare Intensity Distribution

- Does the distribution continue to lower intensities with the -1.8 power-law index?
- What is and what determines the highest “intensity” flare?
- Is coronal heating dominated by “nanoflares”?

## Flare Morphology

- Do single-loop flares exist?
- Do all flare loops or arcades have the cusp structure?
- Do the basic features of the “standard model” apply to all flares?
- Is the “magnetic breakout” model valid?
- Is multipolar magnetic structure necessary for flares?

## Energetic Particles I

- Exactly where are energetic particles injected into the flaring region?
- What is the highest particle energy in each flare?
- What are the lowest particle energies in each flare?
- What is the angular distribution of the particles?

## Energetic Particles II

- How are the energetic particles “seen” in microwaves related to those “seen” in hard X-rays?
- How can electron and ion produced sources be in different locations?
- What is the exciter of white light flares?

## Energetic Particles III – Gamma Ray Results

- Relationship of impulsive SEPs and particles producing flare X-ray and gamma-ray emission.
- Energy content of the low-energy (<1 MeV) ions
- Composition (heavy element and 3He enhancements) of the accelerated particles  producing flare gamma-ray emission.
- Understanding the high-density(>1013 cm–3)-high-temperature(>105 K) environment implied by the positron annihilation line observations.
- Explanation for how the coronal-like high-FIP enhancements implied by gamma-ray line observations can already be present at chromospheric densities.

## Particle Acceleration

- Is there one dominant particle acceleration mechanism?  If so, what is it?
- Is particle acceleration confined to a region high in the corona, or is it more distributed?
- What is the efficiency of particle acceleration?

## Flare Energetics

- What is the relative amount of energy injected directly into plasma heating vs. particle acceleration?
- What is the relative amount of energy injected into electrons vs. ions?
- What is the relative amount of energy injected directly into cooler plasma vs. “hot” plasma?
- What is the relative amount of energy contained in the flare vs. the CME
- What is the total magnetic energy released in each flare?

## Coronal Mass Ejections

- Are there reliable precursors?  Can we predict CMEs?
- How are CMEs initiated and why?
- How do CMEs affect the large-scale corona?
- What is the relationship between CMEs, flares, and filaments?
- What is the 3-D structure of CMEs?
- Where do shocks develop?

## Outstanding SEP issues

- What is the seed population for large SEP events?
- does the composition depend on energy?
- what are the relative contributions of solar wind, coronal, and flare material?
- Do flare particles escape large flaring regions when associated with large/fast CMEs and if so, how?
- Do perpendicular shocks have a higher injection threshold energy than parallel shocks?

- How low in the corona can CME-driven shocks form and accelerate particles?
- to what energies?
- over what time scales?
- What does the energy dependent charge states in impulsive events mean?
- in terms of seed population for flare acceleration
- in terms of stripping in the corona
- in terms of where the acceleration is taking place

## Outstanding SEP Issues

- Why do so many interplanetary shocks not accelerate particles?
- What is the flare acceleration mechanism and can it explain the high enhancements of ultra-heavy ions in impulsive events?
- What does the different spectral shapes of 3He in impulsive events tell us?
- about the acceleration process
- about the transport process