**Previous
abstract** **Next
abstract**

**Session 8 - Corona III.**

*Oral session, Saturday, June 28*

*Ballroom A, Chair: Barry LaBonte*

## [8.04] Role of the Streamer Cavity in CME Energetics

*R. Wolfson, S. Saran (Middlebury College)*
Magnetic energy is commonly believed to power coronal
mass ejections (CMEs). Theory and numerical experiments
show that the energy stored in force-free magnetic fields
is sufficient only to open the coronal magnetic field,
but not to accelerate the mass ejection nor to lift it
against solar gravity. Simple models involving non-force
free cross-field currents can store more magnetic energy,
but in the process they develop large negative gravitational
energies, giving negative total energy.

We have developed a coronal model that incorporates a
more realistic density profile, similar to that of the
coronal helmet streamers in which most CMEs originate.
In this model, the presence of the underdense streamer
cavity permits the growth of magnetic energy without
as much negative gravitational energy. We thus
achieve pre-CME coronal states with positive total energy.
In some cases the positive energy is a mix of magnetic and
gravitational energy; in other cases magnetic energy
dominates. We conclude in the latter cases that
magnetic energy is sufficient to power mass ejections in
our model corona.

**Program
listing for Saturday**