Authors: S. Gibson, Y. Fan; G. Barnes et al.
Affiliation: National Center for Atmospheric Research, High Altitude Observatory;
NorthWest Research Associates, Inc., Colorado Research Associates Division
We consider the implications of a magnetic flux rope topology for the interpretation
of observations of sigmoidal active regions. A region of tangential magnetic
discontinuities can be identified using techniques that determine a bald patch
(BP) and corresponding separatrix surface -- for a flux rope this region can
be S-shaped, or sigmoidal. If such a region is physically driven, it has been
theorized that current sheets can form, yielding conditions appropriate for
reconnective heating. Using a numerical simulation of a magnetic flux rope driven
by the kink instability, Fan and Gibson (2003) showed that current sheets indeed
form a sigmoidal surface.
In this poster we first demonstrate that the current sheets form in the region
of the BP and BP-associated separatrix surface. Second, we demonstrate how the
results of the numerical simulation can be used as proxies for observations:
specifically the simulated field at the base of the flux rope as proxy for the
observed photospheric magnetic field, the sigmoidal current sheets as proxy
for the soft X-ray active region emission, and the location of dipped magnetic
field lines as proxy for a filament. Given such proxy observations, is it possible
to extrapolate a coronal field that captures the essential features of the known
model field?