Investigation of Solar Wind Source Regions by Using Ulysses/SWICS/SWOOPS Composition Data and a Potential Field Source Surface Model to map in situ Measurements back onto the Photosphere

Abstract:

The fast solar wind most likely originates from coronal holes,
primarily the polar coronal holes, as evidently shown by Ulysses/SWICS observations
of the solar wind at high heliographic latitudes. The source of the slow
solar wind, on the other hand, remains elusive and is still under debate.

In order to analyze the transition between different solar wind regimes, we use
Ulysses/SWICS/SWOOPS/VHM solar wind and solar wind composition data to
investigate solar wind dwell (transition from fast to slow wind) and
compression regions (transition from slow to fast wind). Because the solar wind
dwells are dynamically pulled apart, thus magnifying the transition region, we
can observe the nature of the transition with increased accuracy and, in the
near future, will provide limits on models of the origin of the slow solar wind.

We map the composition data provided by SWICS back onto the source surface of the sun.
Utilizing a Potential Field Source Surface (PFSS) model we trace the corresponding
magnetic field lines from the source surface down to the photosphere, which provides a direct link
between the composition measurements of Ulysses/SWICS and its source on the
Sun's photosphere.

In addition ot that, we will trace the field lines to several height layers
between the photosphere and source surface so that we will be able to create a
height profile of the solar wind source regions.

Finally, we will calculate the distance from the determined source locations to the
borders of the open field line regions in order to look for correlations between solar wind
speed, charge state composition and source location.

Here we will show results of our back-mapping analysis and preliminary implications for the solar wind source regions.