Solar wind ionic charge states during the Ulysses pole‐to‐pole pass

Abstract

We analyze and compare the ionic charge composition data for different types of the solar wind (slow wind from equatorial regions, fast wind from low‐latitude coronal hole and fast wind from both south and north polar coronal hole) which the Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses observed during the pole‐to‐pole pass of its primary mission. The implications on the electron temperature, electron density, and ion outflow velocity from the corresponding solar wind source regions are also discussed. We find that the electron temperature in the source region of the slow solar wind is higher than that in the coronal hole. We also find a possible north‐south asymmetry in the electron temperature that may be correlated to the north–south asymmetry in the solar wind speed found in the SWOOPS/Ulysses data. In particular, we make extensive discussions on the latitudinal variations in the polar coronal hole. On the basis of our data without clear constraints from other coronal observations, the preliminary result is that the electron density may be higher, or the heavy ion outflow velocities may be lower toward lower heliographic latitude.