Sources of The Slow Solar wind During the Solar Cycle 23/24 Minimum

TL;DR

This study analyzes the sources and characteristics of slow solar wind during the solar minimum of Solar Cycles 23 and 24, using in-situ observations to identify variations and challenges in source differentiation.

Contribution

It provides a comprehensive analysis of slow solar wind sources during a solar minimum, highlighting the variability and complexity in distinguishing their origins.

Findings

Significant variations in solar wind parameters over the study period.

Difficulty in distinguishing slow solar wind sources based on solar wind conditions.

Some parameters like speed and charge ratios vary with source type, others like Fe/O do not.

Abstract

We investigate the characteristics and the sources of the slow (< 450 km/s) solar wind during the four years (2006-2009) of low solar activity between Solar Cycles 23 and 24. We use a comprehensive set of in-situ observations in the near-Earth solar wind (Wind and ACE) and remove the periods when large-scale interplanetary coronal mass ejections were present. The investigated period features significant variations in the global coronal structure, including the frequent presence of low-latitude active regions in 2006-2007, long-lived low- and mid-latitude coronal holes in 2006 - mid-2008 and mostly the quiet Sun in 2009. We examine both Carrington Rotation averages of selected solar plasma, charge state and compositional parameters and distributions of these parameters related to Quiet Sun, Active Region Sun and the Coronal Hole Sun. While some of the investigated parameters (e.g., speed, the C^{+6}/C^{+4} and He/H ratio) show clear variations over our study period and with solar wind source type, some (Fe/O) exhibit very little changes. Our results highlight the difficulty in distinguishing between the slow solar wind sources based on the inspection of the solar wind conditions.