Abstract
CRRs are characterized by a monotonic decrease of the solar wind speed and are associated with the regions of a small longitudinal extent on the Sun. Differences between properties of protons and alpha particles (the two most abundant ionic components of the solar wind) are often used to identify the source regions of solar wind streams.
However, stream interactions can change alpha-proton relations. In our study, we use near-Earth measurements and focus on the behavior of alpha particles in CRRs.
We observed large variations of the alpha particle relative abundance nα/np in these regions which are usually not connected with the solar wind speed and alpha-proton relative drift changes. We perform a superposed epoch analysis of the collected CRRs with a motivation to determine the global profile of alpha particle parameters across CRRs.
We find that CRRs exhibit a continuous transition of the alpha particle characteristics from fast to slow streams. For a large part of the CRR, nα/np corresponds to values usually observed in the fast solar wind.
We suggest that either a majority of the wind streams in the CRR originate from a coronal hole, or that an additional process altering the alpha parameters occurs in the CRR.