Longitudinally Spaced Observations of a Magnetic Cloud-Like Structure Embedded in a Co-rotating Interaction Region

Abstract

Interaction mechanisms in the solar wind affect the evolution of magnetic structures, thereby mediating the properties acquired during their formation processes at the Sun as they propagate outward. Using remote-sensing and in-situ observations across multiple spacecraft we investigate a Magnetic Cloud-Like structure (MCL) detected in-situ on 3-4 July 2007 near the ecliptic at different longitudes with OMNI, STEREO-A and -B. The MCL is entrained in a Corotating Interaction Region (CIR) originating in the Northern heliospheric sector, creating a Merged Interaction Region (MIR). Our multi-spacecraft analysis, facilitated by the small angular separation of 17° in longitude and the solar minimum background, reveals the 'aging' of the MCL-CIR interaction. Local negative expansion speeds of the MCL indicate compression increasing further downstream. Differences in size, the formation of the sheath, the presence of forward and reverse waves, and the small-scale structuring demonstrate the progression of the interaction. This unique opportunity to observe the temporal evolution of the MCL-CIR interaction highlights the intricate nature of solar wind structures and their interactions at 1 AU.