The Merging of Two Stream Interaction Regions within 1 au: The Possible Role of Magnetic Reconnection

As the Sun rotates, a fast stream can overtake a preceding slow stream, leading to the formation of a stream interaction region (SIR). Two neighboring SIRs may eventually coalesce to produce a merged interaction region (MIR) en route to the outer heliosphere. However, instances of significant interaction and merging of two neighboring SIRs within 1 au are thought to be extremely rare. In this Letter, we present a case report of two interacting and merging SIRs observed near 1 au, which was associated with two adjacent low-latitude coronal holes. The two SIRs were filled with outward propagating Alfvénic fluctuations associated with magnetohydrodynamic turbulence. A reconnection exhaust associated with a current sheet was identified. We suggest that magnetic reconnection represented a potentially important mechanism for the merging of two neighboring SIRs. This observation may shed light on the understanding of the structure and formation of a MIR within 1 au.