Linking Stealthy Signatures of Coronal Mass Ejections at the Sun to 1 AU

Abstract:

One of the underlying problems in the investigation of CME genesis and evolution is relating remote- sensing observations of coronal mass ejections (CMEs) to in-situ observations of interplanetary CMEs (ICMEs). Typically, remote-sensing observations of an eruption are first observed in the low corona, followed by coronagraph observations of the global structure of the CME projected onto the plane of the sky, and then finally local, highly-quantitative measurements of an ICME are made in situ along a spacecraft trajectory. However, the dramatic change in solar activity in recent years has raised awareness of “stealth” CMEs, which are CMEs observed in coronagraph data but not in coronal images, especially in disk view. Largely identified during the deep minimum of cycle 23/24, stealth CMEs appear to be on the rise. Since solar cycle 25 brings with it the possibility of yet another low activity cycle, it is very likely that the number of stealth CMEs will remain a significant fraction of ejecta. We investigate the properties of stealth CMEs during the rise of solar cycle 24 and through the current solar maximum, paying special attention to their proximity to coronal holes. We investigate the existence of mismatched polarity reversals in the magnetic field and electron strahl measured in situ within ICMEs associated with stealth CMEs. We discuss the plausibility of interaction with solar wind emanating from coronal holes as a key element of stealth CME eruption as evidenced by expanding coronal hole boundaries during eruption and the presence of interchange reconnection within ICMEs.