CONICET | Buscador de Institutos y Recursos Humanos

Though their relationship is complex, the presence of suprathermal uni or bi-directional electron streams in ICMEs are treated as signatures of magnetic field lines with one or both ends being connected to the Sun, respectively, while their absence is interpreted as disconnection. However, do we have any reliable signature in the solar corona distinguishing between maintained connection and disconnection? We test two solar signatures against interplanetary suprathermal electron signatures in order to establish their relevance. We test the hypothesis that the recovery of Transient Coronal Holes (TCHs, dimming regions corresponding to the footpoints of CMEs) is a signature of magnetic disconnection from the Sun. Through three case studies we quantitatively demonstrate that magnetic reconnections between field lines of the expanded CME magnetic field and small coronal loops can act to disperse the concentration of CME footpoints (forming the dimming region) out into the surrounding quiet Sun, thus recovering the intensity of the dimming region whilst still maintaining the magnetic connectivity to the Sun. This analysis provides evidence that the recovery of coronal dimming regions can, in fact, be simply reconciled with maintained magnetic connectivity to the Sun. However, disconnection can occur when open field lines are involved in reconnection with CMEs. We show through two well-observed case studies that magnetic reconnection between the expanding CME and a nearby coronal hole (CH) is indeed able to disconnect one leg of the expanding CME magnetic structure, as indicated by uni-directional electron streams in their respective ICMEs. Therefore we suggest that brightenings (signatures of reconnection) appearing along a coronal hole boundary in the wake of a CME can be treated as a signature of (at least partial) disconnection of one of the CME legs from the Sun.

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