Three-dimensional Geometry of a Current Sheet in the High Solar Corona: Evidence for Reconnection in the Late Stage of the Coronal Mass Ejections

Abstract

Motivated by the standard flare model, ray-like structures in the wake of coronal mass ejections (CMEs) have been often interpreted as proxies of the reconnecting current sheet connecting the CME with the postflare arcade. We present the three-dimensional properties of a post-CME ray derived from white light images taken from three different viewing perspectives on 2013 September 21. By using a forward modeling method, the direction, cross section, and electron density are determined within the heliocentric distance range of 5-9 R _⊙. The width and depth of the ray are 0.42 ± 0.08 R _⊙ and 1.24 ± 0.35 R _⊙, respectively, and the electron density is (2.0 ± 0.5) × 10⁴ cm^-3, which seems to be constant with height. Successive blobs moving outward along the ray are observed around 13 hr after the parent CME onset. We model the three-dimensional geometry of the parent CME with the Gradual Cylindrical Shell model and find that the CME and ray are coaxial. We suggest that coaxial post-CME rays, seen in coronagraph images, with successive formation of blobs could be associated with current sheets undergoing magnetic reconnection in the late stage of CMEs.