Near-Sun Flux Rope Structure of CMEs

TL;DR

This study uses the Krall flux-rope model to analyze 53 CMEs, revealing that all have flux-rope structures, with differences in deflection and width affecting their observational signatures.

Contribution

It provides the first comprehensive analysis confirming that all CMEs possess flux-rope structures, highlighting the effects of deflection and width on observations.

Findings

MC-CMEs are wider than EJ-CMEs.

EJ-CMEs are deflected away from the solar disk center.

All CMEs analyzed show flux-rope structures.

Abstract

We have used the Krall flux-rope model (Krall and St. Cyr, Astrophys. J. 2006, 657, 1740) (KFR) to fit 23 magnetic cloud (MC)-CMEs and 30 non-cloud ejecta (EJ)-CMEs in the Living With a Star (LWS) Coordinated Data Analysis Workshop (CDAW) 2011 list. The KFR-fit results shows that the CMEs associated with MCs (EJs) have been deflected closer to (away from) the solar disk center (DC), likely by both the intrinsic magnetic structures inside an active region (AR) and ambient magnetic structures (e.g. nearby ARs, coronal holes, and streamers, etc.). The mean propagation latitudes and longitudes of the EJ-CMEs (18, 11) were larger than those of the MC-CMEs (11, 6) by 7 and 5, respectively. Furthermore, the KFR-fit widths showed that the MC- CMEs are wider than the EJ-CMEs. The mean fitting face-on width and edge-on width of the MC-CMEs (EJ-CMEs) were 87 (85) and 70 (63), respectively. The deflection away from DC and narrower angular widths of the EJ-CMEs have caused the observing spacecraft to pass over only their flanks and miss the central flux-rope structures. The results of this work support the idea that all CMEs have a flux-rope structure.