An Asymmetric Cone Model for Halo Coronal Mass Ejections

TL;DR

This paper introduces an asymmetric cone model to better determine the true parameters of halo CMEs by accounting for flux-rope elongation and elliptical cross sections, improving upon the standard symmetric cone model.

Contribution

The paper presents a novel asymmetric cone model for halo CMEs that accounts for flux-rope elongation and elliptical bases, enhancing parameter estimation accuracy.

Findings

Asymmetric cone model fits observed CME data better than symmetric models.

The model provides more accurate estimates of CME propagation speed and width.

Comparison shows improved alignment with observed CME characteristics.

Abstract

Due to projection effects, coronagraphic observations cannot uniquely determine parameters relevant to the geoeffectiveness of CMEs, such as the true propagation speed, width, or source location. The Cone Model for Coronal Mass Ejections (CMEs) has been studied in this respect and it could be used to obtain these parameters. There are evidences that some CMEs initiate from a flux-rope topology. It seems that these CMEs should be elongated along the flux-rope axis and the cross section of the cone base should be rather elliptical than circular. In the present paper we applied an asymmetric cone model to get the real space parameters of frontsided halo CMEs (HCMEs) recorded by SOHO/LASCO coronagraphs in 2002. The cone model parameters are generated through a fitting procedure to the projected speeds measured at different position angles on the plane of the sky. We consider models with the apex of the cone located at the center and surface of the Sun. The results are compared to the standard symmetric cone model.