Signatures of Two Distinct Initiation Mechanisms in the Evolution of CMEs in the Lower Corona.

We present a comparison of a three-dimensional (3D) simulation of coronal mass ejections (CMEs), in the lower corona, generated with two different initiation mechanisms presented in the literature: Gibson & Low (1998) (as GL98 hereafter) and Titov & Démoulin (1999) (as TD99 hereafter). The simulations are performed using the Space Weather Modeling Framework (SWMF) during the solar minimum (CR1922). Our goal is to understand how the initial magnetic configuration of a CME affects its evolution through the lower corona, until 6R⊙. We found that both CME-driven shocks are quasi-parallel at the nose and that GL98 presents a higher shock acceleration (~150 m/ s2 versus ~100 m/ s2) and a higher Mach number, indicating it would accelerate particles more efficiently. Both CMEs also presented a post-shock compression for R>3R⊙, being slightly larger in the case of TD99. They presented also a similar sheath width that increases while propagating away from the Sun (larger in GL98 case). We also found that in GL98 case the CME is driven by a combination of magnetic and thermal pressure, while in TD99 case the thermal pressure dominates its evolution. One of the reasons why GL98 presents higher force values, is probably related to the fact that its sheath mass is ~20% larger than for TD99. This paper intends to serve as a prototype for future comparisons of CME evolution, in the lower corona.