On existence of two different mechanisms for forming coronal mass ejections

TL;DR

This paper investigates two distinct mechanisms for forming coronal mass ejections, highlighting differences in their initiation phases and suggesting impulsive CMEs originate from magnetic tube emergence driven by Parker instability.

Contribution

It identifies and confirms two different mechanisms for CME formation, emphasizing the role of magnetic tube emergence from the solar photosphere in impulsive CMEs.

Findings

Impulsive CMEs start under the solar photosphere.

Magnetic tubes can reach hundreds of km/s at the photosphere.

Parker instability may trigger the rise of magnetic tubes.

Abstract

We confirm the principal difference of the initiation phase between the impulsive and gradual CME motion trajectory revealed earlier in preliminary studies. Based on studying the dynamics of two impulsive CME (25 March 2008 and 13 June 2010), and also the MHD-approximation computations, we have come to a conclusion that forming impulsive CME starts under the solar photosphere and may be associated with supersonic emergence of magnetic tubes from the convective region. A radial velocity of such tubes at the photosphere level can reach hundreds of km s$^{-1}$, and their angular size $d\approx$ (1-3)$^\circ$. A probable reason of their rise from the convective region is the "slow wave" instability (the Parker instability).