Two types of flare-associated coronal mass ejections

Astronomical Observatory of Jagiellonian University, Cracow, Poland e-mail: michalek@oa.uj.edu.pl

Received: 23 July 2008
Accepted: 15 October 2008

Abstract

Aims. Here, we study the relationship between flares and CMEs.

Methods. For this purpose a statistical analysis of 578 flare-associated CMEs is presented. We considered two types of flare-associated CMEs: CMEs that follow and precede flare onset.

Results. We shown that both samples have quite different characteristics. The first type of CMEs tends to be decelerated (median acceleration = –5.0 m s^-2), faster (median velocity = 519 km s^-1), and physically related to flares (a correlation coefficient between the energy of the CME and the peak of the X-ray flare = 0.80). The CMEs preceding associated flares are mostly accelerated (median acceleration = 5.4 m s^-2), slightly slower (median velocity = 487 km s^-1), and poorly related to flares (a correlation coefficient between the energy of the CME and the peak of the X-ray flare = 0.12).

Conclusions. These two types of flare-associated CMEs demonstrate that magnetic reconnection, which influences the CME acceleration, could be significantly different in the two types of events.