Magnetic properties of flare-CME productive active regions and CME speed

Abstract

Aims:We study the properties of magnetic field of flare-coronal-mass-ejection (flare-CME) productive active regions and their statistic correlations with CME speed.
Methods: We used a sample of 86 flare-CMEs in 55 solar active regions. Four measures, including the tilt angle (Tilt), total flux (Ft), length of the strong-field and strong-gradient main neutral line (Lsg) and effective distance (d_E), are used to quantify the properties of the magnetic field of flare-CME productive active regions.
Results: The results are as follows: (1) for CMEs initiating in active regions, fast CMEs tend to initiate in active regions with large Ft or large d_E. (2) In flare-associated CMEs, faster CMEs tend to be accompanied by more intense flares. (3) The parameters d_E, Lsg and Ft correlate well with one another, especially Ft and Lsg. (4) The occurrence of 11 slow CMEs and 1 fast CME in β type regions with Lsg far below the threshold reminds us of some exceptions to be considered when Lsg with the threshold is used to predict the CME productivity of active regions.

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