Relationship between three-dimensional velocity of filament eruptions and CME association

Daikichi Seki,Takako T Ishii,Ayumi Asai,Kenichi Otsuji,Kiyoshi Ichimoto

doi:10.1186/s40623-021-01378-4

Abstract

It is widely recognised that filament disappearances or eruptions are frequently associated with Coronal Mass Ejections (CMEs). Since CMEs are a major source of disturbances of the space environment surrounding the Earth, it is important to investigate these associations in detail for the better prediction of CME occurrence. However, the proportion of filament disappearances associated with CMEs is under debate. The estimates range from sim 10 to sim 90% and could be affected by the manners to select the events. In this study, we aim to reveal what parameters control the association between filament eruptions and CMEs. We analysed the relationships between CME associations and the physical parameters of filaments including their length, maximum ascending velocity, and direction of eruptions using 28 events of filament eruptions observed in Halpha. We found that the product of the maximum radial velocity and the filament length is well correlated with the CME occurrence. If the product is larger than 8.0 times 10^{6}text {km}^{2}text {s}^{-1}, the filament will become a CME with a probability of 93%, and if the product is smaller than this value, it will not become a CME with a probability of 100%. We suggest a kinetic-energy threshold above which filament eruptions are associated with CMEs. Our findings also suggest the importance of measuring the velocity vector of filament eruption in three-dimensional space for the better prediction of CME occurrence.

Highlights

Filaments are regions of dense cool plasma floating in the corona that are supported by magnetic fields
We investigated the relationships between the physical parameters of filament eruptions and their Coronal mass ejection (CME) associations using 28 events observed by Solar Dynamics Doppler Imager (SDDI) at Hida Observatory
We found that the filament eruptions are well separated into two groups of events, one with and the other without CMEs, according to the product of the normalised maximum ascending velocity (V r_max/V0 ) and the normalised filament length ( L/L0 ) to the power of 0.96, and that among the filament eruptions with are associated with CMEs, and 100% of filament eruptions with the product < 0.80 are not associated with

Summary

Introduction

Filaments are regions of dense cool plasma floating in the corona that are supported by magnetic fields. They are observed in absorption as dark features on the solar disk in H α (6562.8 Å) and in emission as prominences above the solar limb. At the end of its life, a filament disappears by slow fading or exhibits a transient eruption. Before it disappears or erupts, small-scale blobs observed in H α in a filament often show a larger standard deviation of the line-of-sight (LOS) velocity (Seki et al 2017, 2019b). Filament eruptions are often associated with coronal mass ejections (CMEs), which are observed by coronagraphs such as the Large Angle and Spectrometric Coronagraph (LASCO) (Brueckner et al 1995).

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