A Statistical Study on the Morphology of Rays and Dynamics of Blobs in the Wake of Coronal Mass Ejections

TL;DR

This study statistically analyzes the morphology and dynamics of plasma blobs in the wake of coronal mass ejections using LASCO data, revealing variations in blob acceleration, speed, and their relation to magnetic reconnection.

Contribution

It provides the first statistical analysis of blob morphology and motion in CME wakes, highlighting differences from streamer-associated blobs and linking dynamics to magnetic reconnection processes.

Findings

Rays have angular widths of 2.1-6.6 degrees at 3 Rs

58% of blobs are accelerated, 20% decelerated, 22% move at constant speed

Blob speeds and accelerations differ significantly from those above helmet streamers

Abstract

In this paper, with a survey through the Large Angle and Spectrometric Coronagraph (LASCO) data from 1996 to 2009, we present 11 events with plasma blobs flowing outwards sequentially along a bright coronal ray in the wake of a coronal mass ejection. The ray is believed to be associated with the current sheet structure that formed as a result of solar eruption, and the blobs are products of magnetic reconnection occurring along the current sheet. The ray morphology and blob dynamics are investigated statistically. It is found that the apparent angular widths of the rays at a fixed time vary in a range of 2.1-6.6 (2.0-4.4) degrees with an average of 3.5 (2.9) degrees at 3 (4) Rs, respectively, and the observed durations of the events vary from 12 h to a few days with an average of 27 h. It is also found, based on the analysis of blob motions, that 58% (26) of the blobs were accelerated, 20% (9) were decelerated, and 22% (10) moved with a nearly-constant speed. Comparing the dynamics of our blobs and those that are observed above the tip of a helmet streamer, we find that the speeds and accelerations of the blobs in these two cases differ significantly. It is suggested that these differences of the blob dynamics stem from the associated magnetic reconnection involving different magnetic field configurations and triggering processes.