Bridging EUV and White-Light Observations to Inspect the Initiation Phase of a “Two-Stage” Solar Eruptive Event

Abstract

The initiation phase of CMEs is a very important aspect of solar physics, as these phenomena ultimately drive space weather in the heliosphere. This phase is known to occur between the photosphere and low corona, where many models introduce an instability and/or magnetic reconnection that triggers a CME, often with associated flaring activity. To this end, it is important to obtain a variety of observations of the low corona in order to build as clear a picture as possible of the dynamics that occur therein. Here, we combine the EUV imagery of the SWAP instrument on board PROBA2 with the white-light imagery of the ground-based Mk4 coronameter at MLSO in order to bridge the observational gap that exists between the disk imagery of AIA on board SDO and the coronal imagery of LASCO on board SOHO. Methods of multiscale image analysis were applied to the observations to better reveal the coronal signal while suppressing noise and other features. This allowed an investigation into the initiation phase of a CME that was driven by a rising flux rope structure from a "two-stage" flaring active region underlying an extended helmet streamer. It was found that the initial outward motion of the erupting loop system in the EUV observations coincided with the first X-ray flare peak, and led to a plasma pile-up of the white-light CME core material. The characterized CME core then underwent a strong jerk in its motion, as the early acceleration increased abruptly, simultaneous with the second X-ray flare peak. The overall system expanded into the helmet streamer to become the larger CME structure observed in the LASCO coronagraph images, which later became concave-outward in shape. Theoretical models for the event are discussed in light of these unique observations, and it is concluded that the formation of either a kink-unstable or torus-unstable flux rope may be the likeliest scenario.

Interrupted Eruption of Large Quiescent Filament Associated With a Halo Cme

“…In a recent work, there was a similar "two-stage" eruption scenario that was reported by Byrne et al (2014) for the eruptive event on 2011 March 8. The source region of the erupting flux rope in this event was exactly at the western limb for AIA observations.…”

Two-step solar filament eruptions

“…A filament after the first jump decelerates and stops at a greater height as in failed eruptions, but after a rather short period of time it starts to rise again and develops into the successful eruption with a CME formation. Byrne et al (2014) observed on 2011 March 8 at the solar limb the erupting loop system that stayed in a matastable intermediate position for an hour and then proceeded and formed the core of a CME. Gosain et al (2016) analyzed observations of the eruption of a long quiescent filament on 2011 October 22 observed from three viewpoints by space observatories.…”

Evolution of the Coronal Cavity From the Quiescent to Eruptive Phase Associated with Coronal Mass Ejection

“…The green and yellow dotted lines are the same as those described for figure 1. based on their location with respect to the POS, as it is the case for white-light coronagraph images. Therefore, any coronal feature, such as the erupting loop system studied in Byrne et al (2014), which lies away from the POS will appear as different morphological structures in EUV and white-light observations. Coronal cavities are extended tunnel like structures which are mostly associated with the polar crown filaments (Gibson 2015).…”

“…Mierla et al 2013a) and the evolution of a large-scale coronal pseudostreamer in association with cavity system (Guennou et al 2016). SWAP observations also have been used in conjunction with the ground-based Mauna Loa Solar Observatory (MLSO) Mark-IV K-coronameter (Mk4: Elmore et al 2003) to study the initiation phase of a two stage eruptive event (Byrne et al 2014).…”