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.

arXiv comment21 pages, 9 figures, 3 movies

References in corpus (20)

• A Model for Solar Coronal Mass Ejections
• Torus instability
• Ideal kink instability of a magnetic loop equilibrium
• Observations of an extreme storm in interplanetary space caused by successive coronal mass ejections
• Multi-scale Gaussian normalization for solar image processing
• Propagation of an Earth-directed coronal mass ejection in three dimensions
• The SWAP EUV Imaging Telescope Part I: Instrument Overview and Pre-Flight Testing
• Observations and modeling of the early acceleration phase of erupting filaments involved in coronal mass ejections
• The Depiction of Coronal Structure in White Light Images
• Source Regions of Coronal Mass Ejections
• Quasiperiodic acceleration of electrons by a plasmoid-driven shock in the solar atmosphere
• The SWAP EUV Imaging Telescope. Part II: In-flight Performance and Calibration
• Automatic Detection and Tracking of CMEs II: Multiscale Filtering of Coronagraph Data
• Observational evidence of torus instability as trigger mechanism for coronal mass ejections: the 2011 August 4 filament eruption
• The kinematics of coronal mass ejections using multiscale methods
• Improved methods for determining the kinematics of coronal mass ejections and coronal waves
• Causal Relationships between Eruptive Prominences and Coronal Mass Ejections
• Multiscale Edge Detection in the Corona
• Coronal Mass Ejection Detection using Wavelets, Curvelets and Ridgelets: Applications for Space Weather Monitoring
• Automated Solar Feature Detection for Space Weather Applications

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• Observations of an Eruptive Solar Flare in the Extended EUV Solar Corona
• Defining the Middle Corona
• Observations of the Formation, Development, and Structure of a Current Sheet in an Eruptive Solar Flare
• Two Step Filament Eruption During 14-15 March 2015
• Plasma evolution within an erupting coronal cavity
• Observations of the Coronal Mass Ejection with a Complex Acceleration Profile
• Expanding and Contracting Coronal Loops as Evidence of Vortex Flows Induced by Solar Eruptions
• Evolution of Coronal Cavity from Quiescent to Eruptive Phase in Association with Coronal Mass Ejection
• A partial filament eruption in three steps induced by external magnetic reconnection
• Two-step solar filament eruptions
• Investigation of the Middle Corona with SWAP and a Data-Driven Non-Potential Coronal Magnetic Field Model
• Filament Eruption Driving EUV Loop Contraction then Expansion above a Stable Filament
• Solar Total Eclipse of 21 August 2017: Study of the Inner Corona Dynamical Events Leading to a CME
• Self-similar expansion model of cylindrical flux ropes combined with Alfven wave current system
• SunCET: A compact EUV instrument to fill a critical observational gap