Assessing CME Eruptivity through Two-Ribbon Flare Topology and 3D Magnetic Field Modelling

Solar flares can be eruptive or confined depending on whether they are accompanied by a Coronal Mass Ejection (CME). The shape of flare ribbons, a phenomenon occurring at the footpoints of magnetic field loops in the chromosphere, imprints the topology of the 3D magnetic fields and can be connected to event eruptivity. Based on the Standard Flare Model, it has long been argued that a two-ribbon flare is likely to result in an eruption. In this work, we study the relation between the eruptivity and two-ribbon topology in the flares of different soft X-ray (SXR) classes using a catalog of 722 solar flares from Solar Cycle 24 from Kazachenko et al. (2023). Using observations in the 1600 Å channel from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO), we generate the desaturated GIF movies of flare ribbon dynamics for all events and quantify their two-ribbon nature based on experts' input. For C and M-class flares, observations indicate that the presence of a two‑ribbon topology is positively correlated with the occurrence of eruptive behavior. The eruptivity probability does not seem to depend on the ribbon topology for the X-class flares. For a flare of a particular class, very confidently identified as two-ribbon, the eruptivity chances are ~45% (C-class) and ~70% (M-class and X-class). We further extend this study by developing machine learning techniques for the automatic identification of flares whose ribbons exhibit a two-ribbon topology. As an extension of the study, since flare ribbons trace the chromospheric footpoints of coronal magnetic structures, we reconstruct the 3D coronal magnetic field using Non-Linear Force-Free Field (NLFFF) extrapolations. From these extrapolations, we compute quasi-separatrix layer (QSL) maps, which are regions of strong magnetic connectivity gradients and are expected to coincide with the flare ribbons. This study further explores how several properties of the 3D magnetic structure of a flaring active region can indicate if a CME is imminent.