Astrophysics Seminar

The coronal magnetic field, the ultimate driver of space weather, plays an essential role in the formation, evolution, and dynamics of the small and large-scale structures in the solar corona. These structures may lead to gigantic explosions in the solar atmosphere in the form of large-scale eruptions, such as coronal mass ejections (CMEs), which may severely impact near-Earth space. CMEs can reach Earth within several hours to days, and depending on the orientation of its internal magnetic field; they can interact with the Earth’s magnetosphere causing severe geomagnetic storms. Moreover, the shocks generated by CMEs can accelerate the energetic particles leading to highly energetic solar radiation storms. These extreme space weather conditions may damage satellite operations and Earth’s communication and navigation system. Therefore, studying such violent solar eruptions is crucial to understand their consequences on space weather. CMEs are often accompanied by radio emissions, which provide access to observations of the related solar, heliospheric, and ionospheric space weather phenomena. Radio techniques can provide early signatures of particle acceleration associated with solar flares and CMEs, which give insights into CME initialisation and eruption processes (1). These observational techniques also serve as a powerful tool to constrain the coronal and heliospheric models. With state-of-the-art radio instruments such as LOw-Frequency ARray (LOFAR) and legacy instruments such as Nançay Radio Heliograph (NRH), it has now been possible to study these bursts and their structures in great spectral, temporal and spatial resolutions (2). Using these observations and time-dependent data-driven numerical modeling of active region magnetic fields (3), we study the formation and eruption of the coronal flux-ropes leading to CME eruptions. We estimate various properties of the CME flux-rope and compare them with the associated multi-wavelength ground- and space-based observations. In this talk, I will highlight the radio techniques to constrain the initial CME properties close to the Sun and the numerical modeling approach to understanding the initiation and evolution of large-scale solar eruptions.