Scientists have developed a three-dimensional computer simulation model that could improve the forecasting of powerful solar eruptions known as Coronal Mass Ejections (CMEs), including their speed, arrival time and potential impact on Earth.
The multi-institutional study was led by researchers from the Indian Institute of Astrophysics (IIA), an autonomous institute under the Department of Science and Technology, in collaboration with researchers from the United States, Hungary and Finland.
CMEs are enormous eruptions of magnetised plasma from the Sun that can travel through space at millions of kilometres per hour. When directed towards Earth, they can affect satellites, communications and power grids.
The new three-dimensional magnetohydrodynamic (MHD) simulation follows the evolution of magnetic structures in the Sun’s outer atmosphere, from their gradual formation to their eventual eruption.
Researchers focused on magnetic flux ropes (MFRs), twisted structures formed by magnetic field lines embedded in solar plasma. These structures are considered important in triggering CMEs.
The simulation began with a realistic solar-corona model containing a magnetic configuration resembling a coronal streamer observed on the Sun.
Researchers then gradually introduced a twisted magnetic flux rope from below, representing the emergence of magnetic flux from beneath the solar surface.
As the structure rose, it stretched and compressed surrounding magnetic fields. Magnetic reconnection initially developed slowly through a thin sheet of intense electric current formed where opposing magnetic fields came together.
The process eventually intensified, leading to the rapid expulsion of the flux rope into space.
The computational work was carried out using the NOVA high-performance computing facility at the IIA data centre.
The study, published in the Astrophysical Journal, combined numerical simulations with observations of the Sun.
Researchers simulated two successive flux-rope eruptions and compared the results with observational data. The observational analysis used data from NASA’s Helioseismic and Magnetic Imager (HMI) and Atmospheric Imaging Assembly (AIA) instruments.
The comparison revealed a consistent relationship between the rate of magnetic reconnection and CME acceleration.
According to the researchers, an increase in the rate of magnetic reconnection corresponded with greater CME acceleration.
The finding suggests that reconnection flux could help determine not only whether a CME erupts, but also how rapidly and energetically the eruption develops.
This could be important for space-weather forecasting because powerful CMEs directed towards Earth can interfere with technological infrastructure in space and on the ground.
Better understanding of how magnetic energy accumulates and is released could therefore help researchers improve predictions of CME behaviour before the eruptions travel through interplanetary space.
The research team included Dr Samriddhi Sankar Maity, a postdoctoral researcher at NASA and Georgia State University; Dr Piyali Chatterjee of IIA; Ijas S Mytheen, a PhD student at Eötvös University, Hungary; and Dr Ranadeep Sarkar of the University of Helsinki.
The researchers said the study provides new insight into how magnetic structures that gradually accumulate energy on the Sun can transform into some of the most powerful explosions in the solar system.
