What drives fast ejections of magnetised plasma from sun

An international team of space scientists has explained the mysterious physical mechanisms underlying the origin of powerful coronal mass ejections (CMEs) from Sun’s atmosphere that can have profound “space weather” effects on Earth-based power grids and satellites in near-Earth geospace.

Their findings, based on state-of-the-art computer simulations, showed the intricate connection between motions in the Sun’s interior and these eruptions and could lead to better forecasting of hazardous space weather conditions.

CMEs are clouds of magnetic fields and plasma -- a hot gas composed of charged particles. The fastest and most powerful of these events can explode from the Sun at speeds of more than a million miles per hour and release more energy than the current worldwide stockpile of nuclear weapons.

“By studying CMEs we learn not only about the drivers of space weather but also about the structure of the atmosphere of the Sun and other Sun-like stars,” said lead author Ilia Roussev of the Yunnan Astronomical Observatory, Chinese Academy of Sciences (CAS) and the Institute for Astronomy at the University of Hawaii at Manoa.

Geomagnetic storms caused by CMEs can disrupt power grids, satellites that operate global positioning systems and telecommunication networks, pose a threat to astronauts in outer space, lead to rerouting of flights over the polar regions, and cause spectacular auroras. The storms occur when a solar eruption hits Earth’s protective magnetic bubble, or magnetosphere.

“Through this type of computer modeling we are able to understand how invisible bundles of magnetic field rise from under the surface of the Sun into interplanetary space and propagate towards Earth with potentially damaging results”, said SSC researcher Noe Lugaz of the UNH Institute for the Study of Earth, Oceans, and Space.

“These fundamental phenomena cannot be observed even with the most advanced instruments on board NASA satellites but they can be revealed by numerical simulations,” he added.

A long-standing goal of the solar physics community has been the forecasting of solar eruptions and predictions of their impact on the Earth.

The researchers noted, “the model described here enables us not only to capture the magnetic evolution of the CME, but also to calculate the increased X-ray flux directly, which is a significant advantage over the existing models.

Their findings have been just published in Nature Physics.