September 25, 2012
Link Between Coronal Mass Ejections And The Sun’s Interior Motion
April Flowers for redOrbit.com - Your Universe Online
After forty long years of debates and theories and counter-theories, the community of solar physics scientists has still failed to come to a consensus about what causes the sun's powerful coronal mass ejections (CMEs). CMEs have profound "space weather" effects on land based power grids and satellites in near-Earth geospace.
An international team of scientists explains the mysterious physical mechanisms behind the origin of CMEs in a study published in Nature Physics. The results, based on computer simulations, expose the intricate connections between CMEs and motions in the sun's interior. This new data could lead to better forecasting of hazardous space weather conditions.
Clouds of magnetic fields and plasma — a hot gas composed of charged particles — comprise CMEs. The most powerful and fastest of these events explode from the sun at more than a million miles per hour, with an energy release more powerful than the entire 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," says 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.
Disruptions in power grids, satellites that operate GPS or telecommunication systems, pose threats to astronauts in space, cause spectacular auroras, and lead to the rerouting of flights over the polar regions are all effects of geomagnetic storms caused by CMEs. These storms happen when a solar eruption hits Earth's protective magnetic bubble, or magnetosphere.
The study provides an explanation of the origin of these super speed ejections of magnetized plasma and the associated X-ray emissions, demonstrating a fundamental connection between the magnetic processes of the sun's interior and the formation of CMEs.
"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", says SSC researcher NoÃ© Lugaz of the UNH Institute for the Study of Earth, Oceans, and Space. He adds, "These fundamental phenomena cannot be observed even with the most advanced instruments on board NASA satellites but they can be revealed by numerical simulations."
Accurate forecasting of solar eruptions and being able to predict their impact on Earth has long been a goal of solar physicists.
"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," asserts the authors.