Computer models bring researchers one step closer to predicting coronal mass ejections

Every eleven years, the sun goes through a phase referred to as solar maximum where it experiences increased activity in the form of sunspots, solar flares, and occasional violent outbursts known as a coronal mass ejection.  Coronal mass ejections, or CMEs, are enormous clouds of superheated gas, or plasma, which streak through space at millions of miles an hour carrying tremendous amounts of energy.  At present, there are no means of predicting CMEs before they happen, however that is the goal for a team at the University of New Hampshire’s Space Science Center (SSC), which has been conducting research with the aid of powerful computer models.  Through these models they hope to gain a better understanding of how the sun operates in order to recognize the signs of a CME before it occurs.

“These simulations cannot yet predict coronal mass ejections,” said Noé Lugaz, one of the primary researchers at University of New Hampshire, “but it can help us to study them in a self-consistent and physical way.” To perform these simulations, Lugaz and his team rely on super computers to run two integral programs synchronized with each other.  One program, known as the solar coronal code, developed at the University of Michigan and later refined at the University of Hawaii, demonstrates the early stages of a coronal mass ejection.  The other program, named the flux emergence code, simulates magnetic fields in the upper layers of the sun’s atmosphere.  Used in conjunction, these two systems offer a physically accurate model of a CME’s inception.

These models are based on assumed conditions in the sun, including temperature and magnetic field strength, which are believed to play a role in the production of a CME.  These parameters are taken from recorded observations of solar activity in order to best understand the conditions under which a CME may develop.  The goal, however, is to input data from real time observations in order to simulate whether a CME is likely to occur.  “What we have demonstrated so far is a proof of concept using some idealized physical circumstances resembling the sun,” said Ilia Roussev, a researcher at the University of Hawaii and the lead author of a paper recently published in Nature Physics which outlines the results of this computer study.  “Our next goal is to utilize the model described on the paper for case studies of real solar events.”

What is presently understood is that coronal mass ejections occur when part of the sun’s magnetic field erupts from the outermost layer of the surface, or the corona, expelling large amounts of solar material at the same time.  According to Lugaz, the magnetic field gives each ejection an “identity,” ensuring that it remains a cohesive structure as it departs from the sun and into space.

CMEs which are aimed towards the Earth can pose a threat to both life and manmade infrastructures on and in orbit of our planet.  This is because they carry staggering amounts of radiation both in the form of electromagnetic waves and charged particles.  Luckily, CMEs rarely collide with Earth, but even when they do our planet has a natural protective barrier against these stellar furies: the magnetosphere.  This magnetic safe haven regularly diverts charged particles from the sun, otherwise known as solar winds, from striking our planet, protecting the surface from lethal doses of radiation, and on occasion has even proven strong enough to withstand the full brunt of a CME.

Despite Earth’s magnetic field dissipating CMEs before they can unleash their full force, though, there are still many consequences to face following such a massive collision.  “If a once-in-a-century CME hits Earth, we can expect a power failure due to strong currents in the electricity grid.  This would result in a blackout,” explained Lugaz.  “In addition there could be some satellite failure, problems with any space-borne technology.”  Indeed, in 1989, a powerful CME which struck the Earth left such a residual charge in the atmosphere that it short circuited much of Quebec’s power grid, causing a widespread blackout.  And again in 1997, the electrical surge caused by another ejection passing by Earth permanently deactivated one of AT&T’s key satellites.  Due to this threat toward technology and hardware, engineers have been prompted to develop better shielding or establish “safe modes” for their space born equipment to survive the onslaught of a CME.

Another concern researchers take into account when considering the danger CMEs pose is the risk of radiation exposure to transcontinental flights flying above the arctic circle where the magnetic field is weakest.  “CMEs also pose enhanced radiation threat for passengers and crews onboard cross-polar flights,” Roussev noted.  “When major geomagnetic events triggered by CMEs occur, flight crews are advised to reroute their flight to lower latitudes.”  Roussev also remarked that CMEs pose a concern for the safety of astronauts serving on the International Space Station beyond the magnetosphere’s protective cover.

Roussev, Lugaz, and other astronomers are hopeful that advances in computer modeling will allow a better understanding of the origins and nature of coronal mass ejections, and therefore the ability to accurately forecast them in times of high solar activity.  Adequately predicting a CMEs’ formation and trajectory will allow power companies, air traffic control, satellite-based operations and services, and even manned spaceflight, with sufficient time to enact safety procedures.  Much like preparing for an oncoming storm, with enough advanced knowledge these industries would be able to take necessary precautions to protect their assets and their crews.  “What we are building at the moment,” Roussev stated, “is the physical foundation required for space weather forecast.”

While CMEs may sound daunting, for the most part they are harmless albeit dramatic displays of the sun’s raw power, rupturing into space without colliding with the Earth or other astronomical bodies.  It is from this perspective that Roussev and Lugaz work, not yet tracking Earth-bound ejections but rather studying how magnetic fields affect the sun’s corona as a whole.  “The magnetic field is the dominant source of energy in the solar corona,” Roussev elaborated, “and there is no other energy source that can explain the observed properties of these events.”  With time, however, these relationships may be understood, uncovering the secrets behind many stellar phenomenon.