SOLDYN - Dynamics of Solar Flares and Coronal Mass Ejections
Solar flares and coronal mass ejections erupting from the Sun are the most violent phenomena in our solar system. Flares represent an explosive release of energy previously stored in strong magnetic fields associated with sunspots, which leads to localized heating of the solar plasma, acceleration of high- energetic particles and enhanced radiation virtually across the entire electromagnetic spectrum from radio to hard X-rays.
Coronal mass ejections (CMEs) are huge structures of magnetized plasma expelled into interplanetary space at velocities of hundreds to a few thousand kilometers per second, occasionally heading towards Earth. Flares and CMEs are closely related phenomena and can cause severe perturbations of our "space weather", i. e. the conditions in our near-Earth space environment that can influence the performance and reliability of space-borne as well as ground-based technological systems.
Many aspects of the basic physics of solar flares and CMEs, how they relate to each other, and how they affect our Earth system are still not fully understood.
The STEREO mission consists of two spacecraft with identical instrumentation for observations of the faint outermost layer of our Sun, the corona. STEREO-A is moving ahead, STEREO-B behind Earth in its orbit around the Sun, thus facilitating the first three-dimensional view of CMEs.
The Extreme Ultraviolet Imager (EUVI) and COR instruments onboard STEREO provide high cadence imaging of the inner solar corona. This is a highly important region for CME dynamics since it is located at the place where the impulsive CME acceleration takes place due to the expelling magnetic forces. The energy release in the associated flares is best studied in hard X-rays, as currently observed with high spatial, spectral and temporal resolution by NASA’s RHESSI mission.
In SOLDYN we investigate three main topics: (1) the impulsive acceleration phase of CMEs, (2) the CME’s relation to the associated flare’s energy release, and (3) the CME source region characteristics and how they relate to the CME dynamics. These aspects provide essential ingredients for better understanding and modelling the physics of solar flares and CMEs.
University of Graz, Institute of Physics/ IGAM - Astrid Veronig
- NASA Goddard Space Flight Center - Brian Dennis
- University of Zagreb, Hvar Observatory/ Faculty of Geodesy - Bojan Vršnak