Wuppertal 2015 – wissenschaftliches Programm

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SYAB: Symposium Astrophysikalische Beschleuniger

SYAB 1: Astrophysikalische Beschleuniger

SYAB 1.1: Plenarvortrag

Mittwoch, 11. März 2015, 14:00–14:45, K.11.24 (HS 33)

The Sun - observing cosmic particle accelerators in our neighbourhood — •Rami Vainio — Space Research Laboratory, University of Turku, Finland

Solar energetic particles (SEPs) consist of ions and electrons accelerated to relativistic energies in coronal mass ejections (CMEs) and solar flares. SEP events show variations in intensity, spatial extent, abundances and duration that can be used to analyze the origin of the accelerated particles. The so-called impulsive SEP events are common, spatially limited, and related to solar flares and spatially narrow CMEs. They are electron-rich and show increases of the abundances of heavy ions and the rare isotope 3-He, which can be increased to be at par with alpha particles in the energetic particle population. Models suggest that ion acceleration in these impulsive events is related to resonant wave-particle interactions that can accelerate ions stochastically when a turbulent spectrum of waves is present in the plasma, like in a solar flare. The other extreme of SEP events hosts the so-called gradual events, which are related to fast and wide CMEs, showing durations up to a week and intensities far greater than impulsive events. Gradual events have normal ion abundances and are electron-poor. According to most models, SEPs in gradual events are accelerated via the diffusive shock acceleration mechanism in coronal shocks driven by fast CMEs. I will review recent observational and modeling results to understand the acceleration of particles in coronal and heliospheric plasmas and analyze the consequences of these studies to cosmic particle acceleration in more distant objects.