Transcript Acceleration of Solar Energetic Particles Rami Vainio University of Helsinki, Department of Physics, Finland University of Turku, Department of Physics and Astronomy, Finland SPACECAST.

Acceleration of Solar Energetic Particles
Rami Vainio
University of Helsinki, Department of Physics, Finland
University of Turku, Department of Physics and Astronomy, Finland
SPACECAST Stakeholder Meeting, BAS, 7 February 2014
Solar energetic particle events
Lario (2005)
Flares or shocks?
Large gradual SEP events nearly always
accompanied with both!
–30 min
Solar energetic particle events
Lario (2005)
Present paradigm of SEP acceleration in gradual
events
CME-driven shocks are the main
source of deka-MeV protons during
the largest SEP events
CME driven shocks
Diffusive shock acceleration
u2
SW frame
u1
∆u = u2 – u1
Turbulent foreshock
Outward-streaming ions
scattering off turbulence lead
to amplification of fluctuations
Bootstrapping!
Modeling in SPACECAST
Alfvén wave intensity [G2]
Proton intensity [cm–2 sr–1 s–1 MeV–1]
Distance of the shock from the Sun = 14 – 22 R
Mathematical model (—) developed
for turbulent region explains
simulations (- - -)
Three different initial particle distributions
1a
2a
3a
4a
1b
2b
3b
4b
1c

R = 5.8–11 R
θBn = 2.8°
Vs = 1920 km/s

R = 14–22 R
θBn = 5.4°
Vs = 1820 km/s

R = 25–36 R
θBn = 8.7°
Vs = 1620 km/s

R = 40–60 R
θBn = 14°
Vs = 1430 km/s
2c
3c
4c
New tool for space weather
modelling
Summary
• Solar energetic particles are accelerated in flares and CMEdriven shocks
– CME-driven shocks responsible for large gradual events
• SPACECAST project has developed models for particle
acceleration in CME-driven shocks
– First steps taken towards operational direction by analyzing
simulations and developing a semi-analytical description of ion
foreshocks in CMEs
• Next steps: integration of SPACECAST results to a state-of-theart transport code (see Angels Aran’s presentation)
Acknowledgements
•
The research leading to these results has received funding from the European
Union Seventh Framework Programme (FP7/2007-2013) under grant agreement
no 262468, and is supported in part by the University of Helsinki