three-dimensional anisotropic transport of solar energetic particles in the inner heliosphere crism-...
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THREE-DIMENSIONAL ANISOTROPIC THREE-DIMENSIONAL ANISOTROPIC TRANSPORT OF SOLAR ENERGETIC TRANSPORT OF SOLAR ENERGETIC PARTICLES IN THE INNER PARTICLES IN THE INNER HELIOSPHEREHELIOSPHERE
CRISM-2011, Montpellier, 27 June – 1 July, 2011
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Collaborators: W. Dröge, B. Klecker, G.A. Kovaltsov
Y.KartavykhUniversity of Würzburg (Germany),Ioffe Physical-Technical Institute (Russia)
Solar cosmic rays = Solar Solar cosmic rays = Solar Energetic ParticlesEnergetic Particles
Generated in solar explosive Generated in solar explosive processesprocesses
Short time scale in comparison Short time scale in comparison with time scales typical for GCRwith time scales typical for GCR
Anisotropic fluxes at ~ 1 AUAnisotropic fluxes at ~ 1 AU
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are there more than one accelerationprocesses, stages, phases?
are interacting and escaping particlesfrom the same population?
gamma-ray imaging of solar flares
reconstruction of event geometry
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focus here onparticles from impulsive events
avoids complicationsdue to CMEs and interplanetary shocks
energetic particles in the Heliosphere
realistic transport models required to reconstruct particleproperties at the Sun from spacecraft observations:
acceleration time scales, energy and charge spectra, relation to electromagnetic emission close to the Sun(radio, X-ray, gamma-ray)
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Because of anisotropy in SEP events one should consider pitch-angle diffusion
5 Dec 1997 107 keV electrons Wind 3DP PI: R.P.Lin
Pitch-angle distributions for the 2003, March, 17 event
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Variation of peak intensities Im with connection angle Connection plot and electron time profiles for the flare event of 1979 January 15.
Early Multi-Spacecraft Observations of Impulsive Solar EventsWibberenz & Cane (2006)
electrons in the MeV range can be detected more than 80 degrees from the flare longitude
evidence for lateral transport
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DROPOUTS CUTOFFS STEPS
Mazur et al. (2000) ACE ULEIS 1 May 2000 Wind 3DP 4 Nov 1997
• no velocitiy dispersion• time variations correspond to spatial gradients perpendicular to B which are convected past the spacecraft
goal: find a suitable phenomenological description which can be used as starting point for comparison with theory
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SOLAR PARTICLE PROPAGATION
COMBINATION OF:
AZIMUTHAL TRANSPORT CLOSETO THE SUN (CORONAL DIFFUSION)
TRANSPORT PARALLEL TO BPITCH ANGLE SCATTERING, FOCUSING,ADIABATIC LOSSES
POSSIBLE DIFFUSION ACROSS THEAVERAGE MAGNETIC FIELD
considered here only particles from impulsive eventsavoids complications due to CMEs and shocks
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In our model we solve stochastic differential equations
( ) 2 ( )Bdr t dte dW s dt BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB BBB
dtD
LtdWDtd
)1(2
)(2)( 2
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Results of the model: - SEP‘ time profiles - spatial distributions - pitch-angle distributions (therefore, anisotropy, too)
sin)(),,(
0),,(
),,(
2
0
2
0
r
RRr
uBrB
rB
r
RBrB
SW
r
Parker field
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Way of 4 MeV proton, with and without perpendicular diffusion.
=0.01 , =0.3 / cos AU
cos=1/(1+2sin2r2/Usw2)0.5 1111
Droege et al, 2010
Protons,
4 MeV
3.5-4.5 hrs
1212
Droege et al, 2010
1313
107 keV electrons
0.75-1.25 h
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Droege et al, 2010
Protons,
4 MeV,
23.5-24.5 hrs
1515Droege et al, 2010
1616Droege et al, 2010
No perpdiff, one-dimensional or homogen.
Perpdiff, no corotation
Corotation, no perpdiff, perpdiff, 4 degr. flank
1717Droege et al, 2010
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Electron intensities in the energy range 65-105 keV at 1 AU, without perpendicular diffusion, and for two values of α. Angular distances of SC to the source are given on the legends.
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Anisotropies of electrons. Upper panel: location of SC on the magnetic line connected to the flare, α=0.01. Middle panel: angle of observations 30 degrees, α=0.01. Lower panel: angle of observations 30 degrees, α=0.1. In all cases
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Comparison of protons intensities, observed from different longitudes, at a radial distance 0.31 AU (see legend) in case of multiple injection from the point-like source.
Comparison of protons intensities, observed from different longitudes, at a radial distance 1 AU (see legend) in case of multiple injection from the point-like source.
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2010, January 17 event
From N.Dresing 2323
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2010, August, 18 event
From R.Gόmes-Herrero 2525
Time profiles from point-like source
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18 August, 2010
C O N C L U S I O N S
- Propagation of charged particles in a magnetic field strong in comparison with superposed irregularities should be considered in a pitch-angle diffusion approximation
- The observed sharp intensities variations (cutoffs and drop-outs) can be explained by a very weak diffusion in a perpendicular to the large scale magnetic filed direction
- The existing multispacecraft observations can serve as a tool to determine the characteristics of interplanetary space
- Time profiles, together with directional properties of SEP events strongly depend on the angular distance and distance along the magnetic field line from the source.
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