Interplanetary spread of solar energetic protons near a high-speed solar wind stream

Show simple item record Wijsen, N. Aran, A. Pomoell, J. Poedts, S. 2019-12-16T13:51:02Z 2019-12-16T13:51:02Z 2019-04-05
dc.identifier.citation Wijsen , N , Aran , A , Pomoell , J & Poedts , S 2019 , ' Interplanetary spread of solar energetic protons near a high-speed solar wind stream ' , Astronomy & Astrophysics , vol. 624 , A47 .
dc.identifier.other PURE: 124080729
dc.identifier.other PURE UUID: 545fef97-40e5-422b-8df5-ccbc9435fc30
dc.identifier.other WOS: 000463466500001
dc.identifier.other Scopus: 85064250945
dc.identifier.other ORCID: /0000-0003-1175-7124/work/56835719
dc.description.abstract Aims. We study how a fast solar wind stream embedded in a slow solar wind influences the spread of solar energetic protons in interplanetary space. In particular, we aim at understanding how the particle intensity and anisotropy vary along interplanetary magnetic field (IMF) lines that encounter changing solar wind conditions such as the shock waves bounding a corotating interaction region (CIR). Moreover, we study how the intensities and anisotropies vary as a function of the longitudinal and latitudinal coordinate, and how the width of the particle intensities evolves with the heliographic radial distance. Furthermore, we study how cross-field diffusion may alter these spatial profiles. Methods. To model the energetic protons, we used a recently developed particle transport code that computes particle distributions in the heliosphere by solving the focused transport equation (RTE) in a stochastic manner. The particles are propagated in a solar wind containing a CIR, which was generated by the heliospheric model, EUHFORIA. We study four cases in which we assume a delta injection of 4 MeV protons spread uniformly over different regions at the inner boundary of the model. These source regions have the same size and shape, yet are shifted in longitude from each other, and are therefore magnetically connected to different solar wind conditions. Results. The intensity and anisotropy profiles along selected IMF lines vary strongly according to the different solar wind conditions encountered along the field line. The IMF lines crossing the shocks bounding the CIR show the formation of accelerated particle populations, with the reverse shock wave being a more efficient accelerator than the forward shock wave. The longitudinal intensity profiles near the CIR are highly asymmetric in contrast to the profiles obtained in a nominal solar wind. For the injection regions that do not cross the transition zone between the fast and slow solar wind, we observe a steep intensity drop of several orders of magnitude near the stream interface (SI) inside the CIR. Moreover, we demonstrate that the longitudinal width of the particle intensity distribution can increase, decrease, or remain constant with heliographic radial distance, reflecting the underlying IMF structure. Finally, we show how the deflection of the IMF at the shock waves and the compression of the IMF in the CIR deforms the three-dimensional shape of the particle distribution in such a way that the original shape of the injection profile is lost. en
dc.format.extent 12
dc.language.iso eng
dc.relation.ispartof Astronomy & Astrophysics
dc.rights unspecified
dc.rights.uri info:eu-repo/semantics/openAccess
dc.subject solar wind
dc.subject Sun: particle emission
dc.subject Sun: magnetic fields
dc.subject acceleration of particles
dc.subject PROPAGATION
dc.subject IONS
dc.subject 115 Astronomy, Space science
dc.title Interplanetary spread of solar energetic protons near a high-speed solar wind stream en
dc.type Article
dc.contributor.organization Department of Physics
dc.description.reviewstatus Peer reviewed
dc.relation.issn 1432-0746
dc.rights.accesslevel openAccess
dc.type.version publishedVersion

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