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dc.contributor.authorBurger, R.A.
dc.contributor.authorKrüger, T.P.J.
dc.contributor.authorHitge, M.
dc.contributor.authorEngelbrecht, N.E.
dc.date.accessioned2009-12-17T10:05:16Z
dc.date.available2009-12-17T10:05:16Z
dc.date.issued2008
dc.identifier.citationBurger, R.A. et al. 2008. A Fisk-Parker hybrid heliospheric magnetic field with a solar-cycle dependence. Astrophysical journal, 674(1): Article no 511. [https://doi.org/10.1086/525039]en
dc.identifier.issn0004-637X
dc.identifier.issn1538-4357 Online
dc.identifier.urihttp://hdl.handle.net/10394/2677
dc.identifier.urihttps://doi.org/doi:10.1086/525039
dc.identifier.urihttp://www.iop.org/EJ/article/0004-637X/674/1/511/73091.web.pdf
dc.description.abstractWe present a refinement of the Fisk-Parker hybrid field of Burger and Hitge which now includes a region bordering the solar rotational equator where magnetic field footpoint motion occurs only through diffusive reconnection. The hybrid field, therefore, only occurs above a certain latitude in a given hemisphere, and in the equatorial region the field is a pure Parker field. We also propose a simple qualitative model for the solar cycle dependence of the hybrid field, taking into account changes in the tilt angle of the heliospheric current sheet and the latitudinal extend of the polar coronal hole on the photosphere and on the source surface over the course of a solar activity cycle. We find that the amplitude of magnetic field fluctuations for assumed solar minimum parameters would not be observable above the background noise (see Roberts and coworkers). We also show that for these parameters, periodicities associated with differential footpoint motion would be barely distinguishable from rigid rotation at the solar equatorial rate. We point out that the question of periodicities in magnetic field data is perhaps more complicated than previously thought. We confirm the result of Burger and Hitge that a Fisk-type heliospheric magnetic field provides a natural explanation for the observed linear relationship between the amplitude of the recurrent cosmic-ray variations and the global latitude gradient (see Zhang). We show that this relationship holds for helium, protons, and electrons. Moreover, we show that the constant of proportionality is larger when qA > 0 than when qA < 0, as inferred from observations by Richardson and coworkers
dc.language.isoenen
dc.publisherIOP Publishingen
dc.subjectTurbulence
dc.subjectSun: magnetic fields
dc.subjectDiffusion
dc.subjectCosmic rays
dc.titleA Fisk-Parker hybrid heliospheric magnetic field with a solar-cycle dependenceen
dc.typeArticleen
dc.contributor.researchID10188738 - Burger, Renier Adriaan
dc.contributor.researchID12580996 - Engelbrecht, Nicholas Eugene
dc.contributor.researchID10085858 - Hitge, Mariette


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