Heliospheric Magnetic Field and The Parker Model

Abstract

In the Parker model of the heliospheric magnetic field, the ratio of the azimuthal field component $${{B}_{{{\varphi }}}}$$ to the radial component $${{B}_{r}}$$ depends only on the radial speed V of the solar wind and coordinates of the observation point ($$r,\,\theta $$): $${{{{B}_{{{\varphi }}}}} \mathord{\left/ {\vphantom {{{{B}_{{{\varphi }}}}} {{{B}_{r}}}}} \right. \kern-0em} {{{B}_{r}}}} = {{ - \omega r\sin \theta } \mathord{\left/ {\vphantom {{ - \omega r\sin \theta } V}} \right. \kern-0em} V}$$ (at a distance from the Sun r > 1 AU). We checked this relationship near the ecliptic at radial distances up to 19 AU based on data from the spacecraft VOYAGER 1, VOYAGER 2 and ULYSSES and outside the ecliptic according to ULYSSES data. It is shown that the predictions of the Parker model are in good agreement with observations outside the sector zones in time periods close to the solar activity minima. Within the sector zones and during periods of maximal solar activity, there are significant discrepancies between the observational data and the predictions of this model.