The Stationary Electric Field in the Heliosphere and Its Possible Relation to Current Sheets

Abstract

The nature of the large-scale electric field in the heliosphere is discussed in this paper. The electric potential along each line of the magnetic field should be constant in the ideally conductive solar wind. A high electric potential is supposed to be maintained by the rapidly flowing solar wind far from the Sun and, near the Sun, by the unipolar effect caused by the rotation of the Sun. Meanwhile, there is a discrepancy between observations and theoretical concepts. The ratio of the observed electric field and that calculated from a model employing the unipolar effect at the Sun was obtained for the 1994–2008 Ulysses data. It was found that the unipolar effect is insufficient to maintain equipotentiality of magnetic field lines throughout the heliosphere, suggesting the existence of additional sources of the electric field at the Sun. Since the strong electric field is stably observed at high heliolatitudes, its previously unknown sources may be associated with polar conic current sheets and current sheets at the edges of coronal holes.