The Inclination of the Heliomagnetic Equator and the Presence of an Inclined Relic Field in the Sun

Abstract

As the solar magnetic field evolves through its activity cycle the polar field strength changes in both magnitude and sign, and the heliomagnetic equator at 2.5R<SUB>S</SUB> shows a varying inclination from about 0° during solar minimum up to 90° during solar maximum, as measured with respect to the solar equator. This behavior of the heliomagnetic equator is mainly due to the behavior of the dipole component of the field, which is the dominant component at this height. We show that this behavior could be explained by the presence of a small dipolar relic field pointing southward but tilted with respect to the solar rotation axis. This fossil field would lead to a larger polar field during the negative polarity phase of the cycle, in accordance with observations. It may also help to explain the asymmetry observed in the solar activity of the northern and southern hemispheres, the appearance of some particularly active longitudes on the Sun, as well as other asymmetrical characteristics of the solar activity cycles. The possibility of random variations in the dynamo-generated dipole field is also discussed.