The Properties of the Tilts of Bipolar Solar Regions

TL;DR

This study analyzes the tilt properties of bipolar solar regions, revealing two distinct groups with opposite tilts linked to their size, and discusses implications for solar magnetic field dynamics.

Contribution

It identifies two groups of bipoles with opposite tilt signs and links their properties to size, suggesting different origins or magnetic behaviors.

Findings

Bipoles can be divided into two groups with opposite tilt signs.

The dividing point between groups is around 300 MHS in area.

Small and large bipoles show different time-latitude distributions.

Abstract

We investigate various properties associated with the tilt of isolated magnetic bipoles in magnetograms taken at the solar surface. We show that bipoles can be divided into two groups which have tilts of opposite signs, and reveal similar properties with respect to bipole area, flux and bipolar moment. Detailed comparison of these physical quantities shows that the dividing point between the two types of bipoles corresponds to a bipole area of about 300 millionths of the solar hemisphere (MHS). The time-latitude distribution of small bipoles differs substantially from that for large bipoles. Such behaviour in terms of dynamo theory may indicate that small and large bipoles trace different components of the solar magnetic field. The other possible viewpoint is that the difference in tilt data for small and large bipoles is connected with spectral helicity separation, which results in opposite tilts for small and large bipoles. We note that the data available do not provide convincing reasons to prefer either interpretation.