Sunspot Group Development in High Resolution

TL;DR

This study analyzes high-resolution sunspot group development, revealing relationships between area, distance, and asymmetry in leading and following parts, with implications for understanding solar magnetic activity.

Contribution

It provides detailed statistical analysis of sunspot group evolution using high-resolution data, highlighting new relationships and asymmetries in sunspot development.

Findings

Logarithmic relationship between total area and leading-following distance at maximum.

Leading parts move forward and grow faster, especially in larger active regions.

Growth rates depend linearly on maximum umbral area.

Abstract

The Solar and Heliospheric Obseratory/Michelson Doppler Imager--Debrecen Data (SDD) sunspot catalogue provides an opportunity to study the details and development of sunspot groups on a large statistical sample. The SDD data allow, in particular, the differential study of the leading and following parts with a temporal resolution of 1.5 hours. In this study, we analyse the equilibrium distance of sunspot groups as well as the evolution of this distance over the lifetime of the groups and the shifts in longitude associated with these groups. We also study the asymmetry between the compactness of the leading and following parts, as well as the time-profiles for the development of the area of sunspot groups. A logarithmic relationship has been found between the total area and the distance of leading-following parts of active regions (ARs) at the time of their maximum area. In the developing phase the leading part moves forward; this is more noticeable in larger ARs. The leading part has a higher growth rate than the trailing part in most cases in the developing phase. The growth rates of the sunspot groups depend linearly on their maximum total umbral area. There is an asymmetry in compactness: the number of spots tends to be smaller, while their mean area is larger in the leading part at the maximum phase.