The Solar Corona during the Total Eclipse on 16 June 1806: Graphical Evidence of the Coronal Structure during the Dalton Minimum

TL;DR

This study analyzes 1806 eclipse records to compare coronal structures during the Dalton Minimum with those during the Maunder Minimum, providing insights into solar magnetic activity and the solar dynamo during periods of low sunspot activity.

Contribution

It presents graphical records of the 1806 eclipse showing coronal features, offering new visual evidence to contrast Dalton and Maunder minima in terms of solar magnetic activity.

Findings

Coronal rays and streamers observed during the 1806 eclipse.

Comparison of coronal structures between Dalton and Maunder minima.

Consistency with solar cycle models and solar wind reconstructions.

Abstract

Visible coronal structure, in particular the spatial evolution of coronal streamers, provides indirect information about solar magnetic activity and the underlying solar dynamo. Their apparent absence of structure observed during the total eclipses of throughout the Maunder Minimum has been interpreted as evidence of a significant change in the solar magnetic field from that during modern cycles. Eclipse observations available from the more recent Dalton Minimum may be able to provide further information, sunspot activity being between the levels seen during recent cycles and in the Maunder Minimum. Here, we show and examine two graphical records of the total solar eclipse on 1806 June 16, during the Dalton Minimum. These records show significant rays and streamers around an inner ring. The ring is estimated to be ~ 0.44 R_S in width and the streamers in excess of 11.88 R_S in length. In combination with records of spicules or prominences, these eclipse records visually contrast the Dalton Minimum with the Maunder Minimum in terms of their coronal structure and support the existing discussions based on the sunspot observations. These eclipse records are broadly consistent with the solar cycle phase in the modelled open solar flux and the reconstructed slow solar wind at most latitudes.