Research Article

Graphical evidence for the solar coronal structure during the Maunder minimum: comparative study of the total eclipse drawings in 1706 and 1715

¹ Institute for Space-Earth Environmental Research, Nagoya University, 4648601 Nagoya, Japan
² Institute for Advanced Researches, Nagoya University, 4648601 Nagoya, Japan
³ Science and Technology Facilities Council, RAL Space, Rutherford Appleton Laboratory, Harwell Campus, OX11 0QX Didcot, UK
⁴ Nishina Centre, Riken, 3510198 Wako, Japan
⁵ Department of Meteorology, University of Reading, RG6 6BB Reading, UK
⁶ National Astronomical Observatory of Japan, 1818588 Mitaka, Japan
⁷ Space Research Institute, Austrian Academy of Sciences, 8042 Graz, Austria
⁸ Mullard Space Science Laboratory, University College London, RH5 6NT Dorking, UK
⁹ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, 92195 Meudon, France
¹⁰ Konkoly Observatory, Hungarian Academy of Sciences, 1121 Budapest, Hungary

^* Corresponding authors: hisashi@nagoya-u.jp; hisashi.hayakawa@stfc.ac.uk; m.lockwood@reading.ac.uk

Received: 18 October 2019
Accepted: 29 June 2020

Abstract

We discuss the significant implications of three eye-witness drawings of the total solar eclipse on 1706 May 12 in comparison with two on 1715 May 3, for our understanding of space climate change. These events took place just after what has been termed the “deep Maunder Minimum” but fall within the “extended Maunder Minimum” being in an interval when the sunspot numbers start to recover. Maria Clara Eimmert’s image in 1706 is particularly important because she was both a highly accomplished astronomical observer and an excellent artist: it was thought lost and was only re-discovered in 2012. Being the earliest coronal drawings of observational value yet identified, these drawings corroborate verbal accounts a corona without significant streamers, seen at totality of this and another eclipse event in 1652 during the Maunder Minimum. The graphical evidence implies that the coronal solar magnetic field was not lost but significantly weakened and the lack of coronal structure means there was little discernable open flux (either polar or at lower latitudes) even during the recovery phase of the Maunder Minimum. These observations provide evidence for a different state of oscillation of the solar dynamo, and hence behaviour of the Sun, in comparison with that during normal solar cycle minima (when a streamer belt between two polar coronal holes is visible) or near normal sunspot maxima (when coronal structure is caused by coronal holes at all latitudes) even to observers without a telescope.