Speaker
Description
Within four centuries of instrumental sunspot observations, the Maunder Minimum is known as a unique period with extremely small solar cycles and enhanced hemispheric asymmetry of the reported sunspot groups, as well as the apparent loss of the solar coronal streamers. Sunspot group positions have been discussed mostly on the basis of the French and German observers’ records. Some researchers express doubts because of a possible selection bias for the sunspot group detections in this period that might have affected both of these aspects. This presentation aims at independently assessing these possibilities on the basis of the comprehensive analyses of the extensive records of the English sunspot observations. These English records allow us to confirm a concentration of the reported sunspot groups in the southern solar hemisphere, supporting the results of the above-mentioned previous studies. We have also computed the active day fraction, estimated the international sunspot number at that time on this basis, and found their solar cycle amplitudes extremely small, even in comparison with Solar Cycle 24 or the Dalton Minimum. Our result indicates that the Maunder Minimum was not a secular minimum but rather a grand minimum.
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