Catalogues and other records of aurora-borealis events were used to study the long-term spatial and temporal variation of these phenomena in the period from...
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PublicationLong-term Spatial and Temporal Variations of Aurora Borealis Events in the Period 1700 - 1905
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PublicationLong-Term Trends and Gleissberg Cycles in Aurora Borealis Records (1600 - 2015)
The long-term spatial and temporal variation of aurora borealis events from 1600 to the present were studied using catalogues and other records of these...
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PublicationLong-term Variation of Solar Activity by a Dynamo Based on Magnetic Flux Tubes
We show that cyclic activity and Maunder-type grand minima can be explained by a dynamo driven by the instability of magnetic flux tubes in the overshoot layer...
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TalkMagnetic bright points in the quiet Sun
We present a visual determination of the number of bright points (BPs) existing in the quiet Sun, which are structures though to trace intense kG magnetic...
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PublicationModeling of integrated sunlight velocity measurements: The effect of surface darkening by magnetic fields
It has been known since the work by Claverie et al. (1982) that integrated-sunlight velocities measured with the resonance scattering technique show variations...
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TalkMysteries of the magnetic Sun
The Sun presents us with many unsolved mysteries. In this talk I discuss three of them that have intrigued me for the last 50 years. Solar flares are the most...
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PublicationNew windows to the universe; Proceedings of the Eleventh European Regional Astronomy Meeting, Universidad de la Laguna, Spain, July 3-8, 1989. Part II
Recent observational and theoretical investigations of the sun and sunlike stars and of galactic structure and evolution are discussed in reviews and reports...
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PublicationNonlinear time-evolution of kink-unstable magnetic flux tubes in the convective zone of the sun
The nonlinear development of the kink instability in a horizontal magnetic flux tube with a field strength exceeding the equipartition value lying initially in...
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PublicationObservations of the birth and fine structure of sunspot penumbrae
High resolution white-light pictures of sunspot penumbrae are presented. These include pictures showing details of their filamentary structure and some...