University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Friday, December 5th 2014
Speaker: Dr. Mark Giampapa, NSO/NOAO
Subject:  Perspectives on the Solar Cycle and Activity in Solar-Type Stars

The variability we observe in the Sun, as well as stars similar to the Sun is intimately related to the generation and emergence of magnetic fields. This process involves the interaction of convective motions, rotation and extant magnetic fields through a mechanism broadly referred to as the dynamo. Among the most visible manifestations of solar activity is the number of sunspots, which is modulated by the 11-year sunspot cycle. Similarly, solar-type stars exhibit periodic behavior analogous to the sunspot cycle on multi-year time scales along with the rotational modulation of localized regions of strong magnetic flux on their surfaces on multi-day time scales. Recently the Sun has shown indications of a decline in activity relative to previous sunspot cycles in the modern era. Is the recent behavior of the solar cycle unusual and what do current observations indicate about the nature of the next solar cycle? Could the Sun be entering a “Grand Minimum” similar to the Maunder Minimum (1645 – 1715 AD) with its prolonged period of low sunspot activity? What is the nature of cycles and activity in solar-type stars and how do stellar cycles compare to the solar cycle? These are among the questions that will be addressed from the perspective of a solar-stellar astronomer.

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