Mysteries of the magnetic Sun

Authors
Prof.
Jack Harvey
Date and time
29 Apr 2010 - 00:00 Europe/London
Address

Aula

Talk language
English
Slides language
English
Serie number
0
Description
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 powerful explosions in space between here and the nearby stars. The only viable power source is stored magnetic energy. Yet definitive observations of changes in the magnetic field associated with flares have been lacking until recently. Measurements with the GONG network have helped to address this mystery and the results are surprising. Efforts to observe the weak magnetic fields in the solar photosphere date nearly to the discovery of magnetism on the Sun. Improvements in observational capabilities have made this area a 'hot' topic with many important contributions from people at the IAC. High resolution observations are clarifying many features. I will focus on the role played by lower resolution work in defining the uniformity of the still mysterious weak magnetic fields over large spatial and temporal scales. Physics changes from hydrodynamic to magnetic dominance as one moves upward from the photosphere to the chromosphere. This leads to significant and complicated changes in the magnetic field in both the active and quiet Sun. Observations of the chromospheric magnetic field show several unexpected and mysterious features. Solving these mysteries will be an exciting area as observational and spectral inversion capabilities develop.