Dear colleagues,
for this week we have no colloquium planned.
The first colloquium of this semester will be held on
Wed, April 14:
Alexander Kosovichev Stanford University
Sunquakes and Helioseismology
"The interior of the Sun is not transparent to electromagnetic radiation, and thus it is not accessible by traditional astronomical techniques. However, it is transparent to acoustic waves. These waves are excited by turbulent convection near the solar surface, and propagate through the interior. The properties of the waves, frequencies and travel times, depend on physical conditions of the solar plasma (temperature, density, chemical composition, flow velocity). Therefore, measurements of the wave properties provide powerful diagnostic methods for probing the stellar interior. I review the basic principles of helioseismology, and present recent observational results from the SOHO space mission and ground-based networks. In particular, I discuss the structure of the energy-generating core, global circulation of the Sun, and the mechanisms of sunspots and solar activity."
See also http://www.physik.unizh.ch/teaching/kolloquium.html for details.