3 minute oscillations above Sunspots Introduction(1.1)

 

On the nature of 3 minute oscillations above Sunspots

Ca II line intesity as a function of wavelength and time in a sunspot umbra. Observed at the Swedish Solar Vacuum Telescope in 1995 (Bard, 1997).

Viggo Hansteen, Øivind Wikstøl, Nils Brynhildsen,
Per Maltby, Terje Fredvik & Olav Kjeldseth-Moe,
University of Oslo, June 2002