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Spectrum of a random f-mode and the SOHO/MDI data
Received 13 December 1999 / Accepted 5 April 2000
According to the SOHO/MDI observations (Duvall et al. 1998, Antia & Basu 1999) the solar f -mode frequency departs from the parabolic dispersion relation . We propose to explain this behaviour in terms of a space- and time-dependent random flow that occurs in the convection zone. A time-dependent random flow speeds up the f -mode while the effect of a space-dependent random flow is to slow it down. A competition between these two effects brings a reduction of frequencies and a line-width increase at low l. Theoretical estimation of the frequency shift and line-width leads to a conclusion that for the results are consistent with the recent SOHO/MDI data.
Key words: convection Sun: atmosphere Sun: granulation Sun: oscillations turbulence
© European Southern Observatory (ESO) 2000
Online publication: June 26, 2000