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Astron. Astrophys. 317, 925-928 (1997)

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3. Relations to solar active phemomena

We find a pronounced recurrence of [FORMULA] in all channels. This corresponds to a distinguished two sector structure of solar activity in 1994.

A comparison between sunspot numbers and sunspot areas confirms former results (see Fig. 3). In our time scales small activity corresponds to the maxima of solar irradiance. But this relation is not very pronounced. An anticorrelation with the 10.7 cm solar flux is much more distinguished (see also Fig. 3). Here a very good correspondence is to be found and a phase shift is suggested between both curves.

[FIGURE] Fig. 3. Comparison between DIFOS irradiance variations and different parameters of solar activity. Represented are the DIFOS data for 400-1000 nm, the corrected sunspot areas in 10-6 of the hemisphere (mean values from different observatories), the international sunspot numbers, and the Penticton 2800 MHz (10.7 cm) solar flux in solar flux units. Data from Solar Geophysical Data.

Finally we should mention the different behaviour of the infrared channel near 750 nm. In this spectral region we find a secondary minimum near April 27. One rotation before (near April 5) a small secondary minimum is also noticeable. This may be due to a stronger effect of chromospheric activity on this channel compared to the others. This spectral window is sensitive for three very strong CaII lines that are very sensitive to the solar plage activity. A more detailed analysis of this behaviour is planned.

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© European Southern Observatory (ESO) 1997

Online publication: July 8, 1998
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