Physics
Scientific paper
Jun 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994soph..152..201n&link_type=abstract
Solar Physics (ISSN 0038-0938), vol. 152, no. 1, p. 201-206
Physics
4
Centimeter Waves, Cross Correlation, Far Ultraviolet Radiation, Lyman Alpha Radiation, Solar Activity Effects, Time Lag, Limb Brightening, Limb Darkening
Scientific paper
The relations between variations of far UV (FUV) emission in 115 - 210 nm waveband and Lyman-alpha 121.6 nm and F10.7 are studied. The changes of FUV flux are found to lag changes of F10.7 -- as a rule for 1 day. It is shown that such a difference may be caused by two factors: (1) differences between the rates of decrease of local sources' (active regions) brightness in FUV and 10.7 cm; (2) differences between limb-darkening curves for different wavelengths. One may expect the fluxes at different wavelengths to exhibit phase shifts of one relative to another. Cross-correlation analysis reveals no time-delay between emission fluxes within the FUV waveband, in spite of different laws for limb-brightening (darkening) for different spectral intervals. The absence of a phase delay can be caused by relatively small contribution of active regions to the flux of the whole Sun at these wavelengths. Thus the Lyman-alpha line intensity variation reflects variations of Solar FUV emission more precisely than F10.7. Therefore, using the Lyman-alpha intensity for flux intensity calculations of other FUV wavelengths is preferrable to using the F10.7 index.
Katyushina V. V.
Nusinov A. A.
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