403 research outputs found
Correlation study of some solar activity indices in the cycles 21 - 23
The correlation coefficients of the linear regression of six solar indices
versus F10,7 were analyzed in solar cycles 21, 22 and 23. We also analyzed the
interconnection between these indices and F10,7 with help of the approximation
by the polynomials of second order. The indices we've studied in this paper
are: Wolf numbers - W, 530,3 nm coronal line flux - F530, the total solar
irradiance - TSI, Mg II UV-index 280 nm core-to-wing ratio, Flare Index - FI
and Counts of flares. In the most cases the regressions of these solar indices
versus F10,7 are close to linear except the moments of time near to the
minimums and maximums of 11-year activity. For the linear regressions we found
that the values of correlation coefficients Kcorr(t) for the indices versus
F10,7 and W show the cyclic variations with periods approximately equal to the
to half length of 11-year cycle - 5,5 years approximately.Comment: 15 pages, 4 figures, 2 tables. arXiv admin note: text overlap with
arXiv:1106.464
On Chromospheric Variations Modeling for Main-Sequence Stars of G and K Spectral Classes
We present a method of chromospheric flux simulation for 13 late-type
main-sequence stars. These Sun-like stars have well-determined cyclic flux
variations similar to 11 yr solar activity cycle. Our flux prediction is based
on chromospheric HK emission time series measurements from Mount Wilson
Observatory and comparable solar data. We show that solar three - component
modeling explains well the stellar observations. We find that the 10 - 20% of K
- stars disc surfaces are occupied by bright active regions.Comment: 8 pages, 2 figure
Changed Relation Between Radio Flux F10,7 And Some Solar Activity Indices During Cycles 21 - 23
A stable cyclicity of correlation coefficients Kcorr for some solar activity
indices versus F10,7 was found after monthly averages values analysis. These
indices are: Wolf numbers, 10,7 cm radio flux F10,7, 0,1-0,8 nm background, the
total solar irradiance, Mg II UV-index (280 nm core to wing ratio) and counts
of flares. The correlation coefficients of the linear regression of these solar
activity indices versus F10,7 were analyzed for every year in solar cycles 21 -
23. We found out that the values of yearly determined correlation coefficients
Kcorr for solar activity indices versus F10,7 show the cyclic variations with
stable period closed to half length of 11-year cycle (5,5 years approximately)Comment: 113pages, 5 figures, 2 table
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