• E. A. BRUEVICH

      Articles written in Journal of Astrophysics and Astronomy

    • Changed Relation between Solar 10.7-cm Radio Flux and some Activity Indices which describe the Radiation at Different Altitudes of Atmosphere during Cycles 21–23

      E. A. Bruevich V. V. Bruevich G. V. Yakunina

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      The correlation coefficients of the linear regression of six solar indices versus 10.7 cm radio flux 𝐹10.7 were analysed in solar cycles 21, 22 and 23. We also analysed the interconnection between these indices and 𝐹10.7 with help of approximation by polynomials of second order. The indices we have studied in this paper are: the relative sunspot numbers – SSN, 530.3 nm coronal line flux – 𝐹530 , the total solar irradiance – TSI, Mg II 280 nm core-to-wing ratio UV-index, the Flare Index – FI and the counts of flares. In most cases the regressions of these solar indices vs. 𝐹10.7 are close to the linear regression except the moments of time near the minimums and maximums of the 11-year activity. For the linear regressions, we found that correlation coefficients 𝐾corr(𝑡) for the solar indices vs. 𝐹10.7 and SSN dropped to their minimum values twice during each 11-year cycle.

    • New classification parameter of solar flares based on the maximum flux in soft X-rays and on duration of flare

      E. A. BRUEVICH

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      Solar flare activity is characterized by different classification systems, both in optical and X-ray ranges. The most generally accepted classifications of solar flares describe important parameters of flares such as the maximum of brightness of the flare in the optical range – $H_{\alpha}$ flare class (change from F to B), area of the flare in $H_{\alpha}$ (change from S for areas less than 2 square degrees to 4 for areas more than 24.7 square degrees) and the maximum amplitude of the soft X-ray (SXR)-flux in the band 0.1–0.8 nm ($F^{\rm max}_{0.1−0.8}$) – X-ray flares of classes from C to X. A new classification parameter of solar flares is proposed here – the X-ray index of flare XI, based on GOES measurements of solar radiation in the SXR-range. The XI-index has a clear physical interpretation associated with the total flare energy in the SXR-range. XI is easily calculated for each flare with the use of available GOES data. The XI-index can be used along with other geoeffective parameters of Solaractivity to assess both flares and coronal mass ejections that are connected with them.

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      Posted on January 27, 2016

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