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Lyman Decrements of Neutral Hydrogen Lines in the Spectrum of the Sun Based on SDO/EVE Observations. Variations During the 24-th Solar Cycle and in Individual Flares of Classes M and X

  • E. A. BruevichEmail author
  • V. V. Bruevich

Data from satellite observations of fluxes in Lyman series lines and their relative variations, both during the 24-th cycle and in individual class M and X flares, are analyzed. The decrement D1 (D1 = F(Lα)/F(Lβ)) has varied over the 24-th activity cycle by roughly 25% from its maximum values to minimum values during 2014, when there was a secondary maximum in the 24-th cycle according to the main indices. Decrement D2 (D2 = F(Lγ)/F(Lβ)) varies by roughly 10% during the cycle, and decrement D3 (D3 = F(Lδ)/F(Lβ)), by roughly 5% during the cycle. D1, D2, and D3 also vary during the cycle at smaller amplitudes with periods analogous to the periods of the quasi-biennial variations of the main activity indices. In flares of x-ray classes from M to X the variations of the Lyman decrements range from 2 to 20%, with the variations in the decrements being larger on the average for flares with higher energies in the soft x-ray range.


Sun: activity cycles hydrogen emission lines 24-th cycle Lyman decrements flares 


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  1. 1.
    R. E. Gershberg and E. E. Shnol’, Izvestiya KrAO 50, 122 (1974).Google Scholar
  2. 2.
    V. P. Grinin and N. A. Katysheva, Bulletin of the Crimean Astrophysical Observatory 62, 52 (1980).ADSGoogle Scholar
  3. 3.
    V. P. Grinin and N. A. Katysheva, Bulletin of the Crimean Astrophysical Observatory 62, 47 (1980).ADSGoogle Scholar
  4. 4.
    L. Binette, J. Wang, M. Villar-Martin, et al., Astrophys. J. 414, 535 (1993).ADSCrossRefGoogle Scholar
  5. 5.
    S. Gunár, P. Schwartz, B. Schmieder, et al., Astron. Astrophys. 514, A43 (2010).ADSCrossRefGoogle Scholar
  6. 6.
    N. A. Katysheva, T. A. Ermolaeva, and V. P. Grinin, Astrophysics 60, 532 (2017).ADSCrossRefGoogle Scholar
  7. 7.
  8. 8.
    E. A. Bruevich, V. V. Bruevich, and B. P. Artamonov, Research in Astron. Astrophys. 18 (7), 72 (2018).ADSGoogle Scholar
  9. 9.
    E. A. Bruevich, Astro-ph SR 1805.07158 (2018).Google Scholar

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© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.P. K. Shternberg State Institute of AstronomyM. V. Lomonosov Moscow State UniversityMoscowRussia

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