, Volume 60, Issue 3, pp 387–400 | Cite as

Flare Activity of the Sun and Variations in its UV Emission During Cycle 24

  • E. A. Bruevich
  • G. V. Yakunina

The flare activity and ultraviolet emission of the sun during its 24th cycle are analyzed. As opposed to cycles 21-23, where the most powerful flares were observed during the decay phase, in cycle 24 the most powerful flares (>X2.7) occurred in the rising phase and at the maximum. Regression fits of the UV indices to the overall radiation level from the sun are substantially different for cycle 24 compared to cycles 21-23. It is found that for the flare of August 9, 2011 (SDO and GOES-15 observations), the flare propagates in a direction from the upper corona to the lower corona in the chromosphere. A study of the N-S asymmetry in the distribution of the flares in cycle 24 reveals a strong predominance of flares in the N-hemisphere in 2011 and in the S-hemisphere in 2014. It is also found that during cycles 23 and 24, the delays in the onset of proton events relative to the onset of the flares that cause them have a distribution with a distinct maximum corresponding to a delay of 2 hours for protons with energies >10 MeV, as well as for those with energies >100 MeV.


Sun: cycle 24: flares: flare index: variations in UV emission: proton events 


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  1. 1.
    Y. Kleeorin, N. Safiullin, N. Kleeorin, et al., Mon. Not. Roy. Astron. Soc. 460, 3960 (2016).ADSCrossRefGoogle Scholar
  2. 2.
    R. E. Gershberg, Activity of main sequence stars of the sun’s type, Astroprint, Odessa (2002).Google Scholar
  3. 3.
    E. A. Bruevich, V. V. Bruevich, and E. V. Shimanovskaya, Astrofizika 59, 115 (2016), [Astrophysics 59, 101 (2016)].Google Scholar
  4. 4.
    E. A. Bruevich, V. V. Bruevich, G. V. Yakunina, J. Astrophys. Astron. 35, 1 (2014).ADSCrossRefGoogle Scholar
  5. 5.
    M. Snow, W. E. McClintock, T. N. Woods, et al., Solar Phys. 230, 325 (2005).ADSCrossRefGoogle Scholar
  6. 6.
    E. A. Bruevich, and G. V. Yakunina, Astrofizika 59, 413 (2016), [Astrophysics 59, 369 (2016)].Google Scholar
  7. 7.
    M. Snow, M. Weber, J. Machol, et al., Space Weather Space Clim. 4, A04 (2014).CrossRefGoogle Scholar
  8. 8.
    R. T. Bachmann and O. R. White, Solar Phys. 150, 347 (1994).ADSCrossRefGoogle Scholar
  9. 9.
    LISIRD - Composite Solar Lyman-alpha, (2016).
  10. 10.
    T. Atac, Astrophys. Space Sci. 135, 201 (1987).ADSCrossRefGoogle Scholar
  11. 11.
    O. G. Badalyan, Pis’ma v Astron. zh. 38, 51 (2012), [Astron. Lett. 38, 51 (2012)].ADSGoogle Scholar
  12. 12.
    B. Joshi, R. Bhattacharyya, K. Pandey, et al., Astron. Astrophys. 582, A4 (2015).ADSCrossRefGoogle Scholar
  13. 13.
    L. Zhang, K. Mursula, and I. Usoskin, Astron. Astrophys. 529, A23 (2011).ADSCrossRefGoogle Scholar
  14. 14.
    J. Sykora and J. Rybak, Solar Phys. 261, 321 (2010).ADSCrossRefGoogle Scholar
  15. 15.
    G. A. Bazilevskaya, Yu. I. Logachev, E. V. Bashenyuk, et al., Izvestiya RAN, seriya fiz. 79 (5), 627 (2015).Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2017

Authors and Affiliations

  1. 1.P. K. Shternberg State Astronomical InstituteM. V. Lomonosov Moscow State UniversityMoscowRussia

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