Solar Physics

, Volume 289, Issue 4, pp 1143–1152 | Cite as

Bimodal Distribution of Magnetic Fields and Areas of Sunspots

  • Andrey G. Tlatov
  • Alexei A. PevtsovEmail author


We applied automatic identification of sunspot umbrae and penumbrae to daily observations from the Helioseismic Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) to study their magnetic flux density (B) and area (A). The results confirm an already known logarithmic relationship between the area of sunspots and their maximum flux density. In addition, we find that the relation between average magnetic flux density (\(B_{\rm avg}\)) and sunspot area shows a bimodal distribution: for small sunspots and pores (A≤20 millionth of solar hemisphere, MSH), \(B_{\rm avg} \approx 800~\mbox{G}\) (gauss), and for large sunspots (A≥100 MSH), \(B_{\rm avg}\) is about 600 G. For intermediate sunspots, average flux density linearly decreases from about 800 G to 600 G. A similar bimodal distribution was found in several other integral parameters of sunspots. We show that this bimodality can be related to different stages of sunspot penumbra formation and can be explained by the difference in average inclination of magnetic fields at the periphery of small and large sunspots.


Sun: surface magnetism Sunspots Sun: activity 



A.G.T. acknowledges support by the Russian Foundation for Basic Research (RFBR) and the Russian Academy of Sciences (RAS). The National Solar Observatory is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under a cooperative agreement with the National Science Foundation.


  1. Antalova, A.: 1991, Bull. Astron. Inst. Czechoslov. 42, 316. ADSGoogle Scholar
  2. Beck, J.G., Chapman, G.A.: 1993, Solar Phys. 146, 49. ADSCrossRefGoogle Scholar
  3. Bray, R.J., Loughhead, R.E.: 1964, Sunspots, Chapman and Hall, London, 70. Google Scholar
  4. Bumba, V.: 1960, Izv. Krym. Astrofiz. Obs. 23, 134. Google Scholar
  5. Collados, M., Martinez Pillet, V., Ruiz Cobo, B., del Toro Iniesta, J.C., Vazquez, M.: 1994, Astron. Astrophys. 291, 622. ADSGoogle Scholar
  6. Dmitrieva, M.G., Kopecký, M., Kuklin, G.V.: 1968, In: Kiepenheuer, K.O. (ed.) Structure and Development of Solar Active Regions, IAU Symp. 35, 174. CrossRefGoogle Scholar
  7. Ikhsanov, R.N.: 1968, Soviet Astron. 11, 843. ADSGoogle Scholar
  8. Hagyard, M.J., Pevtsov, A.A.: 1999, Solar Phys. 189, 25. ADSCrossRefGoogle Scholar
  9. Hathaway, D.H.: 2010, Living Rev. Solar Phys. 7(1).
  10. Houtgast, J., van Sluiters, A.: 1948, Bull. Astron. Inst. Neth. 10, 325. ADSGoogle Scholar
  11. Liu, Y., Hoeksema, J.T., Scherrer, P.H., Schou, J., Couvidat, S., Bush, R.I., Duvall, T.L., Hayashi, K., Sun, X., Zhao, X.: 2012, Solar Phys. 279, 295. ADSCrossRefGoogle Scholar
  12. Nagovitsyn, Yu.A., Pevtsov, A.A., Livingston, W.C.: 2012, Astrophys. J. Lett. 758, L20. ADSCrossRefGoogle Scholar
  13. Pevtsov, A.A., Bertello, L., Tlatov, A., Kilcik, A., Nagovitsyn, Y., Cliver, E.W.: 2013, Solar Phys. doi: 10.1007/s11207-012-0220-5. Google Scholar
  14. Pietarila, A., Bertello, L., Harvey, J.W., Pevtsov, A.A.: 2013, Solar Phys. 282, 91. ADSCrossRefGoogle Scholar
  15. Rezaei, R., Beck, C., Schmidt, W.: 2012, Astron. Astrophys. 541, A60. ADSCrossRefGoogle Scholar
  16. Ringnes, T.S., Jensen, E.: 1960, Astrophys. Nor. 7, 99. ADSGoogle Scholar
  17. Rucklidge, A.M., Schmidt, H.U., Weiss, N.O.: 1995, Mon. Not. Roy. Astron. Soc. 273, 491. ADSGoogle Scholar
  18. Scherrer, P.H., Schou, J., Bush, R.I., Kosovichev, A.G., Bogart, R.S., Hoeksema, J.T., et al.: 2012, Solar Phys. 275, 207. ADSCrossRefGoogle Scholar
  19. Skumanich, A.: 1992, In: Thomas, J.H., Weiss, N.O. (eds.) Sunspots: Theory and Observations, NATO ASI Series C 375, Kluwer Academic, Dordrecht, 121. CrossRefGoogle Scholar
  20. Skumanich, A.: 1999, Astrophys. J. 512, 975. ADSCrossRefGoogle Scholar
  21. Skumanich, A., Lites, B.W.: 1987, Astrophys. J. 322, 473. ADSCrossRefGoogle Scholar
  22. Solanki, S.K.: 2003, Astron. Astrophys. Rev. 11, 153. ADSCrossRefGoogle Scholar
  23. Tlatov, A.G., Vasil’eva, V.V., Makarova, V.V., Otkidychev, P.A.: 2013, Solar Phys. submitted. Google Scholar
  24. Vitinsky, Yu.I., Kopecký, M., Kuklin, G.V.: 1986, The Statistics of Sunspots (Statistika Pjatnoobrazovatelnoj Dejatelnosti Solntsa), Nauka, Moscow, 397 (in Russian). Google Scholar
  25. Watson, F., Fletcher, L., Dalla, S., Marshall, S.: 2009, Solar Phys. 260, 5. ADSCrossRefGoogle Scholar
  26. Zharkova, V.V., Aboudarham, J., Zharkov, S., Ipson, S.S., Benkhalil, A.K., Fuller, N.: 2005, Solar Phys. 228, 361. ADSCrossRefGoogle Scholar
  27. Zwaan, C.: 1992, In: Thomas, J.H., Weiss, N.O. (eds.) Sunspots: Theory and Observations, NATO ASI Series C 375, Kluwer Academic, Dordrecht, 75. CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  1. 1.Kislovodsk Solar Station of Pulkovo ObservatoryKislovodskRussian Federation
  2. 2.National Solar ObservatorySunspotUSA

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