Abstract
We processed magnetograms that were obtained with the Michaelson Doppler Imager onboard the Solar and Heliospheric Observatory (SOHO/MDI). The results confirm the basic properties of long-period oscillations of sunspots that have previously been established and also reveal new properties. We show that the limiting (lowest) eigenmode of low-frequency oscillations of a sunspot as a whole is the mode with a period of 10 – 12 up to 32 – 35 hours (depending on the sunspot’s magnetic-field strength). This mode is observed consistently throughout an observation period of 5 – 7 days, but its amplitude is subject to quasi-cyclic changes, which are separated by about 1.5 – 2 days. As a result, the lower mode with a period of about 35 – 48 hours appears in the power spectrum of sunspot oscillations. But this lowest mode is apparently not an eigenmode of a sunspot because its period does not depend on the magnetic field of the sunspot. Perhaps the mode reflects the quasi-periodic sunspot perturbations caused by supergranulation cells that surround it. We also analyzed SOHO/MDI artifacts, which may affect the low-frequency power spectra of sunspots.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Bakunina, I.A., Abramov-Maximov, V.E., Lesovoy, S.V., Shibasaki, K., Solov’ev, A.A., Tikhomirov, Yu.V.: 2009a, In: Gopalswamy, N., Webb, D.F. (eds.) Universal Heliophysical Processes, Proc. Internat. Astron. Union Symp. 257, Cambridge Univ. Press, Cambridge, 155. doi: 10.1017/S1743921309029214 .
Bakunina, I.A., Solovyev, A.A., Nagovitsyn, Yu.A., Tikhomirov, Yu.V., Bakunin, V.L., Prosovetsky, D.V., Kuznetsova, S.M.: 2009b, Geomagn. Aeron. 49, 1087. doi: 10.1134/S0016793209080064 .
Beckers, J.M., Schultz, R.B.: 1972, Solar Phys. 27, 61. doi: 10.1007/BF00151770 .
Chorley, N., Hnat, B., Nakariakov, V.M., Inglis, A.R., Bakunina, I.A.: 2010, Astron. Astrophys. 513, A27. doi: 10.1051/0004-6361/200913683 .
Demidov, M.L., Balthasar, H.: 2009, Solar Phys. 260, 261.
Domingo, V., Fleck, B., Poland, A.I.: 1995, Solar Phys. 162, 1. doi: 10.1007/BF00733425 .
Efremov, V.I., Parfinenko, L.D., Solov’ev, A.A.: 2007, Astron. Rep. 51, 401. doi: 10.1134/S106377290705006X .
Efremov, V.I., Parfinenko, L.D., Solov’ev, A.A.: 2009, Cosm. Res. 47, 279. doi: 10.1134/S0010952509040030 .
Efremov, V.I., Parfinenko, L.D., Solov’ev, A.A.: 2010, Solar Phys. 267, 279. doi: 10.1007/s11207-010-9651-z .
Efremov, V.I., Parfinenko, L.D., Solov’ev, A.A.: 2012, Cosm. Res. 50, 44. doi: 10.1134/S0010952511060025 .
Gelfreikh, G.B., Nagovitsyn, Yu.A., Nagovitsyna, E.Yu.: 2006, Publ. Astron. Soc. Japan 58, 29.
Kallunki, J., Riehokainen, A.: 2012, Solar Phys. 280, 347. doi: 10.1007/s11207-012-0021-x .
Koen, C.: 1990, Astrophys. J. 348, 700. doi: 10.1086/168277 .
Leibacher, J.W., Stein, R.F.: 1971, Astrophys. Lett. 7, 191.
Leighton, R.B., Noyes, R.W., Simon, G.W.: 1962, Astrophys. J. 135, 474. doi: 10.1086/147285 .
Liu, Y., Zhao, X., Hoeksema, T.: 2004, Solar Phys. 219, 39.
Pesnell, W.D., Thompson, B.J., Chamberlin, P.C.: 2012, Solar Phys. 275, 3. doi: 10.1007/s11207-011-9841-3 .
Raju, K.P., Singh, J., Srikanth, R., Chou, D.-Y., TON team: 2001, Solar Phys. 199, 1.
Scherrer, P.H., Bogart, R.S., Bush, R.I., Hoeksema, J.T., Kosovichev, A.G., Schou, J., Rosenberg, W., Springer, L., Tarbell, T.D., Title, A., Wolfson, C.J., Zayer, I., MDI Engineering Team: 1995, Solar Phys. 162, 129. doi: 10.1007/BF00733429 .
Scherrer, P.H., Schou, J., Bush, R.I., Kosovichev, A.G., Bogart, R.S., Hoeksema, J.T., Liu, Y., Duvall, T.L. Jr., Zhao, J., Title, A.M., Schrijver, C.J., Tarbell, T.D., Tomczyk, S.: 2012, Solar Phys. 275, 207. doi: 10.1007/s11207-011-9834-2 .
Smirnova, V., Riehokainen, A., Ryzhov, V., Zhiltsov, A., Kallunki, J.: 2011, Astron. Astrophys. 534, A137. doi: 10.1051/0004-6361/201117483 .
Smirnova, V., Riehokainen, A., Solov’ev, A.A., Zhiltsov, A., Kallunki, J.: 2013a, Astron. Astrophys. 552, A23. doi: 10.1051/0004-6361/201219600 .
Smirnova, V., Efremov, V.I., Parfinenko, L.D., Riehokainen, A., Solov’ev, A.A.: 2013b, Astron. Astrophys. 554, A121. doi: 10.1051/0004-6361/201220825 .
Solov’ev, A.A., Kirichek, E.A.: 2008, Astrophys. Bull. 63, 169. doi: 10.1134/S1990341308020077 .
Solov’ev, A.A., Kirichek, E.A.: 2009, Astron. Rep. 53, 675. doi: 10.1134/S1063772909070099 .
Stahn, T., Gizon, L.: 2008, Solar Phys. 251, 31. doi: 10.1007/s11207-008-9181-0 .
Torrence, C., Compo, G.P.: 1998, Bull. Am. Meteorol. Soc. 79, 61.
Yuan, D., Nakariakov, V.M., Chorley, N., Foullon, C.: 2011, Astron. Astrophys. 533, A116.
Acknowledgements
We thank P.H. Scherrer and the SOHO team for providing the SOHO/MDI data. SOHO is a mission of international collaboration between ESA and NASA. The work was supported by grant RFBR 13-02-00714, and by the Programs of the Russian Academia of Science: P-21 and P-22. Wavelet software was provided by C. Torrence and G. Compo (1998) (available at paos.colorado.edu/research/wavelets/ ).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Efremov, V.I., Parfinenko, L.D., Solov’ev, A.A. et al. Long-Period Oscillations of Sunspots Observed by SOHO/MDI. Sol Phys 289, 1983–1998 (2014). https://doi.org/10.1007/s11207-013-0451-0
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11207-013-0451-0