Changes in the umbra brightness and in the magnetic field over time should occur on long-period sunspot oscillations in accordance with Birman’s idea of inhibition of circulation (overturning) convection by a strong vertical magnetic field in antiphase mode.When the sunspot as a whole shifts upward, its power flux tube expands with a fixed magnetic flux, the magnetic field decreases, and the umbra brightness should increase. Vice versa, when the magnetic flux tube of the sunspot is lowered, it is compressed, the field grows, and the umbra brightness should decrease. Until now, this oscillatory process, which is described by the theoretical model of a shallow sunspot, has remained unexplored. This paper attempts to prove the Birman effect (Biermann, 1941) on the example of long-period oscillations of the sunspot 2010/12/07-13 (NOAA 11 133), for which there are available data from both the Solar and Heliospheric Observatory (SOHO) and Solar Dynamics Observatory (SDO).
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Biermann, L.V., Der gegenwärtige Stand der Theorie konvektiver Sonnenmodelle, Viertel jahresschr. Astron. Ges., 1941, vol. 76, pp. 194–200.
Bray, R.J. and Loughead, R.E., Sunspots, London: Chapman and Hall,1964.
Efremov, V.I., Parfinenko, L.D., and Solov’ev, A.A., Investigation of long-period oscillations of sunspots with ground-based (Pulkovo) and SOHO/MDI data, Sol. Phys., 2010, vol. 267, pp. 279–293.
Efremov, V.I., Parfinenko, L.D., and Solov’ev, A.A., Sunspot oscillations as derived from the SOHO/MDI magnetograms, Cosmic Res., 2012, vol. 50, no. 1, pp. 44–55. https://doi.org/10.1134/S0010952511060025
Efremov, V.I., Parfinenko, L.D., Solov’ev, A.A., and Kirichek, E., long-period oscillations of sunspots observed by SOHO/MDI, Sol. Phys., 2014, vol. 289, pp. 1983–1998. https://doi.org/10.1007/s11207-013-0451-0
Efremov, V.I., Parfinenko, L.D., Solov’ev, A.A., and Riehokainen, A., Long-term oscillations of sunspot magnetic field by simultaneous observations of GONG and MDI/SOHO, Geomagn. Aeron. (Engl. Transl.), 2016, vol. 56, no. 7, pp. 897–902. https://doi.org/10.1134/S0016793216070057
Efremov, V.I., Parfinenko, L.D., and Solov’ev, A.A., Analysis of 12-hour orbital artifact in the SDO/HMI data and Low-frequency oscillations of sunspots magnetic field, Geomagn. Aeron. (Engl. Transl.), 2017, vol. 57, no. 8, pp. 1045–1055. https://doi.org/10.1134/S0016793217080072
Efremov, V.I., Solov’ev, A.A., Parfinenko, L.D., et al., Long-term oscillations of sunspot magnetic field and a special class of artifacts in SOHO/MDI and SDO/HMI data, Astrophys. Space Sci., 2018, vol. 363, no. 3, pp. 1–14. https://doi.org/10.1007/s10509-018-3284-3
Golyandina, N., Nekrutkin, V., and Zhigljavsky, A., Analysis of Time Series Structure: SSA and Related Techniques, London: Chapman and Hall/CRC, 2001.
Gurman, J.B. and House, L.L., Vector magnetic fields in sunspots. Part 1. Weak-line observations, Sol. Phys., 1981, vol. 71, no. 1, pp. 5–20.
Korolkova, O.A. and Efremov, V.I., Y-P2P effect according to SDO data and anti-correlation of oscillations of sunspots magnetic field and umbra area, Geomagn. Aeron. (Engl. Transl.), 2019, vol. 59, no. 7, pp. 827–831.https://doi.org/10.1134/S0016793219070181
Makarov, V.I., The size and form of sunspots in some segments of the continuous spectrum, Izv. Gl. Astron. Obs. Pulkove, 1968, no. 184, pp. 58–65.
Sitnik, G.F., On the problem of the nature of sunspots, Publ. Gos. Astron. Inst. im. Shternberga, 1939, vol. 11, pp. 5–41.
Rempel, M., Numerical sunspot models: Robustness of photospheric velocity and magnetic field structure, Astrophys. J., 2012, vol. 750, no. 1, id. 62. https://doi.org/10.1088/0004-637X/750/1/62
Solov’ev, A.A. and Kirichek, E.A., Basic properties of sunspots: equilibrium, stability and eigen oscillations, Astrophys. Space Sci., 2014, vol. 352, no. 1, pp. 23–42. https://doi.org/10.1007/s10509-014-1881-3
Solov’ev, A.A. and Kirichek, E.A., Analytical model of an asymmetric sunspot with a steady plasma flow in its penumbra, Sol. Phys., 2016, vol. 291, no. 6, pp. 1647–1663. https://doi.org/10.1007/s11207-016-0922-1
Solov’ev, A.A., Parfinenko, L.D., Efremov, V.I., et al., Structure of photosphere under high resolution: Granules, faculae, micropores, intergranular lanes, Astrophys. Space Sci., 2019, vol. 364, no. 12, pp. 222–234. https://doi.org/10.1007/s10509-019-3710-1
Zwaan, C., Sunspot models: A study of sunspot spectra, Rech. Astron. Obs. Utrecht, 1965, vol. 17, no. 4.
The authors are grateful to the SOHO and SDO teams for the opportunity to use the observational data.
This work was supported by the Russian Foundation for Basic Research (project no. 18-02-00168).
The authors declare that they have no conflict of interest.
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Efremov, V.I., Solov’ev, A.A., Parfinenko, L.D. et al. Anticorrelation of Variations of the Magnetic Field of a Sunspot and the Brightness of Its Umbra in Long-Period Sunspot Oscillations. Geomagn. Aeron. 60, 1023–1027 (2020). https://doi.org/10.1134/S0016793220080071