Long-term oscillations of sunspots and a special class of artifacts in SOHO/MDI and SDO/HMI data     

V. I. Efremov  A. A. Solov’ev  L. D. Parfinenko  A. Riehokainen  E. Kirichek  V. V. Smirnova  Y. N. Varun  I. Bakunina  I. Zhivanovich 《Astrophysics and Space Science》2018,363(3):61

A specific type of artifacts (named as “p2p”), that originate due to displacement of the image of a moving object along the digital (pixel) matrix of receiver are analyzed in detail. The criteria of appearance and the influence of these artifacts on the study of long-term oscillations of sunspots are deduced. The obtained criteria suggest us methods for reduction or even elimination of these artifacts. It is shown that the use of integral parameters can be very effective against the “p2p” artifact distortions. The simultaneous observations of sunspot magnetic field and ultraviolet intensity of the umbra have given the same periods for the long-term oscillations. In this way the real physical nature of the oscillatory process, which is independent of the artifacts have been confirmed again. A number of examples considered here confirm the dependence between the periods of main mode of the sunspot magnetic field long-term oscillations and its strength. The dependence was derived earlier from both the observations and the theoretical model of the shallow sunspot. The anti-phase behavior of time variations of sunspot umbra area and magnetic field of the sunspot demonstrates that the umbra of sunspot moves in long-term oscillations as a whole: all its points oscillate with the same phase.  相似文献   

Anticorrelation of Variations of the Magnetic Field of a Sunspot and the Brightness of Its Umbra in Long-Period Sunspot Oscillations     

Efremov  V. I.  Solov’ev  A. A.  Parfinenko  L. D.  Zhivanovich  I. 《Geomagnetism and Aeronomy》2020,60(8):1023-1027

Geomagnetism and Aeronomy - 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...  相似文献   

Relationship of the Magnetic-Field Strength and the Brightness of the Sunspot Umbra and the Center of a Facular Knot     

Zhivanovich  I.  Solov’ev  A. A.  Efremov  V. I.  Miller  N. O. 《Geomagnetism and Aeronomy》2020,60(7):865-871

Geomagnetism and Aeronomy - Two main features define a sunspot as an object: a strong magnetic field and a low umbra temperature. The same can be said about a facular knot, in the center of which...  相似文献   

Features of Slow Sunspot Dissipation     

Zhivanovich  I.  Solov’ev  A. A. 《Geomagnetism and Aeronomy》2019,59(8):1055-1061

Geomagnetism and Aeronomy - According to a model of sunspot dissipation through a thin boundary layer between the sunspot magnetic flux tube and the surrounding medium, the rate of decrease in the...  相似文献   

Radial profile of sunspot magnetic field on the SDO data     

I. Zhivanovich  A. A. Solov’ev  V. V. Smirnova  A. Riehokainen  V. G. Nagnibeda 《Astrophysics and Space Science》2016,361(3):102

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Observations and Interpretation of Rotational Properties of Polar Coronal Holes Based on SDO Data     

Smirnova  V. V.  Riehokainen  A.  Korol’kova  O. A.  Zhivanovich  I. 《Geomagnetism and Aeronomy》2020,60(8):1050-1056

Geomagnetism and Aeronomy - The rotational effect observed in variations of areas of polar coronal holes with a period of 14 days is analyzed with SDO data by using Coronal Hole Identification with...  相似文献