Investigation of magnetic fields in solar active regions

Gopasyuk, S. I.; Gopasyuk, O. S.; Zalesov, I. P.; Karkach, D. V.; Svistel’nikov, V. V.

doi:10.1134/1.163872

Cited by 6 publications

(8 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In general such a displacement produces waves going out in each direction along the lines of force with the Alfven velocity. Gopasyuk (1984) studied the magnetic field structure in the sub-photospheric layers via the data on the sunspot torsional oscillations. According to Gopasyuk and Lyamova (1987) the sunspots in the minimum of the solar activity are formed due to the rising of magnetic loops from the upper layers of the convective zone.…”

Section: Introductionmentioning

confidence: 99%

Sunspot Rotations Derived from Magnetic and Velocity Fields Observations

Gopasyuk

2005

Sol Phys

Self Cite

View full text Add to dashboard Cite

The rotation of sunspot penumbrae has been investigated on the longitudinal magnetic and velocity fields, observed in the photospheric line Fe I λ5253Å of five lone sunspots. We reconstructed the entire vectors of both fields from their line-of-sight components. All three components of both vectors revealed that the rotation of the sunspots was, in fact, a torsional oscillation. All components of each sunspot had the same rotational period. The penumbrae oscillation periods were distributed in the range from 3.4 days to 7.7 days. The phase of the velocity azimuthal component oscillation was ahead of the phases of all other components of both vectors. If the penumbra plasma density had been equal to the photospheric plasma density (10 −7 g cm −3 ) then the oscillation magnetic energy of the components exceeded their kinetic energy approximately by a factor of 10-200. The obtained results led to the conclusion that these oscillations were constrained.

show abstract

Section: Introductionmentioning

confidence: 99%

Sunspot Rotations Derived from Magnetic and Velocity Fields Observations

Gopasyuk

2005

Sol Phys

Self Cite

View full text Add to dashboard Cite

show abstract

“…This plot shows a distinct cyclical variation with a mean harmonic amplitude of 0.2 G. A comparison with the behavior of the Wolf number W (Fig. 1b) shows that the curve | B | on average lags behind the W curve by 0.7 (7). Therefore, the maxima of | B | approximately coincide with the epochs of altering the polar poles.…”

Section: The 39-year Behavior Of the Mmf Aboslute Valuementioning

confidence: 79%

“…The discrepancies are believed to be caused mainly by measurement errors and "saturation" of the magnetograph signals in magnetic rope-fibril-filament-fluxtube elements of the photosphere with angular widths less than an arcsecond with a strong magnetic field of about 1.0-1.5 kG, as well as by different temperature sensitivity of different lines (Howard and Stenflo, 1972;Stenflo, 1973;Demidov et al, 2002Demidov et al, , 2005aDemidov et al, , 2005b. In the case of measurements of the "local" fields in sunspots and active regions, additional discrepancies are caused by variations in the line profile and "expansion" of the solar magnetic fluxtubes with height in the solar atmosphere (Howard and Stenflo, 1972;Gopasyuk et al, 1973Gopasyuk et al, , 2000.…”

Section: Introductionmentioning

confidence: 99%

“…This can be caused by a number of reasons, including the effect of spectral and spatial resolution and the spatial mismatch; variations in the line profile, which are difficult to take into account; errors in radial-velocity and brightness compensation; nonsimultaneous measurements; etc. For example, magnetograms obtained in Crimea (Gopasyuk et al, 1973(Gopasyuk et al, , 2000 showed such large differences in the magnetic field values measured using different spectral lines that it is unclear at all which lines give the actual field. Strong quantitative differences in the results of different observatories obtained using different lines were recently pointed out by Demidov et al (2005a).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A paradox in measuring the magnetic field of the Sun

Kotov

2008

Bull.Crim. Astrophys. Observ.

View full text Add to dashboard Cite

-Significant discrepancies are often observed among the values of the mean magnetic field (MMF) of the Sun as a star observed by various instruments using various spectral lines. This is conventionally attributed to the measurement errors and "saturation" of a solar magnetograph in fine-structure photospheric elements with a strong magnetic field. Measurements of the longitudinal MMF performed in 1968-2006 at six observatories are compared in this paper. It is shown that the degree of discrepancy (slopes b of linear regression lines) varies significantly over the phase of the 11-year cycle. This gives rise to a paradox: the magnetograph calibration is affected by the state of the Sun itself. The proposed explanation is based on quantum properties of light, namely, nonlocality and "coupling" of photons whose polarization at the telescope-spectrograph output is determined by spacious parts of the solar disk. In this case, the degree of coupling, or "identity," of photons depends on the field distribution in the photosphere and the instrument design (as Bohr said, "the instrument inevitably affects the result"). The "puzzling" values of slope b are readily explained by the dependence of the coupling on the solar-cycle phase. The very statistical nature of light makes discrepancies unavoidable and requires the simple averaging of data to obtain the best approximation of the actual MMF. A 39-year time series of the MMF absolute value is presented, which is indicative of significant variations in the magnitude of the solar magnetic field with a cycle period of 10.5(7) yr.

show abstract

“…These oscillations were used for investigations of magnetic field structures in the subphotospheric layers (Gopasyuk 1984). Torsional oscillations of sunspots are not unique, but rather an intrinsic feature of sunspot states (Gopasyuk & Lyamova 1987).…”

Section: Introductionmentioning

confidence: 99%