Two types of differential rotation of the solar corona

Badalyan, O. G.

doi:10.1016/j.newast.2009.04.006

Cited by 19 publications

(17 citation statements)

References 18 publications

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“…a recurrence found in [21], behaves opposite, being stronger in mid -latitudes. In [22] there is a statement, that the manifestation of the rotation of the innermost part of sub-photospheric zones might be reflected in the solar corona behavior. Thus, to track the structures hidden in the solar magnetic field we study changes of the coronal green line intensity (CGLI) with wavelength of 530.3 nm, emitted by ionized iron Fe XIV (e.g.…”

Section: Examine the Solar Corona And Discussionmentioning

confidence: 99%

α-ω effect and recurrent changes of galactic cosmic rays intensity

Gil¹,

Alania²

2017

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017)

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We recognize a quasi-recurrence with duration of 3 to 4 Carrington rotations period (3-4 CRP) in changes of amplitudes of the 27-day variation of galactic cosmic rays (GCR) intensity, solar activity (SA) and solar wind (SW) parameters, as well. We attribute this phenomenon to the presence of a spatial topological structure (STS) of the solar magnetic field. STS is created by α-ω effect in the inner solar atmosphere, from photosphere to lower corona. STS exists due to the asymmetry of solar dynamo and solar differential rotation. Studying this phenomenon by the aid of spectral analysis methods we found an existence of the quasi-periodicities with the duration shorter than, and longer than the 3-4 CRP. This 3-4 CRP quasi-periodicity mode corresponds to the extreme interval ∆t of differential rotation periods, ∆t = 35 days-25 days (from poles to equator of the Sun, respectively). We assume also that the process like to α-ω appears in time intervals corresponding to the transitional differential rotation periods, as well, e.g. ∆t1 = 26 days-25 days, ∆t2 = 27 days-25 days, and so forth, to ∆t = 35 days-25 days. We assume that extensive range of quasi-periodicities of GCR intensity, SW and SA parameters can be related to the combined influence of turbulent solar dynamo and solar differential rotation. Thus, STS should be very complex pattern containing a broad modes of oscillations responsible for various types of quasiperiodicities. So, we believe that it is possible to find an evidence that any alternation: periodical or nonperiodical in GCR intensity and in parameters of solar activity and solar wind is strongly related with temporal changes of the various scales of STS.

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Section: Examine the Solar Corona And Discussionmentioning

confidence: 99%

α-ω effect and recurrent changes of galactic cosmic rays intensity

Gil¹,

Alania²

2017

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017)

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“…Moreover, they found that, for the higher latitudes, the rotation period changes very slowly and its value of about 29 days remains up to the polar regions. That is to say, the total rotation of the solar corona could be described as a superposition of two rotation modes: the fast mode near the equator is around 27 days, and the slow mode exceeds 30 days (Badalyan 2010). Using the same but longer database, Badalyan & Obridko (2017) investigated the time variation of the differential rotation parameters of the solar corona, and found that the equatorial rotation rate of the corona increases in the epochs of minimum between the even and odd cycles and arrives at its minimum values between the odd and even cycles.…”

Section: Introductionmentioning

confidence: 99%

Systematic regularity of solar coronal rotation during the time interval 1939–2019

Deng

Zhang

Deng

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Temporal variation of the solar coronal rotation appears to be very complex and its relevances to the eleven-year solar activity cycle are still unclear. Using the modified coronal index for the time interval from 1939 January 1 to 2019 May 31, the systematic regularities of the solar coronal rotation are investigated. Our main findings are as follows: (1) from a global point of view, the synodic coronal rotation period with a value of 27.5 days is the only significant period at the periodic scales shorter than 64 days; (2) the coronal rotation period exhibit an obviously decreasing trend during the considered time interval, implying the solar corona accelerates its global rotation rate in the long run; (3) there exist significant periods of 3.25, 6.13, 9.53, and 11.13 years in the period length of the coronal rotation, providing an evidence that the coronal rotation should be connected with the quasi-biennial oscillation, the eleven-year solar cycle, and the 22-year Hale cycle (or the magnetic activity reversal); and (4) the phase relationship between the coronal rotation period and the solar magnetic activity is not only time-dependent but also frequency-dependent. For a small range around the 11-year cycle band, there is a systematic trend in the phase, and the small mismatch in this band brings out the phase to drift. The possible mechanism for the above analysis results is discussed.

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“…The zones of slow rotation arise at the middle of the ascending branch and extend partly to the maximum. These particularities of rotation inferred from the green-line data were considered in detail in Badalyan, Obridko, and Sýkora (2006); Badalyan (2009Badalyan ( , 2010. On magnetic maps, the zones of slow rotation at high latitudes are mainly observed in other phases of the cycle and become dominant near the cycle minimum.…”

Section: Comparison With the Corona Rotation As Inferred From Green-lmentioning

confidence: 98%

“…This period was taken as the synodic period of the coronal rotation T at a given time at a given latitude. Thus, we obtained the time dependence of the coronal rotation period at a given latitude (for examples see Badalyan and Sýkora, 2005, Badalyan, Obridko, and Sýkora, 2006, Badalyan, 2010. We called this procedure the method of maximum amplitudes.…”

Section: The Rotation Period As a Function Of Distance From The Centementioning

confidence: 99%

Magnetic Field as a Tracer for Studying the Differential Rotation of the Solar Corona

Badalyan

Обридко

2018

Sol Phys

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The characteristics of differential rotation of the solar corona for the period 1976-2004 were studied as a function of the distance from the center of the Sun. For this study, we developed a method using the coronal magnetic field as a tracer. The field in a spherical layer from the base of the corona up to the source surface was determined from photospheric measurements. Calculations were performed for 14 heliocentric distances from the base of the corona up to 2.45 R ⊙ solar radii (the vicinity of the source surface) and from the equator to ±75 • of latitude at 5 • steps. For each day, we calculated three spherical components, which were then used to obtain the field strength. The coronal rotation periods were determined by the periodogram method. The rotation periods were calculated for all distances and latitudes under consideration. The results of these calculations make it possible to study the distribution of the rotation periods in the corona depending on distance, time, and phase of the cycle. The variations in the coronal differential rotation during the time interval 1976-2004 were as follows: the gradient of differential rotation decreased with the increase of heliocentric distance; the rotation remaining differential even in the vicinity of the source surface. The largest rotation rates (shortest rotation periods) were recorded at the cycle minimum at small heliospheric distances, i.e. small heights in the corona. The lowest rotation rate was observed at the middle of the ascending branch at large distances. At the minimum of the cycle, the differential rotation is most clearly pronounced, especially at small heliocentric distances. As the distance increases, the differential gradient decreases in all phases. The results based on magnetic data and on the brightness of the coronal green line 530.3 nm Fe XIV used earlier show a satisfactory agreement. Since the rotation of the magnetic field at the corresponding heights in the corona is probably determined by the conditions in the field generation region, an opportunity arises to use this method for diagnostics of differential rotation in the subphotospheric layers.

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Two types of differential rotation of the solar corona

Cited by 19 publications

References 18 publications

α-ω effect and recurrent changes of galactic cosmic rays intensity

α-ω effect and recurrent changes of galactic cosmic rays intensity

Systematic regularity of solar coronal rotation during the time interval 1939–2019

Magnetic Field as a Tracer for Studying the Differential Rotation of the Solar Corona

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