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Крупномасштабное поле Солнцаи активные долготы.

Обридко В.Н., Иванов Е.В., Чертопруд В.Е.

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Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation (IZMIRAN)

8.02.2010

Использованные данные

Гринвичские наблюдения площадей пятен (1976 -2005)

Наблюдения крупномасштабного магнитного Солнца в WSO (1976-2009).

Расчеты положения глобального магнитного диполя по наблюдениям в WSO (1976-2005)

Наблюдения фоновых полей на SOHO MDI (1998-2003)

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It is evident that the fields of different polarities tend to concentrate in different regions

Low-resolution images only reveal these extended unipolar regions, but if we superimpose a low-resolution map on a high-resolution magnetogram, we shall readily see the agreement of the polarities.

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Из вариации центр-лимб обнаружено, что сильные фоновые поля в основном вертикальные, а слабые -

горизонтальные

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Total magnetic moment of the dipole: a) magnetic moment;b) the inclination angle of dipole axis (latitude), c) the monthly mean Wolf numbers.

Time variation of the vertical vert

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and horizontal horiz

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of the global magnetic dipole (blue lines). The dot lines on both panels show the total magnetic moment.

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Position of the north pole of the magnetic dipole for three solar cycles. The upper panels correspond to the northern hemisphere and the lower ones, to the southern hemisphere. The circles are the contour lines of the values cos given on the scales for each cycle.

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SOHO/MDI. <B2> after time standardization. This procedure combines the fields of both signs and increases the contribution of large background fields. The 11-year cycle is manifested at all latitudes. The cycle maximum moves from pole to pole for two years. Outside the equator, the cycle variation in the background magnetic field energy has two maxima.

Активные долготыВпервые обнаружены в 1897 году Вольфером.

Понятие активных долгот для разных индексов

Дискуссия – одна или две активных долготы.

Зависимость от скорости вращения, широты и мощности индексов

Связь с крупномасштабным полем

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The tendency of the solar cycle to appear at the preferred longitudes was foundby Benevolenskaya, Hoeksema., Kosovichev and Scherrer (1999) and Bumba, Garcia, and Klvana (2000). Left panel: Synoptic maps of the

solar magnetic field for CR 1911–1934 derived from the SOHO/MDI magnetograms during the activity minimum between cycles 22 and 23. Values of the line-of-sight component of the magnetic field are represented in light and dark for positive and negative polarities, respectively. Right panel: More detailed synoptic magnetic maps for CR 1916–1923.

The magnetic flux of the new cycle has a tendency to reappear in the active longitudinal zones. Benevolenskaya, 2009

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• The sunspot occurrence data confirm the existence of two preferred longitudes 180 apart, which migrate in any fixed rotation frame but are persistent throughout 120 years

• The differential rotation is significantly different from the differential rotation of individual spots. This implies that the depth at which sunspots are formed (and affected by the non-axisymmetric component of the field) is different from that

where developed sunspots are anchored (I.G. Usoskin, S.V. Berdyugina and J. Poutanen (2005)

• The lifetime of the sunspot formation zones exceeds significantly that of individual sunspots and may reach 15-20 rotations.

• The stability of the Active Longitudes is larger for the larger spots (Ivanov, 2006)

Longitudinal distribution for major, medium-size

and small short-lived sunspots in the northern hemisphere in cycle 20. (Ivanov, 2006)

Theoretical argumentsAlberto Bigazzi and Alexander Ruzmaikin (2003) explained the Sun’s Preferred Longitudes as a Coupling of Magnetic Dynamo Modes.D. Elstner and H. Korhonen (2005) .To explain this phenomenon, a non-axisymmetric dynamo mode, giving rise to two permanent active longitudes at opposite stellar hemispheres, is needed together with an oscillating axisymmetric magnetic field.Axel Brandenburg and Petri J. K¨apyl¨a (2005) solved a two-dimensional mean field dynamo model where magnetic helicity conservation is fully included. The model develops longitudinal variability with activity patches travelling in longitude. These patches may be associated with active longitudes.

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However, there are objections to the existence of two active longitudes

Baltasar (2007) revealed only one maximum in the Fourier spectrum, i.e., one active longitude.

Losh (1938) found that there is one maximum and one minimum per rotation, and that the phase of the maximum is stable over a solar cycle. Balthasar & Schüssler (1984) investigated sunspot numbers and showed that the phase of the maximum remains more or less the same for two solar cycles and then it changes by about 180◦.

Knaack & Stenflo (2005) and Knaack et al.(2005) used magnetograms from Mt.Wilson and from Kitt Peak and found that the dominant rotation periods are different for cycles 21, 22 and 23. Bouwer (1992) investigated various indicators of solar activity and found that precise periods between 27 and 28 days persist only for a short time, sometimes only for a few solar rotations.J. Pelt, J.M. Brooke , M.J. Korpi, and I. Tuominen (2006)strong and well substantiated evidence for an essential and century-scale persistent nonaxisymmetry in the sunspot distribution does not exist.C. J. Henney, B. R. Durney, 2007 A surprisingly non-negligible likelihood is found, approximately 1 in 3, that observed periodicities from integrated full-disk solar parameters are a chance occurrence for time series of the order of 20 years in duration.

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Хейловскаяграница

Антихейловскаяграница

Цикл 23

Цикл 23

Цикл 22

Цикл 22

В гелиомагнитной системе координат фиксированные долготы определяются точками пересечения гелиомагнитного и гелиографического экваторов (270 и 90 градусов). Их положение не зависит от времени. Меняется только раствор («tilt»). В минимуме эти координаты становятся неопределенными.

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About 70% of the spots with the area >500 m.p.h are located at a distance <20 degrees in longitude from the Large Scale Neutral Line.However, the longitude of the axis of the effective solar dipole (and the longitude of the associated neutral line)changes with the course of time

The longitude of the effective solar dipole shifts by 20.2 degrees per year and by 360 degrees

for 18-20 years

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Это, кстати,объясняет, почему активные долготы в керрингтоновской системе размываются за 2-3 года

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NorthCycle 21 NorthCycle 22 NorthCycle 23

SouthCycle 22 SouthCycle 23SouthCycle 21

Выводы

• Составляющие магнитного поля Солнца образуют единый организм, в то же время циклические вариации и области генерации составляющих могут меняться в зависимости от мощности и характерных размеров.

• Глобальное магнитное поле восстанавливает свою долготно-широтную структуру через 22 года

• Активные долготы лучше проявляются в мощных элементах активности.

• Активные долготы отражают вращение глобального магнитного поля.

• В гелиомагнитной системе координат активные долготы возникают в точках пересечения гелиомагнитного и гелиографического экваторов.

• В каждом цикле в каждом полушарии есть только одна активная долгота определяемая глобальным полем с учетом Хейловских законов полярности

Спасибо за внимание

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Fig. 5. Histogram distribution of recovered spot locations with respect to the semi-annual averages of one active longitude for solar cycles 12 to 22. Error bars correspond to 1σ statistical error. The best-fit double Gaussian function with peaks at phases 0.0 and 0.5 and the standarddeviation of about 0.11 is shown by solid linesS. V. Berdyugina and I. G. Usoskin, 2003)

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Fig. 1. Active longitudes and the flip-flop phenomenon on cool active binary components: on the left, as observed in light curves of Gem, and on the right, in Doppler images of II Peg. The images on the left show the distribution of the spot filling factor on the stellar surface obtained via inversions of the lightcurves (plots in the middle). The II Peg images obtained from inversions of spectral line profiles show the temperature distribution on the stellar surface as seen from the pole. Flip-flops appear as a switch of thedominant activity to the opposite longitudeS.V. Berdyugina (2007)

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Greenwich data for 1879-2005 (cycles 12-23) are used to study the longitude distribution of sunspot group areas summed over a Carrington rotation separately in the southern and northern hemispheres. The active longitudes were studied in two reference frames corresponding to the rotation periods T=27.2753 and T=27.00 days. The AL zones are shown to consist of a set of individual narrow sunspot formation zones rotating rigidly with the Carrington period T~27.2753 days. The lifetime of the sunspot formation zones exceeds significantly that of individual sunspots and may reach 15-20 rotations. Besides the rigidly rotating active longitudes we have revealed the active longitudes that migrate in the Carrington reference frame at different (greater and smaller than Carrington) angular velocities.

E.V. Ivanov , 2006

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Fig. 1. Longitudinal distribution of SCR (d,e,f) for major (s(CR)>2000 m.v.h.), medium-size (100 m.v.h.<s(CR)<2000 m.v.h.), and small short-lived sunspots (10 m.v.h.<s(CR)<100 m.v.h.) in the northern hemisphere in cycle 20. (Ivanov, 2006)

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Fig. 7. Time-longitude diagrams of the rotation-summed sunspot areas s(CR) for sunspots with s(CR)>2000 m.v.h. over the past 6 cycles (18-23) separately in the northern and southern hemispheres.

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• 1. Выявлено два периода вращения, для которых явление активных долгот превышает принятый уровень статистической достоверности. Это позволило сделать предположение о существовании двух систем активных долгот на Солнце.

• 2. Система активных долгот с Р ~ 27 сут. доминирует в наиболее мощных 11-летних циклах активности.

• 3. Система активных долгот с Р ~ 28 сут. наиболее выражена в эпоху минимума векового цикла

S.V. Olemskoy, L.L. Kitchatinov

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