Large-scale magnetic fields of Sun-heliosphere magnetic system
Some results of investigations of solar and interplanetary magnetic fields are presented. The time series of the solar background magnetic field (SBMF) of ±20 degree for 1904–2000, solar mean magnetic field (SMMF) for 1975–2003, and interplanetary magnetic field (IMF) for 1947–2001 were used. A chan...
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Головна астрономічна обсерваторія НАН України
2005
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| Назва видання: | Кинематика и физика небесных тел |
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| Цитувати: | Large-scale magnetic fields of Sun-heliosphere magnetic system / U.M. Leiko // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 187-188. — Бібліогр.: 3 назв. — англ. |
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irk-123456789-796402015-04-04T03:02:16Z Large-scale magnetic fields of Sun-heliosphere magnetic system Leiko, U.M. MS2: Physics of Solar Atmosphere Some results of investigations of solar and interplanetary magnetic fields are presented. The time series of the solar background magnetic field (SBMF) of ±20 degree for 1904–2000, solar mean magnetic field (SMMF) for 1975–2003, and interplanetary magnetic field (IMF) for 1947–2001 were used. A change of the Sun’s rotation regime in the middle of the 20th century is confirmed. The rotation of the sector structures of SBMF, SMMF, and IMF had not identical character during common interval of the observations. 2005 Article Large-scale magnetic fields of Sun-heliosphere magnetic system / U.M. Leiko // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 187-188. — Бібліогр.: 3 назв. — англ. 0233-7665 http://dspace.nbuv.gov.ua/handle/123456789/79640 en Кинематика и физика небесных тел Головна астрономічна обсерваторія НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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English |
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MS2: Physics of Solar Atmosphere MS2: Physics of Solar Atmosphere |
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MS2: Physics of Solar Atmosphere MS2: Physics of Solar Atmosphere Leiko, U.M. Large-scale magnetic fields of Sun-heliosphere magnetic system Кинематика и физика небесных тел |
| description |
Some results of investigations of solar and interplanetary magnetic fields are presented. The time series of the solar background magnetic field (SBMF) of ±20 degree for 1904–2000, solar mean magnetic field (SMMF) for 1975–2003, and interplanetary magnetic field (IMF) for 1947–2001 were used. A change of the Sun’s rotation regime in the middle of the 20th century is confirmed. The rotation of the sector structures of SBMF, SMMF, and IMF had not identical character during common interval of the observations. |
| format |
Article |
| author |
Leiko, U.M. |
| author_facet |
Leiko, U.M. |
| author_sort |
Leiko, U.M. |
| title |
Large-scale magnetic fields of Sun-heliosphere magnetic system |
| title_short |
Large-scale magnetic fields of Sun-heliosphere magnetic system |
| title_full |
Large-scale magnetic fields of Sun-heliosphere magnetic system |
| title_fullStr |
Large-scale magnetic fields of Sun-heliosphere magnetic system |
| title_full_unstemmed |
Large-scale magnetic fields of Sun-heliosphere magnetic system |
| title_sort |
large-scale magnetic fields of sun-heliosphere magnetic system |
| publisher |
Головна астрономічна обсерваторія НАН України |
| publishDate |
2005 |
| topic_facet |
MS2: Physics of Solar Atmosphere |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/79640 |
| citation_txt |
Large-scale magnetic fields of Sun-heliosphere magnetic system / U.M. Leiko // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 187-188. — Бібліогр.: 3 назв. — англ. |
| series |
Кинематика и физика небесных тел |
| work_keys_str_mv |
AT leikoum largescalemagneticfieldsofsunheliospheremagneticsystem |
| first_indexed |
2025-07-06T03:40:04Z |
| last_indexed |
2025-07-06T03:40:04Z |
| _version_ |
1836867340208177152 |
| fulltext |
LARGE-SCALE MAGNETIC FIELDS
OF SUN–HELIOSPHERE MAGNETIC SYSTEM
U. M. Leiko
Astronomical Observatory, National Taras Shevchenko University of Kyiv
3 Observatorna Str., 04053 Kyiv, Ukraine
e-mail: leiko@observ.univ.kiev.ua
Some results of investigations of solar and interplanetary magnetic fields are presented. The time
series of the solar background magnetic field (SBMF) of ±20 degree for 1904–2000, solar mean
magnetic field (SMMF) for 1975–2003, and interplanetary magnetic field (IMF) for 1947–2001
were used. A change of the Sun’s rotation regime in the middle of the 20th century is confirmed.
The rotation of the sector structures of SBMF, SMMF, and IMF had not identical character during
common interval of the observations.
INTRODUCTION
Solar and interplanetary large-scale solar magnetic fields (LSMF) are observed in the form of the sector struc-
ture (SS). It was revealed by Svalgaard and Wilson [2] that the rotation of the SS of interplanetary magnetic
field (IMF) had multicomponent and variable periods during 1926–1973. Investigations of large-scale solar
background magnetic fields (SBMF) over long time interval [1, 3] allowed one to reveal some distinguishing
feature of main SBMF sector structures. But the results of their investigations do not always agree because
the problem statement and method of investigations were different. At present, many questions on behaviour
of SS LSMF are unresolved.
The results of investigations of LSMF several types sector structure rotation are presented below.
DATA AND PROCEDURE
Time series of the solar background magnetic field (SBMF) of the ±20 degrees latitudinal zone for 1904–2000, of
the solar mean magnetic field (SMMF) for 1975–2003, and of interplanetary magnetic field (IMF) for 1947–2000
were used for our analysis. To determine the rotation period of the sector structures of different modes
(m = 1– 7), we used the following procedure. The spectrum was computed in moving window of definite
length N for period range corresponding to the SS of m-mode. The period value of the most power peak of
this spectrum assumed as the main rotation period of the sector structure of m-mode. The window moved with
step h and computing repeated. Finally, the array of rotation period values for the time point t = N/2 + h
was obtained. This array of the rotation period was smoothed by moving average and the time variation of
the rotation period was obtained. The results presented in this paper are derived under the spectrum computing
with moving window of a four-year length and a three-month step.
RESULTS
Solar background magnetic field
It is known that the rotation periods of the ±20 degrees latitude zone lie over the range of 26.9 to 27.7 days.
To find the main rotation periods of SS SBMF, several rotation period ranges were tried on the computations
of the spectrum, and it was revealed that the most appropriate range was 26.5–30.0 days. This period range
was used on obtaining all the results of SBMF investigation mentioned below.
The rotation rate of two-sector structure of SBMF varied with about 11-year cycle during the first half of
investigated interval and with about 8-year cycle during the second half. The maximal value of the rotation
periods and minimal value of its amplitude were observed under a low level of solar activity. But four-sector
structure had about 22-year cycle of the rotation period change and about 11-year cycle of the change of its
amplitude over whole interval. The maximal rotation rate of four-sector structure was observed during maximum
of even cycles (14, 16, 18, 20, 22) and minimal rate of the rotation was observed during maximum of odd cycles
(15, 17, 19, 21).
c© U. M. Leiko, 2004
187
Thus, main sector structures of SBMF are independent and it seems they are generated in different depth
of convective zone.
In the middle of the 20th century the mean rotation rate of the main sector structures of SBMF increased.
It was revealed that until about 1947 the rotation rate of four-sector structure was greater than two-sector
structure rotation rate, after 1947 the rotation rate of both sector structures were almost uniform.
In the middle of the 20th century the power redistribution of the SS occurred as well. The amplitude of
sector structure of higher modes (m ≥ 3) increased and the sector structure character of SBMF changed. For
interval 1960–2000, it was revealed that the sector structure rotation period decreased with the increase of its
mode m.
Solar mean magnetic field
The SMMF means the strength of longitudinal component of the surface magnetic field averaged at the visible
hemisphere of the Sun.
One of interesting features of LSMF is two periods of their quasi-rigid rotation, namely, about 27-day and
about 28-day periods.
A low value of rotation periods (about 27 days) of quasi-rigid rotation of both two-sector and four-sector
structures of near-equatorial magnetic fields corresponds to a high value of its amplitude as well as two-sector
structure of SBMF. But on the contrary to SBMF, the rotation rate of the main sector structure of SMMF
had minimal rotation period under a high level of the solar activity. The main sector structures of SMMF have
synchronous rotation.
The evolution of the second periods of quasi-rigid rotation (about 28-day period) of SMMF has no cyclicyty.
The difference in evolution of two quasi-rigid rotation periods of SMMF confirms the conception of two
independent systems of large-scale magnetic fields.
Interplanetary magnetic field
The main rotation period (about 27-day period) of the two-sector structure of IMF varied with about 22-year
cycle: maximal value of the rotation period of IMMF was during about 1952–1956, 1976, 1997.
An analysis of the spectrums of the whole cycles showed that during the 20th–23rd cycles the rotation
period of IMF and SMMF was greater in even cycles and smaller in odd cycles. During the 18th–19th cycles
the rotation period of IMF was greater during odd cycle and smaller during even cycle.
Possibly, this fact is indicative of a change of the rotation regime of IMF in the middle of the 20th century,
and this is an indirect confirmation of the Sun’s rotation change.
CONCLUSION
The relationships between large-scale magnetic fields of the Sun–heliosphere magnetic system are complex.
We showed that the evolution of primary rotation period of the SS of SBMF, SMMF, and IMF had not
identical character during common interval of observations.
The investigations of the rotation of the SBMF and IMF confirmed a change in the Sun’s rotation regime
in the middle of the 20th century.
Acknowledgements. I would like to thank all the observers for the possibility to work with LSMF data, and
the Organizing Committee for giving me a chance to represent this paper at the Conference.
[1] Obridko V. N., Shelting B. D. Large-scale magnetic field of the Sun: equatorial region // Astron. J.–2000.–77.–
P. 124–133.
[2] Svalgaard L., Wilcox J. M. Long-term evolution of solar sector structure // Solar Phys.–1975.–41.–P. 461–475.
[3] Vasil’eva V. V., Makarov V. I., Tlatov A. G. Rotation cycles of the sector structures of the solar magnetic field
and its activity // Pis’ma Astron. Zh.–2002.–28.–P. 228–234.
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