216 research outputs found
Investigation of magnetic fields on the sun
Magnetic fields of sun and effects on events near eart
Temporal and Periodic Variations of Sunspot Counts in Flaring and Non-flaring Active Regions
We analyzed temporal and periodic behavior of sunspot counts (SSCs) in
flaring (C, M, or X class flares), and non-flaring active regions (ARs) for the
almost two solar cycles (1996 through 2016). Our main findings are as follows:
i) The temporal variation of monthly means of daily total SSCs in flaring and
non-flaring ARs are different and these differences are also varying from cycle
to cycle; temporal profile of non-flaring ARs are wider than the flaring ones
during the solar cycle 23, while they are almost the same during the current
cycle 24. The second peak (second maximum) of flaring ARs are strongly dominate
during current cycle 24, while this difference is not such a remarkable during
cycle 23. The amplitude of SSCs in the non-flaring ARs are comparable during
the first and second peaks (maxima) of the current solar cycle, while the first
peak is almost not existent in case of the flaring ARs. ii) Periodic variations
observed in SSCs of flaring and non-flaring ARs are quite different in both MTM
spectrum and wavelet scalograms and these variations are also different from
one cycle to another; the largest detected period in the flaring ARs is 113
days, while there are much higher periodicities (327, 312, and 256 days) in
non-flaring ARs. There are no meaningful periodicities in MTM spectrum of
flaring ARs exceeding 45 days during solar cycle 24, while a 113 days
periodicity detected from flaring ARs of solar cycle 23. For the non-flaring
ARs the largest period is 72 days during solar cycle 24, while the largest
period is 327 days during current cycle.Comment: Submitted to Solar Physics, 17 pages, 5 figure
Some comments on the matching of photometric and magnetic properties of structures at the solar surface
We investigate sharply outlined features recorded in solar magnetic field
tracers. It is shown that the magnetic boundaries of a sunspot do not coincide
with the photometric ones. Moreover, there is no clear magnetic boundary around
sunspots. Thus, the widely accepted concept of a magnetic tube with clearly
pronounced borders is not always correct and should be used with caution. It is
also shown that even in the periods of complete absence of visible spots on the
Sun, there are magnetic fields over 800 Gauss. The nature of these strong
magnetic fields remains unclear; they may originate at relatively small depths
under the photosphere.Comment: 6 pages, 2 figures. Proceedings of the Fifteenth Workshop "Solar
Influences on the Magnetosphere, Ionosphere and Atmosphere", Primorsko,
Bulgaria, June 202
Alleviation of catastrophic quenching in solar dynamo model with nonlocal alpha-effect
The nonlocal alpha-effect of Babcock-Leighton type is not prone to the
catastrophic quenching due to conservation of magnetic helicity. This is shown
with a dynamo model, which jointly applies the nonlocal alpha-effect, the
diamagnetic pumping, and dynamical equation for the magnetic alpha-effect. The
same model shows catastrophic quenching when the alpha-effect is changed to its
local formulation. The nonlocal model shows the preferred excitation of
magnetic fields of dipolar symmetry, which oscillate with a period of about ten
years and have a toroidal-to-polar fields ratio of about a thousand.Comment: 6 pages, 6 figures, submitted to Astronomische Nachrichte
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