Related papers: Active Latitude Oscillations Observed on the Sun
This work investigates the solar quasi-periodic cycles with multi-timescales and the possible relationships with planetary motions. The solar cycles are derived from long-term observations of the relative sunspot number and microwave…
Solar oblateness has been the subject of several studies dating back to the nineteenth century. Despite diffculties, both theoretical and observational, tangible results have been achieved. However, variability of the solar oblateness with…
The observed persistence of specific periodicities detected in time series associated with solar surface magnetic activity over several solar cycles has led to numerous papers supporting the existence of preferred longitudes. Recent…
Using data of fast-rotating active dwarf stars in the Kepler database, we perform time-frequency analysis of the light curves in order to search for signs of activity cycles. We use the phenomenon that the active region latitudes vary with…
We analyse light curves covering four years of 39 fast-rotating ($P_\mathrm{rot}< 1d$) late-type active stars from the Kepler database. Using time-frequency analysis (Short-Term Fourier-Transform), we find hints for activity cycles of…
The full-disk chromosphere was routinely monitored in the He I 10830\AA\, line at the National Solar Observatory/Kitt Peak from 2004 Nov. to 2013 March, and thereby, synoptic maps of He I line intensity from Carrington rotations 2032 to…
The work is devoted to the study of periodic structures in the magnetic field of the photosphere. The polarity of the Sun's magnetic fields shows cyclicity with periods of 1-3 years, which is possibly due to quasi-biennial variations that…
The solar magnetic activity cycle is responsible for periodic episodes of severe space weather, which can perturb satellite orbits, interfere with communications systems, and bring down power grids. Much progress has recently been made in…
It is well accepted that the solar cycle originates from a magnetohydrodynamics dynamo deep inside the Sun. Many dynamo models have long been proposed based on a lot of observational constraints. In this paper, using 342 NSO/Kitt Peak solar…
The latitudinal location of the sunspot zones in each hemisphere is determined by calculating the centroid position of sunspot areas for each solar rotation from May 1874 to June 2011. When these centroid positions are plotted and analyzed…
We have used solar oscillation frequencies and frequency splittings obtained over solar cycles 23, 24 and the rising phase of solar cycle 25 to investigate whether the tachocline properties (jump i.e., the change in the rotation rate across…
The large-scale convection in the Sun known as supergranulation is manifested as a network structure on the solar surface. The network cells have an average lifetime of 24 hr, a size of about 30 Mm, and a lane width of about 6 Mm. We have…
The visible diameter of Sun oscilates with a period of 160 min. The same type of periodicity is also found in a huge number of solar radiation parameters. To elucidate the origin of these longitudinal radial pulsations we have used the…
Features of the development of activity cycles in the solar-type stars and fast-rotating cool dwarfs have been considered for 65 stars observed in some decades. Cycles with duration of 7-18 years compared to the solar cycle were found for…
The near 155 days solar periodicity, so called Rieger periodicity, was first detected in solar flares data and later confirmed with other important solar indices. Unfortunately, a comprehensive analysis on the occurrence of this periodicity…
In a previous paper, I described a new way of determining the high-latitude solar rotation rate statistically from space-time maps of polar faculae observed in the 6767 \r{A} continuum by the Michelson Doppler Interferometer (MDI) on the…
An analysis of the tilt angles of the active regions in 15-24 activity cycles was performed. We used data from measurements of magnetic fields in the sunspot umbra in the period 1918 -2019 at the Mount Wilson Observatory, as well as the…
Long-term observational data have information on the magnetic cycles of active stars and that of the Sun. The changes in the activity of our central star have basic effects on Earth, like variations in the global climate. Therefore…
It has been established that the Rieger periodicity of approximately 153 days is part of a complex of periodicities, all multiples of a basic period of approximately 25.5 days. However, it has not been clear why the sixth subharmonic of…
The study of the global structure of the large-scale magnetic field of the Sun is extremely important for creating a theoretical model of the dynamics of the Sun and predictions of the real situation in the helio- and geomagnetosphere. The…