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Solar wind charge-state measurements contain a wealth of knowledge related to the properties of the solar corona from where they originated. However, their interpretation has remained challenging because it convolves coronal temperature,…

Space Physics · Physics 2025-01-13 Pete Riley , Roberto Lionello , Yeimy J. Rivera

The rotation of sunspots of 2 yr in two different solar cycles is studied with the data from the Helioseismic and Magnetic Imager on board the \it Solar Dynamics Observatory \rm and the Michelson Doppler Imager instrument on board the \it…

Solar and Stellar Astrophysics · Physics 2016-07-29 Jianchuan Zheng , Zhiliang Yang , Kaiming Guo , Haimin Wang , Shuo Wang

The Sun's net radiative output varies on timescales of minutes to gigayears. Direct measurements of the total solar irradiance (TSI) show changes in the spatially- and spectrally-integrated radiant energy on timescales as short as minutes…

Solar and Stellar Astrophysics · Physics 2016-07-04 Greg Kopp

We perform a high-resolution two-dimensional fully-kinetic numerical simulation of a turbulent plasma system with observation-driven conditions, in order to investigate the interplay between turbulence, magnetic reconnection, and particle…

The solar activity, which is driven by a variable magnetic field, exhibits changes along several time scales, the 11-year being the most known. In addition to the SunSpot Number, the Ca II K index and the Mg II index are indices widely…

Solar and Stellar Astrophysics · Physics 2024-05-28 Raffaele Reda , Valentina Penza

In recent years directional multiscale transformations like the curvelet- or shearlet transformation have gained considerable attention. The reason for this is that these transforms are - unlike more traditional transforms like wavelets -…

Functional Analysis · Mathematics 2009-12-13 Philipp Grohs

Solar wind is probably the best laboratory to study turbulence in astrophysical plasmas. In addition to the presence of magnetic field, the differences with neutral fluid isotropic turbulence are: weakness of collisional dissipation and…

Solar and Stellar Astrophysics · Physics 2015-06-16 Olga Alexandrova , Christopher H. K. Chen , Luca Sorriso-Valvo , Timothy S. Horbury , Stuart D. Bale

The Sun has long been considered a constant star, to the extent that its total irradiance was termed the solar constant. It required radiometers in space to detect the small variations in solar irradiance on timescales of the solar rotation…

Solar and Stellar Astrophysics · Physics 2015-06-11 Sami K. Solanki , Yvonne C. Unruh

Studies on Sun-climate connection have been carried out for several decades, and almost all of them focused on the effects of solar total irradiation energy. As the second major terrestrial energy source from outer space, the solar wind…

Space Physics · Physics 2017-09-19 Hui Li , Chi Wang , Shengping He , Huijun Wang , Cui Tu , Jiyao Xu , Fei Li , Xiaocheng Guo

Activity-related variations in the solar oscillation properties have been known for 30 years. However, the relative importance of the different contributions to the observed variations is not yet fully understood. Our goal is to estimate…

Solar and Stellar Astrophysics · Physics 2016-10-24 A. R. G. Santos , M. S. Cunha , P. P. Avelino , W. J. Chaplin , T. L. Campante

The sunspot number is analyzed by using detailed sunspot data, including aspects of observability, sunspot sizes, and proper identification of sunspot groups as discrete entities of the solar activity. The tests show that besides the…

Solar and Stellar Astrophysics · Physics 2016-06-01 Judit Muraközy , Tünde Baranyi , András Ludmány

The activity of the Sun as a result of cyclic changes of the global magnetic field is studied. As a consequence of the analysis of magnetic activity of solar-type stars the following power dependencies were found: the dependence between the…

Solar and Stellar Astrophysics · Physics 2015-10-22 E. A. Bruevich , I. K. Rozgacheva

A new method is presented for the construction of a natural continuous wavelet transform on the sphere. It incorporates the analysis and synthesis with the same wavelet and the definition of translations and dilations on the sphere through…

Astrophysics · Physics 2007-05-23 J. L. Sanz , D. Herranz , M. Lopez-Caniego , F. Argueso

Due to non-homogeneous mass distribution and non-uniform velocity rate inside the Sun, the solar outer shape is distorted in latitude. In this paper, we analyze the consequences of a temporal change in this figure on the luminosity. To do…

Solar and Stellar Astrophysics · Physics 2011-08-31 Z. Fazel , J. P. Rozelot , S. Lefebvre , A. Ajabshirizadeh , S. Pireaux

This review paper is intended to give a useful guide for those who want to apply discrete wavelets in their practice. The notion of wavelets and their use in practical computing and various applications are briefly described, but rigorous…

High Energy Physics - Phenomenology · Physics 2025-10-20 I. M. Dremin , O. V. Ivanov , V. A. Nechitailo

The solar wind magnetic field contains rotations at a broad range of scales, which have been extensively studied in the MHD range. Here we present an extension of this analysis to the range between ion and electron kinetic scales. The…

Space Physics · Physics 2015-09-16 C. H. K. Chen , L. Matteini , D. Burgess , T. S. Horbury

Some techniques for the study of intermittency by means of wavelet transforms, are presented on an example of synthetic turbulent signal. Several features of the turbulent field, that cannot be probed looking at standard structure function…

chao-dyn · Physics 2007-05-23 Piero Olla , Paolo Paradisi

Solar magnetic activity is expressed via variations of sunspots and active regions varying on different timescales. The most accepted is an 11-year period supposedly induced by the electromagnetic solar dynamo mechanism. There are also some…

Solar and Stellar Astrophysics · Physics 2023-01-19 Valentina V. Zharkova , Irina Vasilieva , Simon Shepherd , Elena Popova

We investigate the anisotropy of Alfv\'enic turbulence in the inertial range of slow solar wind and in both driven and decaying reduced magnetohydrodynamic simulations. A direct comparison is made by measuring the anisotropic second-order…

Space Physics · Physics 2012-08-20 C. H. K. Chen , A. Mallet , T. A. Yousef , A. A. Schekochihin , T. S. Horbury

The sun as an oscillator produces frequencies which propagate in the heliosphere, via solar wind, to the terrestrial magnetosphere. We searched for those frequencies in the parameters of the near Earth solar plasma and the geomagnetic…

Solar and Stellar Astrophysics · Physics 2016-11-11 Ch. Katsavrias , P. Preka-Papadema , X. Moussas