Related papers: Hysteresis in a Solar Activity Cycle
Current helicity and twist of solar magnetic fields are important quantities to characterize the dynamo mechanism working in the convection zone of the Sun. We have carried out a statistical study on the current helicity of solar active…
In this paper, I present the results on large-scale evolution of density turbulence of solar wind in the inner heliosphere during 1985 - 2009. At a given distance from the Sun, the density turbulence is maximum around the maximum phase of…
The spatiotemporal inhomogeneous-homogeneous transition in the dynamics and structures of solar photospheric turbulence is studied by applying the complexity-entropy analysis to Hinode images of a vortical region of supergranular junctions…
We report on the annual variation of quiet-time suprathermal ion composition for C through Fe using Advanced Composition Explorer (ACE)/Ultra-Low Energy Isotope Spectrometer (ULEIS) data over the energy range 0.3 MeV/nuc to 1.28 MeV/nuc…
We study the radial evolution of intermittency of density fluctuations in the fast solar wind. The study is performed analyzing the plasma density measurements provided by Helios 2 in the inner heliosphere between $0.3$ and $0.9$ AU. The…
Using the SIT instrument aboard STEREO we have examined the abundance of the 3He during the ascending phase of solar cycle 24 from January 2010 through December 2012. We report on several cases when 3He-rich solar energetic particle events…
Statistical classification of the Helios solar wind observations into several populations sorted by bulk speed has revealed an outward acceleration of the wind. The faster the wind is, the smaller is this acceleration in the 0.3 - 1 au…
The properties of inertial and kinetic range solar wind turbulence have been investigated with the arbitrary-order Hilbert spectral analysis method, applied to high-resolution density measurements. Due to the small sample size, and to the…
We examine continuous measurements of the high-degree acoustic mode frequencies of the Sun covering the period from 2001 July to June 2014. These are obtained through the ring-diagram technique applied to the full-disk Doppler observations…
The linear scaling of the mixed third-order moment of the magnetohydrodynamic fluctuations is used to estimate the energy transfer rate of the turbulent cascade in the expanding solar wind. In 1976 the Helios 2 spacecraft measured three…
Motivated by recent observations of distinct parallel and perpendicular signatures in magnetic helicity measurements segregated by wave period and angle between the local magnetic field and the solar wind velocity, this paper undertakes a…
We apply the finite size scaling technique to quantify the statistical properties of fluctuations in AU, AL and AE indices and in the epsilon parameter that represents energy input from the solar wind into the magnetosphere. We find that…
The solar wind is highly turbulent, and intermittency effects are observed for fluctuations within the inertial range. By analyzing magnetic field spectra and fourth-order moments, we perform a comparative study of turbulence and…
The long-term evolution of the Sun's rotation period cannot be directly observed, and is instead inferred from trends in the measured rotation periods of other Sun-like stars. Assuming the Sun spins-down as it ages, following rotation rate…
The dependence of the sources and properties of the near-Earth solar wind on solar cycle activity is an important issue in solar and space physics. We use the improved two-step mapping procedure that takes into account the initial…
Characterizing compressible fluctuations in the solar wind is essential for understanding their role in solar wind acceleration and heating, yet their origin and evolution across different turbulence regimes remain poorly understood. In…
Understanding solar wind variability throughout the heliosphere is essential for fundamental space physics and future exploration of the Moon and Mars. The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft has provided upstream…
The statistical properties of magnetic discontinuities in the solar wind are investigated by measuring fluctuations in the magnetic field direction, given by the rotation Delta theta that the magnetic field vector undergoes during time…
Solar magnetism is measured with different indexes: for instance the MPSI and the MWSI, number of sunspots, radio flux at 10.7 cm, Ca II K, Mg II K, EUV, He I or L_alpha. Bachmann & White (1994) had compared these indicators of the solar…
Measurements and simulations of inertial compressive turbulence in the solar wind are characterized by anti-correlated magnetic fluctuations parallel to the mean field and density structures. This signature has been interpreted as…