Related papers: Cluster Hot Flow Anomaly Observations During Solar…
Plasma processes occurring in the corona and solar wind can be probed by studying the thermodynamic properties of different ion species. However, most in-situ observations of positive ions in the solar wind are taken at 1 AU, where…
Unconditional and conditional statistics is used for studying the histograms of magnetic field multi-scale fluctuations in the solar wind near the solar cycle minimum in 2008. The unconditional statistics involves the magnetic data during…
Previous studies have shown that the observed temperature anisotropies of protons and alpha particles in the solar wind are constrained by theoretical thresholds for pressure-anisotropy-driven instabilities such as the…
Small flares frequently occur in the quiet Sun. Previous studies have noted that they share many common characteristics with typical solar flares in active regions. However, their similarities and differences are not fully understood,…
We examine the evolution of the zonal flow pattern in the upper solar convection zone during the current extended solar minimum, and compare it with that during the previous minimum. The results suggest that a configuration matching that at…
Studies of solar wind turbulence traditionally employ high-resolution magnetic field data, but high-resolution measurements of ion and electron moments have been possible only recently. We report the first turbulence studies of ion and…
Recent numerical simulations of the interstellar medium driven by energy input from supernovae and stellar winds indicate that HI clouds can be formed by compression in shock waves and colliding turbulent streams without any help from…
The minimum of solar cycle 24 is significantly different from most other minima in terms of its duration as well as its abnormally low levels of activity. Using available helioseismic data that cover epochs from the minimum of cycle 23 to…
We analyze the steady 1D flow equations for a rotating stellar wind based on a ``nozzle'' analogy for terms that constrain the local mass flux. For low rotation, we find the nozzle minimum occurs near the stellar surface, allowing a…
We used solar observations of a plage/enhanced network with the Atacama Large Millimeter/sub-millimeter Array (ALMA) in Band 3 and Band 6 together with synthetic continuum maps from numerical simulations with Bifrost at the same bands to…
Solar flares are highly energetic events that happen in the solar atmosphere. They are mostly observed as X-ray or gamma-ray bursts located on the Sun's surface. While they are known to be sites of particle acceleration, the acceleration…
Solar observations in the mid-infrared 8-14 \mu\m band continuum were carried out with cadence of 5 frames per second, in December 2007. Rapid small heated sources, with typical duration of the order of seconds, were found on the bright…
In the solar wind, magnetic field power spectra usually show several power-laws. In this paper, magnetic field data from the Cluster mission during an undisturbed interval of slow solar wind is analyzed at 0.28Hz, near the spectral break…
We have measured the meridional motions of the magnetic elements in the Sun's surface layers since 1996 and find systematic and substantial variations. In general the meridional flow speed is fast at cycle minima and slow at cycle maxima.…
Protons and alpha particles in the fast solar wind are only weakly collisional and exhibit a number of non-equilibrium features, including relative drifts between particle species. Two non-collisional mechanisms have been proposed for…
We report detection of oscillations in brightness temperature, size, and horizontal velocity of three small bright features in the chromosphere of a plage/enhanced-network region. The observations, which were taken with high temporal…
A statistical analysis of a large data set of H-alpha flares comprising almost 100000 single events that occurred during the period January 1975 to December 1999 is presented. We analyzed the flares evolution steps, i.e. duration, rise…
Over 54 years of hourly mean value of solar wind velocity from 27 Nov. 1963 to 31 Dec. 2017 are used to investigate characteristics of the rotation period of solar wind through auto-correlation analysis. Solar wind of high velocity is found…
Spacecraft observations have shown that the proton temperature in the solar wind falls off with radial distance more slowly than expected for an adiabatic prediction. Usually, previous studies have been focused on the evolution of the…
We investigate the origin of mesoscale structures in the solar wind called microstreams defined as enhancements in solar wind speed and temperature that last several hours. They were first clearly detected in Helios and Ulysses solar wind…