Related papers: What determines active region coronal plasma compo…
Waves are thought to play a significant role in the heating of the solar atmosphere and the acceleration of the wind. Among the many types of waves observed in the Sun, the so-called p-modes with a 3 mHz frequency peak dominate the lower…
Coronal loops are the basic structures of the solar transition region and corona. The understanding of physical mechanism behind the loop heating, plasma flows, and filling are still considered a major challenge in the solar physics. The…
The large uncertainties associated with measuring the amount of high temperature emission in solar active regions represents a significant impediment to making progress on the coronal heating problem. Most current observations at…
A model for element abundance fractionation between the solar chromosphere and corona is further developed. The ponderomotive force due to Alfven waves propagating through, or reflecting from the chromosphere in solar conditions generally…
Previous solar observations have shown that coronal loops near 1 MK are difficult to reconcile with simple heating models. These loops have lifetimes that are long relative to a radiative cooling time, suggesting quasi-steady heating. The…
Understanding the relationship between the magnetic field and coronal heating is one of the central problems of solar physics. However, studies of the magnetic properties of impulsively heated loops have been rare. We present results from a…
The structure of the solar corona is dominated by the magnetic field because the magnetic pressure is about four orders of magnitude higher than the plasma pressure. Due to the high conductivity the emitting coronal plasma (visible e.g. in…
The relationships among coronal loop structures at different temperatures is not settled. Previous studies have suggested that coronal loops in the core of an active region are not seen cooling through lower temperatures and therefore are…
The solar corona is the origin of very dynamic events that are mostly produced in active regions (AR) and coronal holes (CH). The exact location of these large-scale features can be determined by applying image-processing approaches to…
Flares and eruptions from solar active regions are associated with atmospheric electrical currents accompanying distortions of the coronal field away from a lowest-energy potential state. In order to better understand the origin of these…
Helioseismology has shown that the chemical composition of the Sun has changed over its lifetime. The surface abundance of helium and heavy elements is believed to have decreased by up to 10% relative to their initial values. However, this…
Two of the most widely observed and yet most puzzling features of the Sun's magnetic field are coronal loops that are smooth and laminar and prominences/filaments that are strongly sheared. These two features would seem to be quite…
XMM-Newton has been performing comprehensive studies of X-ray luminous RS CVn binary systems in its calibration and guaranteed time programs. We present results from ongoing investigations in the context of a systematic study of coronal…
Analysis of the solar corona structure during the periods of minimum solar activity from 1867 till 2006 has been carried out. A new flattening index for the large coronal streamers has been proposed. It has been shown that the index has…
We analyse the evolution of coronal plasma upflows from the edges of AR 10978, which has the best limb-to-limb data coverage with Hinode's EUV Imaging Spectrometer (EIS). We find that the observed evolution is largely due to the solar…
The profiles of emission lines formed in the corona contain information on the dynamics and the heating of the hot plasma. Only recently has data with sufficiently high spectral resolution become available for investigating the details of…
This is a study of abundances of the elements He, C, N, O, Ne, Mg, Si, S, Ar, Ca, and Fe in solar energetic particles (SEPs) in the 2 - 15 MeV amu-1 region measured on the Wind spacecraft during 54 large SEP events occurring between…
The steep power-law dependence of element abundance enhancements on the mass-to-charge ratios [A/Q] of the ions in impulsive solar energetic-particle (SEP) events causes these enhancements to reflect the temperature-dependent pattern of Q…
With the aim of understanding how the magnetic properties of active regions (ARs) control the eruptive character of solar flares, we analyze 719 flares of Geostationary Operational Environmental Satellite (GOES) class $\geq$C5.0 during…
Dynamic fibrils (DFs) are commonly observed chromospheric features in solar active regions. Recent observations from the Extreme Ultraviolet Imager (EUI) aboard the Solar Orbiter have revealed unambiguous signatures of DFs at the coronal…