Related papers: Micro-events in the active and quiet solar corona
Magnetic energy is required to heat the corona, the outer atmosphere of the Sun, to millions of degrees. We study the nature of the magnetic energy source that is probably responsible for the brightening of coronal loops driven by…
The High-resolution Coronal Imager (Hi-C) has provided Fe XII 193A images of the upper transition region moss at an unprecedented spatial (~0.3-0.4 arcsec) and temporal (5.5s) resolution. The Hi-C observations show in some moss regions…
Context: Solar flares release a large fraction of their energy into non-thermal electrons, but it is not clear where and how. Bremsstrahlung X-rays are observed from the corona and chromosphere. Aims: We aim to characterize the acceleration…
Transition region explosive events are characterized by non-Gaussian profiles of the emission lines formed at transition region temperatures, and they are believed to be manifestations of small-scale reconnection events in the transition…
The heating of the lower solar corona is examined using numerical simulations and theoretical models of magnetohydrodynamic turbulence in open magnetic regions. A turbulent energy cascade to small length scales perpendicular to the mean…
Observational measurements of active region emission measures contain clues to the time-dependence of the underlying heating mechanism. A strongly non-linear scaling of the emission measure with temperature indicates a large amount of hot…
Small-scale brightenings in solar atmospheric observations are a manifestation of heating and/or energy transport events. We present statistical characteristics of brightenings from a new detection method applied to 1330, 1400, and 2796…
Coronal heating has puzzled solar physicists for decades. The question of why the Sun's upper atmosphere is significantly hotter than its lower atmosphere remains a key mystery. It is commonly believed that the source of coronal heating…
Solar Orbiter EUV observations reveal ubiquitous small-scale brightenings in the quiet-Sun low corona. We analyze the spatial and temporal dissipation scales of these events with a focus on the formation, evolution, and dissipation of…
We present observations of transient active region heating events observed with the Extreme Ultraviolet Imaging Spectrometer (EIS) and X-ray Telescope (XRT) on Hinode. This initial investigation focuses on NOAA active region 10940 as…
The heating of the solar corona and the puzzle of the slender high reaching magnetic loops seen in observations from the Transition Region And Coronal Explorer(TRACE) has been investigated through 3D numerical simulations, and found to be…
Previous observations have not been able to exclude the possibility that high temperature active region loops are actually composed of many small scale threads that are in various stages of heating and cooling and only appear to be in…
The million degree plasma of the solar corona must be supplied by the underlying layers of the atmosphere. The mechanism and location of energy release, and the precise source of coronal plasma, remain unresolved. In earlier work we pursued…
Solar nanoflares are small eruptive events releasing magnetic energy in the quiet corona. If nanoflares follow the same physics as their larger counterparts, they should emit hard X-rays (HXRs) but with a rather faint intensity. A copious…
It is generally agreed that small impulsive energy bursts called nanoflares are responsible for at least some of the Sun's hot corona, but whether they are the explanation for most of the multi-million degree plasma has been a matter of…
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…
During solar flares, a considerable portion of the flare atmosphere becomes heated; however, the energy deposition process is still unclear, especially in the lower solar atmosphere. Here, we present spectroscopic and imaging observations…
Coronal loops on the east limb of the Sun were observed by SUMER on SOHO for several days. Small flare-like brightenings are detected very frequently in the hot flare line Fe~{\small XIX}. We find that the relatively intense events are in…
The heating of the solar chromosphere and corona to the observed high temperatures, imply the presence of ongoing heating that balances the strong radiative and thermal conduction losses expected in the solar atmosphere. It has been…
We present data analysis and interpretation of an M1.4-class flare observed with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) on April 30, 2002. This event, with its footpoints occulted by the solar limb, exhibits a…