Related papers: Hot Plasma in Non-Flaring Active Regions Observed …
A detailed study is presented of the decaying solar active region NOAA 10103 observed with the Coronal Diagnostic Spectrometer (CDS), the Michelson Doppler Imager (MDI) and the Extreme-ultraviolet Imaging Telescope (EIT) onboard the Solar…
We investigate the chromospheric evaporation in the flare of 2007 January 16 using line profiles observed by the EUV Imaging Spectrometer (EIS) onboard Hinode. Three points at flare ribbons of different magnetic polarities are analyzed in…
We use UV spectral observations of active regions with the Interface Region Imaging Spectrograph (IRIS) to investigate the properties of the coronal FeXII 1349.4A emission at unprecedented high spatial resolution (~0.33"). We find that by…
Measuring the relative amount of high-temperature, low-emission-measure plasma is considered to be a smoking gun observation to constrain the frequency of plasma heating in coronal structures. Often, narrowband, extreme ultraviolet images,…
Context. The details of the spectral profiles of extreme UV emission lines from solar active regions contain key information to investigate the structure, dynamics, and energetics of the solar upper atmosphere. Aims. We characterize the…
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 EUV Imaging Spectrometer (EIS) instrument on board the Hinode satellite has access to some of the best coronal density diagnostics and the high sensitivity of the instrument now allows electron number density, N_e, measurements to an…
The identifications of Fe VII emission lines in the wavelength range 193-197 {\AA} are discussed in the light of new measurements of laboratory spectra and atomic data calculations. This region is of importance to studies of solar spectra…
Context: Flare kernels brighten simultaneously in all SDO/AIA channels making it difficult to determine their temperature structure. IRIS is able to spectrally resolve Fe xxi emission from cold chromospheric brightenings, so can be used to…
The Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft observed flare footpoint regions coincident with a surge for a M3.7 flare observed on 25 September 2011 at N12 E33 in active region 11302. The flare was observed in…
We present a Differential Emission Measure (DEM) analysis of the quiet solar corona on disk using data obtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on {\it Hinode}. We show that the expected quiet Sun DEM distribution can…
Wide-field EUV telescopes imaging in spectral bands sensitive to 1 MK plasma on the Sun often observe extended ray-like coronal structures stretching radially from active regions to distances of 1.5-2Rsun, which represent the EUV…
This thesis strives to improve our understanding of solar activity, specifically the behaviour of solar flares and coronal mass ejections. An investigation into the hydrodynamic evolution of a confined solar flare was carried out using…
Recent progress in obtaining high spatial resolution images of the solar corona in the extreme-ultraviolet (EUV) with Hinode, TRACE, SDO and recent Hi-C missions and soft X-ray (SXR) bands opened a new avenue in understanding the solar…
In this paper, with a set of high-resolution He I 10830 \AA\ filtergrams, we select an area in a plage, very likely an EUV moss area, as an interface layer to follow the clues of coronal heating channels down to the photosphere. The…
The excess broadening of high-temperature spectral lines, long observed near the tops of flare arcades, is widely considered to result from magnetohydrodynamic (MHD) turbulence. According to different theories, plasma turbulence is also…
We present Extreme Ultraviolet Explorer spectroscopy and photometry of the nearby F8 V star HD 35850 (HR 1817). The EUVE spectra reveal 28 emission lines from Fe IX and Fe XV to Fe XXIV. The Fe XXI 102, 129 A ratio yields an upper limit for…
The frequency of heating events in the corona is an important constraint on the coronal heating mechanisms. Observations indicate that the intensities and velocities measured in active region cores are effectively steady, suggesting that…
Archived high-resolution X-ray spectra in the 13~\AA\ to 22~\AA\ range from the Flat Crystal Spectrometer (FCS), an instrument on the Solar Maximum Mission operating in the 1980s, are analyzed with reference to nonflaring active regions,…
High resolution spectra of the active binary Capella (G8 III + G1 III) covering the energy range 0.4-8.0 keV (1.5-30 Angstroms) show a large number of emission lines, demonstrating the performance of the HETGS. A preliminary application of…