Related papers: Locating Hot Plasma in Small Flares using Spectros…
We present a detailed study of explosive chromospheric evaporation during a microflare which occurred on 2007 December 7 as observed with the EUV Imaging Spectrometer (EIS) onboard Hinode. We find temperature-dependent upflows for lines…
Magnetic reconnection is believed to be the dominant energy release mechanism in solar flares. The standard flare model predicts both downward and upward outflow plasmas with speeds close to the coronal Alfv\'{e}n speed. Yet, spectroscopic…
In previous studies a very hot plasma component has been diagnosed in solar active regions through the images in three different narrow-band channels of SDO/AIA. This diagnostic from EUV imaging data has also been supported by the matching…
We study spectroscopic observations of chromospheric evaporation mass flows in comparison to the energy input by electron beams derived from hard X-ray data for the white-light M2.5 flare of 2006 July 6. The event was captured in high…
We investigate the August 9, 2011 solar flare of X-ray class X6.9, the "hottest" flare from 2000 to 2012, with a peak plasma temperature according to GOES data of 32.5 MK. Our goal is to determine the cause of such an anomalously high…
Investigate particle acceleration and heating in a solar microflare. In a microflare with non-thermal emission to remarkably high energies ($>50$ keV), we investigate the hard X-rays with RHESSI imaging and spectroscopy and the resulting…
In the classical flare picture, hard X-ray emission from the chromosphere is succeeded by soft-X-ray emission from hot plasma in the flare loop, the soft X-ray emission being a direct consequence of the impact of the non-thermal particle…
Non-thermal velocities, derived from spectral line broadening, can provide crucial insights into plasma dynamics before and during solar flares. To systematically study the pre-flare phase, we constructed a Hinode/Extreme-ultraviolet…
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…
The sites of chromospheric excitation during solar flares are marked by extended extreme ultraviolet ribbons and hard X-ray footpoints. The standard interpretation is that these are the result of heating and bremsstrahlung emission from…
We present direct evidence for the detection of the main energy release site in a non-eruptive solar flare, SOL2013-11-09T06:38UT. This GOES C2.7 event was characterised by two flaring ribbons and a compact, bright coronal source located…
In this paper we analyze soft and hard X-ray emission of the 2002 September 20 M1.8 GOES class solar flare observed by RHESSI and GOES satellites. In this flare event, soft X-ray emission precedes the onset of the main bulk hard X-ray…
Numerical models of solar flares typically focus on the behaviour of directly-heated flare models, adopting magnetic field- aligned, plane-parallel methodologies. With high spatial- and spectral-resolution ground-based optical observations…
We perform a time-dependent ionization analysis to constrain plasma heating requirements during a fast partial halo coronal mass ejection (CME) observed on 2000 June 28 by the Ultraviolet Coronagraph Spectrometer (UVCS) aboard the Solar and…
We present high spatial resolution observations of chromospheric evaporation in the flare SOL2014-03-29T17:48. Interface Region Imaging Spectrograph (IRIS) observations of the FeXXI 1354.1 A line indicate evaporating plasma at a temperature…
From Doppler velocity maps of active regions constructed from spectra obtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft we observe large areas of outflow (20-50 km/s) that can persist for at least a…
A complete understanding of Doppler shift in active region loops can help probe the basic physical mechanism involved into the heating of those loops. Here we present observations of upflows in coronal loops detected in a range of…
EUV observations of warm coronal loops suggest that they are bundles of unresolved strands that are heated impulsively to high temperatures by nanoflares. The plasma would then have the observed properties (e.g., excess density compared to…
One of the defining characteristics of a solar flare is the impulsive formation of very high temperature plasma. The properties of the thermal emission are not well understood, however, and the analysis of solar flare observations is often…
The study of the localized plasma conditions before the impulsive phase of a solar flare can help us understand the physical processes that occur leading up to the main flare energy release. Here, we present evidence of a hot X-ray onset…