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An optically thin view of the flaring chromosphere: non-thermal widths in a chromospheric condensation during an X-class solar flare

Kowalski, Adam F.; Kerr, Graham S.; Allred, Joel C. +2 more

The bulk of solar flare energy is deposited in the chromosphere. Flare ribbons and footpoints in the chromosphere therefore offer great diagnostic potential of flare energy release and transport processes. High-quality observations from the Interface Region Imaging Spectrograph (IRIS) spacecraft have transformed our view of the Sun's atmospheric r…

Non-thermal broadening of coronal lines in a 3D MHD loop model

Peter, H.; Solanki, S. K.; De Moortel, I. +2 more

Observed spectral profiles of emission lines from the corona are found to have widths exceeding the thermal line width. To investigate the physical mechanism, we run a 3D magnetohydrodynamics model of a single, straightened loop in which we partially resolve turbulent motions that form in response to the driving by self-consistently evolving magne…

Spectroscopic diagnostic of the footpoints of the cool loops

Dwivedi, B. N.; Kayshap, Pradeep; Jelínek, P. +2 more

Statistically, the cool loop's footpoints are diagnosed using Si IV resonance lines observations provided by Interface Region Imaging Spectrograph (IRIS). The intensity and full width at half-maximum (FWHM) of the loop's footpoints in β-γ active regions (ARs) are higher than the corresponding parameters of footpoints in β ARs. However, the Doppler…

Effect of area divergence and frequency on damping of slow magnetoacoustic waves propagating along umbral fan loops

Gupta, Girjesh R.; Rawat, Ananya

Waves play an important role in the heating of solar atmosphere; however, observations of wave propagation and damping from the solar photosphere to corona through chromosphere and transition region are very rare. Recent observations have shown propagation of 3-min slow magnetoacoustic waves (SMAWs) along fan loops from the solar photosphere to co…

Imaging and spectroscopic observations of a confined solar filament eruption with two-stage evolution

Xu, Zhe; Xue, Zhike; Yan, Xiaoli +3 more

Solar filament eruptions are often characterized by stepwise evolution due to the involvement of multiple mechanisms, such as magnetohydrodynamic instabilities and magnetic reconnection. In this article, we investigated a confined filament eruption with a distinct two-stage evolution by using the imaging and spectroscopic observations from the Int…

Asymmetry of the spectral lines of the coronal hole and quiet Sun in the transition region

Kayshap, Pradeep; Safari, Hossein; Hosseini, Razieh +1 more

The asymmetry of line profiles, i.e. the secondary component, is crucial to understanding the energy release of coronal holes (CH), quiet Sun (QS), and bright points (BPs). We investigate the asymmetry of Si IV 1393.75 Å of the transition-region (TR) line recorded by Interface Region Imaging Spectrograph (IRIS) and co-spatial-temporal Atmospheric …