Search Publications
High-resolution observational analysis of flare ribbon fine structures
Fletcher, Lyndsay; Nóbrega-Siverio, Daniel; Aulanier, Guillaume +4 more
Context. Since the mechanism of energy release from solar flares is still not fully understood, the study of fine-scale features developing during flares becomes important for progressing towards a consistent picture of the essential physical mechanisms. Aims. Solar flares release most of their luminous energy in the chromosphere. These luminous s…
Observation of super-Alfvénic slippage of reconnecting magnetic field lines on the Sun
Polito, Vanessa; De Pontieu, Bart; Aulanier, Guillaume +3 more
Slipping motions of magnetic field lines are a distinct signature of three-dimensional magnetic reconnection, a fundamental process driving solar and stellar flares. While being a key prediction of numerical experiments, the rapid super-Alfvénic field line slippage driven by the `slip-running' reconnection has remained elusive in previous observat…
Quasiperiodic Super-Alfvénic Slippage along Flare Ribbons Observed by the Interface Region Imaging Spectrograph
Hou, Yijun; Li, Ting; Zhou, Guiping +3 more
The apparent slipping motion of flare loops is regarded as a key feature of the 3D magnetic reconnection in the solar flares. The slippage with a super-Alfvénic speed could be defined as slipping–running reconnection, while the slippage with a sub-Alfvénic speed is called slipping reconnection. Due to the limitation of the observational instrument…
Spectroscopic diagnosis of a B-class flare and an associated filament eruption
Kayshap, Pradeep; Babu, B. Suresh; Tripathi, Sharad C.
The flare ribbon and an associated filament eruption are diagnosed using O IV 1401.16 Å, Si IV 1402.77 Å, and Mg II k 2796.35 Å spectral lines provided by Interface Region Imaging Spectrograph (IRIS). The flare ribbons have downflow (redshifts) in all these lines, and this redshift decreases from the transition region to the chromosphere. While th…
Temporal Evolution of a Network Jet's Physical Properties Inferred from FISS/GST and IRIS Observations
Yurchyshyn, Vasyl; Chae, Jongchul; Cho, Kyuhyoun +6 more
Small-scale jets, such as chromospheric and transition region (TR) network jets, are of great interest regarding coronal heating and solar wind acceleration. Spectroscopic analysis based on multiple spectral lines with different formation temperatures is essential for understanding the physical properties and driving mechanisms of jets. Here, we c…
ALMA Observations of Solar Spicules in a Polar Coronal Hole
Nindos, A.; White, S. M.; Shimojo, M. +2 more
We report observations of solar spicules at millimeter wavelengths (mm-λ) using the Atacama Large Millimeter/submillimeter Array (ALMA). These are supplemented by observations in optical, ultraviolet (UV), and extreme ultraviolet (EUV) wavelengths. The observations were made on 2018 December 25 of the northern polar coronal hole. ALMA obtained tim…
Solar Variability in the Mg II h and k Lines
Solanki, S. K.; Shapiro, A. I.; Krivova, N. A. +3 more
Solar irradiance and its variations in the ultraviolet (UV) control the photochemistry in Earth's atmosphere and influence Earth's climate. The variability in the Mg II h and k core-to-wing ratio, also known as the Mg II index, is highly correlated with the solar UV irradiance variability. Because of this, the Mg II index is routinely used as a pr…
Simultaneous Existence of Oscillations, Counterstreaming Flows, and Mass Injections in Solar Quiescent Prominences
Xu, Zhe; Xue, Zhike; Yan, Xiaoli +8 more
Solar prominences are very spectacular structures embedded in the tenuous and hot solar corona. Counterstreaming flows, a common feature in solar quiescent prominences, have been discovered for more than 20 yr. However, the mechanism driving the counterstreaming flows is still elusive. To unveil the nature of this phenomenon, we analyzed data of a…
On the Magnetic and Thermodynamic Properties of Dark Fibrils in the Chromosphere
Kriginsky, Matheus; Oliver, Ramon
Fibrillar structures are ubiquitous in the solar chromosphere. An accurate determination of their properties requires the use of advanced high-resolution observations, which are now becoming broadly available from different observatories. We exploit the capabilities of multi-atom, multiline spectropolarimetric inversions using the Stockholm Invers…