Search Publications
Extreme-ultraviolet bursts and nanoflares in the quiet-Sun transition region and corona
Peter, H.; Chitta, L. P.; Young, P. R.
The quiet solar corona consists of myriads of loop-like features, with magnetic fields originating from network and internetwork regions on the solar surface. The continuous interaction between these different magnetic patches leads to transient brightenings or bursts that might contribute to the heating of the solar atmosphere. The literature on …
A magnetic reconnection model for hot explosions in the cool atmosphere of the Sun
Ni, Lei; Chen, Yajie; Lin, Jun +2 more
Context. Ultraviolet (UV) bursts and Ellerman bombs (EBs) are transient brightenings observed in the low solar atmospheres of emerging flux regions. Magnetic reconnection is believed to be the main mechanism leading to formation of the two activities, which are usually formed far apart from each other. However, observations also led to the discove…
Solar prominence diagnostics from non-LTE modelling of Mg II h&k line profiles
Barczynski, K.; Schmieder, B.; Labrosse, N. +1 more
Aims: We investigate a new method to for obtaining the plasma parameters of solar prominences observed in the Mg II h&k spectral lines by comparing line profiles from the IRIS satellite to a bank of profiles computed with a one-dimensional non-local thermodynamic equilibrium (non-LTE) radiative transfer code.
Methods: Using a grid of…
Multi-thermal atmosphere of a mini-solar flare during magnetic reconnection observed with IRIS
Heinzel, Petr; Aulanier, Guillaume; Schmieder, Brigitte +4 more
Context. The Interface Region Imaging Spectrograph (IRIS) with its high spatial and temporal resolution facilitates exceptional plasma diagnostics of solar chromospheric and coronal activity during magnetic reconnection.
Aims: The aim of this work is to study the fine structure and dynamics of the plasma at a jet base forming a mini-flare bet…
Spectroscopic observations of a flare-related coronal jet
Li, D.; Zhang, Q. M.; Huang, Z. H. +3 more
Context. Coronal jets are ubiquitous in active regions and coronal holes.
Aims: In this paper, we study a coronal jet related to a C3.4 circular-ribbon flare in the active region 12434 on 2015 October 16.
Methods: The flare and jet were observed in ultraviolet and extreme ultraviolet wavelengths by the Atmospheric Imaging Assembly on boa…
Evidence of the multi-thermal nature of spicular downflows. Impact on solar atmospheric heating
Joshi, Jayant; Martínez-Sykora, Juan; De Pontieu, Bart +4 more
Context. Spectroscopic observations of the emission lines formed in the solar transition region commonly show persistent downflows on the order of 10−15 km s−1. The cause of such downflows, however, is still not fully clear and has remained a matter of debate.
Aims: We aim to understand the cause of such downflows by studying the c…
Balmer continuum enhancement detected in a mini flare observed with IRIS
Heinzel, Petr; Schmieder, Brigitte; Joshi, Reetika +3 more
Context. Optical and near-UV continuum emissions in flares contribute substantially to the flare energy budget. Two mechanisms play an important role for continuum emission in flares: hydrogen recombination after sudden ionization at chromospheric layers, and transportation of the energy radiatively from the chromosphere to lower layers in the atm…
Solar surges related to UV bursts. Characterization through k-means, inversions, and density diagnostics
Guglielmino, S. L.; Sainz Dalda, A.; Nóbrega-Siverio, D.
Context. Surges are cool and dense ejections typically observed in chromospheric lines and closely related to other solar phenomena such as UV bursts or coronal jets. Even though surges have been observed for decades now, questions regarding their fundamental physical properties such as temperature and density, as well as their impact on upper lay…
Spectro-imagery of an active tornado-like prominence: Formation and evolution
Barczynski, Krzysztof; Schmieder, Brigitte; Labrosse, Nicolas +3 more
Context. The dynamical nature of fine structures in prominences remains an open issue, including rotating flows in tornado prominences. While the Atmospheric Imaging Assembly imager aboard the Solar Dynamics Observatory allowed us to follow the global structure of a tornado-like prominence for five hours, the Interface Region Imaging Spectrograph,…
Comparison of active region upflow and core properties using simultaneous spectroscopic observations from IRIS and Hinode
Barczynski, Krzysztof; Brooks, David H.; Kleint, Lucia +2 more
Context. The origin of the slow solar wind is still an open issue. It has been suggested that upflows at the edge of active regions are a possible source of the plasma outflow and therefore contribute to the slow solar wind.
Aims: We investigate the origin and morphology of the upflow regions and compare the upflow region and the active regio…