Search Publications
Spectral Signatures of Chromospheric Condensation in a Major Solar Flare
Allred, Joel; Graham, David R.; Zangrilli, Luca +3 more
We study the evolution of chromospheric line and continuum emission during the impulsive phase of the X-class SOL2014-09-10T17:45 solar flare. We extend previous analyses of this flare to multiple chromospheric lines of Fe I, Fe II, Mg II, C I, and Si II observed with the Interface Region Imaging Spectrograph, combined with radiative-hydrodynamica…
Ion-neutral Interactions and Nonequilibrium Ionization in the Solar Chromosphere
Martínez-Sykora, Juan; De Pontieu, Bart; Nóbrega-Siverio, Daniel +4 more
The thermal structure of the chromosphere is regulated through a complex interaction of various heating processes, radiative cooling, and the ionization degree of the plasma. Here, we study the impact on the thermal properties of the chromosphere when including the combined action of nonequilibrium ionization (NEI) of hydrogen and helium and ion-n…
Hot Plasma Flows and Oscillations in the Loop-top Region During the 2017 September 10 X8.2 Solar Flare
Reeves, Katharine K.; Polito, Vanessa; Chen, Bin +4 more
In this study, we investigate motions in the hot plasma above the flare loops during the 2017 September 10 X8.2 flare event. We examine the region to the south of the main flare arcade, where there is data from the Interface Region Imaging Spectrograph (IRIS) and the Extreme ultraviolet Imaging Spectrometer (EIS) on Hinode. We find that there are …
IRIS Observations of Short-term Variability in Moss Associated with Transient Hot Coronal Loops
Polito, Vanessa; Testa, Paola; De Pontieu, Bart
We observed rapid variability (≲60 s) at the footpoints of transient, hot (∼8-10 MK) coronal loops in active region cores, with the Interface Region Imaging Spectrograph (IRIS). The high spatial (∼0"33) and temporal (≲5-10 s) resolution of IRIS is often crucial for the detection of this variability. We show how, in combination with 1D RADYN loop m…
Onset of Turbulent Fast Magnetic Reconnection Observed in the Solar Atmosphere
Chitta, L. P.; Lazarian, A.
Fast magnetic reconnection powers explosive events throughout the universe, from gamma-ray bursts to solar flares. Despite its importance, the onset of astrophysical fast reconnection is the subject of intense debate and remains an open question in plasma physics. Here we report high-cadence observations of two reconnection-driven solar microflare…
Solar Flare Arcade Modeling: Bridging the Gap from 1D to 3D Simulations of Optically Thin Radiation
Polito, Vanessa; Kerr, Graham S.; Allred, Joel C.
Solar flares are 3D phenomena, but modeling a flare in 3D, including many of the important processes in the chromosphere, is a computational challenge. Accurately modeling the chromosphere is important, even if the transition region and corona are the areas of interest, due to the flow of energy, mass, and radiation through the interconnected laye…
Real-time Flare Prediction Based on Distinctions between Flaring and Non-flaring Active Region Spectra
Kleint, Lucia; Panos, Brandon
With machine learning entering into the awareness of the heliophysics community, solar flare prediction has become a topic of increased interest. Although machine-learning models have advanced with each successive publication, the input data has remained largely fixed on magnetic features. Despite this increased model complexity, results seem to i…
Imaging and Spectral Study on the Null Point of a Fan-spine Structure During a Solar Flare
Yang, Shuhong; Zhang, Jun; Zhong, Ze +3 more
Using the multi-instrument observations, we make the first simultaneous imaging and spectral study on the null point of a fan-spine magnetic topology during a solar flare. When magnetic reconnection occurs at the null point, the fan-spine configuration brightens in the (extreme-)ultraviolet channels. In the Hα images, the fan-spine structure is pa…
The Formation Height of Millimeter-wavelength Emission in the Solar Chromosphere
Martínez-Sykora, Juan; De Pontieu, Bart; Chintzoglou, Georgios +1 more
In the past few years, the ALMA radio telescope has become available for solar observations. ALMA diagnostics of the solar atmosphere are of high interest because of the theoretically expected linear relationship between the brightness temperature at millimeter wavelengths and the local gas temperature in the solar atmosphere. Key for the interpre…
Dynamics of Late-stage Reconnection in the 2017 September 10 Solar Flare
Judge, Philip G.; Long, David M.; Matthews, Sarah A. +2 more
In this multi-instrument paper, we search for evidence of sustained magnetic reconnection far beyond the impulsive phase of the X8.2-class solar flare on 2017 September 10. Using Hinode/EIS, CoMP, SDO/AIA, K-Cor, Hinode/XRT, RHESSI, and IRIS, we study the late-stage evolution of the flare dynamics and topology, comparing signatures of reconnection…