Search Publications
Solar Microflares Observed by SphinX and RHESSI
Mrozek, Tomasz; Kepa, Anna; Sylwester, Barbara +4 more
In 2009, the Russian Complex Orbital Observations Near-Earth of Activity of the Sun (CORONAS-Photon) spacecraft was launched, carrying the Polish Solar PHotometer In X-rays (SphinX). The SphinX was most sensitive in the spectral range 1.2 - 15 keV, thus an excellent opportunity appeared for comparison with the low-energy end of Ramaty High Energy …
A Long-Term Dissipation of the EUV He II (30.4 nm) Segmentation in Full-Disk Solar Images
Didkovsky, Leonid
Some quiet-Sun days observed by the Atmospheric Imaging Assembly (AIA) on-board the Solar Dynamics Observatory (SDO) during the time interval in 2010 - 2017 were used to continue our previous analyses reported by Didkovsky and Gurman (Solar Phys.289, 153, 2014a) and Didkovsky, Wieman, and Korogodina (Solar Phys.292, 32, 2017). The analysis consist…
Small-Scale Activity Above the Penumbra of a Fast-Rotating Sunspot
Bharti, L.; Sobha, B.; Quintero Noda, C. +3 more
High-resolution observations of small-scale activity above the filamentary structure of a fast-rotating sunspot of NOAA Active Region 10930 are presented. The penumbral filament that intrudes into the umbra shows a central dark core and substructures. It almost approached another end of the umbra, like a light bridge. The chromospheric Ca II H ima…
The Interaction of Successive Coronal Mass Ejections: A Review
Temmer, Manuela; Wang, Yuming; Lugaz, Noé +1 more
We present a review of the different aspects associated with the interaction of successive coronal mass ejections (CMEs) in the corona and inner heliosphere, focusing on the initiation of series of CMEs, their interaction in the heliosphere, the particle acceleration associated with successive CMEs, and the effect of compound events on Earth's mag…
Determining the Intrinsic CME Flux Rope Type Using Remote-sensing Solar Disk Observations
Palmerio, E.; Kilpua, E. K. J.; Green, L. M. +4 more
A key aim in space weather research is to be able to use remote-sensing observations of the solar atmosphere to extend the lead time of predicting the geoeffectiveness of a coronal mass ejection (CME). In order to achieve this, the magnetic structure of the CME as it leaves the Sun must be known. In this article we address this issue by developing…
Understanding the Physical Nature of Coronal "EIT Waves"
Long, D. M.; Veronig, A. M.; Vršnak, B. +9 more
For almost 20 years the physical nature of globally propagating waves in the solar corona (commonly called "EIT waves") has been controversial and subject to debate. Additional theories have been proposed over the years to explain observations that did not agree with the originally proposed fast-mode wave interpretation. However, the incompatibili…
Estimation of Reconnection Flux Using Post-eruption Arcades and Its Relevance to Magnetic Clouds at 1 AU
Gopalswamy, N.; Yashiro, S.; Xie, H. +1 more
We report on a new method to compute the flare reconnection (RC) flux from post-eruption arcades (PEAs) and the underlying photospheric magnetic fields. In previous works, the RC flux has been computed using the cumulative flare ribbon area. Here we obtain the RC flux as the flux in half of the area underlying the PEA in EUV imaged after the flare…
Coronal Holes and Open Magnetic Flux over Cycles 23 and 24
Qiu, Jiong; Lowder, Chris; Leamon, Robert
As the observational signature of the footprints of solar magnetic field lines open into the heliosphere, coronal holes provide a critical measure of the structure and evolution of these lines. Using a combination of Solar and Heliospheric Observatory/Extreme ultraviolet Imaging Telescope (SOHO/EIT), Solar Dynamics Observatory/Atmospheric Imaging …
Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): High-Resolution Interferometric Imaging
de Gregorio-Monsalvo, I.; Kim, S.; De Pontieu, B. +25 more
Observations of the Sun at millimeter and submillimeter wavelengths offer a unique probe into the structure, dynamics, and heating of the chromosphere; the structure of sunspots; the formation and eruption of prominences and filaments; and energetic phenomena such as jets and flares. High-resolution observations of the Sun at millimeter and submil…
Nonequilibrium Processes in the Solar Corona, Transition Region, Flares, and Solar Wind (Invited Review)
Krucker, Säm; Meyer-Vernet, Nicole; Del Zanna, Giulio +12 more
We review the presence and signatures of the non-equilibrium processes, both non-Maxwellian distributions and non-equilibrium ionization, in the solar transition region, corona, solar wind, and flares. Basic properties of the non-Maxwellian distributions are described together with their influence on the heat flux as well as on the rates of indivi…