Search Publications
Modelling Quasi-Periodic Pulsations in Solar and Stellar Flares
Nakariakov, V. M.; Jelínek, P.; McLaughlin, J. A. +2 more
Solar flare emission is detected in all EM bands and variations in flux density of solar energetic particles. Often the EM radiation generated in solar and stellar flares shows a pronounced oscillatory pattern, with characteristic periods ranging from a fraction of a second to several minutes. These oscillations are referred to as quasi-periodic p…
Global Non-Potential Magnetic Models of the Solar Corona During the March 2015 Eclipse
Morgan, Huw; Feng, Xueshang; Downs, Cooper +17 more
Seven different models are applied to the same problem of simulating the Sun's coronal magnetic field during the solar eclipse on 2015 March 20. All of the models are non-potential, allowing for free magnetic energy, but the associated electric currents are developed in significantly different ways. This is not a direct comparison of the coronal m…
Detection of Quasi-Periodic Pulsations in Solar EUV Time Series
Zhukov, A. N.; Dolla, L.; Lapenta, G. +2 more
Quasi-periodic pulsations (QPPs) are intrinsically connected to the mechanism of solar flares. They are regularly observed in the impulsive phase of flares since the 1970s. In the past years, the studies of QPPs regained interest with the advent of a new generation of soft X-ray/extreme ultraviolet radiometers that pave the way for statistical sur…
Tracking of an electron beam through the solar corona with LOFAR
Strassmeier, K. G.; McKean, J. P.; Eislöffel, J. +88 more
The Sun's activity leads to bursts of radio emission, among other phenomena. An example is type-III radio bursts. They occur frequently and appear as short-lived structures rapidly drifting from high to low frequencies in dynamic radio spectra. They are usually interpreted as signatures of beams of energetic electrons propagating along coronal mag…
First Detection of Solar Flare Emission in Mid-ultraviolet Balmer Continuum
Heinzel, Petr; Dammasch, Ingolf E.; Schmutz, Werner +8 more
We present the first detection of solar flare emission at mid-ultraviolet wavelengths around 2000 Å by the channel 2 of the Large-Yield RAdiometer (LYRA) on board the PRoject for OnBoard Autonomy 2 mission. The flare (SOL20170906) was also observed in the channel 1 of LYRA centered at the H I Lyα line at 1216 Å, showing a clear non-thermal profile…
Multi-instrument view on solar eruptive events observed with the Siberian Radioheliograph: From detection of small jets up to development of a shock wave and CME
Grechnev, V. V.; Kochanov, A. A.; Uralov, A. M. +7 more
The first 48-antenna stage of the Siberian Radioheliograph (SRH) started single-frequency test observations early in 2016, and since August 2016 it routinely observes the Sun at several frequencies in the 4-8 GHz range with an angular resolution of 1-2 arc minutes and an imaging interval of about 12 s. With limited opportunities of the incomplete …
Predicting the COSIE-C Signal from the Outer Corona up to 3 Solar Radii
Telloni, Daniele; Andretta, Vincenzo; Del Zanna, Giulio +2 more
We present estimates of the signal to be expected in quiescent solar conditions, as would be obtained with the COronal Spectrographic Imager in the EUV in its coronagraphic mode (COSIE-C). COSIE-C has been proposed to routinely observe the relatively unexplored outer corona, where we know that many fundamental processes affecting both the lower co…
Density Fluctuations in a Polar Coronal Hole
Hahn, Michael; D'Huys, Elke; Savin, Daniel Wolf
We have measured the root-mean-square (rms) amplitude of intensity fluctuations, ΔI, in plume and interplume regions of a polar coronal hole. These intensity fluctuations correspond to density fluctuations. Using data from the Sun Watcher using the Active Pixel System detector and Image Processing on the Project for Onboard Autonomy (Proba2), our …
On the Performance of Multi-Instrument Solar Flare Observations During Solar Cycle 24
Milligan, Ryan O.; Ireland, Jack
The current fleet of space-based solar observatories offers us a wealth of opportunities to study solar flares over a range of wavelengths. Significant advances in our understanding of flare physics often come from coordinated observations between multiple instruments. Consequently, considerable efforts have been, and continue to be, made to coord…
Brightening and Darkening of the Extended Solar Corona during the Superflares of September 2017
West, Matthew J.; Podladchikova, O.; D'Huys, Elke +3 more
On 2017 September 6 and 10, the strongest X9.3 and X8.2 flares of the decade occurred in the active region NOAA Active Region 12673. During these flares, the Sun Watcher with Active Pixels and Image Processing (SWAP) telescope on board the Project for Onboard Autonomy 2 (PROBA2) satellite registered the unusual alternate brightening and darkening …