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Time Delays in Quasi-periodic Pulsations Observed during the X2.2 Solar Flare on 2011 February 15

Schmutz, W.; Zhukov, A. N.; Berghmans, D. +10 more

We report observations of quasi-periodic pulsations (QPPs) during the X2.2 flare of 2011 February 15, observed simultaneously in several wavebands. We focus on fluctuations on timescale 1-30 s and find different time lags between different wavebands. During the impulsive phase, the Reuven Ramaty High Energy Solar Spectroscopic Imager channels in t…

New observation strategies for the solar UV spectral irradiance

Dudok de Wit, Thierry; Kretzschmar, Matthieu; Lilensten, Jean +2 more

Many applications in space weather and in space situational awareness require continuous solar spectral irradiance measurements in the UV, and to a lesser degree in the visible band. Most space-borne solar radiometers are made out of two different parts: (i) a front filter that selects the passband and (ii) a detector that is usually based on sili…

The role of photospheric shearing motions in a filament eruption related to the 2010 April 3 coronal mass ejection

Poedts, S.; Romano, P.; Zuccarello, F. P. +1 more

Context. Coronal mass ejections (CMEs) are huge expulsion of solar plasma and magnetic field in the interplanetary medium. Understanding the physics that lies beyond the CME initiation is one of the most fascinating research questions. Several models have been proposed to explain the initiation of CMEs. However, which model better explains the dif…

Preliminary Results on Irradiance Measurements from Lyra and Swap

Berghmans, D.; Kariyappa, R.; Damé, L. +5 more

Extreme ultraviolet solar irradiance during the rising phase of solar cycle 24 observed by PROBA2/LYRA

Dammasch, Ingolf E.; Kretzschmar, Matthieu; Dominique, Marie +3 more

The Large-Yield Radiometer (LYRA) is a radiometer that has monitored the solar irradiance at high cadence and in four pass bands since January 2010. Both the instrument and its spacecraft, PROBA2 (Project for OnBoard Autonomy), have several innovative features for space instrumentation, which makes the data reduction necessary to retrieve the long…

Isolated Sunspot with a Dark Patch in the Coronal Emission

Shibasaki, K.; Ryabov, B. I.; Bezrukov, D. A.

On the base of the 17 GHz radio maps of the Sun taken with the Nobeyama Radio Heliograph we estimate plasma parameters in the specific region of the sunspot atmosphere in the active region AR 11312. This region of the sunspot atmosphere is characterized by the depletion in coronal emission (soft X-ray and EUV lines) and the reduced absorption in t…