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Flare-Induced Excitation of Solar p modes
Basu, Sarbani; Antia, H. M.; Ambastha, Ashok
Solar flares release large amounts of energy at different layers of the solar atmosphere, including at the photosphere in the case of exceptionally major events. Therefore, it is expected that large flares would be able to excite acoustic waves on the solar surface, thereby affecting the p-mode oscillation characteristics. We have applied the ring…
Impulses of activity and the Solar cycle
Benevolenskaya, Elena E.
Extreme-ultraviolet data from EIT/SOHO (1996-2002), soft X-ray data from Yohkoh (1991-2001), and magnetic field data from MDI/SOHO (1996-2002) and Kitt Peak Observatory, NSO/NOAO (1991-2002) are analyzed together in the form of synoptic maps for the investigation of solar cycle variations of the corona and their relation to the magnetic field. The…
ICME Identification from Solar Wind Ion Measurements
Russell, C. T.; Shinde, A. A.
Interplanetary coronal mass ejections (ICMEs), the interplanetary counterpart of coronal mass ejections (CMEs), are most commonly identified by their enhanced magnetic field strengths and rotating magnetic field orientation. However, there are other frequent signatures in the plasma. We use a pair of these signatures, a linearly decreasing plasma …
Energetic Particles and Coronal Mass Ejections: a Case Study From ace and Ulysses
Simnett, G. M.
In 2001 the Ulysses spacecraft crossed the ecliptic plane near perihelion. The heliographic longitude with respect to the Earth was within ± 20° of the west solar limb while it was ± 15° of the ecliptic plane, which meant that coronal mass ejections seen off the solar west limb were likely to pass over Ulysses. On 10 May the largest > 38 keV el…
Dynamics of Blinkers
Harrison, R. A.; Parnell, C. E.; Pike, C. D. +1 more
The relative Doppler and non-thermal velocities of quiet-Sun and active-region blinkers identified in O v with CDS are calculated. Relative velocities for the corresponding chromospheric plasma below are also determined using the He i line. O v blinkers and the chromosphere directly below, have a preference to be more red-shifted than the normal t…
Hard x-ray Pulsations in the Initial Phase of Flares
Karlický, M.; Fárník, F.; Švestka, Z.
When analyzing light curves of hard X-ray bursts recorded by the Hard X-Ray Spectrometer on board the MTI satellite, we have found three events (all associated with major solar flares, two of them in the same active region) which show pulsations in the very initial phase of the burst. Periods of the pulsations range from 25 to 48 s. We compare the…
Magnetic helicity transport in corona and filament eruptions
Romano, P.; Contarino, L.; Zuccarello, F.
Using a 28-hour time series of line-of-sight magnetograms taken by the Michelson Doppler Imager (MDI), we determined the magnetic flux variations and the rate of magnetic helicity transport at the footpoints of a filament in active region NOAA 8375. The filament was characterized by a positive helicity change due to shearing motions in both footpo…
Interaction of an Erupting Filament with the Ambient Magnetoplasma and Escape of Electron Beams
Vršnak, Bojan; Warmuth, Alexander; Otruba, Wolfgang +2 more
A huge filament eruption of 12 September 2000 associated with a two-ribbon spotless flare is described. During the acceleration phase the shape of the filament changed, and signatures of topological restructuring of large-scale coronal magnetic fields were inferred by tracking changes of nearby coronal holes. At the same time electron beams associ…
Variations in Oscillation Frequencies From Minimum to Maximum of Solar Activity
Jain, Kiran; Bhatnagar, A.
The temporal variation in intermediate-degree-mode frequencies is analysed using helioseismic data which cover the minimum to the maximum phase of the current solar cycle. To study the variation in detail, the measured frequency shifts of f and p modes are decomposed into two components, viz., oscillatory and non-oscillatory. The f-mode frequencie…
Coronal Oscillations above Sunspots?
Doyle, J. G.; Dzifćáková, E.; Madjarska, M. S.
Observational data clearly indicate the presence of 3-min oscillations in sunspots in spectral lines covering a vast temperature range from the low chromosphere to those lines normally associated with coronal temperatures. We show that after folding in the sunspot plume emission measure distribution, the contribution functions for lines normally f…