Search Publications
On the Analysis of the Complex Forbush Decreases of January 2005
Malandraki, O.; Mavromichalaki, H.; Papaioannou, A. +5 more
In this work an analysis of a series of complex cosmic ray events that occurred between 17 January 2005 and 23 January 2005 using solar, interplanetary and ground based cosmic ray data is being performed. The investigated period was characterized both by significant galactic cosmic ray (GCR) and solar cosmic ray (SCR) variations with highlighted c…
Investigation of Long-Period Oscillations of Sunspots with Ground-Based (Pulkovo) and SOHO/MDI Data
Solov'ev, A. A.; Efremov, V. I.; Parfinenko, L. D.
We applied special data-processing algorithms to the study of long-period oscillations of the magnetic-field strength and the line-of-sight velocity in sunspots. The oscillations were investigated with two independent groups of data. First, we used an eight-hour-long series of solar spectrograms, obtained with the solar telescope at the Pulkovo Ob…
Three-Dimensional Electron Density from Tomographic Analysis of LASCO-C2 Images of the K-Corona Total Brightness
Lamy, Philippe; Frazin, Richard A.; Vásquez, Alberto M. +1 more
We present the first quantitative three-dimensional (3D) tomographic reconstructions of electron density from coronagraph measurements of the K-corona's total brightness (B) made by LASCO-C2 on SOHO. This is possible because new calibrations of the LASCO-C2 images in both polarized brightness (pB) and B have now been made for the entire mission. T…
Observations of Double-Periodic X-Ray Emission in Interacting Systems of Solar Flare Loops
Zimovets, I. V.; Struminsky, A. B.
We investigate the M1.8 solar flare of 20 October 2002. The flare was accompanied by quasi-periodic pulsations (QPP) of both thermal and nonthermal hard X-ray emissions (HXR) observed by RHESSI in the 3 - 50 keV energy range. Analysis of the HXR time profiles in different energy channels made with the Lomb periodogram has indicated two statistical…
The Diagnostics of the κ-Distributions from EUV Spectra
Dzifčáková, E.; Kulinová, A.
The EUV lines suitable to diagnose possible κ-distributions in the solar corona are examined. A set of synthetic spectra for various values of the κ-parameter, characterizing the non-thermal κ-distributions, electron densities, and the mean energy of the distributions are calculated in the spectral range corresponding to the Hinode/EIS and Coronas…
Multiwavelength Study of the M8.9/3B Solar Flare from AR NOAA 10960
Srivastava, A. K.; Filippov, B.; Kumar, Pankaj +1 more
We present a multiwavelength analysis of a long-duration, white-light solar flare (M8.9/3B) event that occurred on 04 June 2007 from AR NOAA 10960. The flare was observed by several spaceborne instruments, namely SOHO/MDI, Hinode/SOT, TRACE, and STEREO/SECCHI. The flare was initiated near a small, positive-polarity, satellite sunspot at the center…
Solar Intranetwork Magnetic Elements: Evolution and Lifetime
Wang, J. X.; Zhou, G. P.; Jin, C. L.
Based on Hinode SOT/NFI observations with greatly improved spatial and temporal resolution and polarization sensitivity, the lifestory of the intranetwork (IN) magnetic elements are explored in a solar quiet region. A total of 2282 IN elements are followed from their appearance to disappearance and their fluxes measured. By tracing individual IN e…
Response of the Solar Atmosphere to the Emergence of `Serpentine' Magnetic Field
Tsuneta, S.; Hara, H.; Harra, L. K. +3 more
Active region magnetic flux that emerges to the photosphere from below will show complexity in the structure, with many small-scale fragmented features appearing in between the main bipole and then disappearing. Some fragments seen will be absorbed into the main polarities and others seem to cancel with opposite magnetic field. In this paper we in…
Interplanetary Coronal Mass Ejections Observed by Ulysses Through Its Three Solar Orbits
Du, D.; Zhang, X. X.; Zuo, P. B.
An extended Ulysses interplanetary coronal mass ejections (ICMEs) list is used to statistically study the occurrence rate of ICMEs, the interaction of ICMEs with solar wind, and the magnetic field properties in ICMEs. About 43% of the ICMEs are identified as magnetic clouds (MCs). It is found that the occurrence rate of ICMEs approximately follows…
Revealing the Fine Structure of Coronal Dimmings and Associated Flows with Hinode/EIS. Implications for Understanding the Source Regions of Sustained Outflow Following CMEs
van Driel-Gesztelyi, L.; Harra, L. K.; Wills-Davey, M. J. +1 more
We study two CME events on 13 and 14 December 2006 that were associated with large-scale dimmings. We study the eruptions from pre-event on 11 December through the recovery on 15 December, using a combination of Hinode/EIS, SOHO/EIT, SOHO/MDI, and MLSO Hα data. The GOES X-class flares obscured the core dimmings, but secondary dimmings developed re…