Search Publications
Exploring the Capabilities of the Anti-Coincidence Shield of the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) Spectrometer to Study Solar Flares
Klein, K. -L.; Vilmer, N.; Hamadache, C. +3 more
The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) is a European Space Agency hard X-ray/γ-ray observatory for astrophysics, covering photon energies from 15 keV to 10 MeV. It was launched in 2002, and since then the Bismuth Germanate (BGO) detectors of the Anti-Coincidence Shield (ACS) of the Spectrometer on INTEGRAL (SPI) have detect…
North-South Asymmetry in the Distribution of Solar Background Magnetic Field
Obridko, V. N.; Chertoprud, V. E.; Kuzanyan, K. M.
The aim of this article is to investigate how the background magnetic field of the Sun behaves in different hemispheres. We used SOHO/MDI data obtained during a period of eight years from 2003 to 2011 to analyze the intensity distribution of the background magnetic field over the solar surface. We find that the background fields of both polarities…
Simulated (STEREO) Views of the Solar Wind Disturbances Following the Coronal Mass Ejections of 1 August 2010
Feng, X. S.; Zhang, Y.; Dryer, M. +7 more
Images observed by the twin spacecraft Solar TErrestrial RElations Observatory (STEREO) A and B appear as complex structures for two coronal mass ejections (CMEs) on 1 August 2010. Therefore, a series of sky maps of Thomson-scattered white light by interplanetary coronal mass ejections (ICMEs) on 1 August 2010 are simulated using the Hakamada-Akas…
Phase Relationships Between the CME-Energy Cycle, the Sunspot-Area Cycle and the Flare-Index Cycle
Zhong, J.; Xie, J. L.; Gao, P. X.
We study the phase relationships between the coronal-mass-ejection (CME) energy cycle, the sunspot-area cycle, and the flare-index cycle from 1996 to 2010. The results show the following: i) The activity cycle of the flare index significantly leads the activity cycle of the sunspot area. ii) The activity cycle of the CME energy is inferred to be a…
A Change in the Solar He II EUV Global Network Structure as an Indicator of the Geo-Effectiveness of Solar Minima
Gurman, J. B.; Didkovsky, L.
Solar activity during 2007 - 2009 was very low, causing anomalously low thermospheric density. A comparison of solar extreme ultraviolet (EUV) irradiance in the He II spectral band (26 to 34 nm) from the Solar Extreme ultraviolet Monitor (SEM), one of instruments on the Charge Element and Isotope Analysis System (CELIAS) on board the Solar and Hel…
The Evolution of the Net Twist Current and the Net Shear Current in Active Region NOAA 10930
Venkatakrishnan, P.; Ravindra, B.; Jaaffrey, S. N. A. +1 more
The electric current exists because of the non-potential magnetic field in solar active regions. We present the evolution of net current in the solar active region NOAA 10930 as the sum of shear current and twist current by using 27 high-resolution vector magnetograms obtained with Hinode/SOT-SP during 9 - 15 December 2006. This active region was …
The Late Gradual Phase of Large Flares: The Case of November 3, 2003
Auraß, H.
The hard X-ray time profiles of most solar eruptive events begin with an impulsive phase that may be followed by a late gradual phase. In a recent article (Aurass et al. in Astron. Astrophys.555, A40, 2013), we analyzed the impulsive phase of the solar eruptive event on November 3, 2003 in radio and X-ray emission. We found evidence of magnetic br…
Time-Series Analysis of Supergranule Characteristics at Solar Minimum
Williams, Peter E.; Pesnell, W. Dean
Sixty days of Doppler images from the Solar and Heliospheric Observatory (SOHO) / Michelson Doppler Imager (MDI) investigation during the 1996 and 2008 solar minima have been analyzed to show that certain supergranule characteristics (size, size range, and horizontal velocity) exhibit fluctuations of three to five days. Cross-correlating parameter…
Velocities and Linewidths in the Network and Cell Interiors of a Polar Coronal Hole Compared with the Quiet Sun
Raju, K. P.; Bromage, B. J. I.
The relative Doppler velocities and linewidths in a polar coronal hole and the nearby quiet-Sun region have been obtained from the Solar and Heliospheric Observatory (SOHO)/Coronal Diagnostic Spectrometer (CDS) observations using emission lines originating at different heights in the solar atmosphere from the lower transition region (TR) to the lo…