Search Publications
Evidence from the Extreme-Ultraviolet Imaging Spectrometer for Axial Filament Rotation before a Large Flare
Harra, Louise K.; Brooks, David H.; Hansteen, Viggo H. +2 more
In this article, we present observations made with the Extreme-ultraviolet Imaging Spectrometer on-board the Hinode solar satellite, of an active region filament in the HeII emission line at 256.32Å. The host active region AR 10930 produces an X-class flare during these observations. We measure Doppler shifts with apparent velocities of up to 20km…
Physical Properties of Cooling Plasma in Quiescent Active Region Loops
Curdt, W.; Landi, E.; Hara, H. +1 more
In the present work, we use SOHO/SUMER, SOHO/UVCS, SOHO/EIT, SOHO/LASCO, STEREO/EUVI, and Hinode/EIS coordinated observations of an active region (AR 10989) at the west limb taken on 2008 April 8 to study the cooling of coronal loops. The cooling plasma is identified using the intensities of SUMER spectral lines emitted at temperatures in the 4.15…
Statistics of Flares Sweeping Across Sunspots
Zhang, Jun; Li, Leping
Flare ribbons are always dynamic and sometimes sweep across sunspots. After examining 588 (513 M-class and 75 X-class) flare events observed by the TRACE satellite and the Hinode/Solar Optical Telescope from 1998 May to 2009 May, we choose the event displaying one of the flare ribbons that completely sweeps across the umbra of a main sunspot of th…
The radius and other fundamental parameters of the F9V star β Virginis
Stello, D.; Tuthill, P. G.; Lacour, S. +10 more
We have used the Sydney University Stellar Interferometer (SUSI) to measure the angular diameter of the F9V star β Virginis (β Vir). After correcting for limb darkening and combining with the revised Hipparcos parallax, we derive a radius of 1.703 +/- 0.022Rsolar (1.3 per cent). We have also calculated the bolometric flux from published…
Vortex-like plasma flow structures observed by Cluster at the boundary of the outer radiation belt and ring current: A link between the inner and outer magnetosphere
Zhang, H.; Zong, Q. -G.; Daly, P. W. +8 more
Two vortex-like plasma flow structures have been observed at the outer radiation belt and/or the ring current region on 11 April 2002, from 0415 to 0635 UT, when the Cluster fleet entered (in the Southern Hemisphere) and exited (in the Northern Hemisphere) the boundary layer of the inner magnetosphere near 2130 MLT. On 11 April 2002 during the per…
The Dynamics of Saturn's Magnetosphere
Mitchell, D. G.; Cowley, S. W. H.; Carbary, J. F. +2 more
The dynamics of Saturn's magnetosphere differs considerably from that at the Earth. Saturn's magnetosphere responds to both external and internal drivers. The solar wind ram pressure, rather than the solar wind speed and interplanetary field orientation, provides the primary external driver at Saturn, while the planet's rotation provides the main …
Analyses of magnetic field structures for active region 10720 using a data-driven 3D MHD model
Liu, Yang; Wu, S. T.; Yurchyshyn, Vasyl +5 more
In order to understand solar eruptive events (flares and CMEs) we need to investigate the changes at the solar surface. Thus, we use a data-driven, three-dimensional magnetohydrodynamic (MHD) model to analyze a flare and coronal mass ejection productive active region, AR 10720 on January 15, 2005. The measured magnetic field from Big Bear Solar Ob…
Magnetic decrease formation from <1 AU to ∼5 AU: Corotating interaction region reverse shocks
Tsurutani, Bruce T.; Echer, Ezequiel; Guarnieri, Fernando L. +2 more
Magnetic decreases (MDs) have been identified and studied throughout a Ulysses fast latitude scan that lasted from 29 February 1992 to 14 September 1993. Ulysses' distance was ∼5 AU from the Sun. MDs were unbiasedly selected by application of the Interplanetary Magnetic Decrease Automatic Detection code. MDs were found to occur in high-occurrence-…
Rosetta and Mars Express observations of the influence of high solar wind pressure on the Martian plasma environment
Barabash, S.; Lundin, R.; Fränz, M. +18 more
We report on new simultaneous in-situ observations at Mars from Rosetta and Mars Express (MEX) on how the Martian plasma environment is affected by high pressure solar wind. A significant sharp increase in solar wind density, magnetic field strength and turbulence followed by a gradual increase in solar wind velocity is observed during ~24 h in th…
R-matrix electron-impact excitation data for B-like Si and its application in cool stars
Badnell, N. R.; Liang, G. Y.; Whiteford, A. D.
We present the results of an intermediate coupling frame-transformation R-matrix calculation for the electron-impact excitation of Si9+. The target and close-coupling expansions are both taken to be the 125 fine-structure levels (58 LS terms) belonging to the configurations 2sx2py (x+y = 3) and 2sα2p