Search Publications
Confined and Ejective Eruptions of Kink-unstable Flux Ropes
Török, T.; Kliem, B.
The ideal helical kink instability of a force-free coronal magnetic flux rope, anchored in the photosphere, is studied as a model for solar eruptions. Using the flux rope model of Titov and Démoulin as the initial condition in MHD simulations, both the development of helical shape and the rise profile of a confined (or failed) filament eruption (o…
Shock Geometry, Seed Populations, and the Origin of Variable Elemental Composition at High Energies in Large Gradual Solar Particle Events
Cohen, C. M. S.; Mewaldt, R. A.; Maclennan, C. G. +5 more
Above a few tens of MeV per nucleon, large, gradual solar energetic particle (SEP) events are highly variable in their spectral characteristics and elemental composition. The origin of this variability has been a matter of intense and ongoing debate. In this paper, we propose that this variability arises from the interplay of two factors-shock geo…
Direct Observations of the Magnetic Reconnection Site of an Eruption on 2003 November 18
Raymond, J. C.; Ko, Y. -K.; Lin, J. +5 more
We report direct observations of the magnetic reconnection site during an eruptive process that occurred on 2003 November 18. The event started with a rapid expansion of a few magnetic arcades located over the east limb of the Sun and developed an energetic partial-halo coronal mass ejection (CME), a long current sheet, and a group of bright flare…
Helioseismological Implications of Recent Solar Abundance Determinations
Pinsonneault, Marc; Basu, Sarbani; Bahcall, John N. +1 more
We show that standard solar models are in good agreement with the helioseismologically determined sound speed and density as a function of solar radius, the depth of the convective zone, and the surface helium abundance, as long as those models do not incorporate the most recent heavy-element abundance determinations. However, sophisticated new an…
An Ab Initio Approach to the Solar Coronal Heating Problem
Nordlund, Åke; Gudiksen, Boris Vilhelm
We present an ab initio approach to the solar coronal heating problem by modeling a small part of the solar corona in a computational box using a three-dimensional MHD code including realistic physics. The observed solar granular velocity pattern and its amplitude and vorticity power spectra, as reproduced by a weighted Voronoi tessellation method…
Making the Corona and the Fast Solar Wind: A Self-consistent Simulation for the Low-Frequency Alfvén Waves from the Photosphere to 0.3 AU
Inutsuka, Shu-ichiro; Suzuki, Takeru K.
By performing a one-dimensional magnetohydrodynamic simulation with radiative cooling and thermal conduction, we show that the coronal heating and the fast solar wind acceleration in the coronal holes are natural consequences of the footpoint fluctuations of the magnetic fields at the photosphere. We initially set up a static open flux tube with a…
Solar-like Oscillations in α Centauri B
Butler, R. Paul; Bedding, Timothy R.; Marcy, Geoffrey W. +6 more
We have made velocity observations of the star α Centauri B from two sites, allowing us to identify 37 oscillation modes with l=0-3. Fitting to these modes gives the large and small frequency separations as a function of frequency. The mode lifetime, as measured from the scatter of the oscillation frequencies about a smooth trend, is similar to th…
Longitudinal Magnetic Field Changes Accompanying Solar Flares
Harvey, J. W.; Sudol, J. J.
We have used Global Oscillation Network Group (GONG) magnetograms to characterize the changes in the photospheric longitudinal magnetic field during 15 X-class solar flares. An abrupt, significant, and persistent change in the magnetic field occurred in at least one location within the flaring active region during each event. We have identified a …
A Full View of EIT Waves
Chen, P. F.; Shibata, K.; Fang, C.
Early observations by the EUV Imaging Telescope (EIT) on the Solar and Heliospheric Observatory indicated that propagating diffuse wave fronts, now conventionally referred to as ``EIT waves,'' can often be seen on the solar disk with a propagation velocity several times smaller than that of Hα Moreton waves. They are almost always associated with …
Eruption of a Kink-unstable Filament in NOAA Active Region 10696
van Driel-Gesztelyi, Lidia; Démoulin, Pascal; Török, Tibor +2 more
We present rapid-cadence Transition Region and Coronal Explorer (TRACE) observations that show evidence of a filament eruption from NOAA active region 10696, accompanied by an X2.5 flare, on 2004 November 10. The eruptive filament, which manifests as a fast coronal mass ejection some minutes later, rises as a kinking structure with an apparently e…