Search Publications
Nonlinear Force-free Field Modeling of a Solar Active Region around the Time of a Major Flare and Coronal Mass Ejection
Aulanier, G.; Schrijver, C. J.; Amari, T. +14 more
Solar flares and coronal mass ejections are associated with rapid changes in field connectivity and are powered by the partial dissipation of electrical currents in the solar atmosphere. A critical unanswered question is whether the currents involved are induced by the motion of preexisting atmospheric magnetic flux subject to surface plasma flows…
Jets in Coronal Holes: Hinode Observations and Three-dimensional Computer Modeling
Galsgaard, K.; Moreno-Insertis, F.; Ugarte-Urra, I.
Recent observations of coronal hole areas with the XRT and EIS instruments on board the Hinode satellite have shown with unprecedented detail the launching of fast, hot jets away from the solar surface. In some cases these events coincide with episodes of flux emergence from beneath the photosphere. In this Letter we show results of a three-dimens…
Outflows at the Edges of Active Regions: Contribution to Solar Wind Formation?
Young, P. R.; Mandrini, C. H.; van Driel-Gesztelyi, L. +5 more
The formation of the slow solar wind has been debated for many years. In this Letter we show evidence of persistent outflow at the edges of an active region as measured by the EUV Imaging Spectrometer on board Hinode. The Doppler velocity ranged between 20 and 50 km s-1 and was consistent with a steady flow seen in the X-Ray Telescope. …
Acceleration in Fast Halo CMEs and Synchronized Flare HXR Bursts
Temmer, M.; Veronig, A. M.; Maričić, D. +4 more
We study two well-observed, fast halo CMEs, covering the full CME kinematics including the initiation and impulsive acceleration phase, and their associated flares. We find a close synchronization between the CME acceleration profile and the flare energy release as indicated by the RHESSI hard X-ray flux onsets, as well as peaks occur simultaneous…
The Current Sheet Associated with the 2003 November 4 Coronal Mass Ejection: Density, Temperature, Thickness, and Line Width
Raymond, J. C.; Ciaravella, A.
In the wake of the 2003 November 4 coronal mass ejection associated with the largest solar flare of the last sunspot cycle, a current sheet (CS) was observed by the Ultraviolet Coronagraph Spectrometer (UVCS) as a narrow bright feature in the [Fe XVIII] (106.8 K) line. This is the first UV observation in which the CS evolution is follow…
Three-dimensional MHD Simulation of the 2003 October 28 Coronal Mass Ejection: Comparison with LASCO Coronagraph Observations
Vourlidas, Angelos; Lugaz, Noé; Roussev, Ilia I. +6 more
We numerically model the coronal mass ejection (CME) event of 2003 October 28 that erupted from AR 10486 and propagated to Earth in less than 20 hr, causing severe geomagnetic storms. The magnetohydrodynamic (MHD) model is formulated by first arriving at a steady state corona and solar wind employing synoptic magnetograms. We initiate two CMEs fro…
High-Cadence Observations of a Global Coronal Wave by STEREO EUVI
Veronig, Astrid M.; Temmer, Manuela; Vršnak, Bojan
We report a large-scale coronal wave (so-called EIT wave) observed with high cadence by EUVI on board STEREO in association with the GOES B9.5 flare and double CME event on 2007 May 19. The EUVI instruments provide us with the unprecedented opportunity to study the dynamics of flare/CME associated coronal waves. The coronal wave under study reveal…
Magnetic Field Overlying Solar Eruption Regions and Kink and Torus Instabilities
Liu, Y.
Using a potential field source surface (PFSS) model, we study a magnetic field overlying erupted filaments in solar active regions. The filaments studied here were reported to experience a kink instability or a torus instability. The torus instability leads to a full eruption, while the kink instability leads to a full eruption or a failed eruptio…
Observations and Modeling of the Early Acceleration Phase of Erupting Filaments Involved in Coronal Mass Ejections
Title, Alan M.; Török, Tibor; Kliem, Bernhard +2 more
We examine the early phases of two near-limb filament destabilizations involved in coronal mass ejections (CMEs) on 2005 June 16 and July 27, using high-resolution, high-cadence observations made with the Transition Region and Coronal Explorer (TRACE), complemented by coronagraphic observations by the Mauna Loa Solar Observatory (MLSO) and the Sol…
Modeling Nonpotential Magnetic Fields in Solar Active Regions
van Ballegooijen, A. A.; DeLuca, E. E.; Bobra, M. G.
Electric currents are present in the coronae above solar active regions, producing nonpotential magnetic fields that can be approximated as nonlinear force-free fields (NLFFFs). In this paper NLFFF models for two active regions observed in 2002 June are presented. The models are based on magnetograms from SOHO MDI and are constrained by nonpotenti…