Search Publications
Forward modeling of the coronal response to reconnection in an X-ray bright point
Longcope, Dana; Kankelborg, Charles
We use MDI magnetic field observations and the theory of reconnection through a separator to constrain a numerical simulation of an X-ray bright point observed in EUV by TRACE. A gasdynamic model is employed to describe the corona and transition region in the bright point loop. Nonlocal effects such as opacity and ambipolar diffusion are important…
Multiple CME Events Observed With LASCO
Simnett, G. M.; Lyons, M. A.
Observations are reported of two multiple CME events which were detected on 2-3 June 1997 and 9-10 June 1998, using the LASCO instrument on board SOHO. Each event consists of a group of four related CMEs which emerge from progressively higher latitudes over a time period of approximately 16 hours. In both cases there is on-disk activity visible in…
Filament channel structures in a SI IV line related to a 3d magnetic model
Vial, J. -C.; Aulanier, G.; Schmieder, B. +2 more
A recent 3D magnetic model of filament support (Aulanier and Démoulin, 1998) has shown that specific morphologies derived from the model, based on SOHO/MDI magnetograms, match quite well with the observations of a filament observed in Hα and Ca ii lines with the German telescope VTT in Tenerife on 25 September 1996 (Aulanier et al., 1998, 1999a). …
Observations and Modeling of an Explosive Coronal Mass Ejection as Observed by LASCO
Wu, S. T.; Andrews, M. D.; Wang, A. -H.
We present a qualitative and quantitative comparison of a single coronal mass ejection (CME) as observed by LASCO on 5 October 1996 with the results of a two-dimensional magnetohydrodynamic (MHD) model. This event was selected as a clear example of a CME that is not caused by the disruption of a helmet streamer. This CME occurs against the backgro…
Different spatial structures between network regions and active regions indicated by TRACE 171 Å observation
Zhang, H. Q.; Zhang, M.; Wang, H. N. +1 more
By comparing TRACE 171 Å observations with photospheric magnetograms, we find that the root of TRACE 171 Å emission is centered in magnetic elements in simultaneous Huairou photospheric magnetogram and the luminosity of TRACE 171 Å emission is not always in proportion to the strength of the corresponding photospheric magnetic field. While TRACE em…
Post-Impulsive-Phase Acceleration in a Wide Range of Solar Longitudes
Kocharov, Leon; Torsti, Jarmo; Laitinen, Timo +1 more
We have analyzed five solar energetic particle (SEP) events observed aboard the SOHO spacecraft during 1996-1997. All events were associated with impulsive soft X-ray flares, Type II radio bursts and coronal mass ejections (CMEs). Most attention is concentrated on the SEP acceleration during the first 100 minutes after the flare impulsive phase, p…
Coronal heating events in high-cadence TRACE data
Walsh, Robert W.; Ireland, Jack; Wills-Davey, Meredith
On March 23rd 1999 a set of TRACE (Transition Region and Coronal Explorer) observations were taken in support of Solar and Heliospheric Observatory (SOHO) / TRACE Joint Observing Program 83. The program is designed to look for coronal heating mechanisms operating at high cadence and to observe their dynamical effects on coronal loop density, tempe…
Electron densities above a polar coronal hole based on improved Si IX density diagnostics
Doyle, J. G.; Fludra, A.; Keenan, F. P. +2 more
Using new close-coupling excitation rates for the C-like ion Si ix, density-diagnostic ratios based on Si ix lines have been re-evaluated and applied to a sequence of CDS observations taken above a polar coronal hole. The derived electron densities are in excellent agreement with previous values of Neestimated from the N-like ion Si vii…
Comparative morphology of EIT/SOHO images and He II excitation
Venkatakrishnan, P.
Morphological differences between coronal images on the one hand, and a He i image on the other, are used to demonstrate the independence of He ii excitation from coronal radiation. The distribution of magnetic flux is found to be more important for He ii excitation. Collisional excitation by non-thermal electrons produced in nano-flare events is …
NE VII emission lines in the solar EUV spectrum
Keenan, F. P.; Ryans, R. S. I.; Bell, K. L. +3 more
Recent calculations of electron and proton impact excitation rates in Ne vii are used to calculate theoretical emission line ratios involving both Δn=0 (2-2) and Δn=1 (2-3) transitions in the ∼ 97-895 Å wavelength range. A comparison of these with existing solar observations, obtained by instruments on rocket flights and on the Skylab mission, rev…