Search Publications
The Coronal Mass Ejection Waiting-Time Distribution
Wheatland, M. S.
The distribution of times Δt between coronal mass ejections (CMEs) in the Large Angle and Spectrometric Coronagraph (LASCO) CME catalog for the years 1996-2001 is examined. The distribution exhibits a power-law tail ∼(Δt)γ with an index γ≈−2.36±0.11 for large waiting times (Δt>10 hours). The power-law index of the waiting-time distri…
Prominence Motions Observed at High Cadences in Temperatures from 10 000 to 250 000 K
De Pontieu, B.; Kucera, T. A.; Tovar, M.
We report here for the first time observations of prominence velocities over a wide range of temperatures and with a high time cadence. Our study of ultraviolet movies of prominences reveals that multi-thermal features with speeds of 5-70 km s−1 perpendicular to the line of sight are common in the prominences which showed traceable moti…
A Quantitative Method to Optimise Magnetic Field Line Fitting of Observed Coronal Loops
Wiegelmann, T.; Hood, A. W.; Carcedo, L. +2 more
Many authors use magnetic-field models to extrapolate the field in the solar corona from magnetic data in the photosphere. The accuracy of such extrapolations is usually judged qualitatively by eye, where a less judgemental quantitative approach would be more desirable. In this paper, a robust method for obtaining the best fit between a theoretica…
Spectroscopy of Solar Prominences Simultaneously From Space and Ground
Dammasch, I. E.; Wiehr, E.; Stellmacher, G.
We present a comprehensive set of spectral data from two quiescent solar prominences observed in parallel from space and ground: with the VTT, simultaneous two-dimensional imaging of Hβ4862 Å and Caii 8542 Å yields a constant ratio, indicating small spatial pressure variations over the prominence. With the Gregory, simultaneous spectra of Caii 854…
Vertical Dynamics of the Energy Release Process in a Simple two-Ribbon Flare
Warmuth, Alexander; Otruba, Wolfgang; Klein, Karl-Ludwig +2 more
Observations of the quiescent filament eruption and the spotless two-ribbon flare of 12 September 2000 are presented. A simple flare morphology, large spatial scales, and a suitable viewing angle provide insight into characteristics of the energy release process which is attributed to the reconnection process in the current sheet formed below the …
Statistical Characteristics of CMEs and Flares Associated with Solar Type II Radio Bursts
Moon, Y. -J.; Shanmugaraju, A.; Dryer, M. +1 more
We have made a comprehensive statistical study of the characteristics of 290 SOHO/LASCO CMEs and their associated GOES-8 X-ray flares (> C1 class) during the period January 1997-December 2000 of solar cycle 23's rise to maximum. These events were classified into mainly three groups (Group noII - not associated with type IIs, Group II - associat…
Interaction and Dynamics of the Photospheric Network Magnetic Elements
Tarbell, T. D.; Shine, R.; Ryutova, M.
Small-scale magnetic elements in the quiet photospheric network are believed to play a key role in the energy flow from the solar surface to upper layers of atmosphere. Their intense hydro-magnetic activity includes merging and fragmentation of same polarity fluxes, `total' or partial cancellation of neighboring flux elements of opposite polarity,…
Themis, BBSO, MDI and trace observations of a filament eruption
Romano, P.; Yurchyshyn, V. B.; Contarino, L. +1 more
We describe a filament destabilization which occurred on 5 May 2001 in NOAA AR 9445, before a flare event. The analysis is based on Hα data acquired by THEMIS operating in IPM mode, Hα data and magnetograms obtained at the Big Bear Solar Observatory, MDI magnetograms and 171 Å images taken by TRACE. Observations at 171 Å show that ∼ 2.5 hours befo…
Measurements of Flux Cancellation During Filament Formation
Wood, Paul; Martens, Piet
We study the process of flux cancellation and filament formation in a nest of three decaying active regions, using data from SOHO MDI and EIT, and Hα images from Meudon and Big Bear. We find that there are no apparent EUV loops connecting the two poles of a cancelling feature prior to and during cancellation, suggesting an absence of coronal magne…
Coronal Magnetic Field Context of Simple CMEs Inferred from Global Potential Field Models
Luhmann, J. G.; Yashiro, Seiji; Zhao, Xuepu +1 more
Most work on coronal mass ejection (CME) interpretation focuses on the involved active region rather than on the large-scale coronal context. In this paper a global potential-field source-surface model of the coronal magnetic field is used to evaluate the sensitivity of the coronal field configuration to the location, orientation, and strength of …