Search Publications
The Magnetic Helicity Budget of a cme-Prolific Active Region
Mandrini, C. H.; Culhane, J. L.; Démoulin, P. +3 more
Coronal mass ejections (CMEs) are thought to be the way by which the solar corona expels accumulated magnetic helicity which is injected into the corona via several methods. DeVore (2000) suggests that a significant quantity is injected by the action of differential rotation, however Démoulin et al. (2002b), based on the study of a simple bipolar …
Active-Region Monitoring and Flare Forecasting I. Data Processing and First Results
Moon, Y. -J.; Wang, Haimin; Gallagher, Peter T.
This paper discusses a near real-time approach to solar active-region monitoring and flare prediction using the Big Bear Solar Observatory Active Region Monitor (ARM). Every hour, ARM reads, calibrates, and analyses a variety of data including: full-disk Hα images from the Global Hα Network; EUV, continuum, and magnetogram data from the Solar and …
Rhessi and Trace Observations of the 21 April 2002 x1.5 Flare
Krucker, Säm; Gallagher, Peter T.; Dennis, Brian R. +2 more
Observations of the X1.5 flare on 21 April 2002 are reviewed using the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and the Transition Region and Coronal Explorer (TRACE). The major findings are as follows: (1) The 3-25 keV X-rays started < 4 min before the EUV (195 Å) emission suggesting that the initial energy release heated …
Active-Region Filaments and X-ray Sigmoids
Pevtsov, Alexei A.
We use Yohkoh soft X-ray telescope data and Hα full-disk observations to study the evolution of chromospheric filaments and coronal sigmoids in 6 active regions in association with coronal mass ejections (CMEs). In two cases, CMEs are directly observed by the SOHO/LASCO C2 coronagraph. In four cases, other observations (magnetic clouds, geomagneti…
The subsurface radial gradient of solar angular velocity from MDI f-mode observations
Thompson, M. J.; Corbard, T.
We report quantitative analysis of the radial gradient of solar angular velocity at depths down to about 15 Mm below the solar surface for latitudes up to 75° using the Michelson Doppler Imager (MDI) observations of surface gravity waves (fmodes) from the Solar and Heliospheric Observatory (SOHO). A negative outward gradient of around −400 nHz/R
Soho Contribution to Prominence Science
Patsourakos, Spiros; Vial, Jean-Claude
We present the main current issues concerning prominence studies. We recall the large range of plasma parameters found in prominences which makes the work of the MHD modeler more difficult. We also summarize the capabilities of the SOHO instrumentation. We present and discuss the most recent SOHO results concerning the determination of temperature…
Spectroscopic Observation of Coronal Waves
Ichimoto, K.; Raju, K. P.; Sakurai, T. +1 more
A time sequence over 80 min of coronal green-line spectra was obtained with a corona- graph at the Norikura Solar Observatory. Doppler velocities, line intensities, and line widths were derived through fitting a single Gaussian to the observed line profiles. Coronal waves have been clearly detected in the Doppler velocity data. The Fourier analysi…
The topology of a mixed-polarity potential field, and inferences for the heating of the quiet solar corona
Title, Alan M.; Schrijver, Carolus J.
We study the statistical properties of the connectivity of the corona over the quiet Sun by analyzing the potential magnetic field above the central area of source planes sprinkled randomly with some 300 magnetic monopoles each. We find that the field is generally more complex than one might infer from a study of the field within the source plane …
Multiple magnetic clouds in interplanetary space
Wang, S.; Wang, Y. M.; Ye, P. Z.
An interplanetary magnetic cloud (MC) is usually considered the byproduct of a coronal mass ejection (CME). Due to the frequent occurrence of CMEs, multiple magnetic clouds (multi-MCs), in which one MC catches up with another, should be a relatively common phenomenon. A simple flux rope model is used to get the primary magnetic field features of m…
Oscillations Above Sunspots
Fredvik, T.; Kjeldseth-Moe, O.; Brynildsen, N. +1 more
The 3-min oscillations in the sunspot atmosphere are discussed, based on joint observing with the Transition Region and Coronal Explorer - TRACE and the Solar and Heliospheric Observatory - SOHO. We find that the oscillation amplitude above the umbra increases with increasing temperature, reaches a maximum for emission lines formed close to 1-2× 1…