Search Publications
Multi-wavelength study of a high-latitude EUV filament
Heinzel, Petr; Schmieder, Brigitte; Schwartz, Pavol +1 more
A large filament was observed during a multi-wavelength coordinated campaign on June 19, 1998 in the Hα line with the Swedish Vacuum Solar Telescope (SVST) at La Palma, in the coronal lines Fe ix/x 171 Å and Fe xi 195 Å with the Transition Region and Coronal Explorer (TRACE) and in EUV lines with the SOHO/CDS spectrometer and the hydrogen Lyman se…
Measuring Stellar Differential rotation with asteroseismology
Solanki, Sami K.; Gizon, Laurent
The variation of rotation with latitude is poorly known on stars other than the Sun. Several indirect techniques, photometric and spectroscopic, have been used to search for departure from rigid rotation for sufficiently fast rotators. Here we investigate the possibility of measuring stellar differential rotation for solar-type stars through aster…
Solar Irradiance Variations: From Current Measurements to Long-Term Estimates
Solanki, Sami K.; Krivova, Natalie A.
Variations of solar total and spectral irradiance are prime solar quantities purported to have an influence on the Earth's climate. Quantitative estimates of irradiance over as long a time as possible are needed to judge their effectiveness in forcing the climate. In order to do this reliably, first the measured record must be reproduced and a fee…
Geoeffectiveness of interplanetary shocks during solar minimum (1995 1996) and solar maximum (2000)
Echer, E.; Gonzalez, W. D.; Alves, M. V.
Plasma and magnetic field parameter variations across fast forward interplanetary shocks are analyzed during the last solar cycle minimum (1995-1996, 15 shocks), and maximum year 2000 (50 shocks). It was observed that the solar wind velocity and magnetic field strength variation across the shocks were the parameters better correlated with Dst. Sup…
Separators in 3D Quiet-Sun Magnetic Fields
Priest, E. R.; Parnell, C. E.; Close, R. M.
At the confluence of four regions of different magnetic connectivity lies a distinct topological candidate for coronal heating, namely the magnetic separator. In this study, a method for tracing separator curves is developed and the statistical properties of separators in coronal fields are subsequently explored by analysing a model field with an …
Correction of Offset in MDI/SOHO Magnetograms
Liu, Yang; Hoeksema, J. Todd; Zhao, Xuepu
Shutter noise induces a small random shift of the zero point in full-disk magnetograms obtained by the Michelson Doppler Imager (MDI) instrument aboard SOHO. In this paper, we develop a method to remove this offset by fitting the distribution of the magnetic field strength with a Gaussian function (Ulrich et al., 2002). We also discover a systemat…
Prominence corona transition region plasma diagnostics from SOHO observations
Vial, J. -C.; Rovira, M.; Cirigliano, D.
New results concerning prominence observations and in particular the prominence-corona transition region (PCTR) are presented. In order to cover a temperature range from 2 × 104 to 7 × 105 K, several emission lines in many different ionization states were observed with SUMER and CDS on board SOHO. EM and DEM were measured thr…
On Re-sampling of Solar Images
DeForest, C. E.
Digital image data are now commonly used throughout the field of solar physics. Many steps of image data analysis, including image co-alignment, perspective reprojection of the solar surface, and compensation for solar rotation, require re-sampling original telescope image data under a distorting coordinate transformation. The most common image re…
On the Coronal Mass Ejection onset and Coronal Dimming
Howard, Timothy A.; Harrison, Richard A.
A comprehensive case and statistical study of CME onsets has been conducted on the solar limb using the CDS, LASCO and EIT instruments aboard the SOHO spacecraft. This is the first dedicated campaign to establish firmly the EUV signatures of CME onsets and is based on a series of low-corona observing campaigns made in 2002. The event database cons…
A High-Speed Erupting-Prominence CME: A Bridge Between Types
Feynman, Joan; Ruzmaikin, Alexander
Several studies have indicated that there may be two distinct types of coronal mass ejections (CMEs); a high-velocity bright energetic type associated with flares, and a smaller slower less impressive type associated with erupting prominences. How valid is this distinction? We analyze a CME combining attributes of both types, a high-velocity brigh…