Search Publications
Latitude Dependence of the Variations of Sunspot Group Numbers (SGN) and Coronal Mass Ejections (CMEs) in Cycle 23
Kane, R. P.
The 12-month running means of the conventional sunspot number Rz, the sunspot group numbers (SGN) and the frequency of occurrence of Coronal Mass Ejections (CMEs) were examined for cycle 23 (1996 - 2006). For the whole disc, the SGN and Rz plots were almost identical. Hence, SGN could be used as a proxy for Rz, for which latitude data are not avai…
Determination of the True Shape of Coronal Loops
Gontikakis, C.; Alissandrakis, C. E.; Dara, H. C.
Using line of sight velocity measurements from the SUMER and CDS instruments aboard SOHO, in conjunction with a simple geometrical model, we reconstructed the true, 3D shape and the velocity of plasma flow along coronal loops. The projection of the loop on the sky and the position of the footpoints define a family of curves. Assuming that the loop…
Widespread Occurrence of Trenching Patterns in the Granulation Field: Evidence for Roll Convection?
Getling, A. V.; Buchnev, A. A.
Time-averaged series of granulation images are analysed using COLIBRI, a purpose-adapted version of a code originally developed to detect straight or curvilinear features in aerospace images. The image-processing algorithm utilises a nonparametric statistical criterion that identifies a straight-line segment as a linear feature (lineament) if the …
Cross-Calibration of TIMED SEE and SOHO EIT Irradiances
Eparvier, F. G.; Hock, R. A.
Absolutely calibrated solar images are necessary for a variety of solar physics problems, such as the identification of solar variability sources and the derivation of differential emission measure (DEM) maps. SOHO EIT is absolutely calibrated by using TIMED SEE spectra to provide a method of determining physical values of irradiance for EIT image…
Analysis of Two Coronal Loops with Combined TRACE and SOHO/CDS Data
Martens, P. C. H.; Cirtain, J. W.; Scott, J. T.
We use an innovative research technique to analyze combined images from the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO) and the Transition Region and Coronal Explorer (TRACE). We produce a high spatial and temporal resolution simulated CDS raster or "composite" map from TRACE data and use this composite m…
Coronal Mass Ejections, Magnetic Fields, and the Green Corona in Cycle 23
Rušin, V.; Minarovjech, M.; Saniga, M.
We study a time - latitudinal distribution of CMEs observed by the SOHO spacecraft, their projected speeds and associated magnetic fields, as well as the north - south (N - S) asymmetry of solar surface magnetic fields, and the coronal green line intensities. We have found that (a) there exists an intricate relation between the average projected v…
Very Large Array, SOHO, and RHESSI Observations of Magnetic Interactions and Particle Propagation across Large-Scale Coronal Loops
Groff, Tyler D.; Willson, Robert F.
Very Large Array (VLA) observations at wavelengths of 20 and 91 cm have been combined with data from the SOHO and RHESSI solar missions to study the evolution of transequatorial loops connecting active regions on the solar surface. The radio observations provide information about the acceleration and propagation of energetic electrons in these lar…
Dependence of the Characteristics of Solar Wind Discontinuities and Shocks with Heliolatitude and Radial Distance
Dickson Benjamin, A.; Prabhakaran Nayar, S. R.
The distribution of the shocks in the heliosphere and their characteristic variations are investigated using Ulysses observations. The jumps in solar wind velocity, IMF magnitude, and proton density across the shocks and discontinuities are evaluated and used to characterize them. The distribution of these discontinuities with respect to heliolati…
Global Effects of Local Sound-Speed Perturbations in the Sun: A Theoretical Study
Larson, T. P.; Hanasoge, S. M.
We study the effect of localized sound-speed perturbations on global mode frequencies by applying techniques of global helioseismology to numerical simulations of the solar acoustic wave field. Extending the method of realization-noise subtraction (e.g., Hanasoge, Duvall, and Couvidat, Astrophys. J.664, 1234, 2007) to global modes and exploiting t…
The Hinode (Solar-B) Mission: An Overview
Golub, L.; Culhane, J. L.; Yamada, T. +22 more
The Hinode satellite (formerly Solar-B) of the Japan Aerospace Exploration Agency's Institute of Space and Astronautical Science (ISAS/JAXA) was successfully launched in September 2006. As the successor to the Yohkoh mission, it aims to understand how magnetic energy gets transferred from the photosphere to the upper atmosphere and results in expl…