SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 11 - MAY 30, 2006

92 SOLAR PHYSICS
Includes solar activity, solar flares, solar radiation and sunspots.

For related information see 93 Space Radiation.

20060013172 NASA Goddard Space Flight Center, Greenbelt, MD, USA

IHY Modeling Support at the Community Coordinated Modeling Center

Chulaki, A.; Hesse, Michael; Kuznetsova, Masha; MacNeice, P.; Rastaetter, L.; [2005]; 2 pp.; In English; Stereo/Solar-B Science Planning Workshop: Living With a Star, 15-18 Nov. 2005, Oahu, HI, USA; Copyright; Avail.: Other Sources; Abstract Only

The Community Coordinated Modeling Center (CCMC) is a US inter-agency activity aiming at research in support of the generation of advanced space weather models. As one of its main functions, the CCMC provides to researchers the use of space science models, even if they are not model owners themselves. In particular, the CCMC provides to the research community the execution of 'runs-onrequest' for specific events of interest to space science researchers. Through this activity and the concurrent development of advanced visualization tools, CCMC provides, to the general science community, unprecedented access to a large number of state-of-the-art research models. CCMC houses models that cover the entire domain from the Sun to the Earth. In this presentation, we will provide an overview of CCMC modeling services that are available to support activities during the International Heliospheric Year. In order to tailor CCMC activities to IHY needs, we will also invite community input into our IHY planning activities. Author

Models; Space Weather; Heliosphere; Aerospace Sciences

20060013179 NASA Goddard Space Flight Center, Greenbelt, MD, USA

MHD Simulation Heliospheric Magnetic Fields and Turbulence

Roberts, D. Aaron; [2005]; 1 pp.; In English; Calspace-TGPP Numerical Modeling of Space Plasma Flows, 27-31 Mar. 2005, Palm Springs, CA, USA; No Copyright; Avail.: Other Sources; Abstract Only

This talk will present a summary of our results on simulations of heliospheric structure and dynamics. We use a three-dimensional MHD code in spherical coordinates to produce a solar wind containing a rotating, tilted heliospheric current sheet, fast-slow stream and microstream shear layers, waves, 2-D turbulence, and pressure balanced structures that are input to the inner (superAlfvenic) boundary. The evolution of various combinations of these has led to a deeper understanding of sector structure, magnetic holes, fluctuation anisotropies, and general turbulent evolution. We show how the sectors are likely to be connected, how spiral fields can arise, and how field line diffusion can be caused by waves with transverse structure and microstream shears. Author

Magnetohydrodynamics; Simulation; Heliosphere; Magnetic Fields; Turbulence; Spherical Coordinates; Solar Wind; Current Sheets; Shear Layers; Boundaries

20060013194 NASA Goddard Space Flight Center, Greenbelt, MD, USA

UV Observations of Prominence Activation and Cool Loop Dynamics

Kucera, Therese A.; Landi, Enrico; January 2006; 2 pp.; In English; Copyright; Avail.: Other Sources; Abstract Only

In this paper we investigate the thermal and dynamic properties of dynamic structures in and around a prominence channel observed on the limb on 17 April 2003. Observations were taken with the Solar and Heliospheric Observatory's Solar Ultraviolet Measurements of Emitted Radiation (SOHO/SUMER) in lines formed at temperatures from 80,000 to 1.6 MK. The instrument was pointed to a single location and took a series of 90 s exposures. Two-dimensional context was provided by the Transition Region and Coronal Explorer (TRACE) in the UV and EUV and the Kanzelhohe Solar Observatory in H-alpha. Two dynamic features were studied in depth: an activated prominence and repeated motions in a loop near the prominence. We calculated three-dimensional geometries and trajectories, differential emission measure, and limits on the mass, pressure, average density, and kinetic and thermal energies. These observations provide important tests for models of dynamics in prominences and cool (approx. 10(exp 5) K)loops, which will ultimately lead to a better understanding the mechanism(s) leading to energy and mass flow in these solar features. Author

Dynamic Characteristics; Extreme Ultraviolet Radiation; Solar Observatories; Heliosphere; Mass Flow; Thermal Energy

20060013195 NASA Goddard Space Flight Center, Greenbelt, MD, USA

Electron-He(+) P-wave Elastic Scattering and Photoabsorption in Two-electron Systems

Bhatia, A. K.; January 2006; 1 pp.; In English; No Copyright; Avail.: Other Sources; Abstract Only

In a previous paper [Bhatia, Phys. Rev. A 69,032714 (2004)], electron-hydrogen P-wave scattering phase shifts were calculated using the optical potential approach based on the Feshbach projection operator formalism. This method is now extended to the singlet and triplet electron-He(+) P-wave scattering in the elastic region. Phase shifts are calculated using Hylleraas-type correlation functions with up to 220 terms. Results are rigorous lower bounds to the exact phase shifts and they are compared to phase shifts obtained from the method of polarized orbitals and close-coupling calculations. The continuum functions calculated here are used to calculate photoabsorption cross sections. Photoionization cross sections of He and photodetachment cross sections of H(-) are calculated in the elastic region, i.e. leaving He(+) and H in their respective ground states, and compared with previous calculations. Radiative attachment rates are also calculated. Author

Wave Scattering; Elastic Scattering; Photoionization; Correlation; Hydrogen; P Waves; Photoabsorption

20060013196 NASA Goddard Space Flight Center, Greenbelt, MD, USA

Prominence and Cool Loop Energetics Measured in the UV, EUV, and H-alpha

Kucera, Therese A.; Landi, E.; January 2006; 1 pp.; In English; SOHO-17 Workshop, 7-12 May 2006, Sicily, Italy Contract(s)/Grant(s): NNH04AA12I; W10,232; NNG04ED07P; RTOP 370-16-25; Copyright; Avail.: Other Sources; Abstract Only

We investigate the thermal and dynamic properties of moving features in a prominence jet, a approx. 10(exp 5)K loop near a prominence channel, and an erupting prominence. In order to make measurements of the quickly moving features seen in prominences in the UV we use the SOHO/SUMER spectrograph to take a time series of exposures from a single pointing position, providing a measurement of spectral line properties as a function of time and position along the slit. The lines observed cover a broad range of temperatures from 80,000 - 1.6 million K. These measurements are combined with TRACE movies in transition region and coronal temperature bands and with ground based H-alpha data to obtain more complete information concerning prominence structure and motions. The resulting observations allow us perform DEM analysis and to calculate limits on densities, pressures, and the thermal and kinetic energies of the moving sources. Author

Extreme Ultraviolet Radiation; Solar Prominences; Transition Temperature; H Alpha Line; Thermal Energy; Coronas; Dynamic Characteristics; Time Series Analysis; Time Dependence

Source: NASA