SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 7 - April 07, 2006

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

For related information see 93 Space Radiation.

20060009195 Delaware Univ., Newark, DE, USA

Spatial Correlation of Solar-Wind Turbulence from Two-Point Measurements

Matthaeus, W. H.; Milano, L. J.; Dasso, S.; Weygand, J. M.; Smith, C. W.; Kivelson, M. G.; Physical Review Letters;December 2, 2005; Volume 95; 5 pp.; In English; Original contains black and white illustrationsContract(s)/Grant(s): PC251459; UBACYT-X329; PIP-6220; PICT-14163; NAG5-12121; NAG5-8134; NAG5-11603;NAG5-6912; NSF ATM-01-05254; Copyright; Avail.: Other Sources

Interplanetary turbulence, the best studied case of low frequency plasma turbulence, is the only directly quantifiedinstance of astrophysical turbulence. Here, magnetic field correlation analysis, using for the first time only proper two-point,single time measurements, provides a key step in unraveling the space-time structure of interplanetary turbulence.Simultaneous magnetic field data from theWind, ACE, and Cluster spacecraft are analyzed to determine the correlation (outer)scale, and the Taylor microscale near Earth’s orbit. Author

Correlation; Magnetic Fields; Solar Wind; Plasma Turbulence

20060009936 Science Applications International Corp., San Diego, CA, USA

Evidence of Posteruption Reconnection Associated with Coronal Mass Ejections in the Solar Wind

Riley, Pete; Linker, J. A.; Mikic, Z.; Odstracil, D.; Pizzo, V. J.; Webb, D. F.; The Astrophysical Journal; October 20, 2002; Volume 578, pp. 972-978; In English Contract(s)/Grant(s): NASW-02027; NAG5-10833; NSF ATM-96-13834; Copyright; Avail.: Other Sources

Using a coupled 2.5-dimensional, time-dependent MHD model of the solar corona and inner heliosphere, we have simulated the eruption and evolution of a coronal mass ejection containing a flux rope all the way from the Sun to 1 AU. Although idealized, we find that the simulation reproduces many generic features of magnetic clouds. In this paper we report on a new, intriguing aspect of these comparisons. Specifically, the results suggest that jetted outflow, driven by posteruptive reconnection underneath the flux rope, occurs and may remain intact out to 1 AU and beyond. We present an example of a magnetic cloud with precisely these signatures and show that the velocity perturbations are consistent with reconnection outflow. We suggest that other velocity and/or density enhancements observed trailing magnetic clouds may be signatures of such reconnection and, in some cases, may not be associated with prominence material, as has previously been suggested. Author

Solar Wind; Coronal Mass Ejection; Magnetic Clouds; Magnetohydrodynamics; Solar Corona; PerturbationCycles

20060010025 Science Applications International Corp., San Diego, CA, USA

Kinematic Treatment of Coronal Mass Ejection Evolution in the Solar Wind

Riley, Pete; Crooker, N. U.; The Astrophysical Journal; January 10, 2004; Volume 600, pp. 1035-1042; In English Contract(s)/Grant(s): NASW-02027; NAG5-10881; Copyright; Avail.: Other Sources

We present a kinematic study of the evolution of coronal mass ejections (CMEs) in the solar wind. Specifically, we consider the effects of (1) spherical expansion and (2) uniform expansion due to pressure gradients between the interplanetary CME (ICME) and the ambient solar wind.We compare these results with an MHD model that allows us to isolate these effects h m the combined kinematic and dynamical effects, which are included in MHD models. They also provide compelling evidence that the fundamental cross section of so-called ‘force-free’ flux ropes (or magnetic clouds) is neither circular or elliptical, but rather a convex-outward, ‘pancake’ shape. We apply a force-free fit to the magnetic vectors from the MHD simulation to assess how the distortion of the flux rope affects the fit. In spite of these limitations, force-free fits, which are straightforward to apply, do provide an important description of a number of parameters, including the radial dimension, orientation, and chirality of the ICME. Subject headings: MHD - solar wind - Sun: activity - Sun: corona - Sun: coronal mass ejections (CMEs) - On-line material color figures Sun: magnetic fields. Author

Coronal Mass Ejection; Solar Wind; Kinematics; Magnetohydrodynamics; Distortion; Force-Free Magnetic Fields; Magnetic Clouds

Source: NASA