HR: 1340h
AN: SH44A-1732    [Abstracts]
TI: Magnetic Reconnection Site Suggested by a Double Coronal X-ray Source Observed by RHESSI
AU: * Liu, W
EM: weiliu@helio.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Solar Physics Laboratory, Code 671, Heliophysics Science Division, Greenbelt, MD 20771, United States
AU: * Liu, W
EM: weiliu@helio.gsfc.nasa.gov
AF: Stanford University, Center for Space Science and Astrophysics, Stanford, CA 94305, United States
AU: Petrosian, V
AF: Stanford University, Center for Space Science and Astrophysics, Stanford, CA 94305, United States
AU: Dennis, B R
AF: NASA Goddard Space Flight Center, Solar Physics Laboratory, Code 671, Heliophysics Science Division, Greenbelt, MD 20771, United States
AU: Jiang, Y
AF: Stanford University, Center for Space Science and Astrophysics, Stanford, CA 94305, United States
AB: In the classical reconnection model, magnetic field annihilation in a current sheet generates turbulence and outflows of high speed plasmas in opposite directions. The turbulence accelerates particles and heats the background plasma. Observational signatures, such as radio emission and hard and soft X-rays produced by these high-energy particles and hot plasmas, are thus expected to show the two oppositely directed outflows. However, such observations have rarely been reported in the past. In this talk, we present data analysis and interpretation of an M1.4-class flare observed with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) on April 30, 2002. This event, with its footpoints occulted by the solar limb, exhibits such a rarely observed double-source morphology in the corona over the 6--30~keV range. The two coronal sources, appearing at different altitudes, show energy-dependent structures with the higher-energy emission being closer together. Spectral analysis implies that the emission at higher energies in the inner region between the two sources is mainly nonthermal, while the emission at lower energies in the outer region is primarily thermal. The two sources are both visible for about 12 minutes and have similar light curves and power-law spectra (assumed nonthermal) above about 20~keV. These observations suggest that the magnetic reconnection site lies between the two sources. Bi-directional outflows of the released energy in the form of turbulence and/or particle beams away from the reconnection site can be the source of the observed radiation. The spatially resolved thermal emission below about 15~keV, on the other hand, indicates that the lower coronal source has a larger emission measure but a lower temperature than the upper source. This is likely the result of the different magnetic topologies of the two sources. Implications of these results for particle acceleration and plasma heating in theoretical flare models will be discussed.
UR: http://hesperia.gsfc.nasa.gov/~weiliu/research/publications/2007_doubleXR DE: 7519 Flares
DE: 7526 Magnetic reconnection (2723, 7835)
DE: 7554 X-rays, gamma rays, and neutrinos
DE: 7845 Particle acceleration
DE: 7863 Turbulence (4490)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting