HR: 0800h
AN: SH21B-0424    [Abstracts]
TI: Modelling of the Quiet Sun Emission in the Metric Radio Range
AU: * Marque, C
EM: christophe.marque@nrl.navy.mil
AF: Universities Space Research Association, Naval Research Laboratory 4555 Overlook Av SW, Washington, DC 20375 United States
AU: Wang, Y
EM: ywang@pinoak.nrl.navy.mil
AF: Naval Research Laboratory, Naval Research Laboratory 4555 Overlook Av SW, Washington, DC 20375 United States
AU: Thernisien, A F
EM: arnaud.thernisien@nrl.navy.mil
AF: Universities Space Research Association, Naval Research Laboratory 4555 Overlook Av SW, Washington, DC 20375 United States
AU: Howard, R A
EM: russ.howard@nrl.navy.mil
AF: Naval Research Laboratory, Naval Research Laboratory 4555 Overlook Av SW, Washington, DC 20375 United States
AU: Vourlidas, A
EM: angelos.vourlidas@nrl.navy.mil
AF: Naval Research Laboratory, Naval Research Laboratory 4555 Overlook Av SW, Washington, DC 20375 United States
AU: Patel, N S
EM: nishant.patel@nrl.navy.mil
AF: Naval Research Laboratory, Naval Research Laboratory 4555 Overlook Av SW, Washington, DC 20375 United States
AB: The thermal emission from the Quiet Sun can be mapped in the metric radio range when the solar activity is low, and plasma emissions due to non-maxwellian distributions of electrons are weak or non-existent. This occurs mainly in the vicinity of the solar cycle minimum. Metric radio observations have been used in the past to infer the mean coronal temperature, and to map and study large scale coronal structures. Earlier simulations using symmetrical electron density distributions and uniform temperatures were succesful to depict some of the properties of the Quiet Sun emission but are not suitable in detailed comparisons with observations, and furthermore, they predict limb brightening in the high frequency range of the metric domain (150-450 MHz), which has not been observed so far. In this paper, we present simulations of the Quiet Sun emission based on Potential Field Source Surface extrapolations, which are used to build a global density and temperature model of the corona at a given date. Scaling laws involving the loop footpoint field strength and loop length govern the density and temperature distribution in this model. Synthetic radio images are then computed using raytracing techniques, taking into account the refraction of radio waves in the corona, and are compared with actual observations provided by the Nancay Radioheliograph.
DE: 7509 Corona
DE: 7534 Radio emissions
DE: 7594 Instruments and techniques
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting