![]() ![]() Comparisons with soft x ray images and spectra and with hard x ray data specify the magnetic field strength and emission mechanism of flaring coronal loops. In some cases preburst heating and magnetic changes are observed from loops tens of minutes prior to the impulsive phase. The unprecedent spatial resolution of the VLA at 20 cm wavelength showed that the precursor, impulsive, and post-flare components more » of solar bursts originate in nearby, but separate loops or systems of loops. Detailed comparison of simultaneous Solar Maximum Mission (SMM) Satellite and VLA data indicate that physical parameters such as electron temperature, electron density, and magnetic field strength can be obtained, but that some coronal loops remain invisible in either spectral domain. Thermal cyclotron line emission was detected at the apex of coronal loops where the magnetic field strength is relatively constant. Very Large Array observations at 20 cm wavelength can detect the hot coronal plasma previously observed at soft x ray wavelengths. Thermal cyclotron lines provide a sensitive measurement of the coronal magnetic field, while comparisons with simultaneous SMM x-ray observations delineate the various radiation mechanisms. Multiple wavelength VLA observations specify the three-dimensional structure of solar-active regions they uniquely specify the strength, evolution and structure of the magnetic fields in coronal loops, while also providing constraints on the density and temperature of the energetic plasma trapped within them. The ubiquitous coronal loops dominate the structure of the solar corona. All three instruments were used to study the quiescent, or non-flaring emission from coronal loops, radio bursts from coronal loops, and radio bursts from nearby stars. The VLA uniquely provides spatial resolution at radio wavelengths, while the SMM gives x-ray data and the NR provides resolution in time more » and frequency. ![]() Several new insights to these exploding loops are provided using the VLA together with supporting observations with the Solar Maximum Mission (SMM) satellite and the Nancay Radioheliograph(NR). It is shown that energetic particles and radiation are expelled during explosive bursts from coronal loops. Observations of solar-active regions with the VLA have led to new information about the origin and prediction of explosive bursts, or solar flares, that can directly interfere with high-flying aircraft or disrupt communications with them. The coronae of nearby stars are discussed where coherent radiation processes seem to = , The 20-cm and x-ray emission of the coronal plasma are then compared. This is followed by a discussion of the 20 cm radiation of coronal loops and the thermal-cyclotron lines that accurately specify their magnetic field strength. The next section briefly reviews the thermal radiation mechanisms that account for most of the quiescent emission, while also pointing out that current-amplified magnetic fields or non thermal radiation may be required in some instances. Multiple-wavelength VLA observations can specify the strength, evolution and structure of the magnetic fields in coronal loops, while also providing constraints on the electron density and electron temperature of the plasma trapped within the coronal loops. They are often associated with the apex and/or legs of the ubiquitous coronal loops, which heretofore have been observable only with x ray telescopes sent above the atmosphere. Both the quiescent, or nonflaring, microwave sources and the flaring ones are usually resolved. The Very Large Array(VLA) was used to observe solar microwave sources with second-of-arc angular resolution. ![]()
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