Possible Detection of Thermal Cyclotron Lines from Small Sources within Solar Active Regions.
TUFTS UNIV MEDFORD MA DEPT OF PHYSICS
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Theoretical spectra of thermal cyclotron line emission from solar active regions are presented for two frequency bands available at the Very Large Array VLA. VLA synthesis maps of three active regions at 1380, 1540 and 1705 MHz are then presented. The maps of two of these regions show significant changes in the brightness temperature within these narrow frequency ranges. We show that these changes may be attributed to thermal cyclotron line emission in small regions theta 10 ins to 30 ins where the magnetic field is relatively constant with H 125-180 Gauss. An alternative interpretation, involving height-dependent variations in the physical conditions may also explain the changes in one of these regions. The potential to study coronal magnetic fields using VLA observations of cyclotron lines is also discussed.