view Abstract Citations (25) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS VLA observations of solar flares, interpreted with optical, X-ray, and other microwave data. Marsh, K. A. ; Hurford, G. J. ; Zirin, H. Abstract Three small solar flares were observed from the active region McMath 14979 during 1655- 1725 UT on 1977 October 12, using the southwest arm of the Very Large Array (VLA) at 4.9 0Hz. These observations showed the presence of two distinct flare components: (1) A dominant broad component of size 10", with gradual rise-and-fall behavior and circular polarization, and (2) small impulsive components of size 2"-4", 53 987o circularly polarized. Simultaneous interferometric observations of the 1703 UT flare with the Owens Valley solar interferometer at 10.7 0Hz, together with the VLA data, fixed the location of the broad component in two dimensions. Comparison with Ha photographs and magnetograms showed that this component was located in the magnetic arch at whose footpoints the Ha flare occurred. The electron temperature and emission measure implied by OSO8 soft X-ray observations yielded a corresponding free-free microwave flux which entirely accounted for the observed emission at 10.7 0Hz. The microwave spectrum at lower frequencies (2.7 0Hz and 4.9 0Hz) was then consistent with thermal gyroresonance radiation in a magnetic field of 300 gauss. The radio, optical, and X-ray observations thereby suggest that the broad microwave component was a thermal cloud trapped in a magnetic arch. The impulsive events probably occurred at the positive-polarity footpoints of this arch. Subject headings: Sun: flares - Sun: radio radiation - Sun: X-rays Publication: The Astrophysical Journal Pub Date: March 1979 DOI: 10.1086/156885 Bibcode: 1979ApJ...228..610M Keywords: Microwave Spectra; Solar Flares; Solar Radio Emission; Solar X-Rays; Spaceborne Astronomy; Electron Energy; H Alpha Line; Oso-8; Plasma Resonance; Satellite Observation; Stellar Models; Thermal Plasmas; Solar Physics; Radio Radiation:Solar Flares; Solar Flares:X Rays full text sources ADS |