Abstract
view Abstract Citations (60) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Impulsive extreme-ultraviolet and hard X-ray emission during solar flares. Donnelly, R. F. ; Kane, S. R. Abstract Impulsive solar bursts of hard X-rays observed with moderate spectral resolution and high time resolution by the OGO S satellite were compared with concurrent enhancements of extreme- ultraviolet (EUV) radiation observed by means of sudden frequency deviations. The impulsive EUV flux rises and decays, with a time structure most like that of the lowest-energy hard X-rays observed-the 10-20 keV X-rays-but slower than hard X-rays with photon energy greater than 32 keV. These results are interpreted in terms of the dominance of 10-25 keV electrons in exciting the high-density impulsive EUV source. The impulsive EUV emission varies with the central meridian distance of the flare, with a peak in EUV intensity for flares near the central meridian and a marked decline in intensity near the solar limb. These observations are consistent with a model of the impulsive phase in which the EUV burst originates in sources embedded deep in a cool absorbing atmosphere, including fine spatial structure smaller than an arcsec, and in which both the electron precipitation efficiency and the EUV radiation efficiency are small. Subject headings: Sun: flares - Sun: X-rays - ultraviolet: general Publication: The Astrophysical Journal Pub Date: June 1978 DOI: 10.1086/156222 Bibcode: 1978ApJ...222.1043D Keywords: Far Ultraviolet Radiation; Satellite Observation; Solar Flares; Solar X-Rays; Electron Precipitation; Ogo-5; Radiant Flux Density; Solar Activity Effects; X Ray Spectra; Solar Physics; Extreme UV:Solar Flares; Solar Flares:X Rays; Solar X Rays: Hard X Rays full text sources ADS |
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