Abstract
view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Emission of Extreme Ultraviolet Line Radiation from Solar Centers of Activity. Neupert, W. M. Abstract A scanning monochromator, mounted as a pointed experiment on OSO-1, has been used for observation of the solar extreme-ultraviolet emission line spectrum in the spectral range from 50 to 400 A. It is found that increases in ultraviolet fluxes over those observed from the quiet sun can be localized to plage areas existing on the solar disk. The development of these regions of enhanced emission (coronal centers of activity) can be traced through observations covering nearly three solar rotations. The enhancement of radiation from active regions varies from line to line in the spectrum depending upon the origin of the line in the solar atmosphere, the greatest flux increases being associated with the Fe xv and Fe xvi lines. However, the intensity ratio of Fe xvi to Fe xv is found to remain nearly constant in time, showing a slight increase only during an appearance of a group of active Centers in the second and third months of their development. An electron temperature of 1.8 million degrees has been derived from the ratio of Fe xvi to Fe xv for a quiet sun (Zurich Provisional Relative Sunspot Number equal to zero). Observations are discussed in terms of a nonisothermal coronal model. Publication: The Astronomical Journal Pub Date: September 1963 DOI: 10.1086/109102 Bibcode: 1963AJ.....68R.288N full text sources ADS |
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