Quiet and Active Solar Emission of Fe XV 284 A Radiation

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Abstract
Intensity contours of 284 Å radiation from the OS0-7 EUV spectroheliograph observations have been analysed to segregate emissions from the Quiet Sun (Q) and Active Regions (AR) during the period 1972 May to 1974 March. Results are expressed in absolute units using constants from the Goddard Space Flight Center. Measurements include: central, equatorial limb and polar intensities; also Q, AR and total fluxes. Both Q and AR fluxes vary almost in proportion to sunspot number. The Q intensity fits an exponential emission model with scale-height of 0·125 solar radii. Fluxes from individual AR's are closely related to plage–flux data and the relation does not change through the life of the plage. Constants representing the variation of 284 Å emission with the solar cycle have been determined and compared with previous estimates. The absolute emission of the quiet corona has been compared with expected values based on solar eclipse electron densities. The comparison allows an estimate of the coronal irregularity factor x which varies from 4 near the surface to 30 at 1 · 5 solar radii. Coronal densities within well-developed AR's are about five times the Q value.

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