Quiescent sun x-ray measurements made by different workers during the past 19 years have been studied. Analysis of the data available up to April, 1967, confirms the conclusion that the quiescent sun x-ray emission is thermal in nature and is closely related to the solar activity level. The spectrum below 18 Å is mainly continuous and is primarily due to recombination emission. Bremsstrahlung becomes important at high temperatures. The 18 - 100 Å flux is primarily due to line emission and is emitted mainly by the undisturbed coronal regions. Below 20 A the emission is primarily from the active - hotter and denser - coronal regions. In this spectral region the flux varies within wide limits, depending on the number, dimensions, density and temperature of the active regions. Preferred regions of x-ray emission lie above strong calcium plages in the chromosphere and coincide with regions of enhanced centimeter radio emission. Seventy-five percent of the total x-ray flux comes from these regions. The existing theory is capable of predicting x-ray flux within a factor of 2 or 3, using solar radio spectro-heliograms in the centimeter range.
Proceedings of the Iowa Academy of Science
©1968 Iowa Academy of Science, Inc.
Sengupta, P. R.
"Rocket and Satellite Studies of the X-Ray Emission from the Quiescent Sun,"
Proceedings of the Iowa Academy of Science, 75(1), 268-284.
Available at: https://scholarworks.uni.edu/pias/vol75/iss1/37