X-Ray and Microwave Emission of the Sun with Special Reference to the Events of July, 1961

Abstract

view Abstract Citations (37) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-Ray and Microwave Emission of the Sun with Special Reference to the Events of July, 1961 Acton, Loren W. Abstract X-ray (X < 14 A), microwave (X = 10 7 cm), optical, and ionospheric observations are utilized to- gether with theoretical X-ray spectra to derive physical models of some X-ray emitting volumes on the Sun. The following kinds of emitting regions are studied: (1) a large "permanent" coronal condensation; (2) a flare in its flash phase; (3) a yellow-line condensation associated with a post-flare loop-prominence system. Most of the observational data were gathered during the month of July, 1961. This period presented the opportunity to study the X-ray emission of the Sun over a wide range of solar activity and at the same time unambiguously to identify the sources of the emission. Both thermal and non-thermal emission processes seem to be required to account for the X-ray emis- sion from flares. This study indicates that it is not necessary to invoke temperatures higher than 4-5 X 106 O K to account for the thermal radiation of flares. The prolonged enhancements of soft X-rays which follow some large flares appear to be thermal emission from the same "sporadic" coronal condensations which emit the yellow-line of Ca xv. In the case of the yellow-line condensation studied here, the observa- tions are best fitted if 1 per cent of the volume contains 90 per cent of the material Publication: The Astrophysical Journal Pub Date: April 1968 DOI: 10.1086/149546 Bibcode: 1968ApJ...152..305A full text sources ADS |