Kα line emission during solar X-ray bursts

✍ Scribed by K. J. H. Phillips; W. M. Neupert

• Publisher: Springer
• Year: 1973
• Tongue: English
• Weight: 770 KB
• Volume: 32
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00152737

✦ Synopsis

Kct X-ray line emission from S, Ar, Ca and Fe is calculated for conditions likely to exist in solar flares. We consider both the non-thermal and thermal phases of flares as indicated by X-ray observations. Impulsive non-thermal events seen at the onset of a flare at photon energies > 20 keV generally give rise to small Kc~ line fluxes (< 250 photons cm -z s -1-) on the basis of data presented by Kane and Anderson. The amount of S Kc~ radiation in particular depends sensitively on the lowerenergy bound of the non-thermal electron distribution giving rise to the impulsive burst, offering a possible means of determining this. Thermal Kc~ emission is significant for only Fe ions. For S, Ar and Ca, the temperatures required for a sizeable number of electrons with energies greater than the K-ionization potential will also strip these elements to ionization stages too high for Kc~ transitions to be possible. Comparison of thermal Kc~ emission from iron during an intense solar flare leads to a very high emission measure on the basis of these calculations, but such a value seems to be compatible with an analysis of the I-3 2t continuum during the same event.