Barbara Sylwester

Space Research Centre

Session X: Poster session

Thursday 14th September 2023 12:00 – 13:00

abstract:
Using new calibration data from the Bent Crystal Spectrometer (BCS) aboard NASA’s Solar Maximum Mission, the absolute abundance of calcium (Ca) was determined with high accuracy from observed high-resolution soft X-ray spectra.
The calcium abundances were determined based on the analysis of emission in its helium-like ion lines relative to the level of the adjacent continuum. Both the lines and the continuum are formed at plasma temperatures T > 5 MK.
It turned out that for the majority of decay phases of the 194 flares studied, the derived Ca abundance is constant within unprecedently high determination accuracy (1 – 3%). However, for some flares, changes in abundance over time are evident. We show examples of the obtained results and suggest a possible physical scenario explaining the observed changes in Ca abundance.