天体プラズマの高分解能分光観測

概要

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Astrophysical plasmas are of great interest in light of their extreme physical conditions, such as high temperature (> million K) and low density (<1 atom cm-3). However, high resolution spectroscopy of astrophysical plasmas has never been carried out. Two giant x-ray observatories, Chandra (NASA) and Newton (ESA) were launched in 1999 with grating systems. E/dE of about1,000 below 1 keV provides us with high quality spectroscopy data of various sources. This report describes the new data from stars, supernova remnants, active galactic nuclei and cluster of galaxies, and discuss its implications. Line ratios of different species give the abundance, while those of different ionization states indicate the ionization parameters. The ratios of resonance, forbidden and intercombination lines indicate the ionization temperature and density of plasmas. Observed shifts of line energies are due to the bulk motion of the plasmas at velocities up to 1,000 km/s. Grating spectrometers can easily obtain clear results from point sources, though they are not adequate to perform high resolution spectroscopy of diffuse sources such as SNR and cluster of galaxies.
プラズマ・核融合学会の論文
2003-04-25