The Lack of Fundamental Atomic and Molecular Data: A Crisis in Space Astronomy?

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A crisis is now confronting space astronomy. Many current and future investigations at UV and Extreme-UV wavelengths with space observatories such as the International Ultraviolet Explorer (IUE), Hubble Space Telescope (HST), Extreme UV Explorer, and Lyman are limited by the current availability of good fundamental atomic data such as accurate energy levels, wavelengths, and oscillator strengths.

Until very recently, spectroscopic studies using the IUE of hot O-subdwarfs have revealed the vast majority of the photospheric features could not be identified. Our recent detection of species such as Fe V, VI, and VII in very hot white dwarfs was unexpected and has definite implications for observations to be obtained by the EUVE and Lyman. Coadded spectra of these degenerate objects show many other unidentified features. Accurate atomic data for these highly ionized species will be a prerequisite to doing any quantitative analysis of these species and understanding the flux distributions in the EUV, where the strongest lines of these highly-ionized species are located.