Observations of (Fe VII) and (Fe X) in the symbiotic star HM SGE during the interval of 1983-1985.

From observations at both Mt. Wilson and Palomar of the symbiotic star HM Sge, the authors have set new limits on the ratio of [Fe VII]/[Fe X] line intensities near 10^-2 at nearly the same time as soft X-rays were also observed in that star. The resulting number ratio of Fe⁶⁺ ions to Fe⁹⁺ ions is greater than 1.4×10⁴. A possible explanation is offered by analogy with active galactic nuclei in terms of a far-UV, soft X-ray, "big bump" that shows a sharp drop between 100 eV and 300 eV. Radiation near 100 eV would then ionize Fe⁵⁺ ions but there would be a deficiency of radiation to ionize Fe⁸⁺ ions. Radial velocities for various ions during the interval of 1983 - 1985 are also reported.