The Iron Abundance of Iota Herculis From UV Fe II Lines.

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Session 45 -- Early Type Stars
Display presentation, Wednesday, 9:20-6:30, Heller Lounge Room

[45.10] The Iron Abundance of Iota Herculis From UV Fe II Lines.

C.Mulliss, J.Grigsby (Wittenberg University)

A co-added spectrum (Leckrone and Adelman 1989, ApJS 71, 387) of Iota Herculis (B3 IV) has been obtained from individual IUE long-wavelength (LWR) high dispersion spectra. The spectrum was co-added and made available to us by S. Adelman, D. Leckrone, and G. Peters (1992, private communication). LTE synthetic spectra with a resolution identical to that of IUE were produced with Kurucz's model atmosphere code ATLAS9 and spectral synthesis code SYNTHE (Kurucz 1979, ApJS 40, 1). The model was computed with T$_{eff}$=17500 K, log g=3.75 and v sin i=11 km/s (Peters \& Polidan 1985, in IAU Symposium 111, ed. D. S. Hayes et al., Dordrecht: Reidel, 417). From a detailed inspection of IUE spectrum in the 2000 - 3000 A region, 54 Fe II lines whose atomic parameters have been measured in the laboratory (Kurucz 1992,private communication) were chosen as abundance indicators. These lines in the co-added and the synthetic spectra were compared, and both the observed and synthetic equivalent widths were measured. We derived the abundance by fitting a straight line to a plot of the observed equivalent widths vs. the synthetic equivalent widths. We adjusted the abundance of the model until the slope of the fitted line was unity, and we found that a slope of unity occurs when the iron abundance of the model is 0.34 +/- 0.1 times that of the solar value. Based on the Fe II lines alone, we conclude that Iota Herculis is significantly underabundant in iron relative to the sun. This result is in agreement with the conclusion of Pintado and Adelman (1993, preprint), based on optical Fe II lines alone. We thank the Faculty Research Fund Board and the Office of the Provost of Wittenberg University for support of this research.

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