SIMBAD references

The role of optical Feiii absorption lines in B-type stars as iron abundance diagnostics is considered. To date, ultraviolet Fe lines have been widely used in B-type stars, although line blending can severely hinder their diagnostic power. Using optical spectra, covering a wavelength range ∼3560-9200Å, a sample of Galactic B-type main-sequence and supergiant stars of spectral types B0.5 to B7 are investigated. A comparison of the observed Feiii spectra of supergiants, and those predicted from the model atmosphere codes tlusty [plane-parallel, non-local thermodynamic equilibrium (LTE)], with spectra generated using synspec (LTE), and cmfgen (spherical, non-LTE), reveal that non-LTE effects appear small. In addition, a sample of main-sequence and supergiant objects, observed with the Fiber-fed Extended Range Optical Spectrograph (FEROS), reveal LTE abundance estimates consistent with the Galactic environment and previous optical studies. Based on the present study, we list a number of Feiii transitions which we recommend for estimating the iron abundance from early B-type stellar spectra.