The iron abundance of the Magellanic Bridge

• Published in: Monthly notices of the Royal Astronomical Society 2008-04, Vol.385 (4), p.2261-2268
• Main Authors: Dufton, P. L., Ryans, R. S. I., Thompson, H. M. A., Street, R. A.
• Format: Article
• Language: English
• Subjects: Astronomy; Astrophysics; Earth, ocean, space; Exact sciences and technology; galaxies: abundances; galaxies: interactions; Iron; Magellanic Clouds; Spectrum analysis; stars: abundances; stars: early-type; Thermodynamics
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2008.12997.x

High-resolution Hubble Space Telescope ultraviolet spectra for five B-type stars in the Magellanic Bridge and in the Large (LMC) and Small (SMC) Magellanic Clouds have been analysed to estimate their iron abundances. Those for the Clouds are lower than estimates obtained from late-type stars or the optical lines in B-type stars by approximately 0.5 dex. This may be due to systematic errors possibly arising from non-local thermodynamic equilibrium (non-LTE) effects or from errors in the atomic data, as similar low Fe abundances have previously been reported from the analysis of the ultraviolet spectra of Galactic early-type stars. The iron abundance estimates for all three Bridge targets appear to be significantly lower than those found for the SMC and LMC by approximately −0.5 and −0.8 dex, respectively, and these differential results should not be affected by any systematic errors present in the absolute abundance estimates. These differential iron abundance estimates are consistent with the underabundances for C, N, O, Mg and Si of approximately −1.1 dex relative to our Galaxy previously found in our Bridge targets. The implications of these very low metal abundances for the Magellanic Bridge are discussed in terms of metal deficient material being stripped from the SMC.