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New abundance measurements in UKS 1927-177, a very metal-poor galaxy in the Local Group

I. Saviane·L. Rizzi·E. V. Held·F. Bresolin·Y. Momany
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Abstract

We present new results from optical spectroscopy of the brightest Hii region in the dwarf irregular galaxy UKS 1927-177 in Sagittarius (SagDIG). From high signal-to-noise spectra, reddening-corrected line flux ratios have been measured with typical uncertainties of a few percent, from which the oxygen abundance is rediscussed, and new abundance estimates are derived for N and Ne. The O abundance in SagDIG, estimated with the empirical abundance indicator R23 and other methods, is in the range 12+log(O/H)=7.26 to 7.50. The fact that SagDIG is ~10 times closer than IZw18 makes it an ideal target to test the hypothesis of the existence of young galaxies in the present-day universe. Indeed, stellar photometry suggests that this galaxy may harbor a stellar population older than a few Gyr, and possibly an old stellar component as well. The case of SagDIG therefore supports the view that very low chemical abundances can be maintained throughout the life of a dwarf stellar system, even in the presence of multiple star formation episodes.

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I. Saviane, L. Rizzi, E. V. Held, F. Bresolin, Y. Momany. 2002-05-21. New abundance measurements in UKS 1927-177, a very metal-poor galaxy in the Local Group. https://doi.org/10.1051/0004-6361%3A20020750

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