7 research outputs found
New abundance measurements in UKS 1927-177, a very metal-poor galaxy in the Local Group
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.Comment: 6 pages, 3 figures, accepted for publication in A&A, main journa