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Issue A&A
Volume 390, Number 1, July IV 2002
Page(s) 59 - 64
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20020750



A&A 390, 59-64 (2002)
DOI: 10.1051/0004-6361:20020750

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

I. Saviane1, L. Rizzi2, 3, E. V. Held2, F. Bresolin4 and Y. Momany3

1  European Southern Observatory, Casilla 19001, Santiago 19, Chile
2  Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, 35122 Padova, Italy
    e-mail: (rizzi, held)@pd.astro.it
3  Dipartimento di Astronomia, Università di Padova, vicolo dell'Osservatorio 2, 35122 Padova, Italy
    e-mail: momany@pd.astro.it
4  Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822
    e-mail: bresolin@ifa.hawaii.edu

(Received 26 February 2002 / Accepted 15 May 2002 )

Abstract
We present new results from optical spectroscopy of the brightest HII region in the dwarf irregular galaxy 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 R 23 and other methods, is in the range \( 12+\log\, ({\rm O/H})=7.26 \) to 7.50. The fact that SagDIG is \( \sim \)10 times closer than I Zw 18 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.


Key words: galaxies: individual: SagDIG -- galaxies: abundances -- galaxies: dwarf -- galaxies: ISM -- galaxies: irregular -- Local Group

Offprint request: I. Saviane, isaviane@eso.org

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© ESO 2002


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