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A. Aloisi, C. Leitherer, M. Clampin, A. Nota (STScI), L. Greggio, L. Origlia, M. Tosi (Bologna Observatory), B. Barbuy (Universidade de Sao Paulo), K.A. Venn (Macalester College)
NGC 1569 is the closest example of a starburst galaxy outside the Local Group. It has experienced a strong star formation activity over the past few hundred Myr. Chemical evolution models predict a significant \alpha/Fe enhancement in this galaxy. The metal abundances in its gaseous component do not reflect the chemical enrichment history of its ISM, due to the presence of a galactic outflow. The predictions of the chemical evolution models can instead be settled with a direct abundance measurement in recently formed stars. To this purpose we have acquired STIS observations of some bright young A and F supergiant stars in NGC 1569. Low resolution spectra around 4300 Å~ have been used for spectral classification purposes in order to derive Teff and logg. Medium resolution spectra around 6200 Å~ have been obtained to determine element abundances of Fe and several \alpha-elements, being this spectral range very rich in FeI and FeII lines, as well as in O, Mg, Si, and Ca lines. Here we present the results of our STIS observations, and their interpretation with the stellar atmosphere tools we have developed. Our work represents one of the first attempts to determine metal abundances in individual stars outside the Local Group. It is of fundamental importance to understand galaxy evolution, as well as to constrain the enrichment of the intracluster and intergalactic medium.
Support for this work was provided by NASA through grant GO-08291.01.A from STScI.
The author(s) of this abstract have provided an email address for comments about the abstract: aloisi@stsci.edu