SCYON Abstract

Received on May 6 2008

Arp 2 and Terzan 8: a detailed chemical analysis

AuthorsM. Mottini (1), G. Wallerstein (1), and A. McWilliam (2)
Affiliation(1) Astronomy Department,University of Washington, box 351580, Seattle, WA 98195, USA
(2) The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena, CA 91101, USA
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Contactmarta@astro.washington.edu
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Abstract

To compare the globular clusters associated with the Sagittarius Galaxy we report the results obtained from new high resolution spectra of red giant stars in Terzan 8 and Arp 2, collected with the Magellan echelle spectrograph (MIKE) at Las Campanas Observatory. For Ter 8 we find [FeI/H]=[FeII/H]-2.32±0.07, while for Arp 2 [FeI/H]=-1.78±0.04 and [FeII/H]=-1.94±0.07. Other elements usually of interest show the following results. For oxygen we obtain [O/Fe]=0.67±0.16 for Ter 8 and [O/Fe]=0.28±0.22 for Arp 2. For the α-elements (Mg, Si, Ca, Ti) the mean values are 0.35±0.14 dex for Ter 8 and 0.33±0.11 for Arp 2. These values are not too different from the Galactic globular clusters at a similar [Fe/H] value. The heavy s-process elements Ba and Nd show no excesses in Ter 8 and in Arp 2. Our only r-process element, Eu, shows an excess of 0.53 dex in Arp 2, based on the only useful line at 6645Å.