2007A&A...465..815S -
Astronomy and Astrophysics, volume 465815-824 (2007/4-3)
The exotic chemical composition of the Sagittarius dwarf spheroidal galaxy.
SBORDONE L., BONIFACIO P., BUONANNO R., MARCONI G., MONACO L. and ZAGGIA S.
Abstract (from CDS):
The
Sagittarius dwarf spheroidal galaxy is the nearest neighbor of the Milky Way. Moving along a short period quasi-polar orbit within the Halo, it is being destroyed by the tidal interaction with our Galaxy, losing its stellar content along a huge stellar stream. We study the detailed chemical composition of 12 giant stars in the Sagittarius dwarf Spheroidal main body, together with 5 more in the associated globular cluster
Terzan 7, by means of high resolution VLT-UVES spectra. Abundances are derived for up to 21 elements from O to Nd, by fitting lines EW or line profiles against ATLAS 9 model atmospheres and SYNTHE spectral syntheses calculated ad-hoc. Temperatures are derived from (V-I)
0 or (B-V)
0 colors and gravities from FeI - FeII ionization equilibrium. The metallicity of the observed stars is between [Fe/H]=-0.9 and 0. We detected a highly peculiar ``chemical signature'', with undersolar α elements, Na, Al, Sc, V, Co, Ni, Cu, and Zn, among others, and overabundant La, Ce, and Nd. Many of these abundance ratios (in particular light-odd elements and iron peak ones) are strongly at odds with what is observed within the Milky Way, so they may be a very useful tool for recognizing populations originating within the Sagittarius dwarf. This can be clearly seen in the case of the globular
Palomar 12, which is believed to have been stripped from Sagittarius: the cluster shows precisely the same chemical ``oddities'', thus finally confirming its extragalactic origin.
Abstract Copyright:
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Journal keyword(s):
stars: abundances - stars: atmospheres - Galaxy: abundances - galaxies: dwarf - galaxies: individual: Sgr dSph - Galaly: globular clusters: individual: Terzan 7
VizieR on-line data:
<Available at CDS (J/A+A/465/815): table1.dat tablea.dat refs.dat>
Simbad objects:
27
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