Volume 519, September 2010
|Number of page(s)||7|
|Section||Galactic structure, stellar clusters, and populations|
|Published online||07 September 2010|
Light-element abundance variations in the Milky Way halo
Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, 69120 Heidelberg, Germany e-mail: email@example.com
Accepted: 18 May 2010
We present evidence for the contribution of high-mass globular clusters to the stellar halo of the Galaxy. Using SDSS-II/SEGUE spectra of over 1900 G- and K-type halo giants, we identify for the first time a subset of stars with CN bandstrengths significantly larger, and CH bandstrengths lower, than the majority of halo field stars, at fixed temperature and metallicity. Since CN bandstrength inhomogeneity and the usual attendant abundance variations are presently understood as a result of star formation in globular clusters, we interpret this subset of halo giants as a result of globular cluster dissolution into the Galactic halo. We find that 2.5% of our sample is CN-strong, and can infer based on recent models of globular cluster evolution that the fraction of halo field stars initially formed within globular clusters may be as large as .
Key words: stars: abundances / Galaxy: halo / galaxies: formation
© ESO, 2010
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