NOAO > Observing Info > Approved Programs > 2010B-0228
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NOAO > Observing Info > Approved Programs > 2010B-0228 |
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PI: Sarah Martell, Universitat Heidelberg, martell@ari.uni-heidelberg.de
Address: ZAH/ARI, Monchhofstrasse 12-14, Heidelberg, Baden-W\"{u}rttemberg 69120, Germany
CoI: Eva Grebel, ZAH/ARI, Universitat Heidelberg
CoI: David Lai, NSF Postdoctoral Fellow, UC Santa Cruz
Title: Globular Cluster Contributions to the Galactic Halo
Abstract:
The goal of this project is to confirm chemically that globular
clusters are the source of as much as half the population of the
Galactic halo. Using moderate-resolution spectroscopy from the SEGUE
survey, we have identified a previously unknown population of halo field
giants with distinctly strong CN features. CN variations are typically
only observed in globular clusters, so these stars are interpreted as
immigrants to the halo that originally formed in globular clusters. In
one night of Keck/HIRES time, we will obtain high-quality, high-
resolution spectra for five such stars, and determine abundances of O,
Na, Mg, Al, alpha, iron-peak and neutron-capture elements. With this
information we can state clearly whether these unusual CN-strong halo
stars carry the full abundance pattern seen in CN-strong globular
cluster stars, with depleted C, O, and Mg and enhanced N, Na, and Al.
This type of coarse ``chemical tagging'' will allow a clearer division
of the Galactic halo into contributions from globular clusters and from
dwarf galaxies, and will place constraints on theoretical models of
globular cluster formation and evolution.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
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NOAO > Observing Info > Approved Programs > 2010B-0228 |
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