NGC 2419-Another Remnant of Accretion by the Milky Way
Abstract
We isolate a sample of 43 upper red giant branch stars in the extreme outer halo Galactic globular cluster (GC) NGC 2419 from two Keck/DEIMOS slitmasks. The probability that there is more than one contaminating halo field star in this sample is extremely low. Analysis of moderate-resolution spectra of these cluster members, as well as of our Keck/HIRES high-resolution spectra of a subsample of them, demonstrates that there is a small but real spread in Ca abundance of ~0.2 dex within this massive metal-poor GC. This provides additional support to earlier suggestions that NGC 2419 is the remnant of a dwarf galaxy accreted long ago by the Milky Way.
Based in part on observations obtained at the W.M. Keck Observatory, which is operated jointly by the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration.- Publication:
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The Astrophysical Journal
- Pub Date:
- December 2010
- DOI:
- 10.1088/0004-637X/725/1/288
- arXiv:
- arXiv:1010.0031
- Bibcode:
- 2010ApJ...725..288C
- Keywords:
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- Galaxy: formation;
- Galaxy: halo;
- globular clusters: individual: NGC 2419;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted to the Astrophysical Journal