Bibcode
Schiavon, R. P.; Zamora, O.; Carrera, R.; Lucatello, Sara; Robin, A. C.; Ness, Melissa; Martell, Sarah L.; Smith, Verne V.; García-Hernández, D. A.; Manchado, A.; Schönrich, Ralph; Bastian, Nate; Chiappini, Cristina; Shetrone, Matthew; Mackereth, J. Ted; Williams, Rob A.; Mészáros, Szabolcs; Allende Prieto, C.; Anders, Friedrich; Bizyaev, Dmitry; Beers, Timothy C.; Chojnowski, S. Drew; Cunha, Katia; Epstein, Courtney; Frinchaboy, Peter M.; García Pérez, A. E.; Hearty, Fred R.; Holtzman, Jon A.; Johnson, Jennifer A.; Kinemuchi, Karen; Majewski, Steven R.; Muna, Demitri; Nidever, David L.; Nguyen, Duy Cuong; O'Connell, Robert W.; Oravetz, Daniel; Pan, Kaike; Pinsonneault, Marc; Schneider, Donald P.; Schultheis, Matthias; Simmons, Audrey; Skrutskie, Michael F.; Sobeck, Jennifer; Wilson, John C.; Zasowski, Gail
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 465, Issue 1, p.501-524
Advertised on:
2
2017
Citations
175
Refereed citations
158
Description
Formation of globular clusters (GCs), the Galactic bulge, or galaxy
bulges in general is an important unsolved problem in Galactic
astronomy. Homogeneous infrared observations of large samples of stars
belonging to GCs and the Galactic bulge field are one of the best ways
to study these problems. We report the discovery by APOGEE (Apache Point
Observatory Galactic Evolution Experiment) of a population of field
stars in the inner Galaxy with abundances of N, C, and Al that are
typically found in GC stars. The newly discovered stars have high
[N/Fe], which is correlated with [Al/Fe] and anticorrelated with [C/Fe].
They are homogeneously distributed across, and kinematically
indistinguishable from, other field stars within the same volume. Their
metallicity distribution is seemingly unimodal, peaking at [Fe/H]
˜ -1, thus being in disagreement with that of the Galactic GC
system. Our results can be understood in terms of different scenarios.
N-rich stars could be former members of dissolved GCs, in which case the
mass in destroyed GCs exceeds that of the surviving GC system by a
factor of ˜8. In that scenario, the total mass contained in
so-called `first-generation' stars cannot be larger than that in
`second-generation' stars by more than a factor of ˜9 and was
certainly smaller. Conversely, our results may imply the absence of a
mandatory genetic link between `second-generation' stars and GCs. Last,
but not least, N-rich stars could be the oldest stars in the Galaxy, the
by-products of chemical enrichment by the first stellar generations
formed in the heart of the Galaxy.
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