TY - JOUR
T1 - Chemical tagging with APOGEE
T2 - Discovery of a large population of N-rich stars in the inner Galaxy
AU - Schiavon, Ricardo P.
AU - Zamora, Olga
AU - Carrera, Ricardo
AU - Lucatello, Sara
AU - Robin, A. C.
AU - Ness, Melissa
AU - Martell, Sarah L.
AU - Smith, Verne V.
AU - García-Hernández, D. A.
AU - Manchado, Arturo
AU - Schönrich, Ralph
AU - Bastian, Nate
AU - Chiappini, Cristina
AU - Shetrone, Matthew
AU - Mackereth, J. Ted
AU - Williams, Rob A.
AU - Mészáros, Szabolcs
AU - Prieto, Carlos Allende
AU - Anders, Friedrich
AU - Bizyaev, Dmitry
AU - Beers, Timothy C.
AU - Drew Chojnowski, S.
AU - Cunha, Katia
AU - Epstein, Courtney
AU - Frinchaboy, Peter M.
AU - García Pérez, Ana E.
AU - Hearty, Fred R.
AU - Holtzman, Jon A.
AU - Johnson, Jennifer A.
AU - Kinemuchi, Karen
AU - Majewski, Steven R.
AU - Muna, Demitri
AU - Nidever, David L.
AU - Nguyen, Duy Cuong
AU - O'Connell, Robert W.
AU - Oravetz, Daniel
AU - Pan, Kaike
AU - Pinsonneault, Marc
AU - Schneider, Donald P.
AU - Schultheis, Matthias
AU - Simmons, Audrey
AU - Skrutskie, Michael F.
AU - Sobeck, Jennifer
AU - Wilson, John C.
AU - Zasowski, Gail
N1 - Funding Information:
RPS thanks Diederik Kruijssen, Alessio Mucciarelli, Carmela Lardo, Maurizio Salaris, Rob Crain, Renyue Cen, Jenny Greene, David Spergel, David Nataf, and Jakob Walcher for enlightening discussions and/or comments on an early version of thismanuscript, and Ingrid & Oliver for everything. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the US Department of Energy Office of Science. The SDSS-III website is http://www.sdss3.org/. SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, University of Cambridge, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofísica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University. TCB acknowledges partial support for this work from grants PHY 08-22648; Physics Frontier Center/Joint Institute or Nuclear Astrophysics (JINA), and PHY 14-30152; Physics Frontier Center/JINA Center for the Evolution of the Elements (JINA-CEE), awarded by the US National Science Foundation. RC acknowledges support provided by the Spanish Ministry of Economy and Competitiveness under grants AYA2010-16717 and AYA2013-42781P. CAP is thankful for support from the Spanish Ministry of Economy and Competitiveness (MINECO) through grant AYA2014-56359-P. SLM acknowledges the support of the Australian Research Council through DECRA Fellowship DE140100598. SM has been supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences. DAGH was funded by the Ramón y Cajal fellowship number RYC-2013-14182. DAGH and OZ acknowledge support provided by the MINECO under grant AYA-2014-58082-P.
Publisher Copyright:
© 2016 The Authors.
PY - 2017/2/11
Y1 - 2017/2/11
N2 - 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.
AB - 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.
KW - Galaxy: abundances
KW - Galaxy: bulge
KW - Galaxy: halo
KW - Globular clusters: general
KW - Stars: chemically peculiar
KW - stars: abundances
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U2 - 10.1093/mnras/stw2162
DO - 10.1093/mnras/stw2162
M3 - Article
AN - SCOPUS:85014741864
SN - 0035-8711
VL - 465
SP - 501
EP - 524
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -