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Chemical tagging with APOGEE: discovery of a large population of N-rich stars in the inner Galaxy

Schiavon, RP and Zamora, O and Carrera, R and Lucatello, S and Robin, AC and Ness, M and Martell, SL and Smith, VV and Garcia-Hernandez, DA and Manchado, A and Schonrich, R and Bastian, N and Chiappini, C and Shetrone, M and Mackereth, JT and Williams, RA and Meszaros, S and Allende Prieto, C and Anders, F and Bizyaev, D and Beers, TC and Chojnowski, SD and Cunha, K and Epstein, C and Frinchaboy, PM and Garcia Perez, AE and Hearty, FR and Holtzman, JA and Johnson, JA and Kinemuchi, K and Majewski, SR and Muna, D and Nidever, DL and Duy, CN and O'Connell, RW and Oravetz, D and Pan, K and Pinsonneault, M and Schneider, DP and Schultheis, M and Simmons, A and Skrutskie, MF and Sobeck, J and Wilson, JC and Zasowski, G (2017) Chemical tagging with APOGEE: discovery of a large population of N-rich stars in the inner Galaxy. Monthly Notices of the Royal Astronomical Society, 465 (1). pp. 501-524. ISSN 0035-8711

Full text not available from this repository. Please see publisher or open access link below:
Open Access URL: https://arxiv.org/pdf/1606.05651.pdf (Accepted version)

Abstract

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.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record Ricardo P. Schiavon et al. Chemical tagging with APOGEE: discovery of a large population of N-rich stars in the inner Galaxy. Mon Not R Astron Soc 2017; 465 (1): 501-524. doi: 10.1093/mnras/stw2162 is available online at: http://dx.doi.org/10.1093/mnras/stw2162
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Q Science > QD Chemistry
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 07 Apr 2017 11:30
Last Modified: 07 Apr 2017 11:30
DOI or Identification number: 10.1093/mnras/stw2162
URI: http://researchonline.ljmu.ac.uk/id/eprint/6225

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