Bibcode
Sakari, C. M.; Shetrone, Matthew D.; Schiavon, Ricardo P.; Bizyaev, Dmitry; Allende Prieto, C.; Beers, Timothy C.; Caldwell, Nelson; García-Hernández, D. A.; Lucatello, Sara; Majewski, Steven; O'Connell, Robert W.; Pan, Kaike; Strader, Jay
Bibliographical reference
The Astrophysical Journal, Volume 829, Issue 2, article id. 116, 23 pp. (2016).
Advertised on:
10
2016
Journal
Citations
34
Refereed citations
30
Description
Chemical abundances are presented for 25 M31 globular clusters (GCs),
based on moderately high resolution (R = 22,500) H-band integrated light
(IL) spectra from the Apache Point Observatory Galactic Evolution
Experiment (APOGEE). Infrared (IR) spectra offer lines from new
elements, lines of different strengths, and lines at higher excitation
potentials compared to the optical. Integrated abundances of C, N, and O
are derived from CO, CN, and OH molecular features, while Fe, Na, Mg,
Al, Si, K, Ca, and Ti abundances are derived from atomic features. These
abundances are compared to previous results from the optical,
demonstrating the validity and value of IR IL analyses. The CNO
abundances are consistent with typical tip of the red giant branch
stellar abundances but are systematically offset from optical Lick index
abundances. With a few exceptions, the other abundances agree between
the optical and the IR within the 1σ uncertainties. The first
integrated K abundances are also presented and demonstrate that K tracks
the α elements. The combination of IR and optical abundances
allows better determinations of GC properties and enables probes of the
multiple populations in extragalactic GCs. In particular, the integrated
effects of the Na/O anticorrelation can be directly examined for the
first time.