Infrared High-Resolution Integrated Light Spectral Analyses of M31 Globular Clusters from APOGEE
Abstract
Chemical abundances are presented for 25 M31 globular clusters (GCs), based on moderately high resolution (R = 22, 500) H-band integrated light spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE). Infrared spectra offer lines from new elements, of different strengths, and 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 infrared integrated light 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 infrared within the 1{\sigma} uncertainties. The first integrated K abundances are also presented, and demonstrate that K tracks the alpha-elements. The combination of infrared 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.
Keywords
Cite
@article{arxiv.1607.06811,
title = {Infrared High-Resolution Integrated Light Spectral Analyses of M31 Globular Clusters from APOGEE},
author = {Charli M. Sakari and Matthew D. Shetrone and Ricardo P. Schiavon and Dmitry Bizyaev and Carlos Allende Prieto and Timothy C. Beers and Nelson Caldwell and Domingo Anibal Garcia-Hernandez and Sara Lucatello and Steven Majewski and Robert W. O'Connell and Kaike Pan and Jay Strader},
journal= {arXiv preprint arXiv:1607.06811},
year = {2016}
}
Comments
Accepted for publication in the Astrophysical Journal