Catalog of Chromium, Cobalt, and Nickel Abundances in Globular Clusters and Dwarf Galaxies

Creators: Kirby, Evan N.; Xie, Justin L.; Guo, Rachel; Kovalev, Mikhail; Bergemann, Maria

Abstract

We present measurements of the abundances of chromium, cobalt, and nickel in 4113 red giants, including 2277 stars in globular clusters (GCs), 1820 stars in the Milky Way's dwarf satellite galaxies, and 16 field stars. We measured the abundances from mostly archival Keck/DEIMOS medium-resolution spectroscopy with a resolving power of R ~ 6500 and a wavelength range of approximately 6500–9000 Å. The abundances were determined by fitting spectral regions that contain absorption lines of the elements under consideration. We used estimates of temperature, surface gravity, and metallicity that we previously determined from the same spectra. We estimated systematic error by examining the dispersion of abundances within mono-metallic GCs. The median uncertainties for [Cr/Fe], [Co/Fe], and [Ni/Fe] are 0.20, 0.20, and 0.13, respectively. Finally, we validated our estimations of uncertainty through duplicate measurements, and we evaluated the accuracy and precision of our measurements through comparison to high-resolution spectroscopic measurements of the same stars.

Additional Information

© 2018. The American Astronomical Society. Received 2018 April 2; revised 2018 May 23; accepted 2018 May 28; published 2018 July 19. We thank the anonymous referee for a constructive report. This material is based upon work supported by the National Science Foundation under grant No. AST-1614081. Support for this work was also provided by NASA through a grant (HST-GO-14734.011-A) from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. E.N.K. acknowledges funding from generous donors to the California Institute of Technology. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Software: MOOG (Sneden 1973), MAFAGS-OS (Grupp 2004a, 2004b), MARCS (Gustafsson et al. 2008), spec2d pipeline (Cooper et al. 2012; Newman et al. 2013), MPFIT (Markwardt 2012). Facility: Keck:II (DEIMOS). -

Attached Files

Published - Kirby_2018_ApJS_237_18.pdf

Submitted - 1906.08284.pdf

Files

1906.08284.pdf

Files (1.6 MB)

Name	Size	Download all
1906.08284.pdf md5:28cf95f7774338e760a51af86f6263de	508.9 kB	Preview Download
Kirby_2018_ApJS_237_18.pdf md5:b3a575130784c019a85cf0a9d23090c8	1.1 MB	Preview Download

Additional details

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes