View : 17 Download: 0

Medium-resolution Spectroscopy of Red Giant Branch Stars in ω Centauri

Title
Medium-resolution Spectroscopy of Red Giant Branch Stars in ω Centauri
Authors
An D.Lee Y.S.Jung J.I.Rey S.-C.Rhee J.Lee J.-W.Lee Y.-W.Joe Y.H.
Ewha Authors
안덕근
SCOPUS Author ID
안덕근scopus
Issue Date
2017
Journal Title
Astronomical Journal
ISSN
0004-6256JCR Link
Citation
vol. 154, no. 4
Keywords
globular clusters: individual (omega Centauri)-stars: abundances
Publisher
Institute of Physics Publishing
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
We present [Fe/H] and [Ca/Fe] of ∼600 red giant branch (RGB) members of the globular cluster Omega Centauri (ω Cen). We collect medium-resolution (R ∼ 2000) spectra using the Blanco 4 m telescope at the Cerro Tololo Inter-American Observatory equipped with Hydra, the fiber-fed multi-object spectrograph. We demonstrate that blending of stellar light in optical fibers severely limits the accuracy of spectroscopic parameters in the crowded central region of the cluster. When photometric temperatures are taken in the spectroscopic analysis, our kinematically selected cluster members, excluding those that are strongly affected by flux from neighboring stars, include relatively fewer stars at intermediate metallicity ([Fe/H] ∼ -1.5) than seen in the previous high-resolution survey for brighter giants in Johnson & Pilachowski. As opposed to the trend of increasing [Ca/Fe] with [Fe/H] found by those authors, our [Ca/Fe] estimates, based on Ca ii H & K measurements, show essentially the same mean [Ca/Fe] for most of the metal-poor and metal-intermediate populations in this cluster, suggesting that mass- or metallicity-dependent SN II yields may not be necessary in their proposed chemical evolution scenario. Metal-rich cluster members in our sample show a large spread in [Ca/Fe], and do not exhibit a clear bimodal distribution in [Ca/Fe]. We also do not find convincing evidence for a radial metallicity gradient among RGB stars in . © 2017. The American Astronomical Society. All rights reserved.
DOI
10.3847/1538-3881/aa8364
Appears in Collections:
사범대학 > 과학교육과 > Journal papers
Files in This Item:
There are no files associated with this item.


qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE