Abundance variations in the outer halo GC NGC 6229 Virtual Observatory Resource

Authors
  1. Johnson C.I.
  2. Caldwell N.
  3. Rich R.M.
  4. Walker M.G.
  5. Published by
    CDS
Abstract

NGC 6229 is a relatively massive outer halo globular cluster that is primarily known for exhibiting a peculiar bimodal horizontal branch morphology. Given the paucity of spectroscopic data on this cluster, we present a detailed chemical composition analysis of 11 red giant branch members based on high resolution (R~38000), high S/N (>100) spectra obtained with the MMT-Hectochelle instrument. We find the cluster to have a mean heliocentric radial velocity of -138.1_-1.0_^+1.0^ km/s, a small dispersion of 3.8_-0.7_^+1.0^ km/s, and a relatively low (M/L_V_)_{sun}_=0.82_-0.28_^+0.49^. The cluster is moderately metal-poor with <[Fe/H]>=-1.13 dex and a modest dispersion of 0.06 dex. However, 18% (2/11) of the stars in our sample have strongly enhanced [La,Nd/Fe] ratios that are correlated with a small (~0.05 dex) increase in [Fe/H]. NGC 6229 shares several chemical signatures with M75, NGC 1851, and the intermediate metallicity populations of {omega} Cen, which lead us to conclude that NGC 6229 is a lower mass iron-complex cluster. The light elements exhibit the classical (anti-)correlations that extend up to Si, but the cluster possesses a large gap in the O-Na plane that separates first and second generation stars. NGC 6229 also has unusually low [Na,Al/Fe] abundances that are consistent with an accretion origin. A comparison with M54 and other Sagittarius clusters suggests that NGC 6229 could also be the remnant core of a former dwarf spheroidal galaxy.

Keywords
  1. globular-star-clusters
  2. giant-stars
  3. infrared-photometry
  4. radial-velocity
  5. effective-temperature
  6. chemical-abundances
Bibliographic source Bibcode
2017AJ....154..155J
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/154/155
IVOA Identifier IVOID
ivo://CDS.VizieR/J/AJ/154/155
Document Object Identifer DOI
doi:10.26093/cds/vizier.51540155

Access

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https://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/154/155
https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/154/155
http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/154/155
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https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/154/155/table1?
http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/154/155/table1?

History

2018-08-02T08:30:19Z
Resource record created
2018-08-02T08:30:19Z
Created
2018-08-27T07:44:10Z
Updated

Contact

Name
CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr