RGB stars in NGC 6822, Ca II triplet Virtual Observatory Resource

Authors
  1. Swan J.
  2. Cole A.A.
  3. Tolstoy E.
  4. Irwin M.J.
  5. Published by
    CDS
Abstract

We present a detailed analysis of the chemistry and kinematics of red giants in the dwarf irregular galaxy NGC 6822. Spectroscopy at ~8500{AA} was acquired for 72 red giant stars across two fields using FORS2 at the VLT. Line-of-sight extinction was individually estimated for each target star to accommodate the variable reddening across NGC 6822. The mean radial velocity was found to be <v_rad_>=-52.8+/-2.2km/s with dispersion {sigma}_v_=24.1km/s, in agreement with other studies. Ca ii triplet equivalent widths were converted into [Fe/H] metallicities using a V magnitude proxy for surface gravity. The average metallicity was <[Fe/H]>=-0.84+/-0.04 with dispersion {sigma}=0.31dex and interquartile range 0.48. Our assignment of individual reddening values makes our analysis more sensitive to spatial variations in metallicity than previous studies. We divide our sample into metal-rich and metal-poor stars; the former were found to cluster towards small radii with the metal-poor stars more evenly distributed across the galaxy. The velocity dispersion of the metal-poor stars was found to be higher than that of the metal-rich stars {sigma}_vMP_=27.4km/s; {sigma}_vMR_=21.1km/s); combined with the age-metallicity relation this indicates that the older populations have either been dynamically heated during their lifetimes or were born in a less disc-like distribution than the younger stars.. The low ratio v_rot_/{sigma}_v_ suggests that within the inner 10-arcmin, NGC 6822's stars are dynamically decoupled from the HI gas, and possibly distributed in a thick disc or spheroid structure.

Keywords
  1. galaxies
  2. giant-stars
  3. radial-velocity
  4. line-intensities
  5. metallicity
Bibliographic source Bibcode
2016MNRAS.456.4315S
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/456/4315
IVOA Identifier IVOID
ivo://CDS.VizieR/J/MNRAS/456/4315
Document Object Identifer DOI
doi:10.26093/cds/vizier.74564315

Access

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http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/456/4315
https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/456/4315
http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/456/4315
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https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/456/4315/tablea2?
http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/456/4315/tablea2?

History

2016-11-25T09:41:27Z
Resource record created
2016-11-25T09:41:27Z
Created
2024-08-15T20:17:40Z
Updated

Contact

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