The globular cluster system of NGC 6822

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DOIResolve DOI: http://doi.org/10.1093/mnras/stv1259
AuthorSearch for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for:
TypeArticle
Journal titleMonthly Notices of the Royal Astronomical Society
ISSN0035-8711
1365-2966
Volume452
Issue1
Pages320332
Subjectglobular clusters: general; galaxies: individual: NGC 6822; galaxies: kinematics and dynamics; local group
AbstractWe present a comprehensive analysis of the globular cluster (GC) system of the Local Group dwarf irregular galaxy NGC 6822. Our study is based on homogeneous optical and near-IR photometry, as well as long-slit spectroscopic observations which are used to determine new radial velocities for six GCs, two of which had no previous spectroscopic information. We construct optical-near-IR colour–colour diagrams and through comparison to simple stellar population models infer that the GCs have old ages consistent with being 9 Gyr or older, while their metallicities are in the range between −1.6 ≲ [Fe/H] ≲ −0.4. We conduct a kinematic analysis of the GC population and find tentative evidence for weak net rotation of the GC system, in the same sense as that exhibited by the underlying spheroid. The most likely amplitude of rotation is ≈10 km s−1, approximately half the magnitude of the observed velocity dispersion. Finally, we use the GCs to estimate the dynamical mass of NGC 6822 within ∼11 kpc and we formally find it to be in the range between (3 and 4) × 109 M⊙. This implies an overall mass-to-light ratio in the range of ∼30–40 and indicates that NGC 6822 is highly dark-matter-dominated. The mass and the corresponding mass-to-light ratio estimates are affected by various additional systematic effects due to limitations of the data and the model that are not necessary reflected in the formal uncertainties.
Publication date
PublisherOxford University Press
LanguageEnglish
AffiliationNational Research Council Canada; NRC Herzberg Astronomy and Astrophysics
Peer reviewedYes
NPARC number23001682
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Record identifierbfda648a-b550-481c-893c-1f5f28230295
Record created2017-03-17
Record modified2017-03-30
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