NGC 6749: a metal-poor halo globular cluster in a disc field rich in Mira variables

We present V, I photometry of the loose star cluster NGC 6749, and for the first time colour-magnitude diagrams are provided. We confirm that it is a globular cluster and its blue horizontal branch indicates that it is metal-poor. We derive a reddening of E(B— V) = 1.39± 0.04 and a distance from the...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society 1997-08, Vol.289 (3), p.745-752
Main Authors: Rosino, L., Ortolani, S., Barbuy, B., Bica, E.
Format: Article
Language:English
Subjects:
Galaxy: halo
globular clusters: individual: NGC 6749
stars: variables: other
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Summary:We present V, I photometry of the loose star cluster NGC 6749, and for the first time colour-magnitude diagrams are provided. We confirm that it is a globular cluster and its blue horizontal branch indicates that it is metal-poor. We derive a reddening of E(B— V) = 1.39± 0.04 and a distance from the Sun d⊙ = 7.3 ± 0.9 kpc (assuming a total-to-selective absorption R = 3.4). The cluster is projected very close to the Galactic plane, and the derived distance implies a Galactic coordinate Z ≈ — 300 pc. It is thus a halo globular cluster located close to the disc plane. We also discuss the properties of 78 newly discovered long-period variable stars, of which 75 are Miras, projected within 1°of the cluster centre. The variables do not appear to be associated with the globular cluster. From their periods, most of them belong to the metal-rich disc or bulge stellar populations.
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/289.3.745