Identify variable stars

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Goal 2: To identify variable stars belonging to known star clusters

Figure 1: Map of the globular and open cluster positions (full and empty circles) towards the Milky Way bulge and plane. Included in the VVV area are the 33 globular clusters listed in Table 4 (Harris 1996, AJ, 112, 1487), and 355 open clusters (Dias et al. 2006, A&A, 446, 949; Bica et al. 2003, A&A, 400, 533, and A&A, 404, 223). The bulge contours are indicated, as are the extinction contours of Schlegel et al. (1998, ApJ, 500, 525).

There are 33 globular clusters and 355 open clusters located in the VVV area (Figure 1), that would contain: RR Lyrae, type I and II Cepheids, Semiregulars, and EBs. Distances, reddenings, metallicities and horizontal branch (HB) types will be obtained for these clusters from a homogeneous dataset[1]. In some favourable cases, ages can be measured. Table 4 at the end lists the globular clusters to be covered, giving positions in equatorial and galactic coordinates, and distances from the Sun. The asterisks in the last column indicate that more than one third of these clusters have uncertain distances. We will improve the distances for these globulars, and confirm the previous estimates for the rest of the open and globular clusters.


  1. e.g. Catelan et al. 2006, MemSAIt77, 202; Zoccali et al. 2003, A&A, 399, 931
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