Exoplanets & Stellar Populations Group

This cluster is one of the less populated clusters in our Galaxy, resembling some Palomar-like globular as Pal 1 (Rosenberg et al., 1998). As in Pal 1, there are no HB stars in the CMD, and the entire population of observed stars is smaller than 1000 objects. E3 is suspected to have a metallicity close to that of Pal 1. From the δ(V − I)_@2.5 (Rosenberg et al., 1999) measured on the figure on the left, E3 is coeval with the other GGCs of similar metallicity, though the result is necessarily very uncertain, due to the high contamination and the small number of RGB stars. E3 is the cluster with the better defined MS binary sequence (Veronesi et al., 1996, ASP Conf. Ser., 92, 301), which can be also seen in the figure above. Previous CCD CMDs are in:

McClure et al. (1985) (B, V bands)

Gratton & Ortolani (1987) (B, V bands)

Veronesi et al. (1996) ASP Conf. Ser., 92, 301 (B, V, R, I bands)