The field population towards the globular cluster NGC 6553

¹ Astronomical Observatory, Vicolo Osservatorio 5, 35122 Padova, Italy
² Dept. of Astronomy, Vicolo Osservatorio 5, 35122 Padova, Italy

Corresponding author: A. Vallenari, vallenari@pd.astro.it

Received: 10 September 2001
Accepted: 31 October 2001

Abstract

We analyze the colour magnitude diagram of the field population in the direction of the bulge cluster NGC 6553 to discuss the stellar field component projected towards the cluster. In particular we investigate the nature of a peculiar feature, called "red flare" which appears as a faint turnoff, located 2 mag about below the turnoff of the cluster, with a sparse trace of a sub-giant branch just above. A detailed modeling shows that the red flare is consistent with the expected location of the turnoff and sub-giant branch of the bulge population, once that the appropriate metallicity range and spatial distribution of the bulge stars are adopted. From the data, hints can be derived about the spatial shape and the basic stellar parameters of the bulge.