The Structure of the Core of 47 Tucanae from Hubble Space Telescope Observations

Abstract

A set of moderately deep, high-resolution images of the core of the Galactic globular cluster NGC 104 (47 Tucanae) taken by the Faint Object Camera F/48 relay on the Hubble Space Telescope through the filters F140W, F220W, and F342W are presented and analyzed. The core is completely resolved in these bands for the first time, with approximately 3500 stars reliably detected and measured in the 44 x 44-arcsec F342W frame down to instrumental magnitude m(342) of about 19.5. These images are used to derive color magnitude diagrams that extend and confirm the discovery of a population of about 20 blue stragglers in the cluster core. The luminosity function of the brightest stars (AGB, HB, RGB, and SGB) shows that the sample is 99 percent complete at m(342) of about 16, down to 61 percent at m(342) of about 18.