The Center of Gravity and Density Profile of 47 Tucanae

Abstract

From the analysis of HST-FOC images of the globular cluster 47 Tuc, we have determined the position of the center of gravity to be about 6 arcsec away from the luminosity center. The luminosity center is mainly determined by an 'asymmetry' in the luminosity distribution of the stars brighter than m(342) about 16.5. The density profile from the dynamical center shows a central cusp with core radius 8 arcsec and significantly deviates from a King profile up to about 13 arcsec from the center. The 'asymmetry' in the distribution of the bright stars, together with the existence of high-velocity stars, blue stragglers, and millisecond pulsars suggests that the core of 47 Tuc is experiencing a phase of dynamic evolution.