The Density Profile of 47 Tucanae
We have used high-resolution HST-WF/PC images of the core of the globular cluster 47 Tucanae in the U-band to determine its radial density profile. The exceptional photometric quality of the data set ensures highly reliable measurements since no photometric completeness correction is required for stars at and above the turn-off luminosity over the whole field. The position of the center of gravity of the cluster is found to agree very well with that provided by previous FOC observations but differs by ~6" from the position of the luminosity center as measured from the ground. Within the ~40" radius of the cluster center sampled by this data set, the density distribution of stars with masses >~0.85 Msolar is well fitted by a King-type profile with rc ~= 12."2 +/- 2."1. Values of rc larger than ~15" are not compatible with the data and therefore are at variance with those obtained by both ground-based (rc ~= 25") or previous WF/PC studies (rc ~= 23"). We show that the discrepancy with earlier results can be ascribed entirely to the effects of photometric incompleteness.
The Astrophysical Journal
- Pub Date:
- September 1996
- GALAXY: GLOBULAR CLUSTERS: INDIVIDUAL NAME: 47 TUCANAE;
- STARS: STATISTICS