- Gilliland, Ronald L;
- Brown, TM;
- Guhathakurta, P;
- Sarajedini, A;
- Milone, EF;
- Albrow, MD;
- Baliber, NR;
- Bruntt, H;
- Burrows, A;
- Charbonneau, D;
- Choi, P;
- Cochran, WD;
- Edmonds, PD;
- Frandsen, S;
- Howell, JH;
- Lin, DNC;
- Marcy, GW;
- Mayor, M;
- Naef, D;
- Sigurdsson, S;
- Stagg, CR;
- VandenBerg, DA;
- Vogt, SS;
- Williams, MD
We report results from a large Hubble Space Telescope project to observe a
significant (~34,000) ensemble of main sequence stars in the globular cluster
47 Tucanae with a goal of defining the frequency of inner-orbit, gas-giant
planets. Simulations based on the characteristics of the 8.3 days of
time-series data in the F555W and F814W WFPC2 filters show that ~17 planets
should be detected by photometric transit signals if the frequency of hot
Jupiters found in the solar neighborhood is assumed to hold for 47 Tuc. The
experiment provided high-quality data sufficient to detect planets. A full
analysis of these WFPC2 data reveals ~75 variables, but NO light curves
resulted for which a convincing interpretation as a planet could be made. The
planet frequency in 47 Tuc is at least an order of magnitude below that for the
solar neighborhood. The cause of the absence of close-in planets in 47 Tuc is
not yet known; presumably the low metallicity and/or crowding of 47 Tuc
interfered with planet formation, with orbital evolution to close-in positions,
or with planet survival.