A Lack of Planets in 47 Tucanae from an HST Search (2000)
AuthorsGilliland RL, 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 MDshow all
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.
Keywordsastro-ph; binaries: eclipsing; globular clusters: (NGC 104, 47 Tucanae); planetary systems; techniques: photometric
ANZSRC Fields of Research02 - Physical Sciences::0201 - Astronomical and Space Sciences::020110 - Stellar Astronomy and Planetary Systems
02 - Physical Sciences::0201 - Astronomical and Space Sciences