A Lack of Planets in 47 Tucanae from an HST Search

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2000
Authors
Gilliland RL
Brown TM
Guhathakurta P
Sarajedini A
Milone EF
Albrow MD
Baliber NR
Bruntt H
Burrows A
Charbonneau D
Abstract

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.

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astro-ph, binaries: eclipsing, globular clusters: (NGC 104, 47 Tucanae), planetary systems, techniques: photometric
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Fields of Research::51 - Physical sciences::5101 - Astronomical sciences::510109 - Stellar astronomy and planetary systems
Field of Research::02 - Physical Sciences::0201 - Astronomical and Space Sciences
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