An Absence of Hot Jupiter Planets in 47 Tucanae: Results of a Wide-Field Transit Search

This paper presents the results of a comprehensive wide-field search for transiting "hot Jupiter" planets (gas giant planets with an orbital period in the range 1 day ≤ P ≤ 16 days) in the globular cluster 47 Tuc. Motivated by the detection of the transit in HD 209458 and the apparent lack of planetary detections in the core of 47 Tuc by Gilliland and coworkers, this work further addresses the question of giant planet frequency in 47 Tuc by observing from the ground a 52' × 52' field centered on the cluster. Hence, this work is most sensitive to the uncrowded outer regions, where the stellar densities are significantly lower than in the core, and concentrates on 21,920 main-sequence stars within 2.5 mag of the cluster turnoff (hence approaching the solar value in mass). Our work comprises the largest ground-based transit search of a globular cluster to date, incorporating a 33 night time series that allows us excellent sensitivity to detect hot Jupiter planets. Detailed Monte Carlo simulations incorporating the actual temporal sampling and photometric precision of the data predict that seven planets with orbital periods in the range 1-16 days should be present in our data set if 47 Tuc has the same planetary frequency as that observed in the solar neighborhood. A detailed search utilizing a matched filter algorithm, developed specifically for this project, found no transit events. This 3.3 σ result is consistent with the Hubble Space Telescope cluster core null detection of Gilliland and coworkers. Our result indicates that system metallicity rather than crowding is the dominant effect inhibiting hot Jupiter formation in this environment. The 33 night data set used for this result also led to the detection of 100 variable stars, including 69 new discoveries, which are presented in a companion paper.

[1]  T. Brown,et al.  Detection of Planetary Transits Across a Sun-like Star , 1999, The Astrophysical journal.

[2]  D. K. Cullers,et al.  A matched filter method for ground-based sub-noise detection of terrestrial extrasolar planets in eclipsing binaries: application to CM Draconis. , 1996, Icarus.

[3]  G. González The stellar metallicity—giant planet connection , 1997 .

[4]  David Charbonneau,et al.  TrES-1: The Transiting Planet of a Bright K0 V Star , 2004 .

[5]  R. P. Butler,et al.  A Transiting “51 Peg-like” Planet , 2000, The Astrophysical journal.

[6]  P. University,et al.  Planets in 47 Tuc , 2001, astro-ph/0104336.

[7]  G. Basri Extrasolar planets: Too close for comfort , 2004, Nature.

[8]  Penny D. Sackett Searching for Unseen Planets Via Occultation and Microlensing , 1998 .

[9]  Saurabh Jha,et al.  New data and improved parameters for the extrasolar transiting planet OGLE-TR-56b , 2003 .

[10]  D. Queloz,et al.  Two new “very hot Jupiters” among the OGLE transiting candidates , 2004 .

[11]  S. Sigurdsson Planets in globular clusters , 1992 .

[12]  David Charbonneau,et al.  A Lack of Planets in 47 Tucanae from a Hubble Space Telescope Search , 2000 .

[13]  J. Mariotti,et al.  Planets outside the solar system : theory and observations , 1999 .

[14]  Saurabh Jha,et al.  An extrasolar planet that transits the disk of its parent star , 2003, Nature.

[15]  G. Marcy,et al.  Planetary Companions to the Metal-rich Stars BD –10°3166 and HD 52265* , 2000 .

[16]  The metal-rich nature of stars with planets , 2001, astro-ph/0105216.

[17]  A. Burrows,et al.  THEORETICAL RADII OF TRANSITING GIANT PLANETS: THE CASE OF OGLE-TR-56b , 2004, astro-ph/0405264.

[18]  B. Tingley A rigorous comparison of different planet detection algorithms , 2003 .

[19]  William E. Harris,et al.  A Catalog of Parameters for Globular Clusters in the Milky Way , 1996 .

[20]  Saurabh Jha,et al.  A Transiting Extrasolar Giant Planet around the Star OGLE-TR-10 , 2004 .

[21]  P. H. Hauschildt,et al.  Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 209458 , 2003 .

[22]  Melvyn B. Davies,et al.  Planetary dynamics in stellar clusters , 2001 .

[23]  Zucker,et al.  The Spectroscopic Orbit of the Planetary Companion Transiting HD 209458. , 2000, The Astrophysical journal.

[24]  Models for Old, Metal-poor Stars with Enhanced α-Element Abundances. III. Isochrones and Isochrone Population Functions , 2001, astro-ph/0102480.

[25]  David Charbonneau,et al.  Hubble Space Telescope Time-Series Photometry of the Transiting Planet of HD?209458 , 2001 .

[26]  Peter B. Stetson,et al.  A CCD COLOR-MAGNITUDE STUDY OF 47 TUCANAE. , 1987 .

[27]  M. Mayor,et al.  An extended upper atmosphere around the extrasolar planet HD209458b , 2003, Nature.

[28]  John B. Hearnshaw,et al.  The proceedings of the IAU 8th Asian-Pacific Regional Meeting , 2002 .

[29]  P. Sackett,et al.  A Method for the Detection of Planetary Transits in Large Time Series Data Sets , 2004, astro-ph/0411234.

[30]  Marley,et al.  On the Radii of Close-in Giant Planets , 2000, The Astrophysical journal.

[31]  R. Paul Butler,et al.  Scientific Frontiers in Research on Extrasolar Planets , 2003 .

[32]  Michel Mayor,et al.  The missing link: A 4-day period transiting exoplanet around OGLE-TR-111 , 2004 .

[33]  Canada.,et al.  Atmospheric escape from hot Jupiters , 2004, astro-ph/0403369.

[34]  F. Grundahl,et al.  A search for planets in the old open cluster NGC 6791 , 2003, astro-ph/0308072.

[35]  Alan P. Boss,et al.  Gas Giant Protoplanet Formation: Disk Instability Models with Thermodynamics and Radiative Transfer , 2001 .

[36]  K. Freeman,et al.  A Comprehensive Catalog of Variable Stars in the Field of 47 Tucanae , 2004, astro-ph/0405133.

[37]  B. Tingley Improvements to existing transit detection algorithms and their comparison , 2003 .

[38]  R. Lupton,et al.  A Method for Optimal Image Subtraction , 1997, astro-ph/9712287.