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A. Sozzetti, D. W. Latham, G. Torres, R. P. Stefanik (CfA), A. Boss (CIW), B. W. Carney (UNC), J. B. Laird (BGSU)
To date, one of the fundamental questions about the origin/nature of planetary systems still remains unanswered: Do gas giant planets form by core accretion or disk instability? Among the two proposed mechanisms for gas giant planet formation, core accretion is likely to be enhanced in metal-rich stars, as increased surface densities of solids can shorten the overall time-scales for giant planet formation by this mechanism, while disk instability is remarkably insensitive to the primordial metallicity of the protoplanetary disk. Very few metal-poor stars have been searched for planets so far, and the implication that there may be no planets orbiting field metal-poor stars simply has not been tested yet. In fact, the absence of very close-in (P < 8.3 days) planets in the moderately metal-poor ([Fe/H] ~ -0.7) globular cluster 47 Tuc may be due to a lack of planet formation because of the low metallicity. Alternatively, the dense stellar environment in the cluster may have interfered with planet formation, or with migration to close-in orbits, or with planet survival. By conducting a search for planets around a sample of nearby metal-poor dwarfs in the field, where the stellar density is much lower, dynamical interactions in a dense stellar environment can be eliminated as a factor, and it will be possible to unambiguously determine the role of metallicity in gas giant planet formation.
Here we present preliminary results from our search for planets within 1 AU around a well-controlled sample of metal-poor stars using the Keck 1 telescope.
A. S. is greatly indebted to the Smithsonian Astrophysical Observatory for support through the SAO Predoctoral Fellowship program and to the University of Pittsburgh for support through the Mellon Predoctoral Fellowship program.
The author(s) of this abstract have provided an email address for comments about the abstract: asozzetti@cfa.harvard.edu
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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.