Abstract
We report a spectroscopic orbit with period P = 3.52433 ± 0.00027 days for the planetary companion that transits the solar-type star HD 209458. For the metallicity, mass, and radius of the star, we derive [Fe/H] = 0.00 ± 0.02, M* = 1.1 ± 0.1 M☉, and R* = 1.2 ± 0.1 R☉. This is based on a new analysis of the iron lines in our HIRES template spectrum and also on the absolute magnitude, effective temperature, and color of the star, and it uses isochrones from four different sets of stellar evolution models. Using these values for the stellar parameters, we reanalyze the transit data and derive an orbital inclination of i = 86
1 ± 16. For the planet, we derive a mass of Mp = 0.69 ± 0.05 MJup, a radius of Rp = 1.40 ± 0.17 RJup, and a density of ρ = 0.31 ± 0.07 g cm-3.
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Footnotes
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Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The other data were obtained at Observatoire de Haute-Provence (France) and with the 1.2 m Euler Swiss telescope at La Silla Observatory, ESO Chile.