A Planetary System Around HD 155358: The Lowest Metallicity Planet Host Star

Abstract

We report the detection of two planetary mass companions to the solar-type star HD 155358. The two planets have orbital periods of 195.0 and 530.3 days, with eccentricities of 0.11 and 0.18. The minimum masses for these planets are 0.89 and 0.50 Jupiter masses respectively. The orbits are close enough to each other, and the planets are sufficiently massive, that the planets are gravitationally interacting with each other, with their eccentricities and arguments of periastron varying with periods of 2300--2700 years. While large uncertainties remain in the orbital eccentricities, our orbital integration calculations indicate that our derived orbits would be dynamically stable for at least 10^8 years. With a metallicity [Fe/H] of -0.68, HD 155358 is tied with the K1III giant planet host star HD 47536 for the lowest metallicity of any planet host star yet found. Thus, a star with only 21% of the heavy-element content of our Sun was still able to form a system of at least two Jovian-mass planets and have their orbits evolve to semi-major axes of 0.6-1.2 AU.

8 pages, 3 figures. Astrophysical Journal in press, 1 September 2007 issue

References in corpus (17)

• The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities, and kinematic properties of 14,000 F and G dwarfs
• The NextGen Model Atmosphere grid for $3000\le \Teff \le 10000\K$
• The effective temperature scale of FGK stars. II. Teff : color : [Fe/H] calibrations
• The formation and retention of gas giant planets around stars with a range of metallicities
• Stellar Iron Abundances: non-LTE Effects
• Radial Velocity Jitter in Stars from the California and Carnegie Planet Search at Keck Observatory
• Spectroscopic metallicities for planet-host stars: extending the samples
• The solar neighbourhood age-metallicity relation - does it exist?
• Lithium Abundances of the Local Thin Disk Stars
• Lithium abundances for 185 main-sequence stars - Galactic evolution and stellar depletion of lithium
• Abundance Analysis of Planetary Host Stars I. Differential Iron Abundances
• On the Nature of Stars with Planets
• Accurate M Dwarf Metallicities from Spectral Synthesis: A Critical Test of Model Atmospheres
• Planetary Formation Scenarios Revistied: Core-Accretion Versus Disk Instability
• The First HET Planet: A Companion to HD 37605
• The Chemical Compositions of Stars with Planets: A Review
• A Keck/HIRES Doppler Search for Planets Orbiting Metal-Poor Dwarfs. I. Testing Giant Planet Formation and Migration Scenarios

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• Resonant structure, formation and stability of the planetary system HD155358
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