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Keywords:

  • stars: abundances;
  • planetary systems

ABSTRACT

We employ three samples of nearby stars that include stars hosting Doppler-detected planets to test a recent finding by Haywood that the incidence of planets is greater among transition and thick disc stars than it is among thin disc stars in the range [Fe/H]≤−0.20 dex; this implies that distance from the Galactic Centre is the causative factor for planet formation, not [Fe/H]. Thick disc stars with planets do have a smaller mean [Fe/H] value than thin disc stars over this range in [Fe/H], and the most [Fe/H]-poor stars with planets tend to have more negative Vlsr values. However, if we compare stars with planets according to mass abundance of the refractory elements important for planet formation (Mg, Si, Fe), then thick disc and [Fe/H]-poor thin disc stars with planets have similar distributions. There is no need to invoke a new mechanism for giant planet formation to account for the distributions of stars with planets among dwarf stars.