Iota Horologii Is Unlikely to Be an Evaporated Hyades Star

We present a high-precision chemical analysis of ι Hor (iota Horologii), a planet-host field star thought to have formed in the Hyades. Elements with atomic number 6 ≤ Z ≤ 30 have abundances that are in excellent agreement with those of the cluster within the ±0.01 dex (or ≃ 2%) precision errors. Heavier elements show a range of abundances such that about half of the Z > 30 species analyzed are consistent with those of the Hyades, while the other half are marginally enhanced by 0.03 ±0.01 dex (≃7 ± 2%). The lithium abundance, A(Li), is very low compared to the well-defined A(Li)-T_eff relation of the cluster. For its T_eff, ι Hor's lithium content is about half the Hyades'. Attributing the enhanced lithium depletion to the planet would require a peculiar rotation rate, which we are unable to confirm. Our analysis of ι Hor's chromospheric activity suggests P_rot = 5 days, which is significantly shorter than previously reported. Models of Galactic orbits place ι Hor hundreds of parsecs away from the cluster at formation. Thus, we find the claim of a shared birthplace very difficult to justify.