Spectroscopic abundance analysis of dwarfs in the young open cluster IC 4665

We report a detailed spectroscopic abundance analysis for a sample of 18 F-K dwarfs of the young open cluster IC 4665. Stellar parameters and element abundances of Li, O, Mg, Si, Ca, Ti, Cr, Fe, and Ni have been derived using the spectroscopic synthesis tool SME ( Spectroscopy Made Easy). Within the measurement uncertainties the iron abundance is uniform, with a standard deviation of 0.04 dex. No correlation is found between the iron abundance and the mass of the stellar convective zone or between the Li abundance and the Fe abundance. In other words, our results do not reveal any signature of accretion and therefore do not support the scenario that stars with planets (SWPs) acquire their on-average higher metallicity compared to field stars via accretion of metal-rich planetary material. Instead, the higher metallicity of SWPs may simply reflect the fact that planetary formation is more efficient in high-metallicity environs. However, since so many details of the planetary system formation processes remain poorly understood, further studies are needed for a final settlement of the problem of the high metallicity of SWPs. The standard deviation of [Fe/H] deduced from our observations, taken as an upper limit on the metallicity dispersion among the IC 4665 member stars, has been used to constrain protoplanetary disk evolution, terrestrial and giant planets formation, and evolution processes. The total reservoir of heavy elements retained by the nascent disks is limited, and high retention efficiency of planet-building material is supported. Under modest surface density, gas giant planets are expected to form in locally enhanced regions or start efficient gas accretion when they only have a small core of a few Earth masses. Our results do not support the possibility that the migration of gas giants and the circularization of terrestrial planets' orbits are regulated by their interaction with a residual population of planetesimals and dust particles.