Chemical Composition of the Planet-harboring Star TrES-1

We present a detailed chemical abundance analysis of the parent star of thetransiting extrasolar planet TrES-1. Based on high-resolution Keck/HIRES andHET/HRS spectra, we have determined abundances relative to the Sun for 16elements (Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, and Ba).The resulting average abundance of $<[$$X$/H$]>$ $= -0.02\pm0.06$ is in goodagreement with initial estimates of solar metallicity based on iron. We comparethe elemental abundances of TrES-1 with those of the sample of stars withplanets, searching for possible chemical abundance anomalies. TrES-1 appearsnot to be chemically peculiar in any measurable way. We investigate possiblesigns of selective accretion of refractory elements in TrES-1 and other starswith planets, and find no statistically significant trends of metallicity[$X$/H] with condensation temperature $T_c$. We use published abundances andkinematic information for the sample of planet-hosting stars (including TrES-1)and several statistical indicators to provide an updated classification interms of their likelihood to belong to either the thin disk or the thick diskof the Milky Way Galaxy. TrES-1 is found to be a very likely member of the thindisk population. By comparing $\alpha$-element abundances of planet hosts and alarge control sample of field stars, we also find that metal-rich([Fe/H]$\gtrsim 0.0$) stars with planets appear to be systematicallyunderabundant in [$\alpha$/Fe] by $\approx 0.1$ dex with respect to comparisonfield stars. The reason for this signature is unclear, but systematicdifferences in the analysis procedures adopted by different groups cannot beruled out.Comment: 52 pages, 15 figures, 5 tables, accepted for publication in the Astronomical Journa