Chemical abundances for a sample of FGK dwarfs in the Pleiades open cluster from APOGEE

Abstract

ABSTRACT This paper presents chemical abundances of 12 elements (C, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, and Fe) for 80 FGK dwarfs in the Pleiades open cluster, which span a temperature range of $\sim$2000 K in T$_{\rm eff}$, using the high-resolution (R$\sim$22 500) near-infrared SDSS (Sloan Digital Sky Survey)-IV/APOGEE (Apache Point Observatory Galactic Evolution Experiment) spectra ($\lambda$1.51–1.69 $\mu$m). Using a 1D local thermodynamic equilibrium abundance analysis, we determine an overall metallicity of [Fe/H] = +0.03 $\pm$ 0.04 dex, with the elemental ratios [$\alpha$/Fe] = +0.01 $\pm$ 0.05, [odd-z/Fe] = –0.04 $\pm$ 0.08, and [iron peak/Fe] = –0.02 $\pm$ 0.08. These abundances for the Pleiades are in line with the abundances of other open clusters at similar galactocentric distances as presented in the literature. Examination of the abundances derived from each individual spectral line revealed that several of the stronger lines displayed trends of decreasing abundance with decreasing $T_{\rm eff}$. The list of spectral lines that yield abundances that are independent of $T_{\rm eff}$ are presented and used for deriving the final abundances. An investigation into possible causes of the temperature-dependent abundances derived from the stronger lines suggests that the radiative codes and the APOGEE line list we employ may inadequately model van der Waals broadening, in particular in the cooler K dwarfs.