Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program

Abstract

Context. We performed a uniform and detailed abundance analysis of 12 refractory elements (Na, Mg, Al, Si, Ca, Ti, Cr, Ni, Co, Sc, Mn, and V) for a sample of 1111 FGK dwarf stars from the HARPS GTO planet search program. Of these stars, 109 are known to harbor giant planetary companions and 26 stars are exclusively hosting Neptunians and super-Earths. Aims. The two main goals of this paper are to investigate whether there are any differences between the elemental abundance trends for stars of different stellar populations and to characterize the planet host and non-host samples in terms of their [X/H]. The extensive study of this sample, focused on the abundance differences between stars with and without planets will be presented in a parallel paper. Methods. The equivalent widths of spectral lines were automatically measured from HARPS spectra with the ARES code. The abundances of the chemical elements were determined using an LTE abundance analysis relative to the Sun, with the 2010 revised version of the spectral synthesis code MOOG and a grid of Kurucz ATLAS9 atmospheres. To separate the Galactic stellar populations we applied both a purely kinematical approach and a chemical method. Results. We found that the chemically separated (based on the Mg, Si, and Ti abundances) thin-and thick disks are also chemically disjunct for Al, Sc, Co, and Ca. Some bifurcation might also exist for Na, V, Ni, and Mn, but there is no clear boundary of their [X/Fe] ratios. We confirm that an overabundance in giant-planet host stars is clear for all studied elements.We also confirm that stars hosting only Neptunian-like planets may be easier to detect around stars with similar metallicities than around non-planet hosts, although for some elements (particulary α-elements) the lower limit of [X/H] is very abrupt.

Chemical Cartography With Apogee: Large-Scale Mean Metallicity Maps of the Milky Way Disk

“…While one might imagine that this could potentially be an astrophysical effect-e.g., because the cooler stars are more luminous and thus more likely to be located at greater distances-we find that the bimodality persists even within stars in the same Galactic zone (middle panel of Figure 6). When the stars with T eff < 4200 K are removed (bottom panel of Figure 6), the observed [α/M] distribution remains bimodal but with significant scatter, and resembles results obtained with smaller samples from the solar neighborhood (e.g., Adibekyan et al 2012). We defer interpretation of the bimodal [α/M] distribution (e.g., whether it is likely to be a selection effect or intrinsic to the Galaxy) to a later paper.…”

An extreme planetary system around HD 219828

“…The values allow us to conclude that HD 219828 is a typical thin-disk star from the solar neighbourhood; its [α/Fe] 6 abundance ratios are nearly solar (i.e. ∼0.0): no α-element enhancement, typical of thick-disk or halo stars, is observed (see Adibekyan et al 2012b, and references therein).…”

“…We therefore decided to derive detailed abundances for several α-and iron-peak elements in HD 219828 using a combined HARPS spectrum, built from all the data available at the time of this publication 5 . The method we adopted is fully explained in Adibekyan et al (2012b), and we refer to that paper for more details. The stellar atmospheric parameters adopted for the analysis are those listed in Table 2.…”

SYSTEMATIC NON-LTE STUDY OF THE −2.6 ≤ [Fe/H] ≤ 0.2 F AND G DWARFS IN THE SOLAR NEIGHBORHOOD. II. ABUNDANCE PATTERNS FROM Li TO Eu*

“…Most thin-disk stars have, on average, solar Fuhrmann (2008Fuhrmann ( , 2011 from the LTE analysis. Adibekyan et al (2012) derived the LTE abundances of a large sample of nearby stars, and using Mg, Si, and Ti as representatives of the α-process elements, they concluded that the α-enhancement for the thick disk and the stars with [Fe/H] < −0.5 is close to 0.3 dex.…”