Journal Article

Accurate fundamental parameters and detailed abundance patterns from spectroscopy of 93 solar-type <i>Kepler</i> targets*†

H. Bruntt, S. Basu, B. Smalley, W. J. Chaplin, G. A. Verner, T. R. Bedding, C. Catala, J.-C. Gazzano, J. Molenda-Żakowicz, A. O. Thygesen, K. Uytterhoeven, S. Hekker, D. Huber, C. Karoff, S. Mathur, B. Mosser, T. Appourchaux, T. L. Campante, Y. Elsworth, R. A. García, R. Handberg, T. S. Metcalfe, P.-O. Quirion, C. Régulo, I. W. Roxburgh, D. Stello, J. Christensen-Dalsgaard, S. D. Kawaler, H. Kjeldsen, R. L. Morris, E. V. Quintana and D. T. Sanderfer

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 423, issue 1, pages 122-131
Published in print June 2012 | ISSN: 0035-8711
Published online May 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.20686.x
Accurate fundamental parameters and detailed abundance patterns from spectroscopy of 93 solar-type Kepler targets*†

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We present a detailed spectroscopic study of 93 solar-type stars that are targets of the NASA/Kepler mission and provide detailed chemical composition of each target. We find that the overall metallicity is well represented by Fe lines. Relative abundances of light elements (CNO) and α elements are generally higher for low-metallicity stars. Our spectroscopic analysis benefits from the accurately measured surface gravity from the asteroseismic analysis of the Kepler light curves. The accuracy on the log g parameter is better than 0.03 dex and is held fixed in the analysis. We compare our Teff determination with a recent colour calibration of VTKS [TYCHO V magnitude minus Two Micron All Sky Survey (2MASS) KS magnitude] and find very good agreement and a scatter of only 80 K, showing that for other nearby Kepler targets, this index can be used. The asteroseismic log g values agree very well with the classical determination using Fe i–Fe ii balance, although we find a small systematic offset of 0.08 dex (asteroseismic log g values are lower). The abundance patterns of metals, α elements and the light elements (CNO) show that a simple scaling by [Fe/H] is adequate to represent the metallicity of the stars, except for the stars with metallicity below −0.3, where α-enhancement becomes important. However, this is only important for a very small fraction of the Kepler sample. We therefore recommend that a simple scaling with [Fe/H] be employed in the asteroseismic analyses of large ensembles of solar-type stars.

Keywords: stars: abundances; stars: atmospheres; stars: fundamental parameters; stars: solar-type

Journal Article.  6354 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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