Atmospheric parameters of 82 red giants in the Kepler field

• Verfasst von: Thygesen, Anders [VerfasserIn]
• Titel: Atmospheric parameters of 82 red giants in the Kepler field
• Verf.angabe: A.O. Thygesen, S. Frandsen, H. Bruntt, T. Kallinger, M.F. Andersen, Y.P. Elsworth, S. Hekker, C. Karoff, D. Stello, K. Brogaard, C. Burke, D.A. Caldwell, and J.L. Christiansen
• Fussnoten: Gesehen am 30.05.2018
• Titel Quelle: Enthalten in: Astronomy and astrophysics
• Jahr Quelle: 2012
• Band/Heft Quelle: 543(2012) Artikel-Nummer A160, 15 Seiten
• ISSN Quelle: 1432-0746
• DOI: doi:10.1051/0004-6361/201219237
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1575847000

Abstract

Context: Accurate fundamental parameters of stars are essential for the asteroseismic analysis of data from the NASA Kepler mission. Aims: We aim at determining accurate atmospheric parameters and the abundance pattern for a sample of 82 red giants that are targets for the Kepler mission. Methods: We have used high-resolution, high signal-to-noise spectra from three different spectrographs. We used the iterative spectral synthesis method VWA to derive the fundamental parameters from carefully selected high-quality iron lines. After determination of the fundamental parameters, abundances of 13 elements were measured using equivalent widths of the spectral lines. Results: We identify discrepancies in log g and [Fe/H], compared to the parameters based on photometric indices in the Kepler Input Catalogue (larger than 2.0 dex for log g and [Fe/H] for individual stars). The T eff found from spectroscopy and photometry shows good agreement within the uncertainties. We find good agreement between the spectroscopic log g and the log g derived from asteroseismology. Also, we see indications of a potential metallicity effect on the stellar oscillations. Conclusions: We have determined the fundamental parameters and element abundances of 82 red giants. The large discrepancies between the spectroscopic log g and [Fe/H] and values in the Kepler Input Catalogue emphasize the need for further detailed spectroscopic follow-up of the Kepler targets in order to produce reliable results from the asteroseismic analysis.