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Kepler observations of Am stars

L. Balona, V. Ripepi, G. Catanzaro, D. W. Kurtz, B. Smalley, P. De Cat, L. Eyer, A. Grigahcčne, S. Leccia, J. Southworth, K. Uytterhoeven, H. Van Winckel, J. Christensen-Dalsgaard, H. Kjeldsen, D. A. Caldwell, J. Van Cleve, F. R. Girouard

Abstract
We present an analysis of high-resolution spectra for two pulsating Am stars in the Kepler field. The stellar parameters derived in this way are important because parameters derived from narrow-band photometry may be affected by the strong metal lines in these stars. We analyse the Kepler time series of ten known Am stars and find that six of them clearly show δ Scuti pulsations. The other four appear to be non-pulsating.We derive fundamental parameters for all known pulsating Am stars from ground-based observations and also for the Kepler Am stars to investigate the location of the instability strip for pulsating Am stars. We find that there is not much difference between the Am-star instability strip and the δ Scuti instability strip. We find that the observed location of pulsating Am stars in the HR diagram does not agree with the location predicted from diffusion calculations.

Keywords
stars: chemically peculiar - stars: fundamental parameters - stars: oscillations - stars: variables: δ Scuti

Notes
Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fondación Galileo Galilei of the Istituto Nazionale di Astrofisica (INAF), at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, and with the Mercator Telescope operated on the island of La Palma by the Flemish Community.

Monthly Notices of the Royal Astronomical Society
Volume 414, Issue 1, Page 792
2011 June

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Instituto de AstrofĆ­sica e CiĆŖncias do EspaƧo Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
FundaĆ§Ć£o para a CiĆŖncia e a Tecnologia COMPETE 2020 PORTUGAL 2020 UniĆ£o Europeia