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Centro de Astrofísica da Universidade do Porto

Kepler observations of the high-amplitude δ Scuti star V2367 Cyg

L. Balona, P. Lenz, V. Antoci, S. Bernabei, G. Catanzaro, J. Daszyńska-Daszkiewicz, M. Di Criscienzo, A. Grigahcène, G. Handler, D. W. Kurtz, M. Marconi, J. Molenda-Żakowicz, A. Moya Bedón, J. M. Nemec, A. Pigulski, D. Pricopi, V. Ripepi, B. Smalley, J.-C. Suárez, M. D. Suran, J. R. Hall, K. A. Ibrahim, T. C. Klaus

Abstract
We analyse Kepler observations of the high-amplitude δ Scuti (HADS) star V2367 Cyg (KIC 9408694). The variations are dominated by a mode with frequency ƒ1 = 5.6611 d-1. Two other independent modes with ƒ2 = 7.1490 d-1 and ƒ3 = 7.7756 d-1 have amplitudes an order of magnitude smaller than ƒ1. Nearly all the light variation is due to these three modes and their combination frequencies, but several hundred other frequencies of very low amplitude are also present. The amplitudes of the principal modes may vary slightly with time. The star has twice the projected rotational velocity of any other HADS star, which makes it unusual. We find a correlation between the phases of the combination frequencies and their pulsation frequencies, which is not understood. Since modes of highest amplitude in HADS stars are normally radial modes, we assumed that this would also be true in this star. However, attempts to model the observed frequencies as radial modes without mode interaction were not successful. For a star with such a relatively high rotational velocity, it is important to consider the effect of mode interaction. Indeed, when this was done, we were able to obtain a model in which a good match with ƒ1 and ƒ2 is obtained, with ƒ1 being the fundamental radial mode.

Keywords
stars: individual: V2367 Cyg – stars: oscillations – stars: variables: δ Scuti

Monthly Notices of the Royal Astronomical Society
Volume 419, Page 3028
February 2012

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