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  • 2M1938+4603: a rich, multim...
    Østensen, R. H.; Green, E. M.; Bloemen, S.; Marsh, T. R.; Laird, J. B.; Morris, M.; Moriyama, E.; Oreiro, R.; Reed, M. D.; Kawaler, S. D.; Aerts, C.; Vučković, M.; Degroote, P.; Telting, J. H.; Kjeldsen, H.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Borucki, W. J.; Koch, D.

    Monthly Notices of the Royal Astronomical Society Letters, October 2010, Letnik: 408, Številka: 1
    Journal Article

    2M1938+4603 (KIC 9472174) displays a spectacular light curve dominated by a strong reflection effect and rather shallow, grazing eclipses. The orbital period is 0.126 d, the second longest period yet found for an eclipsing sdB+dM, but still close to the minimum 0.1-d period among such systems. The phase-folded Kepler light curve was used to detrend the orbital effects from the data set. The amplitude spectrum of the residual light curve reveals a rich collection of pulsation peaks spanning frequencies from ∼50 to 4500 μHz. The presence of a complex pulsation spectrum in both the p- and g-mode regions has never before been reported in a compact pulsator. Eclipsing sdB+dM stars are very rare, with only seven systems known and only one with a pulsating primary. Pulsating stars in eclipsing binaries are especially important since they permit masses derived from seismological model fits to be cross-checked with orbital mass constraints. We present a first analysis of this star based on the Kepler 9.7-d commissioning light curve and extensive ground-based photometry and spectroscopy that allow us to set useful bounds on the system parameters. We derive a radial-velocity amplitude K1 = 65.7 ± 0.6 km s −1, inclination angle , and find that the masses of the components are M1 = 0.48 ± 0.03 M⊙ and M2 = 0.12 ± 0.01 M⊙.