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arXiv · 1406.6941

Asteroseismology revealing trapped modes in KIC 10553698A

R. H. Østensen·J. H. Telting·M. D. Reed·A. S. Baran·P. Nemeth·F. Kiaeerad
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Abstract

The subdwarf-B pulsator, KIC 10553698A, is one of 16 such objects observed with one-minute sampling for most of the duration of the Kepler Mission. Like most of these stars, it displays a rich g-mode pulsation spectrum with several clear multiplets that maintain regular frequency splitting. We identify these pulsation modes as components of rotationally split multiplets in a star rotating with a period of about 41 d. From 162 clearly significant periodicities, we are able to identify 156 as likely components of l=1 or l=2 multiplets. For the first time we are able to detect l=1 modes that interpose in the asymptotic period sequences and that provide a clear indication of mode trapping in a stratified envelope, as predicted by theoretical models. A clear signal is also present in the Kepler photometry at 3.387 d. Spectroscopic observations reveal a radial-velocity amplitude of 64.8 km/s. We find that the radial-velocity variations and the photometric signal have phase and amplitude that are perfectly consistent with a Doppler-beaming effect and conclude that the unseen companion, KIC 10553698B, must be a white dwarf most likely with a mass close to 0.6 solar masses.

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R. H. Østensen, J. H. Telting, M. D. Reed, A. S. Baran, P. Nemeth, F. Kiaeerad. 2014-06-26. Asteroseismology revealing trapped modes in KIC 10553698A. https://doi.org/10.1051/0004-6361/201423611

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