First Kepler results on compact pulsators - V. Slowly pulsating subdwarf B stars in short-period binaries
The survey phase of the Kepler Mission includes a number of hot subdwarf B (sdB) stars to search for non-radial pulsations. We present our analysis of two sdB stars that are found to be g-mode pulsators of the V1093-Her class. These two stars also display the distinct irradiation effect typical of sdB stars with a close M-dwarf companion with orbital periods of less than half a day. Because the orbital period is so short, the stars should be in synchronous rotation, and if so, the rotation period should imprint itself on the multiplet structure of the pulsations. However, we do not find clear evidence for such rotational splitting. Though the stars do show some frequency spacings that are consistent with synchronous rotation, they also display multiplets with splittings that are much smaller. Longer-duration time series photometry will be needed to determine if those small splittings are in fact rotational splitting, or caused by slow amplitude or phase modulation. Further data should also improve the signal-to-noise ratio, perhaps revealing lower-amplitude periodicities that could confirm the expectation of synchronous rotation. The pulsation periods seen in these stars show period spacings that are suggestive of high-overtone g-mode pulsations.
Physics, Astronomy, and Materials Science
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2010 the authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Stars: binaries: close, Stars: oscillations, Stars: variables: general, Subdwarfs
Kawaler, Stephen D., Michael D. Reed, Roy H. Østensen, Steven Bloemen, Donald W. Kurtz, A. C. Quint, Roberto Silvotti et al. "First Kepler results on compact pulsators–V. Slowly pulsating subdwarf B stars in short-period binaries." Monthly Notices of the Royal Astronomical Society 409, no. 4 (2010): 1509-1517.
Monthly Notices of the Royal Astronomical Society