Exploring B4: A Pulsating sdB star, in a Binary, in the Open Cluster NGC 6791

Herbert Pablo; Steven D. Kawaler; Elizabeth M. Green

doi:10.1088/2041-8205/740/2/L47

Exploring B4: A Pulsating sdB star, in a Binary, in the Open Cluster NGC 6791

Solar and Stellar Astrophysics 2015-05-30 v1

Authors: Herbert Pablo , Steven D. Kawaler , Elizabeth M. Green

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Abstract

We report on Kepler photometry of the hot sdB star B4 in the open cluster NGC 6791. We confirm that B4 is a reflection effect binary with an sdB component and a low-mass main sequence companion with a circular 0.3985 d orbit. The sdB star is a g-mode pulsator (a V1093 Her star) with periods ranging from 2384 s to 7643 s. Several of the pulsation modes show symmetric splitting by 0.62 microHz. Attributing this to rotational splitting, we conclude that the sdB component has a rotation period of approximately 9.63 d, indicating that tidal synchronization has not been achieved in this system. Comparison with theoretical synchronization time provides a discriminant between various theoretical models.

Keywords

stellar variability cataclysmic variable orbital periods

Cite

@article{arxiv.1109.3736,
  title  = {Exploring B4: A Pulsating sdB star, in a Binary, in the Open Cluster NGC 6791},
  author = {Herbert Pablo and Steven D. Kawaler and Elizabeth M. Green},
  journal= {arXiv preprint arXiv:1109.3736},
  year   = {2015}
}

Comments

Accepted for publication in ApJ Letters

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