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Dynamical tides in eccentric binaries and tidally excited stellar pulsations in Kepler KOI-54

Fuller, Jim and Lai, Dong (2012) Dynamical tides in eccentric binaries and tidally excited stellar pulsations in Kepler KOI-54. Monthly Notices of the Royal Astronomical Society, 420 (4). pp. 3126-3138. ISSN 0035-8711. doi:10.1111/j.1365-2966.2011.20237.x. https://resolver.caltech.edu/CaltechAUTHORS:20190425-152213338

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Abstract

Recent observation of the tidally excited stellar oscillations in the main-sequence binary KOI-54 by the Kepler satellite provides a unique opportunity for studying dynamical tides in eccentric binary systems. We develop a general theory of tidal excitation of oscillation modes of rotating binary stars and apply our theory to tidally excited gravity modes (g-modes) in KOI-54. The strongest observed oscillations, which occur at 90 and 91 times the orbital frequency, are likely due to prograde m= 2 modes (relative to the stellar spin axis) locked in resonance with the orbit. The remaining flux oscillations with frequencies that are integer multiples of the orbital frequency are likely due to nearly resonant m= 0 g-modes; such axisymmetric modes generate larger flux variations compared to the m= 2 modes, assuming that the spin inclination angle of the star is comparable to the orbital inclination angle. We examine the process of resonance mode locking under the combined effects of dynamical tides on the stellar spin and orbit and the intrinsic stellar spindown. We show that KOI-54 can naturally evolve into a state in which at least one m= 2 mode is locked in resonance with the orbital frequency. Our analysis provides an explanation for the fact that only oscillations with frequencies less than 90–100 times the orbital frequency are observed. We have also found evidence from the published Kepler result that three-mode non-linear coupling occurs in the KOI-54 system. We suggest that such non-linear mode coupling may explain the observed oscillations that are not harmonics of the orbital frequency.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1111/j.1365-2966.2011.20237.xDOIArticle
https://arxiv.org/abs/1107.4594arXivDiscussion Paper
ORCID:
AuthorORCID
Fuller, Jim0000-0002-4544-0750
Lai, Dong0000-0002-1934-6250
Additional Information:© 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS. Accepted 2011 November 19. Received 2011 October 17; in original form 2011 July 22. This work has been supported in part by the NSF grant AST-1008245.
Funders:
Funding AgencyGrant Number
NSFAST-1008245
Subject Keywords:binaries: close, stars: individual: HD187091 (KOI-54), stars: kinematics and dynamics, stars: oscillations, stars: rotation
Issue or Number:4
DOI:10.1111/j.1365-2966.2011.20237.x
Record Number:CaltechAUTHORS:20190425-152213338
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190425-152213338
Official Citation:Jim Fuller, Dong Lai, Dynamical tides in eccentric binaries and tidally excited stellar pulsations in Kepler KOI-54, Monthly Notices of the Royal Astronomical Society, Volume 420, Issue 4, 11 March 2012, Pages 3126–3138, https://doi.org/10.1111/j.1365-2966.2011.20237.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94994
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:25 Apr 2019 22:44
Last Modified:16 Nov 2021 17:09

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