Title: Koi-54: the kepler discovery of tidally excited pulsations and brightenings in a highly eccentric binary
Authors: Welsh, William F ×
Orosz, Jerome A
Aerts, Conny
Brown, Timothy M
Brugamyer, Erik
Cochran, William D
Gilliland, Ronald L
Guzik, Joyce Ann
Kurtz, D. W
Latham, David W
Marcy, Geoffrey W
Quinn, Samuel N
Zima, Wolfgang
Allen, Christopher
Batalha, Natalie M
Bryson, Steve
Buchhave, Lars A
Caldwell, Douglas A
Gautier, Thomas N
Howell, Steve B
Kinemuchi, K
Ibrahim, Khadeejah A
Isaacson, Howard
Jenkins, Jon M
Prsa, Andrej
Still, Martin
Street, Rachel
Wohler, Bill
Koch, David G
Borucki, William J #
Issue Date: Nov-2011
Publisher: Published by the University of Chicago Press for the American Astronomical Society
Series Title: The Astrophysical Journal. Supplement Series vol:197 issue:1 pages:-
Article number: 4
Abstract: Kepler observations of the star HD 187091 (KIC 8112039, hereafter KOI-54) revealed a remarkable light curve exhibiting sharp periodic brightening events every 41.8 days with a superimposed set of oscillations forming a beating pattern in phase with the brightenings. Spectroscopic observations revealed that this is a binary star with a highly eccentric orbit, e = 0.83. We are able to match the Kepler light curve and radial velocities with a nearly face-on (i = 5 degrees.5) binary star model in which the brightening events are caused by tidal distortion and irradiation of nearly identical A stars during their close periastron passage. The two dominant oscillations in the light curve, responsible for the beating pattern, have frequencies that are the 91st and 90th harmonic of the orbital frequency. The power spectrum of the light curve, after removing the binary star brightening component, reveals a large number of pulsations, 30 of which have a signal-to-noise ratio greater than or similar to 7. Nearly all of these pulsations have frequencies that are either integer multiples of the orbital frequency or are tidally split multiples of the orbital frequency. This pattern of frequencies unambiguously establishes the pulsations as resonances between the dynamic tides at periastron and the free oscillation modes of one or both of the stars. KOI-54 is only the fourth star to show such a phenomenon and is by far the richest in terms of excited modes.
ISSN: 0067-0049
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Institute of Astronomy
× corresponding author
# (joint) last author

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