J. S. Kuszlewicz, T. S. H. North, W. J. Chaplin, A. Bieryla, D. W. Latham, A. Miglio, K. J. Bell, G. R. Davies, S. Hekker, T. L. Campante, S. Deheuvels, M. N. Lund
KOI-3890 is a highly eccentric, 153-d period eclipsing, single-lined spectroscopic binary system containing a red giant star showing solar-like oscillations alongside tidal interactions. The combination of transit photometry, radial velocity observations, and asteroseismology has enabled the detailed characterization of both the red giant primary and the M-dwarf companion, along with the tidal interaction and the geometry of the system. The stellar parameters of the red giant primary are determined through the use of asteroseismology and grid-based modelling to give a mass and radius of M⋆=1.04±0.06M⊙ and R⋆=5.8±0.2R⊙, respectively. When combined with transit photometry, the M-dwarf companion is found to have a mass and radius of Mc=0.23±0.01M⊙ and Rc=0.256±0.007R⊙. Moreover, through asteroseismology we constrain the age of the system through the red giant primary to be 9.1+2.4−1.7Gyr. This provides a constraint on the age of the M-dwarf secondary, which is difficult to do for other M-dwarf binary systems. In addition, the asteroseismic analysis yields an estimate of the inclination angle of the rotation axis of the red giant star of i=87.6+2.4−1.2 degrees. The obliquity of the system – the angle between the stellar rotation axis and the angle normal to the orbital plane – is also derived to give ψ=4.2+2.1−4.2 degrees, showing that the system is consistent with alignment. We observe no radius inflation in the M-dwarf companion when compared to current low-mass stellar models.
asteroseismology; techniques: photometric; binaries: eclipsing; stars: evolution; stars: fundamental parameters; Astrophysics - Solar and Stellar Astrophysics
Monthly Notices of the Royal Astronomical Society
Volume 487, Issue 1, Page 14