Details

Autor(en) / Beteiligte

• Howarth, Ian D
• Morello, Giuseppe

Titel

Rapid rotators revisited: absolute dimensions of KOI-13

Ist Teil von

• Monthly notices of the Royal Astronomical Society, 2017-09, Vol.470 (1), p.932-939

Ort / Verlag

Oxford University Press

Erscheinungsjahr

2017

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Abstract We analyse Kepler light-curves of the exoplanet Kepler Object of Interest no. 13b (KOI-13b) transiting its moderately rapidly rotating (gravity-darkened) parent star. A physical model, with minimal ad hoc free parameters, reproduces the time-averaged light-curve at the ∼10 parts per million level. We demonstrate that this Roche-model solution allows the absolute dimensions of the system to be determined from the star's projected equatorial rotation speed, v e sin i *, without any additional assumptions; we find a planetary radius R P = (1.33 ± 0.05) R♃, stellar polar radius R p★ = (1.55 ± 0.06) R⊙, combined mass M * + M P( ≃ M *) = (1.47 ± 0.17) M⊙ and distance d ≃ (370 ± 25) pc, where the errors are dominated by uncertainties in relative flux contribution of the visual-binary companion KOI-13B. The implied stellar rotation period is within ∼5 per cent of the non-orbital, 25.43-hr signal found in the Kepler photometry. We show that the model accurately reproduces independent tomographic observations, and yields an offset between orbital and stellar-rotation angular-momentum vectors of 60 $_{.}^{\circ}$ 25 ± 0 $_{.}^{\circ}$ 05.