论文标题
Kelt-9 B的不对称苔丝交通由快速恒星旋转和自旋轨道错位引起
KELT-9 b's Asymmetric TESS Transit Caused by Rapid Stellar Rotation and Spin-Orbit Misalignment
论文作者
论文摘要
Kelt-9 B是一种超热木星，在极性轨道上迅速旋转，植入早期的恒星。我们使用来自过渡系外行星调查卫星（\ tess）的光度法对Kelt-9 B的过境光曲线进行快速恒星旋转的影响，以限制行星的真实旋转轨角，并探索KELT-9 B如何受到恒星重力变暗的影响。我们将主机恒星的赤道半径限制为$ 1.089 \ pm0.017 $ $倍，其极性半径及其局部表面亮度在其热杆和冷却器赤道之间变化为$ \ sim38 $ \％。我们对恒星的含量和表面亮度梯度进行建模，并发现它会导致过境光曲线缺乏最小光线周围的通常对称性。我们利用光曲线的不对称来限制Kelt-9 B的真实旋转孔角（$ {87^\ circ}^{+10^\ circ} _ { - 11^\ circ} $），与\ citet {gaudi2017giant}一致。我们还从\ citet {gaudi2017 -giant}对光谱能分布模型应用重力变暗校正，并发现快速旋转的核算可以更好地适应可用光谱，并对恒星的极有效温度产生更可靠的估计。
KELT-9 b is an ultra hot Jupiter transiting a rapidly rotating, oblate early-A-type star in a polar orbit. We model the effect of rapid stellar rotation on KELT-9 b's transit light curve using photometry from the Transiting Exoplanet Survey Satellite (\tess) to constrain the planet's true spin-orbit angle and to explore how KELT-9 b may be influenced by stellar gravity darkening. We constrain the host star's equatorial radius to be $1.089\pm0.017$ times as large as its polar radius and its local surface brightness to vary by $\sim38$\% between its hot poles and cooler equator. We model the stellar oblateness and surface brightness gradient and find that it causes the transit light curve to lack the usual symmetry around the time of minimum light. We take advantage of the light curve asymmetry to constrain KELT-9 b's true spin orbit angle (${87^\circ}^{+10^\circ}_{-11^\circ}$), agreeing with \citet{gaudi2017giant} that KELT-9 b is in a nearly polar orbit. We also apply a gravity darkening correction to the spectral energy distribution model from \citet{gaudi2017giant} and find that accounting for rapid rotation gives a better fit to available spectroscopy and yields a more reliable estimate for the star's polar effective temperature.
