标题： 滴答作响——TESS和Kepler对Kepler-13Ab的联合分析 显示英文标题

标题： The clockwork is moving on -- a combined analysis of TESS and Kepler measurements of Kepler-13Ab

摘要： 开普勒-13Ab（KOI-13）是一颗围绕一颗快速旋转的A型恒星运行的系外行星。 该系统显示出显著的自转轨道不对齐，并且存在变化的凌日持续时间，这很可能是由于轨道进动引起的。 在这里，我们结合了{\it 开普勒}和TESS观测数据，对这个系统进行了自洽分析。 我们假设行星凌星经过一个旋转的扁球状恒星来建模光曲线，该恒星由于旋转导致的重力暗化效应具有强烈的表面温度梯度。 凌日弦以缓慢的速度移动，这是由扁球状恒星激发的轨道进动的涌现特征，其降率在${\rm d}b/{\rm d}t = -0.011/{\rm yr}$的入射参数中，并且根据最新的TESS测量结果，实际值为$b=0.19$。 从{\it 开普勒}的Q2和Q17季度以及TESS测量得到的变化凌日持续时间表明入射参数线性漂移。 恒星自转轴的解表明接近正交的角度，倾角约为$100^\circ$。 显示英文摘要

摘要： Kepler-13Ab (KOI-13) is an exoplanet orbiting a rapidly rotating A-type star. The system shows a significant spin-orbit misalignment and a changing transit duration most probably caused by the precession of the orbit. Here we present a self-consistent analysis of the system combining {\it Kepler} and TESS observations. We model the light curves asssuming a planet transits a rotating oblate star which has a strong surface temperature gradient due to rotation-induced gravity darkening. The transit chord moves slowly as an emergent feature of orbital precession excited by the oblate star with a decline rate in the impact parameter of ${\rm d}b/{\rm d}t = -0.011/{\rm yr}$, and with an actual value of $b=0.19$ for the latest TESS measurements. The changing transit duration that was measured from {\it Kepler} Q2 and Q17 quarters and the TESS measurements indicates a linear drift of the impact parameter. The solutions for the stellar spin axis suggest a nearly orthogonal aspect, with inclination around $100^\circ$.