标题： TOI-1259Ab：围绕K型矮星白矮星双星运行的热木星处于良好对齐的轨道上 显示英文标题

标题： TOI-1259Ab: A Warm Jupiter Orbiting a K-dwarf White-Dwarf Binary is on a Well-aligned Orbit

摘要： 一颗恒星双星系统中某一颗恒星演化成白矮星被提出作为一种触发紧密气态巨行星形成机制。 在AGB阶段恒星的不对称质量损失会给予它一个“踢动”，这可能会引发偏心Lidov-Kozai振荡，导致围绕次星的行星向内迁移并扰动其轨道的偏心率和倾角。 在这里我们呈现了TOI-1259Ab的恒星天顶角测量值，TOI-1259Ab是一个围绕K型恒星运行的紧密轨道气态巨行星，该恒星有一个距离约1650 au的白矮星伴星。 通过使用NEID光谱仪在行星凌日过程中检测Rossiter-McLaughlin效应，我们发现天球投影的天顶角为$\lambda = 6^{+21}_{-22}\,^\circ$。 当结合恒星自转周期、半径和投影自转速度的估计值时，我们发现真实的三维天顶角为$\psi = 24^{+14}_{-12}\,^\circ$ ($\psi < 48^\circ$在95%置信度下)，表明TOI-1259Ab的轨道与恒星赤道平面很好地对齐。 由于行星轨道太宽，预期潮汐重新对齐不会发生，因此TOI-1259Ab可能以这种良好对齐的配置安静地形成。 或者，正如我们通过动力学模拟所展示的，由双星伴星演化引发的偏心Lidov-Kozai振荡预计会导致低天顶角，概率约为$\sim$14%。 显示英文摘要

摘要： The evolution of one member of a stellar binary into a white dwarf has been proposed as a mechanism that triggers the formation of close-in gas giant planets. The star's asymmetric mass loss during the AGB stage gives it a "kick" that can initiate Eccentric Lidov-Kozai oscillations, potentially causing a planet around the secondary star to migrate inwards and perturbing the eccentricity and inclination of its orbit. Here we present a measurement of the stellar obliquity of TOI-1259Ab, a gas giant in a close-in orbit around a K star with a white dwarf companion about 1650 au away. By using the NEID spectrograph to detect the Rossiter-McLaughlin effect during the planetary transit, we find the sky-projected obliquity to be $\lambda = 6^{+21}_{-22}\,^\circ$. When combined with estimates of the stellar rotation period, radius, and projected rotation velocity, we find the true 3D obliquity to be $\psi = 24^{+14}_{-12}\,^\circ$ ($\psi < 48^\circ$ at 95% confidence), revealing that the orbit of TOI-1259Ab is well aligned with the star's equatorial plane. Because the planet's orbit is too wide for tidal realignment to be expected, TOI-1259Ab might have formed quiescently in this well-aligned configuration. Alternatively, as we show with dynamical simulations, Eccentric Lidov-Kozai oscillations triggered by the evolution of the binary companion are expected to lead to a low obliquity with a probability of about $\sim$14%.