论文标题
苔丝发现的近二进制恒星系统中的潮汐捕获脉动
Tidally Trapped Pulsations in a close binary star system discovered by TESS
论文作者
论文摘要
长期以来一直怀疑，近距离二进制恒星中的潮汐力可以改变组成恒星的脉动轴的方向。这样的恒星已经被搜索，但直到现在从未发现。在这里，我们报告了椭圆形变量HD 74423中潮汐捕获的脉动的发现。该系统在1.6-D轨道中包含一个Delta Scuti脉动器，其脉动模式振幅在轨道频率下进行了强烈调节，如果脉冲在恒星的一个半球中具有更大的振幅，则可以解释。我们将其解释为一种倾斜的扭曲偶极子振荡，其脉冲轴与潮汐轴对齐。这是第一次沿潮汐轴倾斜脉动。目前尚不清楚脉动是否被困在针对同伴的半球中，还是在远离脉冲的侧面，但是将来的光谱测量值可以提供解决方案。同时，单面脉动器HD 74423脱颖而出，是一类新的倾斜恒星的原型，其中可以研究恒星脉动和潮汐变形的相互作用。
It has long been suspected that tidal forces in close binary stars could modify the orientation of the pulsation axis of the constituent stars. Such stars have been searched for, but until now never detected. Here we report the discovery of tidally trapped pulsations in the ellipsoidal variable HD 74423 in TESS space photometry data. The system contains a Delta Scuti pulsator in a 1.6-d orbit, whose pulsation mode amplitude is strongly modulated at the orbital frequency, which can be explained if the pulsations have a much larger amplitude in one hemisphere of the star. We interpret this as an obliquely pulsating distorted dipole oscillation with a pulsation axis aligned with the tidal axis. This is the first time that oblique pulsation along a tidal axis has been recognized. It is unclear whether the pulsations are trapped in the hemisphere directed towards the companion or in the side facing away from it, but future spectral measurements can provide the solution. In the meantime, the single-sided pulsator HD 74423 stands out as the prototype of a new class of obliquely pulsating stars in which the interactions of stellar pulsations and tidal distortion can be studied.
