HATS-2行星系统的恒星黑子活动、轨道倾角、透射光谱、物理性质及凌星时间变化（TTVs）
Star-spot activity, orbital obliquity, transmission spectrum, physical properties, and TTVs of the HATS-2 planetary system
AI总结：
本研究利用十余年多仪器凌星观测数据，结合TESS与地面望远镜资料，通过恒星黑子模型分析细化HATS-2行星系统参数，测得系统轨道高度对准，发现可能由潮汐轨道衰减导致的凌星时间变化，并获取低分辨率透射光谱。
摘要：
本文的研究目标是依托跨度超过十年、由不同仪器和通带滤光片采集的凌星观测数据，细化HATS-2行星系统的轨道参数与物理参数，并研究凌星时间变化和大气组成。我们还通过研究主星光球层上的恒星黑子引发的凌星光变曲线异常，探究该系统的轨道对准情况。我们分析了来自地面望远镜和NASA的TESS（凌日系外行星巡天卫星）任务的新凌星事件。大多数光变曲线中都检测到了异常，我们将其建模为凌星过程中被行星掩食的恒星黑子。我们使用JKTEBOP代码拟合干净且对称的光变曲线，使用PRISM+GEMC代码拟合受异常影响的光变曲线，以同时模拟凌星的测光参数以及每个恒星黑子的位置、大小和对比度。我们测得的物理参数与轨道参数，和发现论文及ATLAS9恒星大气模型给出的结果一致。我们识别出多组连续的恒星黑子穿越事件，这些事件的时间间隔不足五天。基于我们观测到的是同一批恒星黑子、在两次连续凌星中被行星两次掩食的假设，我们估算了主星的自转周期，并进而推算了行星的投影轨道倾角和真实轨道倾角。我们发现该系统的轨道是高度对准的。我们识别出该系统可能存在凌星时间变化，其成因可能是潮汐轨道衰减，同时我们还得到了低分辨率透射光谱。
英文摘要：
Our aim in this paper is to refine the orbital and physical parameters of the HATS-2 planetary system and study transit timing variations and atmospheric composition thanks to transit observations that span more than ten years and that were collected using different instruments and pass-band filters. We also investigate the orbital alignment of the system by studying the anomalies in the transit light curves induced by starspots on the photosphere of the parent star. We analysed new transit events from both ground-based telescopes and NASA's TESS mission. Anomalies were detected in most of the light curves and modelled as starspots occulted by the planet during transit events. We fitted the clean and symmetric light curves with the JKTEBOP code and those affected by anomalies with the PRISM+GEMC codes to simultaneously model the photometric parameters of the transits and the position, size, and contrast of each starspot. We found consistency between the values we found for the physical and orbital parameters and those from the discovery paper and ATLAS9 stellar atmospherical models. We identified different sets of consecutive starspot-crossing events that temporally occurred in less than five days. Under the hypothesis that we are dealing with the same starspots, occulted twice by the planet during two consecutive transits, we estimated the rotational period of the parent star and, in turn the projected and the true orbital obliquity of the planet. We find that the system is well aligned. We identified the possible presence of transit timing variations in the system, which can be caused by tidal orbital decay, and we derived a low-resolution transmission spectrum.
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