AI 中文总结
该研究针对X射线双星HD 49798的TESS光变曲线观测，发现其存在与恒星自转周期吻合的谐波序列增亮，提出该现象或与热亚矮星表面温度不均匀性（如磁场或罗斯贝波）相关。
AI 中文摘要
HD 49798是一个X射线双星，由一颗富氦热亚矮星主星和一颗吸积致密伴星组成，轨道周期为1.55天。TESS对其光学光变曲线的观测显示，正弦型变化上叠加了短周期增亮；正弦型变化可归因于主星的潮汐变形，而对额外变化的频率分析显示存在多达11个频率，形成以1.4天为周期的谐波序列，与光谱独立推断的恒星自转周期高度吻合。这些增亮可由热亚矮星表面缓慢变化且不均匀的温度分布解释，该分布可能与磁场或恒星包层中存在的罗斯贝波相关。
英文摘要
HD 49798 is an X-ray binary consisting of a hot helium-rich subdwarf primary and an accreting compact companion with an orbital period of 1.55 d. TESS observations of its optical light curve suggest short-period brightenings superimposed on a sinusoidal variation. The latter can be attributed to the tidal deformation of the primary, while frequency analysis of the additional variations shows up to eleven frequencies which form an harmonic series based on a period of 1.4 d, in excellent agreement with the stellar rotation period inferred independently from spectroscopy. These brightenings may be explained by a slowly changing and inhomogeneous temperature distribution across the surface of the hot subdwarf, such as might be associated with a magnetic field or with the presence of Rossby waves in the stellar envelope.
Comments5 pages, 4 figures. MNRAS in press
