标题： TIC441725813：一颗具有核幔差旋的新亮混合型sdB脉动星 显示英文标题

标题： TIC441725813: A new bright hybrid sdB pulsator with differential core/envelope rotation

摘要： 我们对一颗由TESS发现并监测了670天的新发现的混合（p-模式和g-模式）sdB脉动星TIC441725813（TYC 4427-1021-1）进行了详细分析。 对该恒星的TESS光曲线使用预白化技术进行了分析，以准确提取模式频率。 然后通过包括渐近周期间距关系和旋转多重分裂识别的方法来解释脉动谱。 我们还利用TESS441725813的高信噪比（S/N）、低分辨率光谱以及非局部热平衡（NLTE）模型大气网格来推导其大气参数。 有趣的是，几个被解释为深层探测g-模式旋转分裂的频率多重分裂表明至少有$85.3 \pm 3.6$天的缓慢自转周期，而主要探测包层的p-模式分裂则表明显著更短的自转周期为$17.9 \pm 0.7$天，这意味着核心（主要是氦包层，可能还包括它周围的部分混合的氦燃烧核心）的自转速度至少比包层慢4.7倍。 径向速度曲线表明TIC441725813处于一个与低光度伴星（可能是白矮星）密切相关的双星系统中。 虽然在可用的TESS测光数据中难以察觉，但发现了一个对应于$\sim 6.7$小时周期的低频信号，尽管信噪比较低。 TIC441725813是一颗特别有趣的sdB星，其包层的自转速度比核心快。 我们假设这可能是由于与伴星的潮汐相互作用造成的，尽管在这种情况下，需要进一步研究这种伴星的存在。 本分析为使用优化技术对TIC441725813进行更详细的地震探测铺平了道路，将在第二篇论文中展示。 显示英文摘要

摘要： We present the detailed analysis of a new hybrid (p- and g-mode) sdB pulsator, TIC441725813 (TYC 4427-1021-1), discovered and monitored by TESS over 670 days. The TESS light curves available for this star were analysed using prewhitening techniques to extract mode frequencies accurately. The pulsation spectrum is then interpreted through methods that include asymptotic period spacing relationships and rotational multiplets identification. We also exploited a high signal-to-noise ratio (S/N), low-resolution spectrum of TIC441725813 using grids of non-local thermodynamic equilibrium (NLTE) model atmospheres to derive its atmospheric parameters. Interestingly, several frequency multiplets interpreted as rotational splittings of deep-probing g-modes indicate a slow rotation period of at least $85.3 \pm 3.6$ day, while splittings of mostly envelope-probing p-modes suggest a significantly shorter rotation period of $17.9 \pm 0.7$ day, which implies the core (mainly the helium mantle with possibly the deeper partially-mixed helium-burning core that it surrounds) rotates at least ~4.7 times slower than the envelope. The radial velocity curves indicate that TIC441725813 is in a close binary system with a low-luminosity companion, possibly a white dwarf. While elusive in the available TESS photometry, a low-frequency signal that would correspond to a period of $\sim 6.7$ h is found, albeit at low S/N. TIC441725813 is a particularly interesting sdB star whose envelope rotates faster than the core. We hypothesise that this might be caused by the effects of tidal interaction with a companion, although in the present case, the presence of such a companion will have to be further investigated. This analysis paves the way toward a more detailed seismic probing of TIC441725813 using optimisation techniques, which will be presented in a second paper.