[论文解读] Long-term eclipse time variations in white dwarf binaries

Amalie Yates, S. G. Parsons+16 more|arXiv (Cornell University)|Feb 19, 2026

Stellar, planetary, and galactic studies被引用 0

一句话总结

该研究使用具有长期定时数据的43对食分白矮星双星，旨在识别日食时变的主要机制，结果显示Applegate-或Lanza样的过程是大多数系统的最可能驱动因素，而非行星伴星。

ABSTRACT

The overwhelming majority of eclipsing white dwarf (WD) binary systems show quasi-periodic variations in eclipse timings on many year timescales. Currently, the mechanism behind these eclipse time variations (ETVs) is not known, with the main competing theories being the planetary hypothesis and the Applegate/Lanza mechanisms. Here, we present a comprehensive study of 43 WD binary systems, the vast majority of which have more than a decade of eclipse timing measurements, analysing their global properties to determine which driving force is the likely origin of the observed ETVs. Long-term, high-speed photometry data obtained with ULTRACAM, ULTRASPEC and HiPERCAM have allowed us to track the evolution of the ETVs in these systems, and analyse any previously unseen trends. From this analysis, we find a clear difference in the level of observed ETVs past the fully convective boundary, where systems with partially radiative companion stars consistently showing high levels of variation. While some systems may be affected by the presence of an unknown planet, the results from this study strongly indicates that an Applegate- or Lanza-like mechanism is the most likely driving force for the timing variations seen in the majority of systems in this sample. However, as found in previous studies, the Applegate/Lanza mechanisms are still not able to reproduce the large and rapid timing variations seen in the vast majority of systems, with the companion star to the WD unable to provide sufficient energy on these short timescales.

研究动机与目标

• 调查在食分白矮星双星中长期日食时间变（ETVs）的起源。
• 评估行星光行时效应或磁性/四极矩机制是否能解释观测到的ETVs。
• 检查ETV振幅如何与双星属性及伴星内部结构（对流边界）相关。

提出的方法

• 使用ULTRACAM、ULTRASPEC和HiPERCAM进行高速光度测量，以分辨日食的进入/离开相。
• 将时刻转换为BMJD(TDB)并进行重心校正。
• 使用已公布的系统参数，利用LCURVE拟合光变曲线；拟合中 eclipse 时刻（T0）和次星温度（T_sec）。
• 从线性演能表构建O−C图以识别定时变化。
• 分析ETV的RMS对基线时间和双星参数的依赖，以寻找全局趋势。
• 将观测到的RMS趋势与行星、Applegate和Lanza机制的预测进行比较（对比）。

Figure 1: Grid of the O $-$ C plots for the WD binaries in the ETV programme with > 2 measured eclipse times. The y -axis is the O $-$ C value, measured in seconds. The x -axis is the MJD(BTDB) time. The red dashed line at y =0 is added to highlight the deviations from the expected O $-$ C value if

实验结果

研究问题

• RQ1 样本中43对WD双星的观测日食时间变的主导驱动机制是什么？
• RQ2 ETV振幅是否与伴星质量或伴星内部结构（对流边界）相关？
• RQ3 结果能否在行星假说与Applegate/Lanza型机制之间区分ETVs的源头？
• RQ4 ETV趋势在不同双星类型（WDMS、WDBD、DWD）随基线与轨道周期如何演化？

主要发现

• 在完全对流边界之后，ETV水平存在明显差异；部分放射性伴星的系统表现出持续的高变动。
• 许多系统的ETV更符合Applegate-或Lanza样的机制，而非行星伴星的驱动力。
• Applegate/Lanza机制不太可能完全再现观测到的最大、最快的定时变，暗示能量约束仍是一个挑战。
• 显著趋势：ETV的RMS随伴星质量提高而增大，与Applegate类过程的能量预算预期一致。
• 两对长周期WDMS双星显示较低RMS，与较大分离时的四极驱动效应减弱相符；也存在个别例外。
• 总体而言，结果支持Applegate/Lanza机制作为大多数样本中定时变的主要驱动因素，行星解释不足以解释所有观测特征。

Figure 2: The log of the RMS of the O $-$ C values as a function of the baseline of observation, measured in years. The shape of the points indicates the type of binary - a circle means the binary is WDMS, a square means WDBD, and a triangle indicates a DWD binary. The colour of the point indicates